process industry practices process control -...

COMPLETE REVISIONMarch 2003

Process Industry PracticesProcess Control

PIP PCCCV001Selection of Control Valves

PURPOSE AND USE OF PROCESS INDUSTRY PRACTICES

In an effort to minimize the cost of process industry facilities, this Practice hasbeen prepared from the technical requirements in the existing standards of majorindustrial users, contractors, or standards organizations. By harmonizing thesetechnical requirements into a single set of Practices, administrative, application, andengineering costs to both the purchaser and the manufacturer should be reduced. Whilethis Practice is expected to incorporate the majority of requirements of most users,individual applications may involve requirements that will be appended to and takeprecedence over this Practice. Determinations concerning fitness for purpose andparticular matters or application of the Practice to particular project or engineeringsituations should not be made solely on information contained in these materials. Theuse of trade names from time to time should not be viewed as an expression ofpreference but rather recognized as normal usage in the trade. Other brands having thesame specifications are equally correct and may be substituted for those named. AllPractices or guidelines are intended to be consistent with applicable laws andregulations including OSHA requirements. To the extent these Practices or guidelinesshould conflict with OSHA or other applicable laws or regulations, such laws orregulations must be followed. Consult an appropriate professional before applying oracting on any material contained in or suggested by the Practice.

This Practice is subject to revision at any time by the responsible Function Teamand will be reviewed every 5 years. This Practice will be revised, reaffirmed, orwithdrawn. Information on whether this Practice has been revised may be found atwww.pip.org.

© Process Industry Practices (PIP), Construction Industry Institute, TheUniversity of Texas at Austin, 3925 West Braker Lane (R4500), Austin,Texas 78759. PIP member companies and subscribers may copy this Practicefor their internal use. Changes, overlays, addenda, or modifications of anykind are not permitted within any PIP Practice without the express writtenauthorization of PIP.

PIP will not consider requests for interpretations (inquiries) for this Practice.

PRINTING HISTORYOctober 1995 IssuedMarch 2003 Complete Revision

Not printed with State funds

COMPLETE REVISIONMarch 2003

Process Industry Practices Page 1 of 24

Process Industry PracticesProcess Control

PIP PCCCV001Selection of Control Valves

Table of Contents

1. Introduction.................................21.1 Purpose ............................................. 21.2 Scope................................................. 2

2. References ..................................22.1 Process Industry Practices ................ 22.2 Industry Codes and Standards .......... 22.3 Government Regulations ................... 3

3. Definitions...................................4

4. Body - General ............................5

5. Globe Valves...............................7

6. Rotary Valves..............................9

7. Trim............................................10

8. Bonnet .......................................118.1 General ............................................ 118.2 Gaskets............................................ 128.3 Packing ............................................ 128.4 Bolting.............................................. 13

9. Sizing Considerations..............149.1 General ............................................ 14

9.2 Pressure-Drop Determination forNonpumped Systems ...................... 14

9.3 Pressure-Drop Determination forPumped Systems............................. 15

9.4 Secondary Control Valves ............... 159.5 Operating Range ............................. 15

10.Noise Considerations .............. 15

11.Actuator .................................... 1711.1 General ............................................ 1711.2 Diaphragm Actuator......................... 1911.3 Piston and Vane Actuators .............. 2011.4 Volume Tank ................................... 20

12.Positioner/Current-to-PneumaticTransducer (I/P)........................ 21

13.Accessories .............................. 2113.1 Handwheel Operator........................ 2113.2 Limit Switches and Solenoid Valves 22

14.Marking, Identification, andNameplate ................................. 23

PIP PCCCV001 COMPLETE REVISIONSelection of Control Valves March 2003

Page 2 of 24 Process Industry Practices

1. Introduction

1.1 Purpose

This Practice provides designers and vendors the requirements for the selection andsizing of control valves.

1.2 Scope

This Practice specifies requirements for selection and sizing of pneumaticallyactuated control valves, including requirements for body, bonnet, trim, actuator,accessories, and noise considerations. This Practice, along with a completedPIP PCSCV001, PIP PCECV001, and the individual control valve data sheets (i.e.,ISA20 or equivalent), defines the minimum requirements for selection, materials,construction, and installation of control valves. This Practice does not coverrequirements for motor-operated valves, on-off valves intended for emergencyisolation, or valves with hydraulic actuators.

Comment: The intention is that the owner will fill out the PIP PCSCV001control valve specification sheet to define company and locationgeneric requirements for control valves.

This document is a complete revision of PIP PCCCV001, and therefore, revisionmarkings are not provided.

2. References

Applicable requirements in the latest edition (or the edition indicated) of the followingstandards shall be considered an integral part of this Practice. Short titles will be used hereinwhen appropriate. The owner shall be informed if portions of this Practice do not complywith referenced codes, standards, and regulations.

2.1 Process Industry Practices (PIP)

– PIP PCECV001 - Guidelines for Application of Control Valves

– PIP PCSCV001 - Specification of Control Valves

– PIP PCSIP001 - Instrument Piping and Tubing Systems Specifications

2.2 Industry Codes and Standards

• American Society for Mechanical Engineers (ASME)

– Boiler and Pressure Vessel Code, Section VIII, Division 1

– ASME B16.5 - Pipe Flanges and Flanged Fittings

– ASME B31.3 - Process Piping

• Fluid Controls Institute Inc. (FCI)

– ANSI/FCI 70-2- Control Valve Seat Leakage

COMPLETE REVISION PIP PCCCV001March 2003 Selection of Control Valves


• The Instrumentation, Systems, and Automation Society (ISA)

– ISA20 - Specification Forms for Process Measurement and ControlInstruments, Primary Elements, and Control Valves

– ISA75.03 - Face-to-Face Dimensions for Integral Flanged Globe-StyleControl Valve Bodies (ANSI Classes 125, 150, 250, 300, and 600)

