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10.1 EXECUTIVE SUMMARY

On December 31, 1973, the American Society of MechanicalEngineers (ASME) published Subsection NF [1] of the ASMEBoiler and Pressure Vessel Code Section III, Division 1 (hereafteraddressed as Subsection NF) as part of the winter 1973 addenda tothe 1971 Code edition [2]. This was a historic publication; prior toit, supports (also called pipe hangers and restraints) were notaddressed as part of ASME Section III. Existing nuclear plants andplants under construction during that time were using ANSI B31.1[3], ANSI B31.7 [4], MSS-SP58 [5], and the AISC Manual ofSteel Construction [6] to design supports. ASME Section III,Subsection NF, provided a stabilizing position for future nuclearplant support design by designating a single source of rules for thedesign, construction, fabrication, and examination of supports.

This criteria-and-commentary chapter provides information onthe origins and evolution of design rules and is intended to allowdesigners, engineers, and fabricators to make better use ofSubsection NF of the ASME Code. Topics of greatest interest arediscussed and addressed from both a technical and historicalviewpoint. It is not the intent, however, to address every detail oranticipate every question associated with the use of the subsec-tion. However, there will be situations when engineering judg-ment and special considerations will be used in conjunction withSubsection NF to qualify supports.

ASME Boiler and Pressure Vessel Code Section III, Division 1,Subsection NF, was developed in an attempt to provide rules forthe estimated 10,000 piping and component supports existing in atypical nuclear power plant. These rules have evolved so dramati-cally that the existing support rules seldom resemble the originalrules of 1973. This document follows the evolution of SubsectionNF as the industry attempted to apply the subsection’s rules.Commentary is provided to explain how the criteria are used, thesource and technical basis for the equations and the rationale, andthe reasons for change. It is anticipated that readers will develop abetter understanding of Subsection NF to appreciate its complexi-ties and usefulness.

10.2 NF-1000 INTRODUCTION

Article NF-1000 provides readers with general informationregarding component supports such as their scope and classifica-tion, and also regarding types of supports and attachments. Whenit was first published, Subsection NF [1] was titled “Component

Supports,” since the term “component” was relevant to bothsupports for nuclear components (e.g., tanks, pumps, and vessels)and supports for piping, which is also defined as a component. Ina major rewrite first published in the winter 1982 addenda to the1980 edition [7], the generic term “component supports” wasredefined as “supports.” This subtle change allowed supports to beseparated into two distinct categories: component supports andpiping supports, which resulted in a revised philosophy ofSubsection NF. The changes and impact resulting from this revi-sion are discussed in various sections of this chapter.

10.2.1 ScopeSubsection NF contains rules for the materials, design, fabrica-

tion, examination, installation, and preparation of certificationdocuments (certificate of compliance and NS-1 certificate of con-formance for supports) for Classes 1, 2, 3, and MC construction.This statement appears at the beginning of Subsection NF anddefines the scope in only one sentence. However, the interpreta-tion of this scope by industry users and the Working Group hasprovided many inquiries and discussions over the past 25 years orso. Simply stated, the purpose of a support is to provide a path totransmit specified loads from the pressure boundary component tothe building structure. It should be noted that supports are notpressure-retaining components but rather structural components.Until the appearance of Subsection NF in the ASME Section IIIBoiler and Pressure Vessel Code, all components were, by defini-tion, pressure-retaining. Because many of the requirements thateventually were included in Subsection NF were taken from thepressure-retaining portions of Subsections NB, NC, ND, NE, andNG, implementation of these rules was sometimes difficult. Manyusers of Subsection NF regarded some of the rules as too stringentbecause their purpose was for use on pressure boundary applica-tions, a view that became more apparent when the boundaries ofjurisdiction were established for supports. (See Section 10.2.4 ofthis chapter for a detailed discussion of this subject.)

10.2.2 Types of SupportsSince there are thousands of supports in a typical nuclear power

plant, it was considered prudent to identify various types of sup-ports based on their historical use in both fossil fuel and nuclearpower plants. Initially, component supports were separated intothree types: plate-and-shell supports, linear supports, and compo-nent standard supports. Subsection NF defined plate-and-shellsupports as supports that are normally subjected to a biaxial stress

SUBSECTION NF—SUPPORTS

Uma S. Bandyopadhyay1

1 Robert J. Masterson was the author of this Chapter for the first edition but revised by Uma S. Bandyopadhyay for the previous edition and this edition.

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field and are fabricated from plate-and-shell elements. Exampleswere given as vessel skirts and saddles. It was apparent from thisdefinition that plate-and-shell supports are closely related to pressureboundary items; these types of supports essentially represent amethod of making the transition from the pressure boundary of thevessel or piping into the support load path. It was common for plate-and-shell supports to be integrally attached (i.e., welded) to the pres-sure boundary component and designed and analyzed as part of thecomponent. An example of this was a vessel skirt, which normallywould be provided with the vessel. It was initially believed thatsupplying plate-and-shell supports with the components would be anormal procedure (this was often the case as Subsection NF wasimplemented). Also, the number of plate-and-shell supports turnedout to be very low relative to the other two types of supports.

Subsection NF defined linear supports as acting under a singlecomponent of direct stress that also may be subjected to shearstress. Examples given included tension and compression strutsand beams and columns subjected to bending stresses. Linear sup-ports were meant to be structural steel members used to connectthe supports and complete the load path to the building structure.Linear supports were also intended to form unique piping andcomponent restraints when these components were subjected toloads other than simple deadweight. These loads were dynamic(both seismic and hydrodynamic); transient, such as water andsteam hammer; and thermal operation. Based on the number ofsupports in a typical plant, linear supports constituted the majority.

Finally, Subsection NF created a new category of supportscalled standard supports, which were defined as one or more gen-erally mass produced units usually referred to as catalog items. Fordesign, fabrication, and examination purposes, standard supportswere further classified as being of the linear or plate-and-shelltype; this classification was required to maintain consistency withthe other two support types. Based on the sheer numbers of stan-dard supports, the linear type again constituted the vast majority.

The concept of the standard support was unique considering itssheer numbers. Standard supports were created to take advantageof the historically good manufacturing record of catalog supports.At one of the early Subsection NF meetings (circa 1973 or 1974),a Working Group member who was an employee of a supportmanufacturer, described standard supports as having a “time-testedhistory of success,” a statement that was proven correct becausevery few if any failures of catalog supports were documentedunder normal operating conditions on older fossil fuel and nuclearpower plants. The design factor of safety and the quality assuranceused in the manufacturing process of these catalog supports servedas powerful arguments for establishing this category of supports.Figure 10.1 provides pictorial representations of typical standardsupports. As we will see, the advantage of this type of support ismanifested in the relaxation (i.e., the less stringent) of require-ments for materials, design, fabrication, and examination.

With the publication of the winter 1982 addenda to the 1980edition [7], component supports were redefined to more closelyrepresent their use in service. The term component support initiallywas used on the cover of Subsection NF and was descriptive ofthe entire family of supports. The winter 1982 addenda separatedsupports into two groups: component supports and pipingsupports, a Code revision that was the outcome of years of debatewithin the Code Committee on how to make Subsection NF moreuseful for the engineering community. It was apparent from the many guests attending the Working Group’s meetings that amore descriptive categorization of supports was required to makeimplementation more efficient. The term component support

ceased to be the term used to describe the entire family of sup-ports and also to describe the type of supports used to supportcomponents; it was redefined as the group that supported nuclearcomponents, and piping support was defined as the group thatsupported nuclear piping. The types of supports remained thesame because there could be plate-and-shell, linear, and standard(previously termed component standard) supports in both groupsof component and piping supports. This descriptive revision wasmost profoundly beneficial in Article NF-3000 “Design.”

10.2.3 Intervening ElementsAs more nuclear power plants were designed to Subsection NF,

it became apparent that each type of support had its place in theoverall design of piping and components. Many support assem-blies consisted of standard supports, such as clamps, that attachedto the pressure boundary, and also of linear supports, such as steelbeams, that attached to the building structure. In some cases, stan-dard supports composed the entire assembly; similarly, in othercases, linear supports composed the entire assembly. There was,however, another species of support that was about to make anappearance. After four years of Subsection NF implementation, aCode revision was needed to address the concept of a non-Codeitem in the support load path between the pressure boundary andthe building structure. Such items as diesel engines, electricmotors, coolers, valve operators, and access structures were bear-ing on supports or were welded to, bolted to, pinned to, or clampedto them. By definition, supports extending from the pressureboundary to the building structure were within the support loadpath. Guests attending the Working Group’s meetings submittedinquiries concerning what should be done with these interveningelements that were within the load path. After many debates,Subsubarticle NF-1110(c) was revised and paragraph NF-1111 andsubparagraph NF-1131.6 were added in the summer 1978 addendato the 1977 edition [8] to introduce the concept of intervening ele-ments. In addition, Fig. NF-1131-1 was revised to add sketches(g), (h), (i), (j), and (k) to illustrate the many ways that an interven-ing element may be used in the support load path (see Figs. 10.2and 10.3). Essentially, intervening elements were outside theSubsection NF jurisdiction; however, paragraph NF-1111 providedthe clear requirement that the owner’s Design Specification shallfurnish specific information to the designer of the intervening ele-ments regarding loads, materials, temperature, environmentaleffects, design, fabrication, examination, testing, and installation.

Addressing the concept of intervening elements was a challengethat the Working Group was likely to encounter given the nature ofthe support load path, that is, between two existing boundaries ofjurisdiction. With so many components and other equipment vyingfor the space between the piping and the building structure, it wasinevitable that the concept of intervening elements would even-tually manifest itself. What was ironic, however, was that the con-cept of intervening elements was a jurisdictional boundary issue,but not the most difficult one to address and solve. Working Groupmembers found that addressing the basic concept of the boundaryon each side of the support load path, the piping, or component andthe building structure, became a monumental task.

10.2.4 Boundaries of JurisdictionFrom the initial issue of Subsection NF in the winter 1973

addenda to the 1971 edition of ASME Section III [1], it eventual-ly became clear that the most challenging task facing the WorkingGroup would be to explain and defend the requirements forboundaries of jurisdiction. At first glance, it seemed to be a

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COMPANION GUIDE TO THE ASME BOILER & PRESSURE VESSEL CODE • 3

straightforward task to establish the boundaries of jurisdiction forsupports at the pressure boundary and building structure ends ofthe support. In fact, the Working Group was convinced that Fig. NF-1131-1 provided a simplified illustration to define theboundaries and to specify under which subsection the connectionresponsibilities rested.

For the pressure boundary side of the support load path, itappeared that the figure did indeed provide such an illustration.

No doubt existed about when the pressure boundary ended andwhen the support began. Even for supports welded to the pressureboundary, it was clear that the weld was in accordance to thepressure-retaining portion of the Code (NB, NC, ND, or NE) andthe support jurisdiction began with the item that was welded tothe component. However, the building structure end of the supportwas another matter. Because many supports could contain struc-tural steel elements in their design, and because the building

FIG. 10.1 TYPICAL STANDARD SUPPORTS (Source: Fig. NF-1211.4-1, Subsection NF of the ASME B&PV Code)

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FIG. 10.2 ILLUSTRATIONS OF JURISDICTIONAL BOUNDARIES [Source: Fig. NF-1131.1.(a)–(f), Subsection NF of the ASMEB&PV Code]

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FIG. 10.3 ILLUSTRATIONS OF JURISDICTIONAL BOUNDARIES [Source: Fig. NF-1131.1.(h)–(k), Subsection NF of the ASMEB&PV Code]

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structure boundary was generally composed of structural steel, theactual boundary of jurisdiction could become difficult to identifyaccurately. One school of thought, implemented initially to createFig. NF-1131-1, defined the building structure as the surface ofconcrete or steel as shown on civil/structural drawings. Any addi-tional steel framed between existing steel or concrete (also calledsupplementary steel) and needed to support piping or componentswould be under Subsection NF jurisdiction. The debate on bound-aries of jurisdiction began soon after the publication ofSubsection NF in December 1973 [1]. Many potential users haddifficulty identifying the boundary at the building structure, andguests at the Working Group meetings began to have jurisdictionalboundary questions. One typical case, which would eventuallychange philosophy in a future Code revision, concerned base-plates and concrete anchor bolts. Initially, with the first edition ofSubsection NF, it was clear that baseplates and anchor bolts werewithin the jurisdiction of Subsection NF. Figure 10.2 [Fig. NF-1131-1(e) and (f)] clearly states that an integral or nonintegralsupport connected to the building structure has a connection inaccordance with Subsection NF, which means that a baseplatesecured to the concrete by anchor bolts (e.g., Hilti Quik bolts andPhillips Red Heads) would conform exactly to the Fig. 10.2(f)sketch. The nonintegral support (the baseplate) was connected tothe building structure (the concrete) by means of the anchor bolts;the connection was in accordance with Subsection NF.

However, as clear as the boundary to the building structure mayappeared to have been, a large number of users questioned itslocation. On March 30, 1978, Interpretation III-1-78-47 [9] waspublished in an attempt to answer one of the jurisdictional bound-ary dilemmas. The following is a verbatim presentation of thequestion and reply:

Question: How are the jurisdictional boundaries betweenstructural members fabricated and installed with the build-ing structure and supports for Section III components to bedetermined?

Reply: It is the responsibility of the Owner to define thejurisdictional boundaries of component supports in theDesign Specification (NCA-3254) [10]. Items furnished aspart of the building structure are normally constructed to theappropriate portion of the building code used for the designand construction of the building structure. The Owner isresponsible for designating whether or not metallic supportsfor Section III components, which are attached to the itemsdefined as part of the building structure, are required to beconstructed with the provisions of Section III, Subsection NF.The Owner is also responsible for the compatibility of theboundaries and corresponding loads between the buildingstructure and the component supports constructed in accor-dance with Section III.

This interpretation clearly put the responsibility of determiningthe boundary of jurisdiction with the owner and the DesignSpecification where, in actuality, the responsibility belonged.Subsection NCA clearly stipulates that one responsibility of theowner’s Design Specification was the identification of the bound-aries of jurisdiction. Therefore, the interpretation answered theinquiry by using existing Code words.

