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1. Scope This welding specification covers the shop and field welding of the piping ,steel structures and other welding works for Sample water treatment project. Welding , testing & inspection of piping systems is performed according to ASME B31.1 Fabricating , welding and inspection of steel structures in the project is performed in accordance with AWS D1.1. One of the most important subject of a welding specifications is the procurement of welding procedure specification. For this reason, in this welding specification, a completely discussion of welding procedure specification is given. Essentially, two quite different types of welding procedure specifications are in common use. One is a broad, general type that applies to all welding of a given kind on a specific material. The other is a narrower, more definitive type that spells out in detail the welding of a single size and type of joint in a specific material or part. Only the broader, more general type is usually required by code, classification agency, customer, building, insurance, or other regulatory agencies. The narrower, more definitive type is most frequently used by manufacturers for their own control of repetitive in-plant welding operations or by purchasers desiring certain specific metallurgical, chemical or mechanical properties. The first type of welding procedure specification has been considered in this welding specification. 2. Applicable Codes, Standards & Specifications 1- ASME BPV Code Sec. IX : Welding & Brazing Qualification 2- ASME BPV Code Sec. II : Material Specifications Part A: Ferrous Materials

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Part B : Nonferrous Materials Part C : Welding Rods, Electrodes & Filler Metals 3- AWS A3.0 : Terms and Definitions

4- ASME B31.1 : Power Piping 5- ANSI / AWS : Specifications for Welding Filler Materials 5.1 ANSI / AWS A5.1: Covered Carbon Steel Arc Welding Electrodes. 5.2 ANSI / AWS A5.4: Covered Corrosion - Resisting Chromium and Chromium Nickel Steel Welding Electrodes.. 5.3 ANSI / AWS A5.5: Low Alloy Steel Covered Arc Welding Electrodes 5.4 ANSI / AWS A5.9: Corrosion Resisting Chromium & Chromium-Nickel Steel Bare & Composite Metal Cored & Stranded Welding Electrodes & Welding Rods. 5.5 ANSI/AWS A5.18: Carbon Steel Filler Metals for Gas Shielded Arc Welding. 6- ANSI / AWS D104 : Recommended Practices for Welding Austenitic Chromium- Nickel Stainless Steel Piping and Tubing. 7-AWS/ANSI D1.1: Structural welding code steel. .

3. Used Abbreviations For terms and definitions, reference is made to AWS A3.0 . WPS : Welding Procedure Specification PQR : Procedure Qualification Record WPQ : Welder’s Performance Qualification PWHT : Postweld Heat Treatment BPV : Boiler and Pressure Vessel SEC : SECTION DIV : DIVISION HAZ : Heat Affected Zone GTAW : Gas Tungsten Arc Welding NDT : Non Destructive Testing GMAW : Gas Metal Arc Welding ASME : American Society of Mechanical Engineers API : American Petroleum Institute IPS : Iranian Petroleum Standard

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AWS : American Welding Society SMAW : Shielded Metal Arc Welding DCEN : Direct Current Electrode Negative DCEP : Direct Current Electrode Positive DCRP : Direct Current Reverse polarity DCSP : Direct Current straight polarity

4. Welding Procedure Specification Many factors contribute to the end result of a welding operation, whether manual shielded metal arc welding of plain carbon steel, or gas shielded arc and electron beam welding of the superalloys.

Because of these variations, it is always desirable and often essential that the vital elements associated with the welding of joints are described in sufficient detail to permit exact reproduction and to afford a clear understanding of the intended practices by all concerned. Generally, proposed practices have to be proved adequate by either procedure qualification tests or by sufficient prior use and service experience to guarantee dependability. The purpose of a welding procedure specification is, therefore, to define and document the details that are to be carried out in welding specific materials or parts. To fulfill this purpose efficiently, welding procedure specifications should be as concise and clear as possible without extraneous detail. In this project welding procedure specifications (wps) are prepared according to ASME sec. IX. A typical form for welding procedure specification is given in Appendix A. The qualified welding procedures shall include the following: a) Welding Process: Identify the specific process utilized and whether manual, semi-automatic, or

automatic or any combination of these.

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b) Pipe & Fitting Material:

Identify the materials to which the procedure applies. All of the material is grouped under P-number.

c) Diameter Group - Wall Thickness Group: Identify the ranges of diameters and wall thickness over which the procedure is

applicable. d) Joint Design: Show by sketch the angle of bevel, size of root face, and root opening or space

between abutting members. Show the shape and size of fillet welds. Designate the type of backup if used.

e) Filler Metal (or Electrode) & Number of Beads: Designate sizes and classification number of filler metal (or electrode),

minimum number and sequence of beads. f) Electrical Characteristics: Designate current and polarity, show range of voltage and amperage for each

electrode or filler metal (rod or wire) . g) Flame Characteristics: Designate whether neutral, carburizing or oxidizing and size of orifice in torch

tip for each size of filler metal (rod or wire). h) Position: Roll or position welding. i) Direction of Welding: Show whether uphill or downhill. j) Time Lapse Between Passes: Designate maximum time between completion of root bead and start of second

bead, maximum time between the completion of second bead and start of other beads.

k) Type of Line - Up - Clamp, if Used: Show whether internal, external, or none required. l) Removal of Line - Up - Clamp: Show minimum percentage of root bead welding before release of clamp.