– ANSI/ISA75.04 - Face-to-Face Dimensions for Flangeless Control Valves(ANSI Classes 150, 300, and 600)

– ANSI/ISA75.05.01 - Control Valve Terminology

– ANSI/ISA 75.08 - Installed Face-to-Face Dimensions for Flanged Clamp orPinch Valves

– ISA 75.08.04 - Face-to-Face Dimensions for Buttweld-End Globe-StyleControl Valves (Class 4500)

– ISA 75.08.07 - Face-to-Face Dimensions for Separable Flanged Globe-StyleControl Valves (ANSI Classes 150, 300, and 600)

– ANSI/ISA 75.15 - Face-to-Face Dimensions for Buttweld-End Globe-StyleControl Valves (ANSI Classes 150, 300, 600, 900, 1500, and 2500)

– ANSI/ISA 75.16 - Face-to-Face Dimensions for Flanged Globe-Style ControlValve Bodies (ANSI Classes 900, 1500, and 2500)

– ISA 75.17 - Control Valve Aerodynamic Noise Prediction

– ANSI/ISA 75.22 - Face-to-Centerline Dimensions for Flanged Globe-StyleAngle Control Valve Bodies (ANSI Classes 150, 300, and 600)

• International Electrotechnical Commission (IEC)

– IEC 60534-8-3 - Industrial-Process Control Valves, Part 8, NoiseConsiderations, Section 8: Control Valve Aerodynamic Noise PredictionMethod

– IEC 60534-8-4 - Industrial Process Control Valves, Part 8, NoiseConsiderations, Section 8: Prediction of Noise Generated by HydrodynamicFlow

2.3 Government Regulations

• U. S. Environmental Protection Agency (EPA) Code of Federal Regulations(CFR)

– EPA 40 CFR, Part 60, Appendix A, Attachment 1, Reference Method 21 -Determination of Volatile Organic Compound Leaks

– EPA 40 CFR, Part 61 - Monitoring Requirements

– EPA 40 CFR, Part 63, Subpart H - National Emissions Standard for OrganicHazardous Air Pollutants from Synthetic Organic Chemical ManufacturingIndustry Equipment Leaks

• U. S. Occupational Safety and Health Administration (OSHA)

– OSHA 1910.95 - Occupational Noise Exposure



3. Definitions

The following terms and their definitions are derived from ANSI/ISA75.05.01:

ball valve: a valve with a rotary motion closure member consisting of a full ball or asegmented ball

butterfly valve: a valve with a circular body and a rotary motion disk closure member,pivotally supported by its stem

closure member: the movable part of the valve that is positioned in the flow path to modulatethe rate of flow through the valve. Examples include the plug for a plug valve, the disk for abutterfly valve, and the ball for a ball valve.

eccentric rotary disk: a spherical segment in a rotary motion valve that is not concentric withthe disk shaft and moves into the seat when closing

equal percentage characteristic: an inherent flow characteristic, which, for equal incrementsof rated travel, will ideally give equal percentage changes of the existing flow coefficient(Cv)

flangeless control valve: a valve without integral line flanges, which is installed by boltingbetween companion flanges, with a set of bolts, or studs, generally extending through thecompanion flanges

full ball: a closure member having a complete spherical surface with a flow passage throughit. The flow passage may be round, contoured, or otherwise modified to yield a desired flowcharacteristic.

globe body: a valve body distinguished by a globular-shaped cavity around the port region,wherein the closure member motion is linear and normal to the plane of the port

lugged body: a thin annular section body with lug protrusions on the outside diameter of thebody, having end surfaces mounted between the pipeline flanges or attached to the end of thepipeline without any additional flange or retaining parts, using either through bolting and/ortapped holes

plug valve: a valve with a closure member that may be cylindrical, conical, or a sphericalsegment

segmented ball: a closure member that is a segment of a spherical surface, which may haveone edge contoured to yield a desired flow characteristic

travel: the movement of the closure member from the closed position to an intermediate orthe rated full open position

wafer body: A thin annular section butterfly body having end surfaces located between thepiping flanges and clamped there by bolts extending from flange to flange



4. Body - General

4.1 Material, end connections, pressure rating, gaskets, and packing of valve body shall,as a minimum, conform to the applicable piping specification. The materialsengineer shall approve any deviation from the piping specification.

Comment: Special alloy bodies that differ from the piping specification may berequired in conditions such as high temperature, severeerosion/corrosion, or critical applications such as oxygen.

4.2 Valves shall not be cast iron. Carbon steel shall be the minimally acceptable materialon control valve bodies.

4.3 Control valves in flashing water service require harden body material such as5 Cr-1/2 Mo.

4.4 Ratio of nominal pipe size to body size shall not be greater than 2:1.

4.5 Valves 1 inch and larger shall not be screwed.

4.6 Valves with welded end connections shall be approved by the owner.

Comment: Welded valves are often used in high-pressure steam applicationsand in high-temperature applications.

4.7 Flanged connections shall be required in the following services:

• Flammable, toxic, or lethal services

• Services above 400ºF

• Where subject to deep thermal cycling

• Where steam pressure is greater than 50 psig

• Where fire-safe design is required

4.8 Control valve body size shall not exceed the line size.

4.9 Body sizes 1-1/4, 2-1/2, 3-1/2, 5, or higher odd numbers shall not be used. If valvecalculations indicate a requirement for such sizes, reduced trim shall be used instandard size valve bodies, i.e., NPS 3 valve with 2-1/2-inch trim.