The jurisdictional boundary questions continued for manyWorking Group meetings. A Task Group was established toresolve the questions and produce the appropriate Code revision

or Code Case. The 1986 edition of Subsection NF published arevision to subsubarticle NF-1130 [11], which defined the bound-aries of jurisdiction applicable to Subsection NF. The old Fig. NF-1131-1 (Figs. 10.2 and 10.3), a generic presentation of theboundaries between both the component and the building struc-ture, was replaced with Fig. NF-1132-1 (Figs. 10.4, 10.5, and10.6). This figure was applicable only to the boundary betweenthe piping support and the building structure. The jurisdictionalboundary between supports and the component was deferred toparagraphs NB-1132 [12], NC-1132 [13], ND-1132 [14], or NE-1132 [15] as applicable. A review of this figure shows that Fig.1132-1(d), (g), and (i) now specifies that the baseplate and anchorbolts are part of the building structure. This is a complete reversalfrom the original Code edition for identifying jurisdictionalboundaries between baseplates and anchor bolts and the buildingstructure. This new revision, however, more realistically separatesnormal building structure items from support items; historically,baseplates and anchor bolts were normally regarded as buildingstructure components. Since the initial jurisdictional boundaryquestions were eventually resolved, Subsection NF has evolvedwithout any additional substantial jurisdictional boundary issues.

10.3 NF-2000 MATERIALS

10.3.1 Permitted MaterialWith the initial publication of Subsection NF in 1973, ASME

Section III Boiler–Pressure Vessel Code Division 1 [1] was pro-viding rules for non–pressure-retaining components. Prior to this,ASME Section III was a pressure-retaining code, concerned pri-marily with pressure-retaining components such as pumps,valves, piping, vessels, and tanks. Subsection NF, however,brought a new concept on a large scale to ASME Section IIIbecause supports were non–pressure-retaining structural elements,of which there were thousands in a typical nuclear plant. Toaccommodate support design and material requirements, materialsspecifically designated for supports were needed. MandatoryAppendices Tables I-11.1 (Table 10.1), I-12.1 (Table 10.2), I-13.1(Table 10.3), and I-13.3 (Table 10.4) were included to providedesign stress intensities, allowable stresses, and yield strengthvalues for Class 1, 2, 3, and MC plate-and-shell type and lineartype supports. With the publication of the 1992 edition, the Coderequires that material for supports shall conform to the require-ments of the specifications for materials listed in the tables ofSection II, Part D [35]. Initially, these tables accounted for a verylimited number of permitted material specifications (less than 20support materials and 20 bolting material specifications). It soonbecame evident that additional material specifications were need-ed to address the numerous materials used by different supportmanufacturers.

A Materials Task Group was formed consisting of all occupa-tions from the Working Group including the Nuclear RegulatoryCommission (NRC). The purpose of the Task Group was to devel-op a Code Case to permit additional materials and to provide thedesign stress intensities, allowable stresses, and yield strength val-ues for these materials. After several Task Group meetings, CodeCase 1644 [16] was issued to permit the use of numerous addition-al structural material specifications. The intent of this Code Casewas to expedite the publication of structural materials needed forthe design and construction of Subsection NF supports. It wasplanned that a Code Revision would eventually be published tocomplete the action.

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In November 1976, as part of the 1974 edition, Code Case1644 Revision 6 [17] was issued as Code Case N-71 [18] underthe revised Code Case numbering system. Subsequently, CodeCase N-71 has been revised numerous times to add and deletematerial specifications as needed. At one point between March1978 and March 1982, Code Case N-71 was revised to removethe material specifications that did not permit welding. Thesematerials were placed in the new Code Case N-249 [19]. The most current revision to each Code Case is N-71-18 [20] and

N-249-14 [21]. As mentioned previously, the Working Group’sintention was to eventually incorporate Code Cases N-71 and N-249 into the body of Subsection NF, an action currently that isbeing prepared as Mandatory Appendix NF-1 [22].

10.3.2 Exempt MaterialSince some Subsection NF supports were designed with non-

metallic and/or bearing materials, the concept of exempt materi-als needed to be addressed by the Working Group. Subparagraph

FIG. 10.4 TYPICAL EXAMPLES OF JURIDICTIONAL BOUNDARIES BETWEEN PIPING SUPPORTS AND THE BUILDINGSTRUCTURE [Source: Fig. NF-1132.1.(a) and (d), Subsection NF of the ASME B&PV Code]

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NF-2121(b), “Permitted Material Specifications,” provides guid-ance for those materials for which the requirements of ArticleNF-2000, “Materials,” do not apply. Items such as gaskets,seals, springs, compression spring end plates, bearings, retainingrings, washers, wear shoes, and hydraulic fluids, are exemptfrom the requirements of Article NF-2000. Initially, some users

made the assumption that since a material is exempt fromSubsection NF-2000, the material must also be exempt from theremaining articles of Subsection NF. This belief was incorrectbecause it was clear from subparagraph NF-2121(b) that theexemption applied only to materials, not to design, fabrication,and examination. However, a recent Subsection NF action has

FIG. 10.5 TYPICAL EXAMPLES OF JURIDICTIONAL BOUNDARIES BETWEEN PIPING SUPPORTS AND THE BUILDINGSTRUCTURE [Source: Fig. NF-1132.1.(e) and (g), Subsection NF of the ASME B&PV Code]

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reversed this stand, and the requirements of all Subsection NFarticles no longer apply to exempt materials, except for a minorlist of caveats.

Additionally, NF-2121 (b) states that (1) exempt materialrequirements, if any, shall be stated in the Design Specification;(2) the material shall not be affected by fluid, temperature, or

irradiation conditions; (3) the materials do not require the materialmanufacturer’s Certificate of Compliance (COC); and (4) the sup-port manufacturer shall provide the owner with a list of exemptmaterials. These additional provisions, with the exception of theCOC, are intended to provide the owner with the assurance thatexempt materials meet the most basic ASME Section III

FIG. 10.6 TYPICAL EXAMPLES OF JURISDICTIONAL BOUNDARIES BETWEEN PIPING SUPPORTS AND THE BUILDINGSTRUCTURE [Source: Fig. NF-1132.1 (h) and (i), Subsection NF of the ASME B&PV Code]

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TABLE 10.1 ASME SECTION III MANDATORY APPENDIX I, DESIGN STRESS INTENSITY VALUES, Sm,FOR FERRITIC STEELS FOR CLASS 1 PLATE-AND-SHELL-TYPE COMPONENT SUPPORTS

(Source: Table I-11.1, Section III, Appendix 1 of the ASME B&PV Code)

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TABLE 10.2 ASME SECTION III MANDATORY APPENDIX I, ALLOWABLE STRESS VALUES, S, FOR FERRITIC STEELS FOR CLASS 2, 3, AND MC PLATE-AND-SHELL-TYPE COMPONENT SUPPORTS


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TABLE 10.3 ASME SECTION III MANDATORY APPENDIX I, YIELD STRESS VALUES, SY,FOR FERRITIC STEELS FOR CLASS 1, 2, 3, AND MC LINEAR-TYPE COMPONENT SUPPORTS


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TABLE 10.4 ASME SECTION III MANDATORY APPENDIX I, YIELD STRENGTH VALUES SY,FOR BOLTING MATERIALS FOR CLASS 1, 2, 3, AND MC COMPONENT SUPPORTS


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requirements. It is important that users be aware that materialsexempt from Article NF-2000 requirements must still meet somebasic concerns. Currenly, guidance for exempt materials is shownin Subparagraph NF 1110 (e).

10.3.3 Certification of MaterialMany nuclear plant components require the highest level of

material certification—the Certified Material Test Report (CMTR).The NF Working Group determined that because of the large num-ber of supports in a nuclear power plant, requiring a CMTR for allsupports was impractical and unnecessary because of the structuralrather than pressure-retaining nature of supports. SubsubarticleNF-2130 requires CMTRs for Class 1 plate-and-shell and linearsupports, as well as for material of other types and classes of sup-ports where impact testing is required. Certificates of Compliancewith the material specification, grade, class, and heat-treatmentcondition may be provided for all other supports, which means thatthe majority of supports could be supplied with a COC rather thana CMTR because of the relatively few Class 1 plate-and-shell orlinear supports. Support manufacturers would benefit greatlybecause maintaining full traceability throughout the manufacturingprocess for supports with COCs is not required. Also, many simplesupports such as rods, clamps, and clevises could be manufacturedand shipped with a single COC. However, material for small itemswould need to be controlled during the manufacturing process sothat it is identifiable as acceptable material until the material isactually consumed in the final product. To meet this requirement,many support manufacturers would transfer a color-coding systemto material after cutting so that the material identification remainedon both items of the cut material.

10.3.4 Impact Testing and Fracture ToughnessBecause most support material is structural, the Working Group

did not consider it necessary to require support materials to beimpact tested when Subsection NF was first published. As previ-ously mentioned, if impact testing were required, material for anyclass or type of support would need to be supplied with CMTRs.Doing so would require support manufacturing facilities to initiatea comprehensive material separation and control system for thefull line of products. The Working Group concluded that impacttesting would be required only when specifically stated in theowner’s Design Specification. Based on service conditions, mostsupport Design Specifications would specify impact testing for allsupport materials being used in cold environments, such as below�40°F. When impact testing was required, however, severalexemptions were in effect especially for small products. Impacttesting would not be required for such items as material thickness

in. and less; bolting nominal size 1 in. and less; austenitic stain-less steel; nonferrous materials; bars of 1 sq. in. in area; supportswith a maximum stress not exceeding 6000 psi; and other materialdimensional limits. Paragraph NF-2311 was revised in the winter1982 addenda to the 1980 edition [7] to require impact testing forall classes of Component supports. Piping and Standard supportswould still need the Design Specification to state whether impacttesting was required.

10.3.5 Quality System ProgramMaterial organizations were required to have quality system pro-

grams that met the requirements of ASME Section III, SubarticleNCA-3800 [23]. However, except for paragraph NCA-3862 [24],the other requirements of subarticle NCA-3800 did not need to bemet for small products that were defined as pipe, tubing, bolting

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material including nuts, and structural material meeting specificdimensional limits. Similar to the NPT stamp required for weldedproducts, material organizations needed to successfully completean ASME Quality Systems survey to obtain a Quality SystemsCertificate for support material.

10.4 NF-3000 DESIGN

When Subsection NF was first published in the winter 1973addenda of the 1971 edition of ASME Section III [1], the Codewas considered complete because it now addressed all majornuclear plant components. Supports were different from manyother components because they were non–pressure-retainingstructural components rather than pressure-retaining components.In fact, much of the structural steel required for support designand construction closely resembles the building structural steel.This critical difference, non–pressure-retaining components,required the Working Group to establish new rules for structuralelements of supports. Design rules for supports were initiallyestablished for two types of supports: plate-and-shell and linear.Although both procedures were structural, the plate-and-shelltechniques were more consistent with those from other Code sub-sections. Because Subsections NB, NC, ND, and NE containedrules for pressure-retaining components such as pumps, valves,piping vessels, and tanks, ASME concluded that component sup-ports with a design exhibiting a biaxial stress field should followsimilar design rules. This conclusion was a reasonable one andallowed rules for plate-and-shell supports to be established thatwere familiar to owners and Architectural Engineers (AEs).

Similarly, the rules for linear supports were patterned after anaccepted and recognized structural Code found in the seventh edi-tion of the Manual of Steel Construction [25], published by theAmerican Institute of Steel Construction (AISC). The AISC SteelManual was well recognized by support designers because it wasextensively used to design steel supports and other structures infossil fuel and pre–Subsection NF nuclear power plants.Allowable stresses were based on the material minimum specifiedyield strength rather than on allowable stresses and stress intensi-ties. The AISC specification was incorporated in its entirety withsome enhancement of design criteria such as temperature andbuckling requirements.

This section discusses the design rules for supports—bothplate-and-shell and linear. All aspects of design are consideredincluding stress theory, loadings, welding, bolting, load testing,and functional requirements.

10.4.1 Design Loadings and Service ConditionsBecause design loadings and service conditions are established

as a requirement of the Design Specification (NA/NCA-3252) [26],Subsection NF is also governed by these requirements. Designloadings are defined as design temperature and design mechanicalloads. Because supports are subjected to non–pressure-retainingloads, temperature-generated loads are transmitted to supports bythe movement of piping and equipment. Structural loads are trans-mitted to supports through the deadweight of piping and its con-tents and also of piping components such as valves, flanges,flowmeters, and in-line pumps. Design mechanical loads alsoinclude dynamic loads caused by earthquakes, flow-induced loadssuch as water and steam hammer, and hydrodynamic loads.

The assortments of design loadings are combined based onidentified service conditions with specified service limits. When

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Subsection NF was first published [1] in 1973, these service con-ditions were identified as normal, upset, emergency, faulted, andtesting. The winter 1976 addenda to the 1974 edition of ASMESection III [27] changed the term “service condition” to “servicelimit.” “Normal condition” was changed to “Level A servicelimit”; the term pertains to specified loadings to which supportsmay be subjected for its specified service function. “Upset condi-tion” was changed to “Level B service limit”; the term pertains tospecified loadings on supports that must be withstood withoutdamage requiring repair. “Emergency condition” was changed to“Level C service limit”; the term pertains to specified loadingsthat permit large deformations in areas of structural discontinu-ities and that may require removal of the support from service forinspection or repair. “Faulted condition” was changed to “Level Dservice limit”; the term pertains to specified loadings that permitgross general deformations and may require the removal of thesupport from service.

10.4.2 Code Class and Design ProceduresSupports are grouped by class as all ASME Section III compo-

nents. Support Classes 1, 2, 3, and MC (metal containment) fol-low the definitions of paragraph NA/NCA-2131 [28]. Becausethere are more supports in a nuclear power plant than there areany other components (the total number is in the thousands), onlya few were anticipated as being Class 1 supports; indeed, only100–200 supports are usually classified as Class 1 supports, andthe remaining 5,000–10,000 fall into Classes 2 and 3. This is sig-nificant because material, design, and examination rules are lessstringent for Class 2 and 3 supports. As discussed later in thischapter, there is also a significant advantage for Class 2 and 3standard supports, especially material certification, design certifi-cation, load capacity data sheets, and visual examination ofwelds. The Working Group’s intent was to provide less stringentrules for standard supports to take advantage of the industry’sexceptional manufacturing history. Many support manufacturershad developed an extensive line of pipe support products, manywith designs that were based on physical and empirical testing. A safety factor of 5 was a common design factor for these catalog products, and failure of supports in field use was a rareoccurrence.

Associated with support class is the type of support and thedesign procedure to be used for Code qualification. Based onexisting support designs and how they are used, the WorkingGroup created three types of supports: plate-and-shell, linear, andstandard. Plate-and-shell supports exhibit a biaxial stress field (ina flat plate this would be membrane and bending stresses in bothof the plate’s in-plane axes, that is, Sx and Sy). Also, plate-and-shell supports are more associated with pressure-retaining compo-nents and usually are vessel skirts and saddles. Very few supportsin a nuclear plant will be of the plate-and-shell category. Linearsupports are defined as supports that essentially act under a singlecomponent of direct stress such as a structural beam or column.Component standard supports (later redefined as standard sup-ports) are defined as support assemblies composed of severalcatelog items and are generally mass produced.