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m) Cleaning: Show whether power tools or hand tools used.

n) Preheat, Post Weld Heat Treatment: Specify the methods, temperature, temperature control method, ambient

temperature range. o) Shielding Gas & Flow Rate: Designate composition of gas and range of flow rate. p) Shielding Flux: Designate type and size. q) Speed of Travel: Show the range in inches (mm) per minute for each pass.

5. Procedure Qualification Record Prior to start of production welding a detailed procedure specification shall be established and qualified to demonstrate, that welds having suitable mechanical properties (such as strength, ductility and hardness) and soundness can be made by this procedure. ASME sec. IX is used for preparation of PQR(S) The quality of the welds shall be determined by destructive testing. The details of each qualified procedure shall be recorded. This record shall show complete results of the procedure qualification test. Form similar to Appendix B should be used. The procedure used in welding pressure parts and in joining load - carrying non-pressure parts, such as all permanent or temporary clips and lugs, to pressure parts shall be qualified in accordance with ASME Section IX . The procedure used in welding non-pressure - bearing attachments which have essentially no load - carrying function (such as extended heat transfer surfaces, insulation support pins, etc.), to pressure parts shall meet the following requirements:

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- When the welding process is manual, machine or semiautomatic, procedure qualification is required in accordance with ASME Section IX .

- When the welding is any automatic welding process performed in accordance

with a welding procedure specification, procedure qualification testing is not required.

5.1 Requalification of welding procedure specification A welding procedure must be re-established as a new procedure specification and must be completely re-qualified when any of the changes listed below are made in the procedure. Changes other than those given below may be made in the procedure without the necessity for requalification, provided the procedure specification is revised to show these changes. 5.1.1 Variables for SMAW a) For the multipass process, the maximum thickness qualified for 1.5 in. and over

thicknesses T of the test coupon of QW-451.1 shall be 8 inch for the conditions shown in QW-451.1. (Refer to ASME Section IX).

For thicknesses greater than 8 in. , the procedure test coupon thickness shall be not less than the thickness of the joint to be welded in production divided by 1.33, and the maximum thickness of base metal and deposited weld metal qualified is 1.33 T, or 1.33 t as applicable.

b) Change in base metal thickness beyond the range qualified in QW-451, except

as otherwise permitted by QW-202.4 (b) . (Refer to ASME Section IX ) c) For single-pass or multipass welding in which any pass is greater than 0.5 in.

thick, an increase in base metal thickness beyond 1.1 times that of the qualification test coupon.

d) Base metals specified in the WPS shall be qualified by a procedure qualification

test which was made using base metals in accordance with QW-424. (Refer to ASME Section IX)

e) Change from one P-No. 5 to any other P-No. 5 (viz P-No. 5A to P-No. 5B or P-

No. 5C or vice versa). Change from P-No. 9A to P-No. 9B but not vice versa.

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Change from one P-No. 10 to any other P-No. 10 (viz P-No. 10A to P-No. 10Bor P-No. 10C, etc. or vice versa).

f) Change from one F-No. in QW-432 to any other F-No. or to any other filler

metal not listed in QW-432. (Refer to ASME Section IX) . g) (Applicable only to ferrous metals). Change in the chemical composition of the

weld deposit from one A-No. to any other A-No. in QW-442. (Refer to ASME Section IX)

Qualification with A-No. 1 shall qualify for A-No. 2 and vice versa. h) Change in deposited weld metal thickness beyond the range qualified in

QW-451 for procedure qualification, except as otherwise permitted in QW-303.1. (Refer to ASME Section IX)

i) Decrease of more than 38C in the preheat temperature qualified. The minimum

temperature for welding shall be specified in the WPS. j) A separate PQR is required for each of the following conditions:

j-1) For P-No. 1, P-No. 3, P-No. 4, P-No. 5, P-No. 6, P-No. 9, P-No.10 and P-No. 11 materials, the following postweld heat treatment conditions apply:

1- No PWHT. 2- PWHT below the lower transformation temperature. 3- PWHT above the upper transformation temperature. (e.g. , normalizing)

4- PWHT above the upper transformation temperature followed by heat

treatment below the lower transformation temperature. (e.g., normalizing or quenching followed by tempering)

5- PWHT between the upper and lower transformation temperatures.

j-2) For all other materials, the following postweld heat treatment conditions

apply:

1- No PWHT. 2- PWHT within a specified temperature range.

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k) For test coupon (PQR) receiving a postweld heat treatment in which the upper transformation temperature is exceeded, the maximum qualified thickness for production welds is 1.1 times the thickness of the test coupon.