4.10 Face-to-face dimensions of valve body shall conform to ISA standards in accordancewith the following Table 1:

Table 1 - Valve Body Face-to-Face Dimensions

Body Style ISA StandardGlobe-style with integral flanges ISA75.03 or ANSI/ISA75.16

depending on ANSI class ratingGlobe-style with separable flanges ISA75.08.07Flangeless ISA75.04Buttweld-end globe ISA75.08.04 or ANSI/ISA 75.15

depending on ANSI class ratingGlobe-style angle flanges ISA75.22

4.11 Flanged connections shall be raised face (RF), conforming to ASME B16.5.



4.12 Flanges with tag welds or flanges with partial penetration welding are notacceptable.

4.13 Flangeless valves shall have centering means (e.g., lugs, holes, or equivalent) toensure proper alignment of valve and gasket. Valve body gasket surface areas shallbe the same as that of the mating flanges.

4.14 Separable flanges must be approved by the owner. The manufacture shall supply apermanent, yellow tag on the valves with separable flanges that can rotate when thebolts are loosened. The tag shall be inscribed with the following statement:

“Warning - This valve has separable flanges and may rotate when bolts areloosened. The actuator must be supported before loosening the bolts.”

4.15 If separable flanges are specified, the flange-retaining ring shall be zinc-plated orshall be made of stainless steel.

4.16 Welding procedures, performance of welders, and welding operators shall meet therequirements of ASME B31.3.

4.17 Only valves in critical applications that require minimum leakage shall haveANSI Class VI seat leakage rating. Valves with this seat leakage rating shall besubmitted to the owner for approval before they are incorporated into the design.

4.18 Flow direction, where applicable, shall be permanently marked on the valve body.

4.19 Mechanically linked valves shall not be used for split process flows in lieu of three-way valves.

4.20 Severe service valves (e.g., globe or angle with hardened trim, specially designedmulti-hole/path cavitation trim, or noise abatement trim) shall be used forapplications where conventional valves (globe, ball, butterfly, etc.) are notappropriate because of loss of control characteristics over time. Examples ofconditions where severe service valves shall be considered are as follows:

• Liquid valves

Cavitation potential exists: (P1-P2)/(P1-Pv) > 0.6

Application is a flashing service: (P2 < Pv)

• Gas valves

(P1-P2)/P1 > 0.5

where

P1 is the upstream pressure;

P2 is the downstream pressure;

Pv is the vapor pressure of the process fluid at flowing temperature.



4.21 Severe service valves shall be used in the following service applications:

• Intermittent letdown (e.g., high-noise, errosive service) in daily service

• Recirculation in daily service where cavitation is predicted

• Where high vibration and/or high noise is expected from the application

• Where history of valve failures or need for severe service trim exists

5. Globe Valves

5.1 Globe valves are acceptable for all applications and pressure classes listed inTable 2, as follows.



Table 2 - Acceptable Applications for Valve Body Types

Body Type (Note 1)

ProcessCharacteristic

Valve ANSIFlangeRating

(Note 2)

Globe(Straight)

Globe(Angle)

WaferEccentric

Disc

RotaryE-Disc /

SegmentalBall

Ball andPlug

A. Process Gas or Liquid

= 150 M,S,O --- M,O M,S,O S,O

= 300 M,S,O --- M,O M,S,O S,O

= 600 M,S,O --- --- M,S,O ---

1. Clean service(liquid - nocavitation orflashing)(Note 4)

> 900 M,S,O --- --- --- ---

B. Process Liquid

= 150 M,S,O M --- --- ---

= 300 M,S,O M --- --- ---

= 600 M,S,O M --- --- ---

1. Clean service(cavitation orflashingcondition)

> 900 M,S,O M --- --- ---

= 150 --- M,S --- M,S(Note 6)

S,O(Note 7)

= 300 --- M,S --- M,S(Note 6)

S,O(Note 7)

= 600 --- M,S --- M,S(Note 6)

---

2. Suspendedsolids(erosive)(Note 3)

> 900 --- M,S --- --- ---

= 150 M,S,O --- --- M,S,O M,S,O(Note 8)

= 300 M,S,O --- --- M,S,O M,S,O(Note 8)

= 600 M,S,O --- --- M,S,O ---

3. Corrosive

> 900 M,S,O --- --- --- ---

= 150 --- --- --- M,S,O M,S,O

= 300 --- --- --- M,S,O M,S,O

= 600 --- --- --- M,S,O ---

4. Viscous ornonerosiveslurry

> 900 --- --- --- --- ---

Notes:1. "M" indicates valves that are acceptable for modulating service;

"S" indicates valves that are acceptable for shutdown service;"O" indicates valves that are acceptable for on/off service.

2. The ANSI flange rating relates to the pipe flanges for flangeless valves.3. Valve selection for nonerosive suspended solids service is the same as that for process gas or liquid

(A1).4. Utility (steam, air, water) valve selection is the same as that for process gas or liquid (A1 and B1).5. Control valves used in streams that have a combination of the above process characteristics or

process characteristics not listed shall be selected according to project requirements.6. Valve must be installed in accordance with the manufacturer's recommendation.7. Full port valves only.8. Plug valves are acceptable in corrosive service. Ball valves are not typically available in corrosion-

resistant materials.



5.2 Single-seated globe valves are required unless otherwise approved by the owner.

5.3 Cage guiding shall not be used in applications with suspended solids. Globe valvesshall be used for high-pressure-drop applications, low-flow applications, clean liquidand gas service applications (corrosive and non-corrosive), and clean liquid service,particularly where cavitation, flashing, or noise are design considerations.

5.4 Globe valves with split bodies shall not be used unless otherwise approved by theowner.

5.5 To reduce the exit velocity of the valve and to dissipate energy, control valve bodiesin the following applications shall be no smaller than one size less than line size.

Comment: The proper reduced trim size must also be specified in these severeservice applications:

• To reduce the valve body liquid flow velocity below amaximum of 33 ft/sec

• To reduce the valve body gas/vapor outlet velocity below amaximum of 0.3 Mach

• When the calculated noise not including special noise trim orother noise reduction methods exceeds the maximumcontinuous operating noise level entered on PIP PCSCV001data sheet.