Three design procedures also were specified: design-by-analysis,experimental stress analysis, and load rating. The design-by-analysis procedure was established to allow a calculation stressanalysis method for Code qualification similar to Subsections NB,NC, and ND. However, because supports can be both plate-and-shell or linear in design, a different design-by-analysis proce-dure was provided for each support type. Plate-and-shell supports

are required to be analyzed by elastic analysis based on the maxi-mum shear stress theory for Class 1 construction and the maxi-mum stress theory for Class 2, 3, and MC construction. Linearsupports are required to be analyzed by elastic analysis based onthe maximum stress theory for Class 1, 2, 3, and MC construc-tion. The design-by-analysis procedure for standard supportseither will be the maximum shear stress theory or the maximumstress theory depending on whether the standard support is con-structed of plate-and-shell or linear elements.

The maximum shear stress theory calculates principal stressesand transforms these into stress differences or stress intensities.At any point on the support, the stress components for each typeof loading may be calculated: namely, �x, �y, and �z, or �l, �r , and�t. These loadings may result in general primary membranestress, Pm; primary bending stress, Pb; expansion stress, Pe; orsecondary stress, Q. (Definitions for these stresses are given inparagraph NF-3121 [29].) For each category of stress the algebraicsum of the j stresses for each loading is obtained and the l, r, and tstress components are translated into principal stresses, �1, �2, �3,.Finally, the stress differences, S12, S23, and S31 are calculated,where S12 � �1 � �2, S23 � �2 � �3, and S31 � �3 � �1. The cal-culated stress intensity for each location on the support is thelargest absolute value of S12, S23, and S31.

The maximum stress theory calculates membrane, bending, andshear stresses as direct, not principal, stresses. Membrane stress,�1, is the average stress across a solid section. It includes theeffects of discontinuities but not local stress concentrations.Bending stress, �2, is the linearly varying portion of the stressacross the solid section. It excludes the effects of discontinuitiesand concentrations. With the initial publication of Subsection NFin 1973 [1], a third direct stress was required to be evaluated. Themaximum tensile stress, �3, at the contact surface of a weld pro-ducing a tensile load in a direction through the thickness of aplate or rolled shape, had a reduced allowable stress. This reduc-tion in stress was intended to reduce the maximum load on theconnection to prevent plates with the potential of laminationsfrom experiencing the full allowable stress—a behavior thatapplied to all classes and types of supports. The fact that thisrequirement was a design and manufacturing anomaly was even-tually discovered because the intent to limit the load to addressthe lamination concern in effect exacerbated the condition. Asnoted in Fig. NF-3321.1(c)-1 (Fig. 10.7), for any given joint,because the allowable stress was essentially limited to 50% of thenormal allowable stress, the maximum applied load permitted waseffectively reduced. To circumvent this low allowable stress,many designers simply made the weld contact surface larger topermit larger loads but still remain within the reduced allowablestress. It was quickly experienced that increasing the weld sizeincreased the heat input to the joint, and for those plates thatexhibited laminations, these conditions caused some joint designsto be compromised. The Working Group was made aware of thiscondition and quickly revised Subsection NF between the 1977[30] and 1980 [31] editions to remove this requirement. It was feltthat additional rules for fabrication and examination of thesetypes of welded joints were needed as a better approach to theproblem.

Experimental stress analysis is the second design procedurepermitted by Subsection NF. Designers are directed to ASMESection III, Division 1, Appendix II [32], which contains manda-tory rules for employing experimental stress analysis. It was theintent of the Working Group to permit a design procedure that pro-vided Code qualification by means of physical testing to determine

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stress levels within supports. The procedure uses strain gages todetermine stresses within actual supports under load. Appendix IIcontains complete guidelines for performing the tests, obtainingresults, and interpreting the results.

A third design procedure, known as load rating, was created toprovide support manufacturers with a method of establishingmaximum load ratings for standard supports using techniques andtest reports newly and/or previously developed by the manufac-turer. Many manufacturers had established testing procedures andmethods that allowed load ratings to be published with confi-dence. It was the Working Group’s intent to permit existing

testing and test reports to be used in conjunction with additionaltesting and the load rating equations in Subsubarticle NF-3280[33] to establish Code qualification, especially for standard sup-ports. This topic is discussed in more detail in Section 10.4.10 ofthis chapter.

10.4.3 Stress Intensities and Allowable StressesAllowable stresses for all types and classes of supports are cat-

egorized in Table NF-2121 (a)-1 (Table 10.5). For Class 1 plate-and-shell supports, design stress intensity values, Sm, are used tolimit the calculated stresses. Allowable stresses values, S, are usedfor Class 2, 3, and MC plate-and-shell supports, and yieldstrength values, Sy, are used for all classes of linear supports andfor all classes and types of bolting. Component standard supportsare qualified using design stress intensity values, and allowablestress values or yield strength values are based on whether thestandard support elements are composed of plate-and-shell or lin-ear items.

The specific values for Sm, S, and Sy for supports were providedin ASME Section III, Division 1, Appendix I Tables I-1.1, I-1.2,I-2.1, I-2.2, I-7.1, I-7.2, I-8.1, I-8.2, I-10.1, I-10.2, I-11.1 (givenhere as Table 10.1), I-12.1 (given here as Table 10.2), I-13.1(given here as Table 10.3), and I-13.3 (given here as Table 10.4)until the publication of the 1992 edition of ASME Section II [34].At that time, all material property tables were transferred fromSection III, Appendix I, to Section II, Part D [35] for both ferrousand nonferrous materials. For supports, these are Tables 1A, 1B,2A, 2B, 3, 4, U, and Y-1. These tables contain essentially thesame data used in Tables 10.1–10.4. Similarly, Section II, Part Acontains the material specifications for all materials permitted foruse in Section III construction. The basis for establishing thedesign stress intensity and allowable stress values are currentlyfound in Section II Part D, Appendices 1 [36] and 2 [37]. TheseAppendices are very useful for determining stress values becausethey are essentially a function of yield strength, Sy, and ultimatestrength, Su, values at temperature and at room temperature. Inmany cases, the ultimate strength value at temperature of a partic-ular material specification is not published in Section II, Part D.Appendix 1 and/or Appendix 2 can be used conservatively todetermine the Su value if either the S or Sm values are published.Because Appendix 1 stipulates that the design stress intensityvalue, Sm, can be established as Su at temperature (this choice isthe most conservative of the ones given), the value of Sm can beestablished as Su � 3Sm. Similarly, Appendix 2 can be used toestablish Su � 4S, and the smallest value of Su should then beused. This method was used by the Nuclear RegulatoryCommission (NRC) in Regulatory Guide 1.124 [38] in SectionC2c, Regulatory Position Method 3.

It was recognized early after the initial publication ofSubsection NF in 1973 that the material specifications permittedin Appendix I, Section III (later Section II, Part D), were not ofsufficient quantity to address the materials used by many supportmanufacturers. The Working Group acted quickly to establish aTask Group to identify and bring these additional materials intoASME Section III for use in Subsection NF. It was expected thatadditional structural materials would become necessary becausemost of the existing material specifications were required fromthe pressure-retaining nature of ASME Section III. This importantTask Group comprised all Working Group professional disci-plines: utilities, manufacturers, AEs, consultants, and regulatorymembers. The Task Group worked closely with the ASMESection III Subgroup on Materials; consequently, in 1975 Code

13

FIG. 10.7 ILLUSTRATION OF MAXIMUM DESIGN STRESSIN THROUGH-THICKNESS DIRECTION OF PLATES ANDELEMENTS OF ROLLED SHAPES [Source: Fig. NF-3321.1(c)-1, Subsection NF of the ASME B&PV Code]

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TABLE 10.5 MATERIALS TABLES REQUIRED FOR SUPPORTS[Source: Table I-NF-2121(a)-1, Subsection NF of the ASME B&PV Code]

17

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Case 1644 [16] was published. This Code Case contained a con-siderable number of material specifications used by support andsnubber (both hydraulic and mechanical) manufacturers. In 1976,Code Case 1644 was renamed Code Case N-71 [18]; it containedmaterial specifications for both welded and nonwelded construc-tion. The alternative rules for bolted joints eventually wereremoved from the Code Case and published as part of the “NF-3000 rewrite” in the winter 1982 addenda to the 1980 edition toASME Section III [7]. In 1980 the nonwelded materials wereremoved from CCN-71 and placed in a new CCN-249 [19]. Sincetheir original publication, both Code Cases have been revisedmany times and currently appear as CCN-71-17 [20] and CCN-249-13 [21]. All revisions to these Code Cases are addressed andapproved for use with caveats in NRC Regulatory Guide 1.85“Code Case Acceptability ASME Section III Materials.” Materialspecifications have been added and removed over the years; how-ever, currently there is an effort to reduce the number of materialspecifications to only those that are in use at any given moment.Future plans are to move both Code Cases into Subsection NF asAppendices.

10.4.4 Plate-and-Shell SupportsWhile the Working Group was preparing Subsection NF for its

initial publication, it wrestled with the concept of writing rules forstructural and non–pressure-retaining components in what wasessentially a pressure boundary Code. The Working Group finallyagreed to create three types of supports: plate-and-shell, linear,and component standard supports. As defined previously, plate-and-shell supports exhibit a biaxial stress field (in a flat plate,membrane and bending stresses would develop in both in-planedirections together with shear stress). When using the design-by-analysis procedure, calculations used to qualify Class 1 plate-and-shell supports would essentially be the same as structural calculationsfor Class 1 pressure boundary components. Terms relating todesign-by-analysis were presented in paragraph NF-3121 [29],which contained definitions for the following stresses: normal,shear, membrane, bending, primary, secondary, free-end displace-ment, expansion, and total. When Subsection NF was initiallypublished in 1973 [1], Table NF-3217-1 (Table 10.6) contained amatrix that provided classification of stresses for some typicalcases. Also associated with Class 1 plate-and-shell design-by-analysis are the design and operating conditions that allow vary-ing allowable limits of stress intensity based on the type of stress(primary and secondary) and the conditions (design and operat-ing) for the plate-and-shell support. This concept is presented inFig. NF-3221-1 (Fig. 10.8), also known as the Hopper Chart, andis essentially identical to Figs. NB-3221-1 [39] and NB-3222-1[40] except for the stresses in Class 1 pressure boundary compo-nents that are not required to be evaluated in Subsection NF.These stresses are Q stresses as well as secondary membrane andbending stresses (except expansion stress, Pe), an example ofwhich is thermal stress within the support. Unlike piping andother pressure-retaining components, supports were not requiredto be evaluated for thermal stresses within the support, that is,thermal stress caused by a large differential in temperature in thethrough-thickness direction of a plate or shell. The only exceptionto this was expansion stress caused by the restraint of free-enddisplacement (of piping) and the effect of differential support orrestraint motions. Initially, expansion stress, Pe, was considered asecondary stress because it was self-limiting, or local yielding andminor distortions would satisfy the conditions that caused thestress to occur; failure from one application of stress would not be

expected. However, the Task Group, during one of the meetingsfor the “NF-3000 rewrite” in the winter 1982 addenda [7], rede-fined expansion stresses in supports caused by free-end displace-ment of piping as primary stresses. It was concluded that thegrowth in the piping caused by thermal expansion was a true sec-ondary stress in the piping; however, the support would see this asa primary load and thus a primary stress.

Design-by-analysis of plate-and-shell supports for Class 2 and3 construction is less complicated than Class 1 supports. Becausethe maximum stress theory is used rather than the maximum shearstress theory, true allowable stresses are employed to qualify sup-ports rather than design stress intensities. Calculated membraneand bending stresses are compared directly to the allowable stress,S, and to factors of S to account for the differences in membraneand bending action and the different operating conditions (servicelimits). It should be noted that the total number of plate-and-shellsupports for all Classes is relatively small when compared to thelinear and standard supports. Based on the many pre-SubsectionNF nuclear power plants designed to ASME B-31.1 [3] and USAS B31.7 [4] Codes for Power Piping, the dramatic difference inquantities of linear and standard supports with plate-and-shelltype supports was anticipated by the Working Group. It was thisdistinction in the quantity of linear and standard supports thatprompted the Working Group to concentrate its efforts to establishnew rules for supports that exhibited mainly structural behavior.

10.4.5 Linear SupportsDuring the early days of the Subsection NF Working Group’s

mandate to write rules for supports applicable to ASME Section III,Division 1 philosophy, it was evident that the task of addressing lin-ear and standard supports would be a challenge. The literally thou-sands of supports that were composed of various structural steelelements (viz., wide flanges, channels, structural angles, squaretubing, structural pipe, and manufacturers’ standard catalog prod-ucts) presented some difficulties for the Working Group. It even-tually became apparent that in lieu of creating exclusively newdesign rules for linear and standard supports, the Working Groupshould take a more pragmatic approach by investigating rules forthese supports already existing in other design Codes. For linearsupports, this document was the seventh edition of AISC Manualfor Steel Construction [41]. Originally used to design buildingstructures, such as commercial steel buildings, the AISC Codewas also already in use at nuclear power plants to design thebuilding structures that housed the nuclear piping and other com-ponents. In fact, almost all linear and/or standard supports areattached to the building structure at one end of their load path.Therefore, it was a reasonable approach to extend the AISC rulesto include the design of linear supports because many of the sup-port elements were the same as those of the AISC Code [41].Because the distinct differences between building structures andnuclear power plants, especially in areas of varying temperatures,environmental conditions, and multiple operating conditions,some additional considerations needed to be added to the designrules of AISC to adjust the rules for supports for use in nuclearplants.

At this juncture, the Working Group considered it necessary toinclude the structural rules in ASME Section III as opposed tomaking reference to the AISC Manual of Steel Construction.When Subsection NF was first published in the winter 1973addenda to the 1971 edition of ASME Section III, Division 1 [1],the design rules for linear supports were published in MandatoryAppendix XIII [42]. However, when the 1974 edition was

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published, the rules for linear support design were moved toMandatory Appendix XVII [43], where they remained until thewinter 1982 addenda [7] when the major revision to Article NF-3000—the NF-3000 rewrite—was published.

As stated earlier, linear supports exhibit essentially a singlecomponent of direct stress (uniaxial stress) and they also may besubjected to shear stress. This is best demonstrated by a simplysupported or cantilever wide flange beam with a vertical load. Theresulting stresses are bending about the strong axis of the beamand shear stress in the beam. Because linear supports weredesigned by elastic analysis based on the maximum stress theoryas stipulated in paragraph NF-3143 [44], principal stresses are notrequired to be calculated. Each individual direct stress resultingfrom all loadings is compared to an allowable stress for the corre-sponding type of stress. Appendix XVII [45] is organized so thatthese individual stresses can be easily evaluated; that is, tension,compression, bending (weak and strong axis), and both shear andbearing stresses are clearly identified together with their allowablestresses for all load aplications.

Similar to the AISC Code, Appendix XVII [45] uses the speci-fied minimum yield strength as the basis for the allowable stresses.However, the working group included some additional require-ments in Appendix XVII to account for the differences in nuclear

power plants and commercial buildings. A list of these additionalcaveats follows.

• Appendix XVII accounts for the specified minimum yieldstrengths at temperature.

• To avoid column buckling in compression applications theallowable stress is limited to two-thirds of the critical buckling stress.

• An upper limit of 0.5Su is applicable to tension stress exceptfor pin-connected members.

• Shear stress on the effective area in resisting tearing failure islimited to 0.3Su.

• Increases in allowable stresses are permitted for differentoperating conditions (service limits).

• The maximum bearing load on the projected area of bolts inbearing connections is limited to 1.5Su.

• Commencing with the NF-3000 rewrite, allowable stresses forbolting are based on percentages of Su.

Between 1973 and 1982 many interested Subsection NF usersattended Working Group meetings and advocated a more usefuldesign Code. A Task Group was formed with the mandateto rewrite Article NF-3000, an effort that culminated with the

TABLE 10.6 CLASSIFICATION OF STRESSES FOR SOME TYPICAL CASES(Source: Table I-NF-3217-1, Subsection NF of the ASME B&PV Code)

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FIG. 10.8 STRESS CATEGORIES & LIMIT OF STRESS INTENSITIES FOR PLATE-AND-SHELL ANALYSIS FOR CLASS 1 SUPPORTS (Source: Fig. NF-3321-1, Subsection NF of the ASME B&PV Code)

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publishing of a complete revision to Article NF-3000 in the win-ter 1982 addenda to the 1980 edition of ASME Section III,Division 1 [7]. The three major Subsection NF changes thatappeared in this revision were (1) the introduction of the conceptof piping supports and component supports, (2) the introductionof stress limit factors to establish the increased allowable stressesfor various service loadings, and (3) the incorporation ofMandatory Appendix XVII into Subarticle NF-3300.

Initially, Subsection NF viewed component supports as theentire family of supports within its scope of responsibility. Withthe winter 1982 addenda, Subsection NF divided all supports intotwo categories: piping supports and component supports. Pipingsupports were considered those supports used to support nuclearpiping and that were frequently of the linear or standard types;additionally, they included supports on piping used to supportother piping components, such as in-line valves and pumps.Component supports were considered those supports that wereused to support nuclear components such as vessels, tanks, andother pressure components and were commonly of the plate-and-shell type. It was expected that this categorization of supportswould put the major emphasis for more stringent design and con-struction rules with the newly defined component supports.Historically, piping supports that constituted the vast majority ofsupports in a nuclear power plant were simple in design and con-struction. A failure of a piping support would normally not be

catastrophic to its piping system, but the failure of a support ona major nuclear component could have serious consequences.Therefore, more stringent rules were contemplated for compo-nent supports. This concept was strongly supported by theWorking Group and had considerable input from regulatorypersonnel.

The second major revision to the winter 1982 addenda toSubsection NF [7] was the introduction of stress limit factors toprovide increased design stress intensities and allowable stressesfor Class 1, 2, 3, and MC plate-and-shell, linear, and standardsupports for both component and piping supports. For Class 1plate-and-shell supports, Tables NF-3522.2-1 (Table 10.7) andNF-3622.2-1 (Table 10.8) replaced the old Hopper chart (Figure10.8). Similarly, Tables NF-3552.2-1 (Table 10.9) and NF-3652.2-1(Table 10.10) provide stress limit factors for Class 2, 3, and MCplate-and-shell supports; Tables NF-3523.2-1 (Table 10.11) andNF-3623.2-1 (Table 10.12) provide stress limit factors for Class 1,2, 3, and MC linear supports. The purpose of these tables was topresent the increase factors for various service levels (A, B, C, D,and testing) in a concise, simplified form and to provide consis-tency for different types and categories of supports. Additionally,these tables also introduced the concept of piping and componentsupports. One major consideration that was included was theredefinition of restraint of free-end displacement and anchormotions of piping as a primary rather than a secondary stress.

TABLE 10.7 ELASTIC ANALYSIS STRESS CATEGORIES AND STRESS LIMIT FACTORS FOR CLASS 1 PLATE-AND-SHELL SUPPORTS DESIGNED BY ANALYSIS—COMPONENT SUPPORTS

(Source: Table NF-3522.2-1, Subsection NF of the ASME B&PV Code)

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The third important revision was the incorporation of AppendixXVII, “Design of Linear Type Supports by Linear Elastic andPlastic Analysis,” into Subarticle NF-3300 [46], an act done tomake Subsection NF a more complete Code. It was concludedthat a major source of mandatory design rules should not be in anAppendix, but rather merged into its appropriate location in thesubsection. Because of the task of moving the linear design rulesinto Subsection NF and of the task of rewriting Article NF-3000were both large, a cross-reference–type table was provided toidentify the previous location of each NF-3000 item. This tablewas extremely helpful, for it enabled users to understand themany changes in this revision and also provided a roadmap for thenew NF-3000.

10.4.6 Standard SupportsOne of the unique ideas introduced to ASME Section III with

the initial publication of Subsection NF was the concept of com-ponent standard supports (presently called “standard supports”).Early in the preparation of Subsection NF, the Working Grouprealized that nuclear plants contained thousands of supports ofvarious designs and application. The support industry had evolvedwith manufacturers developing catalogues of what were known as“catalog” or “standard” supports. These supports were groupedinto various families such as rod hangers, spring hangers, rigidsupports, seismic supports, clamps, and clevises. These standard

supports and their families grew over the years as they wereapplied to fossil fuel and nuclear power plants. The concept wasto identify and categorize designs that could be mass-producedand stored on the manufacturer’s shelf. Key to their success wasthe design margin of 5 on failure that all manufacturers advertisedin their catalogues. These products proved popular because manydifferent categories of standard supports existed to address thetypes of applications that engineers were designing.

When it was first discussed in the Working Group meetings, theconcept of standard supports appealed to many members.Underlying this concept was the idea that providing design andconstruction rules would be simple and not require stringent con-siderations. The reason for allowing a group of supports with lessrigorous rules was to take advantage of the fact that standard sup-ports were catalog items and normally mass-produced. Discussedat length during the early meetings of the Working Group, but notincluded in the text of Subsection NF, was that standard supportshad a time-tested history of success. Very few, if any, failures ofthese supports were ever documented because of incorrect or poordesigns. Usually, when a failure was discovered, the cause wasdetermined to be an overload or product misapplication. This“time-tested history of success” was instrumental in convincingthe Working Group that this type of support should be included inSubsection NF. Standard supports, then, were permitted to pos-sess less stringent material, design, fabrication, and examination

TABLE 10.8 ELASTIC ANALYSIS STRESS CATEGORIES AND STRESS LIMIT FACTORS FOR CLASS 1 PLATE-AND-SHELL SUPPORTS DESIGNED BY ANALYSIS PIPING SUPPORTS


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TABLE 10.9 ELASTIC ANALYSIS STRESS CATEGORIES AND STRESS LIMIT FACTORS FOR CLASS 2, 3, AND MC PLATE-AND-SHELL SUPPORTS DESIGNED BY ANALYSIS—COMPONENT SUPPORTS


TABLE 10.10 ELASTIC ANALYSIS STRESS CATEGORIES AND STRESS LIMIT FACTORS FOR CLASS 2, 3, AND MC PLATE-AND-SHELL SUPPORTS DESIGNED BY ANALYSIS—PIPING SUPPORTS


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24 • Chapter 10

rules than plate-and-shell and linear supports as a result of theirsuccessful use over the years as a unique group of supports. Since1973, standard supports have proven to be, and continue to be, apopular type of support and have maintained an excellent histori-cal record of safe products.

10.4.7 Component and Piping SupportsComponent and piping supports were addressed briefly in

Section 10.4.5, Linear Supports, to explain their role in the NF-3000 rewrite of the winter 1982 addenda to the 1980 editionof ASME Section III [7]. Initially, all supports were defined ascomponent supports (see the title on the cover of Subsection NFfrom 1973 through the 1992 edition). As defined in SubsubarticleNF-1110(c) [47], these structural elements are used to supportnuclear components. Because components encompass vessels,tanks, pumps, and piping, the terminology of component supportsseemed appropriate, for all of these components would requiresome type of support. However, after the industry had usedSubsection NF for several years, the Working Group consideredestablishing separate categories for supports for those used onpiping and those used on components. This consideration was theresult of many queries from members and inquiries concerningthe actual use of supports in the everyday application ofSubsection NF. It was concluded that the vast majority of supportsused on piping were either linear or standard supports. Similarly,

many of the supports used on components such as vessels andother pressure-retaining items were plate-and-shell supports. Itseemed appropriate, then, to create these categories of supports tobetter define how supports were used in actual practice. This sep-aration was also acceptable to the regulatory authorities becauseplate-and-shell supports normally used to support componentswere of great interest to the NRC and the more stringent require-ments for plate-and-shell supports seemed appropriately placed.With the publication of the NF-3000 rewrite in the winter 1982addenda to the 1980 edition [7], the inclusion of component andpiping supports brought Subsection NF up to date with the use ofsupports in the nuclear power plant industry.

10.4.8 SnubbersBecause ASME Section III requires that dynamic loads caused

by such events as earthquakes be considered, the support manu-facturers saw the opportunity to suggest the use of hydraulicsnubbers (shock suppressors) for piping to address this require-ment. Prior to this application, snubbers were commonly used infossil fuel plants to restrain piping and equipment during waterand steam hammer events. The application of snubbers to restrainearthquake loadings seemed to be a natural outgrowth of thedesign of snubbers, which allows relatively unrestrained growthof piping during thermal excursions; however, snubbers “lock up”during rapid dynamic events such as earthquakes.

TABLE 10.11 ELASTIC ANALYSIS STRESS CATEGORIES AND STRESS LIMIT FACTORS FOR CLASS 1, 2, 3, AND MC LINEAR-TYPE SUPPORTS DESIGNED BY ANALYSIS—COMPONENT SUPPORTS


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Few support products have generated as much controversy andhave produced both popular yet questionable responses from theindustry as snubbers. Initially, snubbers were of the hydraulicdesign and were used liberally throughout the nuclear industry.After several years of use, mostly in the passive sense (i.e., beingstroked in unrestrained thermal applications and not in activateddynamic events), hydraulic snubbers began to exhibit leakage ofthe hydraulic fluid. This was unacceptable and resulted in actionby the regulatory authorities (NRC). Technical specifications werewritten that required continuous inspection and testing of snub-bers to identify those snubbers in use that had fallen outside ofpredetermined parameters. (Inspection and testing of snubberswas conducted under the auspices of ASME Section XI.) Basedon statistical sampling and testing, snubbers that did not meet thetechnical specifications needed to be replaced. As the number ofreplaced snubbers increased, manufacturers saw an opportunity tooffer a different snubber design that was not beset by leakage andother technical specification problems.

At that time, approximately in the mid-1970s, the mechanicalsnubber was introduced to the industry. The paramount reason forthe popularity of mechanical snubbers was because they did notleak fluid. As utilities slowly began to replace hydraulic snubbers,many of them implemented snubber reduction programs thatbecame practical with new and more aggressive piping analysistechniques and rules. The reduction programs were popular

because there were fewer snubbers to test and replace. Eventuallymechanical snubbers began to exhibit their own problems. Unlikehydraulic snubbers, which failed in the passive mode, that is, loss ofhydraulic fluid meant the snubber would fail to restrain the pipe dur-ing low probability dynamic events, mechanical snubbers began tofail in the active mode. This failure involved the snubbers locking upin a thermal excursion, thereby placing potentially large thermalloads on piping and equipment. Recently, some utilities began mak-ing a return to newly designed hydraulic snubbers because of theunacceptability of failing mechanical snubbers in the active mode.It seems that snubber design has made a complete turnabout withthe return to hydraulic snubbers; however, most utilities wouldagree that the fewer the snubbers the better.

10.4.9 Welding and BoltingTwo specialized areas of support design-by-analysis that

demands some attention are welding and bolting design. Both ofthese are connection design and historically can be the weak linkof a support design. Permissible types of welded joints for Class 1plate-and-shell supports were initially presented in Fig. NF-3291(a)-1 (Fig. 10.9) and later in Fig. NF-3226.1-1 (Fig. 10.10). Thesedesigns consisted of full penetration and fillet welds in butt, lap,angle, corner, and T-joints. Class 1, 2, 3, and MC linear supports per-mitted full-penetration, partial-penetration, and fillet welds in vari-ous configurations as specified in Table NF-3292.1-1 (Table 10.13),

TABLE 10.12 ELASTIC ANALYSIS STRESS CATEGORIES AND STRESS LIMIT FACTORS FOR CLASS 1, 2, 3, LINEAR-TYPE SUPPORTS DESIGNED BY ANALYSIS—PIPING SUPPORTS

(Source: Table I-NF-3623.2-1, Subsection NF of the ASME B&PV Code)

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later in Table NF-3324.5(a)-1 (Table 10.14) and in Appendix XVII-2450 [48], later in subparagraph NF-3324.5 [49]. The stresslimits in Table 10.13 were essentially identical to the weldingstress limits in the AISC Manual of Steel Construction [25].Welding of linear supports, which constituted the vast majorityof supports, also had restrictions, such as a minimum and maximumsize of fillet welds. This was necessary because of differences

in the thickness of the parts being joined. Also of considerationwas welding to a plate in a T-joint configuration, also known asthe through-thickness direction; this was discussed in detail inSection 10.4.2 regarding stress theories and types of stresses.The requirement to reduce the allowable stress in this joint con-figuration was eventually removed and addressed as a fabrica-tion consideration in later editions of Subsection NF.