Comment: Velocity must be below 0.3 Mach foreffective noise treatment.

• Choked flow services

• Flashing services

• Erosive services maximum velocity shall not exceed 20 ft/sec

6. Rotary Valves

6.1 Rotary valves include all types of ball or plug valves (e.g., ball, segmented ball) andbutterfly valves (e.g., eccentric disk). Rotary valves are acceptable for allapplications and pressure classes listed in Table 2.

6.2 Rotary valves in applications where cavitation or high-noise conditions are presentrequire approval by owner. These applications normally use a globe valve.

6.3 Flangeless valves shall have centering guides to ensure proper alignment of valveand gasket.

6.4 Flangeless and wafer-style valves shall not be used in toxic and/or highly corrosiveservices.

6.5 Flangeless valves that exceed a body width of 5-1/2 inches shall be subject to ownerapproval. Lugged body flanges shall be through-bolted. Threaded lugged flangesrequire owner approval.

6.6 Unless otherwise specified, the valve shaft shall be oriented in the horizontal plane.



6.7 Rotary valves shall be designed such that a mechanical failure will not expel theshaft of the stem from the valve body.

Comment: When the stem breaks and is expelled from the valve, a leak pathdevelops that is equal to the cross section of the stem. This failurescenario has caused considerable damage to plants. Sincemaintenance may remove the actuator while under pressure, thepreferred mechanism to retain the stem should be independent of theactuator. If the actuator is used to retain the stem, the valve shallhave a tag that states this possibility as a warning statement.

6.8 The actuator end of the valve stem shall be the spline or keyed design. Shear pins arenot acceptable. Shafts shall be made of one piece. The shear safety factor shall be aminimum of 150% at the specified shutoff-pressure-drop condition. The valve stembearing shall be designed to prevent the stem guide bushing from rotating in thevalve body. Bearing material shall be selected to prevent galling of the bearing orvalve stem.

6.9 The valve shaft bearing shall be designed to prevent the shaft guide bushing fromrotating in the valve body.

6.10 Bearing material shall be selected to prevent galling of the bearing or valve shaft andto operate at the maximum and minimum process temperatures.

6.11 The valve disk and shaft for lined, carbon steel, and stainless steel valves shall bemade of stainless steel. Other trim parts shall also be made of stainless steel, as aminimum, or of material that meets the process requirements.

6.12 Because the disk in wafer-style valves may project beyond the valve body duringpart of the disk rotation, clearance shall be maintained between the disk and the pipewall, particularly if the pipe is of heavy wall construction.

7. Trim

7.1 For maximum allowable control valve seat leakage, refer to PIP PCSCV001 controlvalve specification sheet. On individual valves, the maximum allowable seat leakageANSI/FCI 70-2 Class shall be stated on the individual control valve data sheet.

7.2 Control valves that must provide a tight shutoff (TSO) shall be an ANSI/FCI 70-2Class V or better. The actual leakage rate shall be communicated to the processengineer for approval.

Comment: This requirement does not pertain to isolation valves and safetyvalves. Leakage requirement for these valves must be definedindividually by process requirements.

7.3 Because of close tolerances between the cage and plug, cage trim valves shall beused only in clean liquid, vapor, or gas service.

7.4 Cage-guided trim in dirty services shall be subject to owner approval.

7.5 Trim shall be 13 Cr (400 series SS) as a minimum for control valves with cage-guided design and for other valves where such metallurgy is of standardconstruction.



7.6 Trim for valves in services that contain erosive or solids-bearing fluids shall behardened with a minimum hardness of 38 Rockwell C.

7.7 Trim material shall meet the requirements of Table 3 as a minimum.

Table 3 Hardened Trim Applications

Flowing dP psid Gases Steam Water HC Liquids

0-100 1 2 1 1

100-200 1 2 4 2

200-400 1 2 4 4

500-600 1 3 4 4

600-800 1 3 4 4

800-up 1 3 4 4

1 = Manufacture’s standard valve trim (316 or 400 seriesstainless minimum)

2 = 400 series stainless minimum3 = Stellite trim (alloy 6 or 316/alloy 6 overlay for the seat

ring and plug)4 = Standard trim 400 series stainless or hard-faced stellite

unless valve is cavitating or flashing.• If cavitating, use anti-cavitating trim or harden trim

according to the manufacturer’srecommendation.

• If flashing, use harden trim (stellite, 440C, orColmonoy® 6)

7.8 Valve stem and plug shall be pinned and welded or be of a one-piece design.

7.9 Threaded trim parts, except seat rings, shall be pinned or spot-welded to supplementthe threaded attachment.

7.10 In erosive or corrosive services, self-flushing valves shall be preferred instead ofpermanent flushing connections built into the control valve.

7.11 Permanent flushing connections shall be subject to owner approval.

7.12 Valves that require cavitation or noise trim shall be submitted to the owner forapproval. Do not use small passage cavitation/noise trim on processes that containparticulates, solids, or plugging material.

Comment: To avoid plugging, conical strainers shall be considered forinstallation upstream of valves with anti-noise or anti-cavitationtrim.

7.13 If operating temperature exceeds 700°F, guide post areas and rings shall be hard-faced stellite or equivalent.

8. Bonnet

8.1 General

8.1.1 The bonnet shall have a bolted design.

8.1.2 Extended or finned bonnet shall be used for service temperatures below 0°Fand above 750°F.



Comment: Extended bonnets may be avoided in processes above 400°Fand below 750°F if graphite-based or other high-temperaturepacking is used.

8.1.3 Bonnet bolts shall not be used to attach actuators or mounting brackets.

8.2 Gaskets

8.2.1 Default bonnet gasket material shall be as specified on the PIP PCSCV001control valve specification sheet.

8.2.2 Bonnet gasket shall be compatible with the process, the maximumtemperature, and maximum pressure. The gasket material shall be incompliance with the piping specification.