FIG. 10.9 PERMISSIBLE WELDED JOINTS FOR COMPONENT SUPPORTS [Source: Fig. NF-3291(a)-1, Subsection NF of theASME B&PV Code]

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Historically, piping support welds are primarily fillet and flarebevel welds, and component support welds are more often partial-and full-penetration welds. Fillet welds are frequently analyzedby treating the weld profile as a line rather than an area of welddeposition. By using this technique, the analyst establishes anallowable weld stress as a force per in. as opposed to a force persq. inch. The shape of the weld profile, that is, the contour of theweld around the connection between two or more items, is dictatedby the manner in which the items are connected. This orientationof the connection will determine the type of weld joint; examplesof such types include the butt joint, T-joint, and angle joint. Themost common weld joint in supports is the T-joint because of the

nature of supports designed to restrain load in any or all of thethree orthogonal directions. Fillet weld joint analysis is common-ly performed by using the methods of Omer W. Blod-gett [50],who provides bending and twisting properties of many weldprofiles treated as a line. These properties allow an analyst todetermine weld stresses for connection profiles of many commonstructural shapes such as angles, channels, wide flange beams,square tubing, and structural pipe. Based on the type of loadingon the welded connection, the analyst determines the resultantweld stress as the square root sum of the squares (SRSS) of thenormal stress (sum of bending and tension) and the shear stresses(sum of direct shear and torsional shear). This resultant stress is

FIG. 10.10 PERMISSIBLE WELDED JOINTS FOR CLASS 1 PLATE-AND-SHELL-TYPE SUPPORTS [Source: Fig. NF-3326 1-1. (h) and (i), Subsection NF of the ASME B&PV Code]

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28 • Chapter 10

TABLE 10.13 ALLOWED STRESS LIMITS FOR LINEAR COMPONENT SUPPORT WELDS—ALL CLASSES(Source: Table NF-3292.1-1, Subsection NF of the ASME B&PV Code)

TABLE 10.14 ALLOWABLE STRESS LIMITS FOR CLASS 1 SLINEAR-TYPE SUPPORT WELDS[Source: Table NF-3324.5(a)-1, Subsection NF of the ASME B&PV Code]

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compared to an allowable stress calculated as a percentage of theultimate strength of the material based on the throat thickness ofthe weld size.

Bolting design for all types and classes of supports was gov-erned by the rules for linear supports in Appendix XVII-2460[51], later in subparagraph NF-3324.6 [52]), and Table XVII-2461.1-1 (given here as Table 10.15). Initially, the allowablebolt tension and shear stresses in Table XVII-2461.1-1 wassimilar to comparable allowable stresses in the AISC Manualof Steel Construction [25]. This table, however, providedallowable stresses for a limited number of bolting materialspecifications. With the publication of the winter 1982 adden-da to the 1980 edition of ASME Section III [7], the boltingrequirements were totally revised and were no longer based onthe AISC Manual of Steel Construction. Subparagraph NF-3324.6 [52] presented new rules for the design of bolted jointsthat were based on work performed by John W. Fisher [53].

Tension and shear allowable stresses are specified as a functionof ultimate strength, Su, rather than the previously used yieldstrength, Sy, basis. Because the allowable stresses are given inequation form rather than table form, the material specifica-tions are no longer limited. In fact, separate tension and shearequations are given for ferritic and austenitic steels to accountfor the differences in the ratio of yield strength to ultimatestrength, Sy/Su. When the yield strength is less than half of theultimate strength, which is the case for austenitic materials,using the tension equation for the ferritic steel would result inan allowable stress above the yield strength. It is for this rea-son-keeping the allowable stress below the yield strength - thata larger denominator is used in the equations for austeniticsteel. The new rules also provide for combined tension andshear stresses (normally used with concrete anchor bolts),bearing- and friction-type joints, slip resistance joints, andminimum and maximum edge distances.

TABLE 10.15 ALLOWABLE BOLT TENSION AND SHEAR STRESSES(Source: Table XVII-2461.1-1, Subsection NF of the ASME B&PV Code)

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30 • Chapter 10

10.4.10 Load RatingSubsubparagraph NF-3132.1(a)(3) [54], later Subarticles NF-

3280 [55] and 3380 [56]), identifies load rating as the third designprocedure permitted for use for support qualification. Since manysupport manufacturers had established a complete line of catalogsupports, the load rating procedure was advantageous, especiallybecause many products had catalog load ratings previously estab-lished by some form of load testing. The load rating procedure isa series of simple equations based on operating conditions (latercalled service level limits). The equations establish the productload rating as a function of a test load multiplied by the ratio ofallowable stress, S, to ultimate strength, Su, for plate-and-shellsupports; the ratio of allowable stress, Fall, to ultimate strength, Su,for linear supports; and the ratio of either S or Fall to Su for com-ponent standard supports, depending on whether it is producedfrom plate-and-shell or from linear items. The term “test load” isdefined as the support test load equal to or less than the loadunder which the component support fails to perform its specifiedsupport function. Also, the tests are required to be performed on astatistically significant number of full-size samples, or a 10%reduction in load rating results is taken if only one sample wastested. It soon became apparent that a 10% reduction in the loadrating results was a small price to pay because (1) it was very dif-ficult to define a “statistically significant number of samples” tosatisfy the design organization, the owner, and the regulatoryauthorities; and (2) testing one rather than several samples wasmore economically attractive to the manufacturer.

When it was first published in 1973 [1], load rating was a newconcept, and the definition of the term “test load” caused someconfusion in the industry. It was unclear whether the phrase “failsto perform its specified support function” was referring to thesupport exceeding the yield strength or the ultimate strength ofthe material. The working group had many discussions regardingthe meaning of this phrase and concluded that its meaning isdependent upon the product being tested and what the testerdetermines to be the mode of failure of the support. If the testerbelieves a support no longer performs its support function, whenthe load applied to the support reaches the support material yieldstrength, then this load is the test load. Similarly, it may be atcomplete failure, ultimate strength, at which the tester feels thesupport no longer performs its support function. Historically,many manufacturers used yield strength as their threshold todetermine the test load for catalog products. In many instances,catalog load ratings could have been increased based upon theresults of the load rating tests; however, manufacturers believedthat the success history of their products was attributed to the cat-alog loads that had persisted for many years. Therefore, manymanufacturers’ catalog load ratings remained unchanged.

The winter 1983 addenda to the 1983 edition of ASME SectionIII [57] included a major revision to the load rating procedure.The revision to Subarticles NF-3280 [55] and NF-3380 [56]addressed the earlier concern regarding whether yield or ultimatestrength should be used to determine if the support test samplefailed to perform its support function. The new requirementsdirected the tester to determine a yield test load and an ultimatetest load that were then multiplied by the ratio of the appropriateallowable stress to either the actual yield strength or the actualultimate strength as applicable. The load rating would then be thelower of the two values. The use of the actual yield strength, Syact,and the actual ultimate strength, Sauct, is needed, since these val-ues vary with different Certified Material Test Reports (CMTRs).

Load ratings determined with this approach would be more realis-tic because the strength of the actual material used in the test isused as the basis for establishing the load ratings.

10.4.11 High-Cycle Fatigue and Limit AnalysisSubsection NF required evaluation of high-cycle fatigue for

Class 1 linear supports and their connections (Appendix XVII-3000 [58], later Subsubarticle NF-3330 [59]), which were subject-ed to more than 20,000 cycles of fatigue loading. This requirementwas unique for supports and was not considered necessary for themany support designs. Most supports were not expected to under-go more than 20,000 cycles of fatigue loading; therefore, thisrequirement was not considered to be a normal criterion for sup-ports. In fact, user questions and requests for interpretations serveas a measure of how often a particular topic is addressed by theengineering community. Because the topic of high-cycle fatiguedid not manifest itself as a common topic at Working Groupmeetings, it can be assumed that not many users of Subsection NFavailed themselves of this requirement. In fact, the author found itnecessary to use this Subsection NF requirement for the first timeonly recently.

Similarly, limit analysis design (Appendix XVII-4000 [60],later Subsubarticle NF 3340 [61]) was intended to be an alterna-tive to elastic analysis for Class 1 linear supports. In this casesimple or continuous beams and rigid frames may be propor-tioned on the basis of plastic design — namely, on the basis ofthe lower bound collapse load. This strength shall not be less thanthat required to support a factored load equal to 1.7 times those of the normal (Level A) and upset (Level B) conditions and 1.3 times that of the emergency (Level C) condition. Again,because this topic was rarely discussed at Working Group meet-ings, it can be concluded that this option to elastic design wasvery seldom used.

10.4.12 Functional RequirementsEven though Article NF-3000 was a design Code, functional

requirements of supports were also addressed. These considera-tions were important, even though they did not specify require-ments. Paragraph NF-3122 [62] (later NF-3123 [63]) specifiedthat the Design Specification shall indicate when a support is tobe designed to perform a specific function. Some examples ofsupport functional requirements that Article NF-3000 addressedfollow:

• Vibration—Piping shall be arranged and supported so thatvibration shall be minimized.

• Movement of supported component—Consideration shall begiven to the relative motion of the supported piping or othersupported component and the component support.

• Rolling and Sliding supports—Shall permit free movement ofthe component or the component shall be designed to includethe imposed load and frictional resistance.

• Sway Brace and Vibration Dampeners—The effect of swaybraces shall be included in the stress analysis of the component.

• Snubbers—The end connection of the snubber shall bedesigned to accommodate the vertical and horizontal movement of the component.

• Support spacing—Supports for piping shall be spaced to pre-vent excessive shear stresses resulting from sag and bendingin the piping.

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10.5 NF-4000 FABRICATION AND INSTALLATION

10.5.1 General RequirementsFabrication and installation are important steps in the overall

support construction process. Prior to the existence of SubsectionNF, supports were fabricated and installed based on manufac-turer’s practices and recommendations and also on standardssuch as MSS SP-58 [5], MSS SP-69 [64], and MSS SP-89 [65].Article NF-4000 [66] for the first time presented a structuredapproach to control the fabrication and installation of supports.These rules attempted to provide requirements for the entire fab-rication cycle, including forming, fitting, aligning, welding, heattreatment, and bolted connections. The Working Group believedthat requiring reasonable and beneficial fabrication and installa-tion practices would enhance the quality and inherent safety ofsupports.

10.5.2 Form, Fitting, and AligningThese requirements addressed such support fabrication topics

as cutting, forming, bending, tolerances, aligning methods, andtack welds. Since the majority of supports consisted of either lin-ear or standard supports, Article NF-4000 [66] had its largestimpact on support manufacturers. The requirements for forming,cutting, and bending affected the manufacturers’ complete line ofsupport products. Standard products such as clamps, beam attach-ments, variable- and constant-support spring hangers, formed andforged clevises, baseplates, and saddle supports were fabricatedusing a variety of standard forming operations such as cold- andhot-forming, shearing, and thermal cutting. Consideration neededto be given to preheating before thermal cutting and the effect ofreducing impact properties of materials below minimum values asa result of the fabrication process. Material identification duringthese operations is required to be maintained throughout the man-ufacturing process. Original identification markings are requiredto be transferred to subsequent parts when they were cut or other-wise separated during the process.

Non-Mandatory Appendix NF-D [102] incorporates all toler-ances, was published in 2007 edition of ASME Section III[103]. These tolerance guidelines, though non-mandatory, werefollowed by most support manufacturers and installers. Many ofthese tolerances were prevalent in other support standards ormanufacturing practices. Fitting and aligning methods includesuch operations as bars, jacks, clamps, and tack welds. Tackwelds are used to secure alignment and shall be removed com-pletely or incorporated into the final weld after the proper weldpreparation.

10.5.3 Welding and Heat TreatmentWelding of support products is the most prevalent of all fabri-

cation processes. Even though Subsection NF is a structural ratherthan pressure-retaining Code, many of the welding rules andrequirements have their origins in the other subsections that per-tain to pressure-retaining design and construction. Welding proce-dure qualification requirements of ASME Section IX [68] applyto supports fabricated to Subsection NF. Emphasis is placed onwelding qualification and maintenance and certification ofrecords. These qualification and certification records are crucialfor a manufacturer to maintain his ASME stamping certification.Because welding is considered “Code work” (the material proper-ties are altered during this process), support manufacturers who

employ welding as a fabrication process are required to obtainand maintain an ASME NPT (nuclear parts) stamp. This stamp isobtained initially through an ASME survey and maintainedthrough subsequent surveys on a 3 yr. audit basis.

Class 1 plate-and-shell and linear supports are required to showidentification marks of the welders who construct welded joints.This is a form of material identification as defined inSubsubarticle NF-2150 [69]. For all other classes and types ofsupports, the manufacturer must certify that only qualifiedwelders are used in making all welds. Subarticle NF-4400 [70]presents the rules governing the making and repairing of welds.Prewelding considerations, such as identification, storage andhandling of welding materials, and the cleanliness of weldsurfaces, are of great importance and must be addressed by manu-facturers and installers of supports. Rules are provided for themaking of the welded joint including backing strips, peening,weld surface quality, butt weld reinforcement, and the shape andsize of fillet welds. Defects discovered in welds by means of weldexamination (Article NF-5000 [71]) are subject to weld repairs.Surface defects may be removed by grinding or machining ratherthan repair by welding when specific conditions pertaining todesign thickness, blending, and magnetic particle or liquid pene-trant examination are considered. Repair by welding is permittedwhen defects result in reduction of design thickness. Weld repairsmust use materials, welders, and welding procedures in accor-dance with the provisions of this article. After the weld repair isperformed consideration must be given to blending, examination,and heat treatment (when required) of repaired areas.

Heat treatment of welded joints is a process that may be speci-fied under the welding procedure qualification requirements ofASME Section IX [68]. Preheat may be necessary depending onsuch factors as chemical analysis, elevated temperature, physicalproperties’ material thickness, and the degree of restraint of thejoined parts. The preheat method must not harm or alter the basematerial or preapplied weld metal. Limitations of interpass temperatures must be considered for quenched and temperedmaterials to avoid detrimental effects on the materials’ mechani-cal properties. Post-weld heat treatment (PWHT) is a more com-mon practice and is required for all welds, including repair welds,except for those exempted in subparagraph NF-4622.7 [72] andTable NF-4622.7(b)-1 (Table 10.16). This table is organized bymaterial P-number (ASME Section IX, QW-420 [73]) and type ofweld. A considerable number of materials and weld types areexempted based on material thickness, percent of carbon, andpreheat requirements. Factors and requirements for PWHT aretime-temperature recordings (required for the AuthorizedInspector), nominal thickness definition, holding time at tempera-ture, dissimilar P-number materials, heating and cooling rates,and heating methods.