8.2.3 Gaskets containing asbestos are unacceptable.

8.2.4 If the valve is required to be fire safe, the following materials are consideredfire safe:

• Metal gaskets

• Flexible graphite gaskets

8.3 Packing

8.3.1. Packing material shall be compatible with piping specification.

8.3.1.1 Packing shall not require lubrication.

8.3.1.2 The cooling effects from use of an extended bonnet shall not betaken into account when selecting the packing.

8.3.1.3 Packing material containing asbestos is unacceptable.

8.3.1.4 For applications in temperatures above 750°F, an extended bonnetshall be used to protect the positioner and actuator from heat.

8.3.1.5 See the PIP PCSCV001 control valve specification sheet for packingtype for non-fugitive emission and fugitive emission versus processtemperature.

8.3.1.6 Packing shall conform to vendor’s sizing and selection criteria fortemperature/pressure curves. The packing material shall be incompliance with the piping specification.

8.3.1.7 For fire-safe applications, graphite-based packing shall be used.

8.3.1.8 Bellow seals shall require owner approval.

8.3.2 Fugitive emissions considerations are as follows:

8.3.2.1 Packing shall limit fugitive emissions. Fugitive emissions of anysubstance containing more than 5% by weight of volatile hazardousair pollutant as defined in the EPA 40 CFR, Part 63, shall be limitedin accordance with the applicable local regulation or limited to amaximum of 500 parts per million, whichever is more stringent.



8.3.2.2 Determination of leaks and monitoring requirements shall complywith EPA 40 CFR, Parts 60 and 61, respectively.

Comment: Methods of meeting the above-mentionedrequirement include application of twin packingdesigns, live-loaded packing, and bellows seals.Bellows seals, while relatively expensive, should beconsidered for cases in which no leakage across thestem can be tolerated or for cases in which excessivepacking friction results in unreasonably largepacking friction forces.

Comment: Increased emphasis on limiting packing leaks hasresulted in the development of new packingmaterials and methods. Valve vendors are offeringincreasingly effective designs, and they should beconsulted for recommendations on specific fugitiveemission control applications.

Comment: To meet fugitive emissions, the stem should befinished to a maximum of 8 microinches RMS.Smooth finish assists in reducing fugitive emissionsover service life of control valve.

8.3.2.3 Packing design shall be approved by the owner beforeimplementation.

8.3.2.4 Control valves shall be designed, selected, and installed to permiteasy access of monitoring packing areas prone to fugitive emissionswithout removing equipment or devices.

8.3.2.5 PIP PCSCV001 control valve specification sheet, which indicatesthe testing criteria, identifies whether fire-safe packing is required.

8.4 Bolting

8.4.1 Vendor-recommended bonnet bolts shall be used unless owner specifiesdifferently.

8.4.2 Valve bonnets shall be bolted type with a retained-type gasket.

8.4.3 Plated bolting material shall not be used for pressure-containing parts.

8.4.5 The following valve components shall be 304 or 316 SS minimum:

• Gland studs and nut (e.g., packing bolts)

• Packing flange and follower

8.4.6 Packing glands and followers shall be bolted for valves larger than 1 inch.

8.4.7 Carbon steel screwed packing followers shall not be acceptable.



9. Sizing Considerations

9.1 General

9.1.1 Valve-sizing procedure shall address the full range of expected flowconditions. Appropriate differential pressure shall be applied as loadchanges. Flow equations specified in PIP PCSCV001 control valvespecification sheet shall be used.

9.1.2 When sizing a valve, only the characteristcs of the plug shall be consideredfor an accurate understanding of the plug stroke at the various conditions. Apositioner with characterization such as equal percentage may be used ontrim with an inherent linear characterization to enhance control.

9.1.3 Linear trim design shall be preferred if pressure drop across valve does notvary more than 20% between maximum flow and minimum flow; i.e.,dP(max flow) – dP(min flow)/dP(min flow)<20%. This practice typicallyachieves an installed linear characteristic. If the linear valve does not havesufficient rangeablilty to meet the minimum and maximum conditions, anequal percentage valve is prefered.

9.1.4 The manufacturer shall be consulted in sizing of a two-phase, liquid-vapormixture.

9.1.5 Body outlet velocity, defined as the fluid velocity at the discharge flange of acontrol valve, shall not exceed the following:

• 0.3 Mach for gas, vapor, and steam services except in vacuum services

• 0.4 Mach for infrequent services (i.e., services for which the controlvalve is closed for more than 4 hours during an 8-hour shift, includingemergency vent and emergency depressurizing services)

• 33 ft/sec for liquid services other than water

• 18 ft/sec for water service

• 20 ft/sec for erosive fluid (e.g., those that contain errosive particles)

Comment: Oversized control valve bodies with reduced trim may berequired to meet these limits.

Comment: If manufacturer’s plug guiding or construction governsmaximum allowable velocities, manufacturer’srecommended lower velocities shall be used.

9.1.6 Final valve sizing shall be confirmed by valve manufacturer and shall beapproved by owner.

9.2 Pressure-Drop Determination for Nonpumped Systems

Control valves shall be sized for a minimum pressure drop of 20% of variable systempressure drop, excluding drop across control valves.



9.3 Pressure-Drop Determination for Pumped Systems

9.3.1 The pressure drop shall be adequate to provide control at all processconditions including start-up.

9.3.2 Primary control valves shall have a minimum pressure drop that is thegreater of the following:

• 15 psi

• A minimum of 30% of the total system pressure drop (defined assystem frictional pipe losses) excluding the pressure drop across thecontrol valve at pump-rated flow

9.4 Secondary Control Valves

9.4.1 Secondary control valves (e.g., temperature control valve at inlet toexchanger) shall have a minimum pressure drop that is the greater of thefollowing:

• 5 psi

• 20% of exchanger pressure drop in fouled condition at maximumoperating flow rate

Comment: The “secondary” control valve is defined as the valve thatindividually controls sub-systems of a major system such asstreams to multiple exchangers, streams to multiple heaters,or boilers. Typically, the primary and secondary controlvalves will be in series with a header or similarconfiguration. As an example, the main pump dischargefeeds into a header via a “primary” control valve, and theflow is split into multiple streams via a “secondary” controlvalve.

9.5 Operating Range

9.5.1 Operating ranges for linear motion and rotary valve types shall comply withthe following:

• The Cv of control valve through all conditions shall be sized to operatewithin 15% through 80% of maximum rated Cv of the control valve.

• Stem travel/rotation at normal design flow conditions shall be within40% through 65%.

10. Noise Considerations

10.1 Noise level produced by control valves shall conform to the limits identified on thein PIP PCSCV001 control valve specification sheet. The noise level is based on1 meter downstream and 1 meter from the surface of the attached piping. Thesecalculations shall include all process conditions as stated on the data sheet formaximum, normal, and minimum flow.



Comment: OSHA 1910.95 defines a maximum allowable equivalent noise dose,which is based on the noise level and the length of exposure time tothis level during an operating shift.

10.2 Control valve noise calculations shall be performed for all control valves. Foraerodynamic noise of gases, steam, or vapor, ISA 75.17 or IEC 60534-8-3calculations shall be used. For hydrodynamic noise, the vendor method orIEC 60534-8-4 shall be used.

10.3 For the noise calculations to be valid, the maximum valve body exit velocity must bebelow 0.3 Mach.

10.4 Noise emissions shall not exceed the limits stated on PIP PCSCV001 control valvespecification sheet for the following conditions, which are the definitions of termsused in the noise section of PIP PCSCV001 control valve specification sheet:

• Continuous: Operation is for more than 2 hours per shift.

• Infrequent: Each occurrence is less than 30 minutes in duration. Totalcumulative effect of each occurrence shall be less than 2 hours per year (e.g.,emergency and relief conditions).

• Intermittent: Each occurrence is no more than 2 hours per shift or includesstartups and shutdowns.

• Remote: These are areas in which personnel are not normally present duringperiods of higher noise emission (e.g., tank farm, flare line).

• Normally attended: These include fence line areas to publicly travel areas,areas bordering residential areas, and normally traveled areas within the plant.More stringent noise criteria may need to be applied to these applications on acase-by-case basis.

10.5 The control valve vendor shall advise the owner if the calculated noise level exceedsthe 85 dB(A) value as stated on the PIP PCSCV001 control valve specification sheet.

10.6 Calculated noise level shall not exceed 110 dB(A). The control valve manufacturershall be consulted to verify that the control valve will perform correctly for theexpected duration with no damage at noise greater than 100 dB(A).

10.7 Control valve noise shall be treated at the source except as noted below. Theprovision of low-noise multipath-multistage trim designs is required because itreduces noise at multiple operating points. Diffusers, baffle plates, and silencers,either inside the valve body or downstream of the valve, shall not be permitted forthe following applications:

• Process control/feed regulation

• Continuous letdown

• Intermittent letdown in daily service

• Recirculation in daily service

Comment: For other applications, special attention shall be given to thepossible limited flow ranges of these devices (i.e., noise reduction



from these devices is generally reduced at low-flow conditions).Noise generated by diffusers or baffle plates shall be calculated withISA 75.17 or with IEC 60534-8-3 as a separate system from thevalve trim and included in the overall noise source. If a diffuser isbeing considered, then the noise level shall be calculated at half thedesign flow.

10.8 Hardened materials in trim design shall be used to assist in prolonging the life of thecontrol valve.

11. Actuator

11.1 General

11.1.1 Unless otherwise specified, valve actuator shall be pneumatic diaphragm-type or piston-type. Vane and other type actuators may be appropriate forrotary-type valves.

Comment: Use of electric motor or electro-hydraulic actuator may beconsidered for special applications, particularly if pneumaticpower is not available or if very high thrust forces arerequired.

11.1.2 The actuator shall drive the valve to a safe position on loss of signal ormotive power. The actuator shall have an enclosed spring to achieve fail-safeaction. Valve failure position shall comply with owner-approved P&IDs andthe control valve data sheet. When sizing the spring, the process pressureshall not be considered if this pressure assists in achieving the fail-safeposition.

Comment: Using an actuator having an enclosed spring design providesthe most reliable fail-safe operating parameter. If fail-safeposition cannot be ensured by an enclosed spring, volumetanks may be used with prior owner approval to provide thenecessary motive power.

11.1.3 The actuator shall be sized to meet control, shutoff, and leakage class at theminimum instrument air pressure identified on the PIP PCSCV001 controlvalve specification sheet

Comment: Valves that must shut off against reverse flow shall beidentified on the individual control valve data sheet, and theactuator shall be sized appropriately.

11.1.4 PIP PCSCV001 control valve specification sheet identifies the shutoffcriteria for valves on the loss of motive force (e.g., air supply) as follows:

• The shutoff classification must be met with spring force only. Thespring must be sufficient to maintain shutoff classification atmaximum delta P on loss of motive force.

• On loss of motive force, the valve shall return to required end positionusing spring force only. Air assistance may be used in conjunction



with spring force to maintain shutoff classification at maximumdelta P.

• On loss of motive force the valve shall return to required end positionusing spring force only. Process pressure assistance may be consideredin conjunction with spring force to maintain shutoff classification atmaximum delta P.

11.1.5 Sufficient actuator thrusts, tubing diameter, and accessories sizes shall beprovided to minimize the dead band, hysteresis, frequency response, andspeed of response at all process conditions.