10.5.4 BoltingSubarticle NF-4700 [74] provides the fabrication and installa-

tion requirements for bolted construction including both items inthe connection, the bolt, and the connected parts. Bolting is asignificant item in the support load path because many standardsupports use bolting to connect support products both to the com-ponent (clamping device) and the building structure (beam attach-ment). Thread engagement is the primary mechanism throughwhich the bolted connection performs its function. Threads forbolts and studs are required to be engaged for the full length ofthe thread in the load-carrying nut. Thread lubricants must not

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react unfavorably with support materials except in friction-typejoints where contact surfaces must be free of lubricants.

Bolt tensioning, or preload, is a form of locking device that iscommon for high-strength bolts (yield strength � 80 ksi) and isdesignated in the Design Specification. Preload may be obtainedby (1) turn-of-the-nut method, (2) calibrated wrenches (hardened

washer required), (3) load-indicating washers, and (4) directextension indicators. For other than high-strength bolts, lockingdevices, which are required to prevent loosening during service,may be any of the following: elastic stop nuts, lock nuts, and free-spinning and prevailing torque. Upset threads may be used as alocking device when the threads are upset by cold-working or

TABLE 10.16 EXEMPTIONS OF MANDATORY PWHT[Source: Table NF-4622.7(b)-1, Subsection NF of the ASME B&PV Code]

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tack welding. When locking devices cannot be installed becauseof the assembly geometry, preloading of fasteners with yieldstrengths � 80 ksi can be used if specific preload values are main-tained, dynamic testing is performed, and acceptable preloadmethods are used. Bolted connections are also used in pure shearand shear combined with tension. Bolts loaded in pure shear shallnot have the threads located in the load-bearing part of the shankunless permitted by the Design Specification, which is more of afunctional requirement. In addition to the bolt part of the connec-tion, requirements also apply to the mating portion of the connectedpart. Bolt holes shall have specific requirements regarding thediameter of bolt holes relative to the diameter of the bolt.Oversized and slotted holes shall have specific dimensions andmay have restrictions regarding the direction of loading.

10.6 NF-5000 EXAMINATION

Nondestructive examination of support welds was a relativelynew requirement for support manufacturers and had its origins inthe other ASME Section III subsections that dealt with pressure-retaining design. The Working Group recognized that structuralelements did not require the more stringent examination tech-niques except for specific conditions. Since there were thousandsof supports in a nuclear plant, examination requirements neededto be practical by taking advantage of the different types of sup-ports and their construction methods. Examination of supportswould have a dramatic impact on support manufacturers by itseffect on the fabrication process of the many different standardsupport products. The Working Group provided rules for nonde-structive examination, conducted in accordance with ASMESection V [75]), that would address manufacturers’ considerationsand ensure a safe product.

10.6.1 Examination MethodsThe vast majority of supports fall into the linear and/or stan-

dard support type of Class 2 and 3 construction. Initially,Subarticle NF-5200 [76] was organized based on the type of sup-port: plate-and-shell, linear, or standard support. However,Subarticle NF-5200 was revised in the winter 1978 addenda to the1977 edition of ASME Section III [77] to present examinationrequirements based on class of construction. Paragraph NF-5221[78] identifies the method of examination based upon the type ofweld and weld throat dimension for Class 2 and MC primarymember welded joints. Primary members of supports are thosemembers designed to carry load under any postulated condition,whereas secondary members are those members typically used asbracing and not designed to sustain any significant stress (>50%of the allowable stress). Primary members that have groove depthdimensions less than 1 in., T-joint welds that have throat dimen-sions less than in., and all secondary member welded joints needonly to be examined by the visual method. All Class 3 weldedjoints for both primary and secondary members require visualexamination except for primary member welded joints with agroove depth greater 1 in., in which case liquid-penetrant ormagnetic-particle examination is required.

Liquid-penetrant or magnetic-particle examination is also requiredfor Class 1 primary member welds other than full-penetration buttwelds, which must be radiographed. Class 2 primary member buttwelds, Class 2 primary member partial-penetration or fillet weldswith groove depth dimensions greater than 1 in., and T-jointwelds with throat dimensions in. or greater also require liquid-1

2

12

penetrant or magnetic-particle examination. A closer scrutiny ofthese requirements shows that fillet welds typically used in struc-tural applications use predominantly visual examination, whereasthe full-penetration butt welds normally seen in pressure bound-ary applications primarily require more rigorous examinationmethods. The Working Group intended this approach to maintainthe ASME philosophy regarding pressure boundary–type weldswhile realizing that most support welds, being structural in nature,would fall into the fillet weld category.

10.6.2 Acceptance StandardsAcceptance standards are given for all five examination methods:

ultrasound, radiography, liquid penetrant, magnetic particle, andvisual. Indications identified by the particular method of examina-tion are characterized as imperfections and are unacceptable whenthey exceed specific dimensional limits. Visual examination doesnot identify indications as a result of a supporting test, as is thecase for the other examination methods. Therefore, there aremany dimensional acceptance standards that address such para-meters as weld size, weld fusion, overlap, craters, surface porosity,undercut depth, weld location and length, arc strikes, blemishes,and slag.

10.6.3 Special ConsiderationsArticle NF-5000 [71] contains examination requirements for

items with special considerations. These requirements do not fallunder the examination methods categorized by support class asindicated in Section 10.6.1; instead, they have special require-ments as follows.

• For weldments that impose loads in the through-thicknessdirection of primary members 1 in. and greater in thickness,the base material beneath the weld shall be ultrasonicallyexamined when required by subsubarticle NF-4440 for allclasses of supports.

• When this article requires radiographic examination, inertiaand continuous drive friction welds shall also be examined bythe ultrasonic method to verify bonding over the entire area.

• Springs for Class 1 variable, constant, and sway standard sup-ports shall be examined after coiling by the liquid-penetrantor magnetic-particle method.

• Weld repairs and special welded joints may require examina-tion by the ultrasonic, liquid-penetrant, or magnetic-particlemethods.

10.7 NF-8000 NAMEPLATES, STAMPING,AND REPORTS

When Subsection NF was first published in the winter 1973addenda to the 1971 edition of ASME Section III [1], require-ments for Code symbol stamping were not included. However, thewinter 1974 addenda to the 1974 edition of ASME Section III[79] included stamping requirements for Subsection NF. Thismeant that for any component support contract written betweenJuly 1, 1974 (when the 1974 edition became mandatory) and July 1,1975 (when the winter 1974 addenda [79] became mandatory),Code symbol stamping was not required. This stamping require-ment would have a major impact on support manufacturersbecause, for the first time, an Authorized Inspector would berequired to inspect welds at a manufacturer’s plant on a daily

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basis. After this time, support manufacturing for all types andclasses of supports would never be the same. During the periodfrom July 1, 1974 to July 1, 1975, a concerted effort to sign asmany component support contracts as possible was the goal ofmany support manufacturers. Utilities also had a vested interest incommitting to the earlier Code Edition to reduce their exposure tothe requirements of nameplates, stamping, and data reports.

10.7.1 General RequirementsArticle NF-8000 [80] is concise, simply stating that the require-

ments for certificates of authorization, nameplate, stamping, anddata reports are specified in NCA-8000 [81]. It also states thatstamping is not required for supports fabricated from materials(i.e., not welded). This is an important consideration because per-forming “Code work” or welding would require that a supportmanufacturer apply for an ASME NPT stamp, which necessitatesan initial ASME Survey and subsequent renewal surveys everythree years. In November 1976, the first support manufacturersuccessfully scheduled and passed the ASME survey and receivedthe first NPT stamp for supports. Since 1975 several attemptshave been made to eliminate the requirement for stamping of sup-ports, with the Working Group discussing in depth CodeRevisions and Code Cases that would eliminate this requirement.Code Cases CCN-500 [82] and CCN-570 [83] have currentlyaccomplished this task: CCN-500 allows support manufacturersto design and construct standard supports to a support manufac-turer’s standard MSS-SP-58 [5], which does not require name-plates, stamping, or data reports; and similarly, CCN-570 allowslinear and standard supports to be designed to ANSI/AISC N-690[84], a specification that does not require nameplates, stamping,or data reports.

The Working Group has discussed this topic at length over thepast 25 years or so, and its consensus was that stamping of stan-dard and linear supports (normally piping supports) should not bea requirement. As a result of these discussions, the WorkingGroup has succeeded in gaining approval of a very recent (July 1,1999) Code Revision to Article NF-8000 [85] that eliminates therequirements for Code symbol stamping of all supports. In con-junction with this revision, Subsubarticle NCA-3680 [86] intro-duced a new entity, the NS Certificate Holder. This CertificateHolder essentially has responsibilities similar to that of the NPTCertificate Holder (which formerly pertained to welded supports)except that Code symbol stamping is not required (the rules applyto all supports). Other differences are that (1) the duties of theAuthorized Inspection Agency (AIA) have been greatly reduced,(2) a new data report form—NS-1 Certificate of ConformanceNCA-8100 [87]—is required for welded items, and (3) aCertificate of Compliance is required for nonwelded support.

10.8 NF APPENDICES

From 1982 to 1984, the Working Group on Supports (knownthen as component supports) began discussions to determine thefeasibility of publishing Appendices to Subsection NF that wouldprovide aid and guidance for frequent users of that subsection.Several areas of consideration, including materials, stress analysismethods, Design Specification contents, design reports, and spe-cial design considerations, were identified as topics worthy ofinclusion into these proposed Appendices. Initiating these topicsand developing them into Code language for the Appendices wasa formidable task. Several Working Group members were

involved with this effort, which culminated in the initial publica-tion of the first Appendix in the 1995 edition, A96 addenda [88].In actuality, two Appendices were identified. However, MandatoryAppendix NF-I [89] was published as being in the course ofpreparation, and it is being reserved for the transfer of additionalpermitted material table data on allowable stress values, designstress intensity values, specified minimum yield strength values,and ultimate strength values. Code Cases N-71 [20] and N-249[21] currently permit these additional materials. When theWorking Group completes the appropriate effort, these materialswill be transferred to Appendix NF-I and Code Cases N-71 andN-249 will be annulled.

Appendix NF-II [90] presented the design requirements forsingle angle members, which were not included in SubsectionNF-3300 [91]. Single-angle members require more comprehen-sive design requirements because their unique structural shapemakes them asymmetrical at either of their axes. Structural angleshave both geometric and principal axes. Seely and Smith [92]define the geometric axes as “the perpendicular axes lying in atransverse section of the beam and passing through the centroid ofthe section” and define the principal axes as “the centroidal prin-cipal axes of inertia of a transverse section of the beam.” For a lat-erally unrestrained structural angle, determining the bendingstress with a load not passing through the angle’s shear center andusing the section modulus of the angle’s geometric axes will con-siderably understate the true bending stress. This MandatoryAppendix accounts for the differences between the geometric andprincipal axes of a single angle.

Additional Appendices were published in the 1998 edition ofSubsection NF [93]. Mandatory Appendix NF-III [94] containsrules in addition to those of Article NF-3000 [95] for the designand construction of linear supports using energy-absorbing mater-ial designed to yield by dissipating energy associated withdynamic piping movements. Two Non-Mandatory Appendiceswere included in the 1998 edition of ASME Section III [93]. Non-Mandatory Appendix NF-A [96] considers structural bolt preload-ing of steel to steel joints for bolting materials other than A-490and A-325, which are included in the AISC Steel Manual [6].Non-Mandatory Appendix NF-B [97] provides background forthe allowable stresses and design stress intensities used for thedesign of supports in Article NF-3000 [95]. Non-MandatoryAppendix NF-C [101] provides design basis for Linear-TypeSupports. Another Non-Mandatory Appendix NF-D [102] whichprovides tolerances was included in the 2007 edition of ASMESection III [103].

10.9 CODE CASES ANDINTERPRETATIONS

10.9.1 Code CasesAfter the initial publication of any Code, and if users of that

Code begin to deal with its effects, questions concerning Coderules and requirements are inevitable. One mechanism to dealwith these questions and concerns is for the appropriate CodeGroup (e.g., the Subgroup or Working Group) to develop a CodeCase that addresses additional or alternative rules. Since 1973,several Code Cases have been published addressing SubsectionNF. Essentially, Code Cases provide some aspect of relief toexisting Code rules either by enhancing existing rules or by pro-viding alternative rules for the particular Code topic. It should benoted that Code Cases pertaining to design and fabrication are

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addressed with respect to their acceptability in NRC RegulatoryGuide 1.84 [98] and, similarly, Code Cases pertaining to materialsare addressed in NRC Regulatory Guide 1.85 [99]. Also, theowner must approve the use of any Code Case and must docu-ment its use in all applicable design reports and calculations.Table 10.17 lists selected important Code Cases addressingSubsection NF that have been approved for use by ASME sinceSubsection NF’s inception. These Code Cases are not listed in theReferences because the information is given in Table 10.17, andno revision level for each is given.

10.9.2 InterpretationsA second technique for determining Code intent or clarification

is the inquiry-and-interpretation process. Code users from anyorganization may ask a question (i.e., prepare an inquiry) andrequest an interpretation from ASME of any Code Section. Thisprocess requires the author of a question to state the question andpropose a response. After reviewing the inquiry, ASME will thenissue an official interpretation as a response. An important aspectof the inquiry-and-interpretation process is that the interpretationwill attempt to use existing Code words in response to the inquiry.Table 10.18 lists some selected important interpretations issued forSubsection NF. As with the Code Cases in Table 10.17, these inter-pretations are not listed in the References because the informationis given in Table 10.18, and no revision level for each is given.

10.10 SUMMARY OF CHANGES

Table 10.19 lists all the changes in 2007 edition of ASMEBPVC, Section III, Subsection NF, Supports. [102]

10.11 ASME B31.1 AND B31.3 SUPPORTS

As an enhancement to this chapter, it is appropriate to mentiona few words about Code rules for supports of other jurisdictions,such as power piping (non-nuclear power plants) and petrochemi-cal piping. ASME B31.1 [3] is the Code for power piping for non-nuclear power plants. Before the initial publication of SubsectionNF [1], ASME B31.1 was the Code of record for pipe supports ofboth fossil fuel and nuclear power plants. The B31.1 power pipingCode was essentially a design Code for piping with some basicrules for supports. In comparison, Subsection NF [93] contains185 pages of design, fabrication, and examination rules for sup-ports, whereas ASME B31.1 [3] contains less than five pages. It isclear that Subsection NF established a new standard for the designfabrication and examination of supports.

ASME B31.1 [3] primarily addresses standard (normally cata-log) supports. Paragraph 121.1 [3] specifies that MSS SP-58 [5]shall be used for the design of standard supporting elements.Paragraph 121.2 [3] provides allowable stress values for materialsother than those in MSS SP-58 [5]. The remainder of the designsection, paragraph 121 [3], is concerned with providing additionalrules addressing hanger adjustments, hanger spacing, anchors andguides, rigid hangers, springs (variable and constant support),shock suppressors (snubbers), and structural attachements. Theseadditional rules are used in conjunction with MSS SP-58 toensure a comprehensive support design.