11.1.6 Actuators shall be sized for positioning the closure member against aminimum of the maximum differential pressure at all process conditionsunless otherwise specified in PIP PCSCV001. Maximum differentialpressure shall be considered the maximum upstream pressure with thecontrol valve fully closed and downstream pressure at atmospheric pressure.If there is a vacuum on the control valve outlet, then the maximum vacuumpressure on the valve outlet shall be used to determine the maximumdifferential pressure

11.1.7 Valves in services that cause the control valve stem to stick shall have theactuator sized with a 1.25 design factor.

11.1.8 For rotary valve actuator, the vendor shall confirm the breakout torquerequirements and the maximum percentage opening limit for stableoperation.

11.1.9 The actuator case shall be rated for the maximum available pneumaticsupply pressure.

11.1.10 The actuator material of construction shall be the vendor’s standard material.

11.1.11 Valve yokes shall be nodular iron, high-tensile-strength cast iron, or steelunless specified otherwise in the individual control valve data sheet.

11.1.12 Springs, internal parts, fasteners, and hardware shall be resistant to thecorrosive effects of the environment.

11.1.13 The actuator exterior shall be painted with the vendor’s standard paint andcolor, unless specified otherwise.

11.1.14 The sliding stem actuator shall have a valve position indicator that showsposition of valve stem against a full travel linear scale.

11.1.15 A travel indicator, graduated in opening percentages, shall be attached to therotary valve actuator end of the shaft.

11.1.16 The actuator and associated accessories shall be assembled, piped, andmounted on the control valve and aligned, tested, and shipped as a completeunit.

11.1.17 The designer shall coordinate the installation and orientation of valveaccessories with the vendor before final assembly and shipment.



11.1.18 Refer to PIP PCSIP001 for piping and tubing specifications. Tubing shall besized to meet the required valve stroke response time.

11.1.19 The actuator shall have a permanently attached stainless steel tag. The tagshall be stamped with the vendor’s standard data and the owner’s itemnumber.

11.1.20 The valve vendor shall supply filter or filter/regulator, whichever isapplicable according to the control valve data sheet.

11.2 Diaphragm Actuator

11.2.1. Nominal diaphragm spring ranges shall be 3 to 15 psig or 6 to 30 psig.

Comment: Although some applications will allow the use of actuatorsthat stroke over the input range of from 3 to 15 psig, higherdiaphragm pressures often will be required. Generally, thevalve should be specified to control and provide thenecessary shutoff force with a 6- to 30-psig diaphragmpressure range.

11.2.2 If the control valve is not provided with a positioner, instrument air supplyshall be regulated in accordance with the following:

• Instrument air supply shall be minimum of 10 psi above spring range(bench set) of actuator.

• The 10-psi requirement may be increased if additional instrument airsupply pressure may reduce actuator size or provide more force toachieve the ANSI-class leakage shutoff requirement.

• All devices in the instrument air loop for control valve assembly shallbe rated/designed for this regulated pressure, including air supplyfilter, air supply regulator, I/P, diaphragm, actuator housing, andsolenoid valves.

• If 10 psi above spring range exceeds rated/designed pressure of anycomponent, pressure for instrument air shall be regulated at the designpressure of the component having the lowest design pressure.

11.2.3 If the control valve is provided with a positioner, the instrument air supplyshall be regulated at a minimum of 5 psig above the actuator-requiredpressure to achieve fully open or closed positions (e.g., if actuator requires6-30 psig, then the supply pressure will be set at a minimum of 35 psig).

• All devices in the instrument air loop for control valve assembly shallbe rated/designed for 50 psig, including air supply filter, air supplyregulator, I/P, positioner, diaphragm, actuator housing, and solenoidvalves.

11.2.4 If 50 psig exceeds rated/designed pressure of any component, pressure forinstrument air shall be regulated at design pressure of the component that haslowest design pressure.



11.3 Piston and Vane Actuators

11.3.1 Piston and vane actuators shall be used in the following situations:

• when valve stem or shaft loading is high

• where fast valve action response is require

• where a compact physical installation is required

11.3.2 The actuator shall be designed to meet control and shutoff requirements withthe minimum available air supply.

11.3.3 Air exhaust connections shall be oriented and/or equipped to exclude orminimize the entry of water, dirt, and insects.

11.3.4 Valves with piston operators shall be sized at the minimum instrument airpressure stated in PIP PCSCV001 control valve specification sheet. Only afilter shall be provided.

11.3.5 The following shall apply for control valves:

• All devices in the instrument air loop for the control valve assemblyshall be rated/designed for instrument air header pressure, includingair supply filter (required), positioner, actuator housing, actuatorinternals, and solenoid valves.

Comment: Typically the I/P requires a separate filter/pressureregulator set at a pressure compatible to the device.

• If the instrument air header pressure exceeds the rated/designedpressure of any component (e.g., solenoid valve), the instrument airpressure shall be regulated at the design pressure of the componentthat has the lowest design pressure.

11.4 Volume Tank

11.4.1 Use of volume tank shall be approved by owner.

11.4.2 Volume tank shall be sized to fully stroke the valve through two travelcycles.

11.4.3 If the volume tank, by virtue of size, pressure rating, or local regulation mustconform to Part U-1 of Section VIII, Division 1, of the ASME Boiler andPressure Vessel Code, capacity tank shall be ASME Code stamped and beequipped with a pressure relief device.

11.4.4 Volume tank shall be equipped with the proper accessories (tubing, fittings,pressure transmitters, solenoid valves, etc.) to ensure that the valve fails inthe safe position.

Comment: The pressure transmitter is required only if identified on thePIP PCSCV001 control valve specification sheet.



12. Positioner/Current-to-Pneumatic Transducer (I/P)

12.1 A positioner shall be used on all valves unless its use would be detrimental to goodprocess control. Local pneumatic loops do not require a positioner.

12.2 The positioner shall be mounted on plates or bosses on the valve dedicated for thatpurpose.

12.3 The positioner shall be mounted, piped, and aligned by the vendor to provide acomplete control valve assembly.

12.4 The positioner shall be equipped with the manufacturer’s standard supply, input, andoutput gauges unless otherwise specified.

12.5 A positioner bypass shall be provided only if specified by the owner.

12.6 Pneumatic boosters shall be used in conjunction with positioners in applications suchas pressure control to achieve the required response time.

12.7 Positioners shall

• Use two-wire loop power.

• Provide pneumatic output signal in which range is as required by actuator.

• Meet electrical area classification where they are installed.

12.8 Digital positioners shall

• Use standard digital communication and 4-20 mA as input signal.

• Provide diagnostic functions and information through hand-heldcommunicator, laptop computer, or computer console.

12.9 Electropneumatic transducers (I/P) shall

• Convert 4 to 20 mA DC electronic signal to 3 to 15 psig output signal.

• Be configured to be direct acting rather than reverse acting.

• May be integrally mounted on control valve, with owner approval, iftransducers are rated for operating conditions, such as maximum temperatureand vibration.

• Have minimum air flow rating of 0.25 scfm.

• Meet area classification and NEMA 4X.

13. Accessories

13.1 Handwheel Operator

13.1.1 Control valves shall have a handwheel operator only if specified by theowner.



13.1.2 The handwheel operator shall be continuously connected and shall operablethrough an integral declutching mechanism.

Note: Declutchable means a shaft-mounted worm gear that can bedetached from the power of the actuator.

Comment: Handwheel operator may be side mounted, lockable, orscrew or gear driven if accessibility is not a consideration.

13.1.3 The handwheel operator on a rotary valve shall be mounted directly on theshaft, and the clutch shall be installed so that it can be declutchable.

13.1.4 Top-mounted jacks or handwheels shall not be used unless approved byowner.

13.1.5 A valve-to-open direction arrow shall be permanently marked on thehandwheel.

13.1.6 Handwheels shall not be used to eliminate block and bypass valves

13.1.7 Handwheels shall not be used as limit stops.

Comment: When handwheels are used as limit stops, the adjustmentcan be changed inappropriately.

13.2 Limit Switches and Solenoid Valves

13.2.1 General

13.2.1.1 All accessories shall be suitable for the electrical areaclassification.

13.2.1.2 Solenoid valves and limit switches shall be mounted and tubed bythe valve vendor unless directed differently by the owner. Forinstruments without terminal strips, the valve vendor shall providea terminal strip and housing.

13.2.2 Limit Switches

13.2.2.1 Unless otherwise specified, limit switches shall be hermeticallysealed.

13.2.2.2 Unless otherwise specified, limit switches shall be proximity types.

13.2.2.3 Limit switches shall be enclosed in watertight, dust-proof housings.

13.2.3 Solenoid Valves

13.2.3.1 Solenoid valves shall be rated for continuous duty and shall have aminimum of Class F high-temperature encapsulated coils; Class Hcoils are preferred.

13.2.3.2 The solenoid coil shall be molded in epoxy.

13.2.3.3 The solenoid coil shall be rated for continuous duty.

13.2.3.4 The solenoid valve for tripping the control valve shall be betweenthe positioner and actuator or in the tubing that provides the motivepower to the actuator.



13.2.3.4 Tripping the solenoid valve shall provide sufficient capacity toexhaust the actuator chamber air volume within the time required toallow the valve to fail in a safe position. If solenoid valve Cv is notsufficient, a “quick exhaust” valve shall be provided that works in“conjunction” with the tripping solenoid valve if needed.

13.2.3.5 If the solenoid valve vent port is open to the atmosphere, it shallhave an insect screen.

13.2.3.6 The solenoid valve shall be capable of switching under conditionsof maximum and minimum operating differential pressure.

13.2.3.7 Instrument air supply piping must be of adequate size to stroke thevalve in the time specified.

13.2.4 Boosters and Quick Exhaust

13.2.4.1 Boosters shall be provided when necessary to achieve the requiredstroke time. A volume booster shall be used only if approved byowner.

13.2.4.2 Instrument air supply piping to boosters must be of adequate sizenot to limit the supply to the boosters. The piping size selectionmust also include drops across filters and regulators. Normally,pipe is used for supplies. Larger pipe may be required for extensivepipe runs. The flow through the boosters must not be restricted. Insome cases, connections in the actuators must be enlarged.

13.2.4.3 Conditions may exist making it desirable for the valve to moverapidly in one direction but slower in the other. This can beaccomplished by selectively restricting one side of the booster orboosters.

13.2.5 Air Sets and Auxiliary Equipment

13.2.5.1 Air sets that are required at valves shall be rigidly mounted to valveyoke if mounting pads are provided.

13.2.5.2 Pressure gages supplied with positioners that are not enclosed inpositioner housing shall have stainless steel cases.

13.2.5.3 If approved by owner, auxiliary solenoid valves, position switchesand transmitters, and pneumatic relays associated with controlvalves may be integrally mounted on control valve.

13.2.5.4 Air sets shall not be supported by pipe nipples from positioners. Airsets for positioners bolted to control valve yoke shall be permitted.

14. Marking, Identification, and Nameplate

14.1 The direction of flow shall be marked on the valve. The flange rim of three-wayvalves shall be identified.

14.2 The trim position of rotary valves shall be engraved on the shaft end.



14.3 A permanently fastened (e.g., by stainless steel rivets) stainless steel nameplate,showing the following information, shall be provided on each control valve:

• Tag number specified on the individual control valve data sheet

• Manufacturer’s name, model number, and valve serial number

• Body material, valve size, and flange rating

• Trim material, trim size, and Cv

• Trim characteristic type

• Stem travel distance in inches

• Actuator model, size, and bench set and actuator serial number

• Actuator failure position

• Actuator maximum allowable case pressure

• Operating range (air signal to operator with valve under pressure)

• Bench setting (air signal to operator with no pressure in valve body); appliesonly to diaphragm-actuated valves

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