ASME B31.3 [100] provides similar rules and requirements forsupports as ASME B31.1 [3], including reference to MSS SP-58.One major difference between ASME B31.3 and ANSI/ASMEB31.1 concerns how to establish the allowable stresses for materi-als other than bolting materials. B31.1 paragraph 102.3.1(c) identifies

TABLE 10.17 SELECTED SUBSECTION NF CODE CASES(Source: ASME Section III, Division 1, Code Case Supplements)

CCN No. Title

N-71 Additional Materials for Subsection NF Class 1, 2, 3, and MC Component Supports Fabricated by Welding, Section III, Division 1

N-249 Additional Materials for Subsection NF Class 1, 2, 3, and MC Component Supports Not Fabricated by Welding, Section III, Division 1

N-74 Interim Requirements for Certification of Component Supports, Section III, Subsection NF N-175 Welded Joints in Component Standard Supports, Section III, Division 1N-180 Examination of Weld Repairs of Springs for Class 1 Component Standard Supports, Section III, Division 1 N-111 Minimum Edge Distance Bolting for Section III, Division 1, Class 1, 2, 3, and MC Construction of Component

SupportsN-116 Weld Design for Use for Section III, Division 1, Class 1, 2, 3, and MC Construction of Component Supports N-86 Furnace Brazing Section III, Subsection NF, Component Supports N-220 Code Effective Date for Component Supports, Section III, Division 1 N-225 Certification and Identification of Material for Component Supports, Section III, Division 1 N-337 Use of ASTM B 525-70 Grade II, Type II, Sintered Austenitic Stainless Steel for Class 2, 3, and MC Component

Standard Supports, Section III, Division 1N-357 Certification of Material for Component Supports, Section III, Division 1 N-403 Reassembly of Subsection NF Component and Piping Supports, Section III, Division 1 N-413 Minimum Size of Fillet Welds for Subsection NF Linear-Type Supports, Section III, Division 1 N-414 Tack Welds for Class 1, 2, 3, and MC Component and Piping Supports, Section III, Division 1 N-420 Linear Energy Absorbing Supports for Subsection NF, Classes 1, 2, and 3 Construction, Section III, Division 1 N-476 Classes 1, 2, and 3 Linear Component Supports—Design Criteria for Single Angle Members, Section III, Division 1,

Subsection NFN-500 Alternative Rules for Standard Supports for Class 1, 2, 3, and MC, Section III, Division 1 N-570 Alternative Rules for Linear Piping and Linear Standard Supports for Class 1, 2, 3, and MC, Section III, Division 1

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36 • Chapter 10

TABLE 10.18 SELECTED SUBSECTION NF INTERPRETATIONS (Source: ASME Section III, Division 1,Interpretations: Vols. 1–35)

Interpretation No. Subject

III-1-77-110 (Vol. 1) Section III, Division 1, NF-2400—CMTRsIII-1-77-120 (Vol. 1) Section III, Division 1, Stamping and Inspection of Component SupportsIII-1-77-144 (Vol. 2) Section III, Division 1, NF-3133.3, Piping Support AdjustmentsIII-1-77-164 (Vol. 2) Section III, Division 1, Component Supports—Certificate of AuthorizationIII-1-77-169 (Vol. 2) Section III, Division 1, NF-5410—Class 1 SpringsIII-1-77-217 (Vol. 2) Section III, Division 1, NF-2000—Bolting MaterialIII-1-77-233 (Vol. 2) Section III, Division 1, Stamping and Inspection of Component SupportsIII-1-77-259 (Vol. 2) Section III, Division 1, Subsection NF, Component Supports—Code JurisdictionIII-1-77-262 (Vol. 2) Section III, Division 1, Table NF-3132.1(b)-1 and NF-3292—WeldingIII-1-77-269 (Vol. 2) Section III, Division 1, NF-1214, Component Standard SupportsIII-1-78-19 (Vol. 3) Section III, Division 1, NF-1214 and NCA-3820, Material SupplierIII-1-78-47 (Vol. 3) Section III, Division 1, NF-1120 — Jurisdictional BoundariesIII-1-78-49 (Vol. 3) Section III, Division 1, NF-1130 — Jurisdictional BoundariesIII-1-78-93 (Vol. 3) Section III, Division 1, NF-4452, Elimination of Surface DefectsIII-1-78-121 (Vol. 3) Section III, Division 1, NF-4721(e), High Strength BoltsIII-1-78-124 (Vol. 3) Section III, Division 1, Class 1 Component Supports—Stress ReportsIII-1-78-134 (Vol. 3) Section III, Division 1, NF-2130, Certification of Material; NCA-3867.5, Transmittal

of Documents of a Material SupplierIII-1-78-165 (Vol. 3) Section III, Division 1, NF-5200, NF-5352, and NF-5342—Weld ExaminationIII-1-78-180 (Vol. 3) Section III, Division 1, NF-3212, Appendix F-1323.1(a)III-1-78-207 (Vol. 3) Section III, Division 1, Design of Component Support AssembliesIII-1-81-110 (Vol. 12) Section III, Division 1, NF-1214 Component Standard Supports, and NCA-3820 Quality System

CertificateIII-1-83-05 (Vol. 12) Section III, Division 1, NF-2130, Certification of MaterialIII-1-83-10 (Vol. 12) Section III, Division 1, NF-1110 Elements for Construction; NF-1133.1 Intervening Elements

Connected to Pressure-Retaining Components; Code Case N-160 Finned Tubing for ConstructionIII-1-83-12 (Vol. 12) Section III, Division 1, NF-4720, BoltingIII-1-83-49 (Vol. 13) Section III, Division 1, NF-4725, Locking Devices (1980 edition with winter 1980 addenda)III-1-83-54 (Vol. 13) Section III, Division 1, NF-2121 Permitted Material SpecificationsIII-1-83-128 (Vol. 14) Section III, Division 1, NF-3280 Design by Load RatingIII-1-83-142 (Vol. 14) Section III, Division 1, NF-1130 Boundaries of JurisdictionIII-1-83-168 (Vol. 14) Section III, Division 1, Table NF-3324.5(a)-1 Allowable Stress Limits for Linear-Type Supports,

Class 1, 2, 3, and MC (editions and addenda prior to the winter 1982 addenda)III-1-83-176 (Vol. 14) Section III, Division 1, NF-3292 Design of Welded Joints; NF-3392 Permissible Types of Welded

Joints in Linear-Type Joints (1974 edition with winter 1976 addenda)III-1-83-196 (Vol. 15) Section III, Division 1, NF-2130 Certification of Material (1980 edition with summer 1982

addenda)III-1-83-213 (Vol. 15) Section III, Division 1, NF-1121 Rules for Supports; NF-3213.10 Free-End Displacement;

NF-3231.1 Elastic Analysis (1974 edition with winter 1974 addenda); Thermal Stress (1980 edition with winter 1982 addenda)

III-1-83-266 (Vol. 16) Section III, Division 1, NF-4724 Bolt Tension (all editions)III-1-86-26 (Vol. 18) Section III, Division 1, NF-1130 Boundaries of Jurisdiction (all editions)III-1-86-60 (Vol. 19) Section III, Division 1, NF-3324.6(a)(3)(b) Friction Type Joints; NF-3324.6(a)(4) Slip

Resistance—Friction-Type Joints (1983 edition with winter 1985 addenda)III-1-86-69 (Vol. 20) Section III, Division 1, NF-3200 Design of Class 1 Component Supports, Appendix XVII

(1974 edition)III-1-90-11 (Vol.27) Section III, Division 1, Table NF-3523(b)-1 Elastic Analysis Stress Categories and Stress Limit

Factors (1989 edition)III-1-90-21 (Vol. 27) Section III, Division 1, NF-3290 & NF-3390 Design of Welded JointsIII-1-91-05 (Vol. 29) Section III, Division 1, NF-1214 Standard Supports (1986 edition with any 1987 addenda)III-1-92-05 (Vol. 30) Section III, Division 1, NF-3282 and NF-3382 Load Ratings in Relation to Service LoadingsIII-1-92-77 (Vol. 35) Section III, Division 1, NF-2121 and NF-5400 Material Specification, Examination, and

Acceptance Criteria—Coiled Wire Rope (1974 edition and later editions and addenda throughthe 1992 edition with the 1992 addenda)

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TABLE 10.19 SUMMARY OF CHANGES (Reference: ASME BOILER AND PRESSURE VESSEL CODE SECTION III,SUBSECTION NF, SUPPORTS, THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS, 2007 ed. [103])

Page Location Change

4 Fig. NF-1132-1 Illustration (g) corrected by errata7 Fig. NF-1214-1 Illustration for “Welded Attachment” corrected by errata10 Table NF-2121(a)-1 (1) Under “Yield Strength Values” column, [Note (1)]

moved next to “Table 4” by errata(2) Under “Yield Strength Values” column, “Table Y-1”

added by errata12 NF-2222.1 First parenthetical number corrected to 19 000 by errata13 NF-2224 Paragraph head corrected by errata14 NF-2311(b)(l) Metric value added by errata15 Table NF-2311(b)-1 Under the third column, third parenthetical number corrected by errata16 Fig. NF-2311(b)-l On the vertical axis, fourth parenthetical number from the top corrected

by errata22 NF-2351(b)(3) Parenthetical number corrected by errata24 NF-2431.1(b) Revised42 NF-3256.2(b) Last table designation corrected by errata47–49 NF-3322.1(d)(1)(a)(2) Parenthetical sentence corrected by errata

NF-3322.1(d)(l)(a)(3) Parenthetical sentence corrected by errataNF-3322.1(d)(2) Parenthetical sentences corrected by errataNF-3322.1(d)(3) Parenthetical sentences corrected by errataNF-3322.1(d)(5)(b) Last value in first paragraph corrected by errataNF-3322.1(d)(6) Parenthetical sentence corrected by errata

51, 52 NF-3322.2(d)(1)(b)(l) Parenthetical sentence corrected by errataNF-3322.2(d)(1)(b)(2) Parenthetical sentence corrected by errataNF-3322.2(d)(1)(b)(3) Parenthetical sentence corrected by errataNF-3322.2(d)(2)(b)(1) Parenthetical sentence corrected by errataNF-3322.2(d)(2)(b)(2) Parenthetical sentence corrected by errataNF-3322.2(d)(2)(b)(3) Parenthetical sentence corrected by errata

52–54 NF-3322.2(e)(2) “NF-3322.2(d)(5) or (d)(6)” corrected to read “NF-3322.2(e)(5) or (e)(6)” by errata

NF-3322.2(e)(3)(b) Parenthetical sentence corrected by errataNF-3322.2(e)(3)(c) Corrected by errataNF-3322.2(e)(5) Denominator of second equation corrected by errata

55 NF-3322.4(a)(3)(a) Parenthetical sentence corrected by errataNF-3322.4(a)(3)(b) Parenthetical sentence corrected by errata

56 NF-3322.6(a) Parenthetical sentence corrected by errata58 NF-3322.6(e)(2) Parenthetical sentence corrected by errata

NF-3322.6(e)(4)(d) Metric unit corrected by errata62 NF-3324.2(b)(5) Metric unit in definition of M corrected by errata

NF-3324.3(b)(1) Parenthetical sentence corrected by errata79 NF-3412.2 Last two sentences added by errata92 Table NF-4232-1 Values in last two rows corrected by errata101 Table NF-4622.1-1 Values in first box under fourth column corrected by errata104 Table NF-4622.7(b)-1 Entries for 10C Gr. 1 corrected by errata111 NF-5521(a) NCA paragraph designation in footnote 3 corrected by errata123 NF-A-1311 Units added to definitions of RB and RT by errata126 NF-B-1200 First sentence corrected by errata134 NF-D-1320(c)(2) Units and last sentence added by errata140 Table NF-D-1330-1 (1) Plus/minus sign added to first value in sixth row under

second column by errata(2) Two minus signs added to values in last row under

second column by errata

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38 • Chapter 10

ASME Section II, Part D [36], as the source for the basis of estab-lishing allowable stresses. One calculation specified in ASMESection II, Part D, Appendix 1, for establishing allowable stressesis one-fourth of the specified minimum tensile strength at temper-ature [36]. This is one of several calculations, the lowest of whichestablishes the allowable stress. Comparatively, ASME B31.3paragraph 302.3.2(d)(1) specifies that one of the calculations forestablishing allowable stresses is one-third of the specified mini-mum tensile strength at temperature [100]. If it is compared toASME B31.1, this difference results in higher allowable stressesfor ASME B31.3 for the same material. One possible reason forthese higher allowable stresses is that ASME B31.1 power plantsare designed for a longer life; thus a lower, more conservativeallowable stress is warranted because the material will be subjectedto stress for a longer time.

10.11 REFERENCES

1. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Component Supports; The American Society of MechanicalEngineers, winter 1973 addenda, 1971 ed.

2. ASME Boiler and Pressure Vessel Code Section III, Nuclear PowerPlant Components; The American Society of Mechanical Engineers,winter 1973 addenda, 1971 ed.

3. ASME B31.1, Power Piping; The American Society of MechanicalEngineers, 1995 ed.

4. USA Standard B31.7, Nuclear Power Piping, 1969 ed.

5. MSS SP-58, Pipe Hangers and Supports—Materials, Design, andManufacturer; Manufacturers Standardization Society of the Valveand Fittings Industry, Inc., 1993 ed.

6. AISC Manual of Steel Construction; The American Institute of SteelConstruction, 9th ed., 1990.


8. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Component Supports; The American Society of MechanicalEngineers, summer 1978 addenda, 1977 ed.

9. ASME Boiler & amp; Pressure Vessel Code Interpretation III-1-78-47, Paragraph NF-1120, Section III, Division 1; The American soci-ety of Mechanical Engineers, March 30, 1978.

10. ASME Boiler and Pressure Vessel Code Section III, Subsection NCA,Paragraph NCA-3254, Design Specification; The American Society ofMechanical Engineers, 1977 ed.

11. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Subsubarticle NF-1130, Boundaries of Jurisdiction; The AmericanSociety of Mechanical Engineers, 1986 ed.

12. ASME Boiler and Pressure Vessel Code Section III, Subsection NB,Paragraph NB-1132, Boundary Between Components and Attachments;The American Society of Mechanical Engineers, 1986 ed.

13. ASME Boiler and Pressure Vessel Code Section III, Subsection NC,Paragraph NC-1132, Boundary Between Components and Attachments;The American Society of Mechanical Engineers, 1986 ed.

14. ASME Boiler and Pressure Vessel Code Section III, Subsection ND,Paragraph ND-1132, Boundary Between Components and Attachments;The American Society of Mechanical Engineers, 1986 ed.

15. ASME Boiler and Pressure Vessel Code Section III, Subsection NE,Paragraph NE-1132, Boundary Between Components and Attachments;The American Society of Mechanical Engineers, 1986 ed.

16. ASME Boiler and Pressure Vessel Code Section III, Division 1, CodeCase 1644, Additional Materials for Component Supports; TheAmerican Society of Mechanical Engineers, 1975.

17. ASME Boiler and Pressure Vessel Code Section III, Division 1, CodeCase 1644 (Revision 6); The American Society of MechanicalEngineers, March 3, 1976.

18. ASME Boiler and Pressure Vessel Code Section III, Division 1, CodeCase N-71, Additional Materials for Component Supports andAlternative Design Requirements for Bolted Joints; The AmericanSociety of Mechanical Engineers, Rev. March 3, 1976.

19. ASME Boiler and Pressure Vessel Code Section III, Division 1, CodeCase N-249, Additional Materials for Subsection NF Class 1, 2, 3,and MC Component Supports Fabricated Without Welding; TheAmerican Society of Mechanical Engineers, Rev. 1980.

20. ASME Boiler and Pressure Vessel Code Section III, Division 1, CodeCase N-71-17 (Revision 17); The American Society of MechanicalEngineers, Sept. 24, 1999.

21. ASME Boiler and Pressure Vessel Code Section III, Division 1, CodeCase N-249-13 (Revision 13); The American Society of MechanicalEngineers, May 11, 1997.

22. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Mandatory Appendix NF-I (in course of preparation); The AmericanSociety of Mechanical Engineers, A95 addenda, 1995 ed.

23. ASME Boiler and Pressure Vessel Code Section III, Subsection NCA,Subarticle NCA-3800, Metallic Material Organization’s Quality SystemProgram; The American Society of Mechanical Engineers, 1998 ed.

24. ASME Boiler and Pressure Vessel Code Section III, Subsection NCA,Paragraph NCA-3862, Certification of Material; The AmericanSociety of Mechanical Engineers, 1998 ed.

25. AISC Manual of Steel Construction; The American Institute of SteelConstruction, 7th ed., first revised printing 1970.

26. ASME Boiler and Pressure Vessel Code Section III, Subsection NCA,Paragraph NCA-3252, Contents of Design Specification; TheAmerican Society of Mechanical Engineers, 1998 ed.

27. ASME Boiler and Pressure Vessel Code Section III, Nuclear PowerPlant Components; The American Society of Mechanical Engineers,winter 1976 addenda, 1974 ed.

28. ASME Boiler and Pressure Vessel Code Section III, Subsection NCA,Paragraph NCA-2131, Code Classes and Rules of Division 1; TheAmerican Society of Mechanical Engineers, 1998 ed.

29. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Paragraph NF-3121, Terms Relating to Design by Analysis; TheAmerican Society of Mechanical Engineers, 1998 ed.

30. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Component Supports; The American Society of MechanicalEngineers, 1977 ed.

31. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Component Supports; The American Society of MechanicalEngineers, 1980 ed.

32. ASME Boiler and Pressure Vessel Code Section III, MandatoryAppendix II, Experimental Stress Analysis; The American Society ofMechanical Engineers, 1998 ed.

33. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Subsubarticle NF-3280, Design by Load Rating; The AmericanSociety of Mechanical Engineers, 1998 ed.

34. ASME Boiler and Pressure Vessel Code Section III, Nuclear PowerPlant Components; The American Society of Mechanical Engineers,1992 ed.

35. ASME Boiler and Pressure Vessel Code Section II, Part D, Materials,Properties; The American Society of Mechanical Engineers, 1995 ed.

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36. ASME Boiler and Pressure Vessel Code Section II, Appendix 1, PartD, Materials, Properties; The American Society of MechanicalEngineers, 1998 ed.

37. ASME Boiler and Pressure Vessel Code Section II, Appendix 2, PartD, Materials, Properties; The American Society of MechanicalEngineers, 1998 ed.

38. NRC Regulatory Guide 1.124, “Service Limits and LoadingCombinations for Class 1 Linear Type Component Supports,” rev. 1,Jan. 1978.

39. ASME Boiler and Pressure Vessel Code Section III, Subsection NB,Fig. NB-3221-1, Stress Categories and Limits of Stress Intensity forDesign Conditions; The American Society of Mechanical Engineers,1998 ed.

40. ASME Boiler and Pressure Vessel Code Section III, Subsection NB,Fig. NB-3222-1, Stress Categories and Limits of Stress Intensity forLevel A and Level B Service Conditions; The American Society ofMechanical Engineers, 1998 ed.

41. AISC Manual of Steel Construction, Specification for the Design,Fabrication, and Erection of Structural Steel for Buildings, 7th ed.,Feb. 12, 1969.

42. ASME Boiler and Pressure Vessel Code Section III, MandatoryAppendix XIII, Design of Linear Type Supports by Linear Elastic andPlastic Analysis; The American Society of Mechanical Engineers,winter 1973 addenda, 1971 ed.

43. ASME Boiler and Pressure Vessel Code Section III, MandatoryAppendix XVII, Design of Linear Type Supports by Linear Elasticand Plastic Analysis; The American Society of MechanicalEngineers, 1974 ed.

44. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Paragraph NF-3143, Linear Type Supports—Analysis Procedure; TheAmerican Society of Mechanical Engineers, 1998 ed.

45. ASME Boiler and Pressure Vessel Code Section III, MandatoryAppendix XVII, Design of Linear Type Supports by Linear Elasticand Plastic Analysis; The American Society of MechanicalEngineers, 1998 ed.

46. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Subarticle NF-3300, Design Rules for Linear Type Supports; TheAmerican Society of Mechanical Engineers, winter 1982 addenda,1980 ed.

47. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Subsubarticle NF-1110(c), Aspects of Construction Covered by TheseRules; The American Society of Mechanical Engineers, 1998 ed.

48. ASME Boiler and Pressure Vessel Code Section III, MandatoryAppendix XVII, Paragraph XVII-2450, Design of Linear TypeSupports by Linear Elastic and Plastic Analysis; The AmericanSociety of Mechanical Engineers, 1974 ed.

49. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Subparagraph NF-3324.5, Design of Welded Joints; The AmericanSociety of Mechanical Engineers, 1998 ed.

50. Blodgett, O. W., Design of Welded Structures, James F. Lincoln ArcWelding Foundation, June 1966.

51. ASME Boiler and Pressure Vessel Code Section III, MandatoryAppendix XVII, Paragraph XVII-2460, Design of Linear TypeSupports by Linear Elastic and Plastic Analysis; The AmericanSociety of Mechanical Engineers, 1974 ed.

52. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Subparagraph NF-3324.6, Design Requirements for Bolted Joints;The American Society of Mechanical Engineers, 1998 ed.

53. Kulak, G. L., Fisher, J. W., and Struik, J. H. A., Guide to DesignCriteria for Bolted and Riveted Joints; New York: John Wiley & Sons,1st ed., 1974.

54. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Subsubparagraph NF-3132.1(a)(3), Types of Procedures—LoadRating; The American Society of Mechanical Engineers, 1974 ed.

55. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Subsubarticle NF-3280, Plate and Shell Supports—Design by LoadRating; The American Society of Mechanical Engineers, 1998 ed.

56. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Subsubarticle NF-3380, Linear Supports—Design by Load Rating;The American Society of Mechanical Engineers, 1998 ed.


58. ASME Boiler and Pressure Vessel Code Section III, MandatoryAppendix XVII-3000, Design of Linear Type Supports by Lin earElastic and Plastic Analysis—High Cycle Fatigue Analysis for Class 1;The American Society of Mechanical Engineers, 1974 ed.

59. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Subsubarticle NF-3330, High Cycle Fatigue Analysis for Class 1; TheAmerican Society of Mechanical Engineers, 1998 ed.

60. ASME Boiler and Pressure Vessel Code Section III, MandatoryAppendix XVII-4000, Design of Linear Type Supports by LinearElastic and Plastic Analysis—Limit Analysis Design for Class 1; TheAmerican Society of Mechanical Engineers, 1974 ed.

61. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Subsubarticle NF-3340, Limit Analysis Design for Class 1; TheAmerican Society of Mechanical Engineers, 1998 ed.

62. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Paragraph NF-3122, Functional Requirements; The American Societyof Mechanical Engineers, winter 1976 addenda, 1974 ed.

63. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Paragraph NF-3123, Functional Requirements; The American Societyof Mechanical Engineers, 1998 ed.

64. MSS SP-69, Pipe Hangers and Supports—Selection and Application;Manufacturers Standardization Society of the Valve and FittingsIndustry, Inc., 1991 ed.

65. MSS SP-89, Pipe Hangers and Supports—Fabrication andInstallation Practices; Manufacturers Standardization Society of theValve and Fittings Industry, Inc., 1991 ed.

66. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Article NF-4000, Fabrication and Installation; The American Societyof Mechanical Engineers, 1974 ed.

67. ASME Boiler and Pressure Vessel Code Section III, Non-MandatoryAppendix K, Tolerances; The American Society of MechanicalEngineers, 1998 ed.

68. ASME Boiler and Pressure Vessel Code Section IX, Welding andBrazing Qualifications; The American Society of MechanicalEngineers, 1998 ed.

69. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Subsubarticle NF-2150, Material Identification; The AmericanSociety of Mechanical Engineers, 1998 ed.

70. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Subarticle NF-4400, Rules Governing Making, Examining, andRepairing Welds; The American Society of Mechanical Engineers,1998 ed.

71. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Article NF-5000, Examination; The American Society of MechanicalEngineers, 1998 ed.

72. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Subparagraph NF-4622.7, Exemptions to Mandatory Requirements;The American Society of Mechanical Engineers, 1998 ed.

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40 • Chapter 10

73. ASME Boiler and Pressure Vessel Code Section IX, Paragraph QW-420, Material Groupings; The American Society of MechanicalEngineers, 1998 ed.

74. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Subarticle NF-4700, Requirements for Bolted Construction; TheAmerican Society of Mechanical Engineers, 1998 ed.

75. ASME Boiler and Pressure Vessel Code Section V, NondestructiveExamination; The American Society of Mechanical Engineers, 1998 ed.

76. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Subarticle NF-5200, Required Examination of Welds; The AmericanSociety of Mechanical Engineers, 1974 ed.

77. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Subarticle NF-5200, Required Examination of Welds; The AmericanSociety of Mechanical Engineers, winter 1978 addenda, 1977 ed.

78. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Paragraph NF-5221, Examination of Class 2 and MC Support Welds,Primary Member Welded Joints; The American Society ofMechanical Engineers, 1998 ed.


80. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Article NF-8000, Certificates of Authorization, Nameplates,Stamping, and Data Reports; The American Society of MechanicalEngineers, 1998 ed.

81. ASME Boiler and Pressure Vessel Code Section III, Subsection NCA,Article NCA-8000, Certificates, Nameplates, Code Symbol Stamping,and Data Reports; The American Society of Mechanical Engineers,1998 ed.

82. ASME Boiler and Pressure Vessel Code Section III, Division 1, CodeCase N-500, Alternative Rules for Standard Supports for Class 1,2, 3,and MC; The American Society of Mechanical Engineers, Dec. 9,1993.

83. ASME Boiler and Pressure Vessel Code Section III, Division 1, CodeCase N-570, Alternative Rules for Linear Piping and Linear StandardSupports for Class 1, 2, 3, and MC; The American Society ofMechanical Engineers, Aug. 9, 1996.

84. ANSI/AISC N-690, Nuclear Facilities—Steel Safety-RelatedStructures for Design, Fabrication, and Erection; The AmericanNational Standards Institute, July 19, 1984.

85. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Article NF-8000, Certificates of Authorization and Certificates ofConformance; The American Society of Mechanical Engineers, A99addenda, 1998 ed.

86. ASME Boiler and Pressure Vessel Code Section III, Subsection NCA,Article NCA-3680, Responsibilities of an NS Certificate Holder; TheAmerican Society of Mechanical Engineers, A99 addenda, 1998 ed.

87. ASME Boiler and Pressure Vessel Code Section III, Subsection NCA,Article NCA-8100, Authorization to Perform Code Activities; TheAmerican Society of Mechanical Engineers, A99 addenda, 1998 ed.

88. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Supports; The American Society of Mechanical Engineers, A96addenda, 1995 ed.

89. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Mandatory Appendix NF-I (in course of preparation); The AmericanSociety of Mechanical Engineers, A96 addenda, 1995 ed.

90. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Mandatory Appendix NF-II, Design of Single Angle Members; TheAmerican Society of Mechanical Engineers, A95 addenda, 1995 ed.

91. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Subarticle NF-3300, Design Rules for Linear Type Supports; TheAmerican Society of Mechanical Engineers, A95 addenda, 1995 ed.

92. Seely, F. B., and Smith, J. O., Advanced Mechanics of Materials;New York: John Wiley and Sons, 2nd ed., 1952.

93. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Supports; The American Society of Mechanical Engineers, 1998 ed.

94. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Mandatory Appendix NF-III, Energy-Absorbing Support Material;The American Society of Mechanical Engineers, 1998 ed.

95. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Article NF-3000, Design; The American Society of MechanicalEngineers, 1998 ed.

96. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Non-Mandatory Appendix NF-A, Structural Bolt Preloading; TheAmerican Society of Mechanical Engineers, 1998 ed.

97. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Non-Mandatory Appendix NF-B, Design Allowable Stresses forPlate-, Shell-, and Linear-Type Supports; The American Society ofMechanical Engineers, 1998 ed.

98. U.S. NRC Regulatory Guide 1.84, “Code Case Acceptability, ASMESection III Design and Fabrication,” Rev. 31, May 1999.

99. U.S. NRC Regulatory Guide 1.85, “Code Case Acceptability, ASMESection III Materials,” Rev. 31, May 1999.

100. ASME B31.3, Chemical Plant and Petroleum Refinery Piping; TheAmerican Society of Mechanical Engineers.

101. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Non-Mandatory Appendix NF-C, Design Basis for Linear-TypeSupports; The American Society of Mechanical Engineers, 2004 ed.

102. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Non-Mandatory Appendix NF-D, Tolerances; The American Societyof Mechanical Engineers, 2007 ed.

103. ASME Boiler and Pressure Vessel Code Section III, Subsection NF,Supports, The American Society of Mechanical Engineers, 2007 ed.

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