5.1.2 Variables for GTAW a) The same as 5.1.1. a . b) The same as 5.1.1. b. c) The same as 5.1.1. d . d) The same as 5.1.1. e. e) The same as 5.1.1. f. f) The same as 5.1.1. g . g) The deletion or addition of filler metal h) The same as 5.1.1. h. i) The same as 5.1.1. i. j) The same as 5.1.1. j. k) The same as 5.1.1. k.

l) Change from a single shielding gas to any other single shielding gas or to a

mixture of shielding gases, or change in specified percentage composition of shielding gas mixture, or omission of shielding gas.

m) The addition or deletion of gas backing, a decrease of 15% or more in the gas

backing flow rate beyond that qualified, or change in the nominal composition of the gas backing mixture beyond that qualified, for groove welds in P-No. 4X and all welds of P-No. 5X, P-No.6X, P-No. 10I, P-No. 10J, and P-No. 10K metals.

n) For P-No. 10I , P-No. 5X, and P-No. 6X metals, the deletion of trailing shielding

gas, a change in the trailing gas composition, or a decrease of 10% or more in the trailing gas flow rate.

o) Change from closed chamber to out-of-chamber conventional torch welding in

P-No. 5X metals, but not vice versa.

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6. Welder’s Performance Qualification A welder or welding operator may be qualified by radiography of a test coupon , radiography of his initial production welding, or by bend tests taken from a test coupon.Welder(s) and welding operator(s) shall be qualified according to ASME sec. IX before any welding works in the project. Each manufacturer or contractor (an assembler or an installer is to be included within this premise) shall be responsible for conducting the above tests to qualify the performance of welders and welding operators in accordance with qualified welding procedure specifications.

The purpose of this requirement is to ensure that the manufacturer of contractor has determined that his welders and welding operators using his procedures are capable of developing the minimum requirements specified for an acceptable weldment. Tests conducted by one manufacturer shall not qualify a welder or welding operator to do work for another manufacturer. However, in piping welding, an employer may accept a performance qualification made for another employer, provided that the inspector specifically approves. Acceptance is limited to qualification on piping using the same or equivalent procedure wherein the essential variables are within the limits in ASME Section IX. The employer shall obtain a copy from the previous employer of the performance qualification test record, showing the name of the employer, name of the welder or welding operator, procedure identification, date of successful qualification, and the date that the individual last used the procedure on pressure piping. The records of such tests shall be as follows: a) Each welder or welding operator shall be assigned an identifying number, letter,

or symbol by the fabrication or erection manufacturer. b) The fabrication or erection manufacturer shall maintain a record of the welders

or welding operators employed by him, showing the date and result of tests and the identifying mark assigned to each. These records shall be certified by the fabrication or erection manufacturer and shall be accessible to the inspector.

A typical form for welder’s performance qualification is given in Appendix C.

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6.1 Requalification of welder’s performance A welder shall be re-qualified whenever a change is made in one or more of the following variables listed for each welding process. Where a combination of welding processes is required to make a weldment, for example if it is used the GTAW process for the root pass and the SMAW process for the fill pass, each welder shall be qualified for the particular welding process or processes he will be required to use in production welding. A welder may be qualified by making tests with each individual welding process, or with a combination of welding processes in a single test coupon. 6.1.1 Variables for SMAW

a) The deletion of the backing in single-welded groove welds. Double - welded

groove welds are considered welding with backing. b) A change in the pipe diameter beyond the range qualified in QW-452, except as

otherwise permitted in QW-303.1 and QW-303.2. (Refer to ASME Section IX) c) A change from one P-No. to any other P-No. or to a base metal not listed in

QW-422, except as permitted in QW-423. (Refer to ASME Section IX)

d) Qualification with an F-No. 4X nickel or nickel alloy filler metal shall qualify to weld with any other F-No. 4X filler metal. (Refer to ASME Section IX)

e) A change from one F-No. in QW-432 to any other F-No. or to any other filler

metal, except qualification under any F-No. up to and including F-No. 4, shall qualify a welder for all lower F-Numbers. (Refer to ASME Section IX)

f) A change in deposited weld metal thickness beyond the range qualified in QW-

452 (Refer to ASME Section IX), except as otherwise permitted in QW-303.1 and QW-303.2 . (Refer to ASME Section IX). When a welder is qualified using radiography, the thickness ranges of QW-452.1 apply. (Refer to ASME Section IX)

g) The addition of other welding positions than those already qualified. (See

ASME Section IX, QW-120, QW-130 and QW-303) h) A change from upward to downward, or from downward to upward, in the

progression specified for any pass of a vertical weld, except that the cover or

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wash pass may be up or down. The root pass may also be run either up or down when the root pass is removed to sound weld metal in the preparation for welding the second side.

6.1.2 Variables for GTAW

a) The deletion of the backing in single-welded groove welds. Double-welded

groove welds are considered welding with backing. b) A change in the pipe diameter beyond the range qualified in QW-452 (Refer to

ASME Section IX), except as otherwise permitted in QW-303.1 and QW 303.2. (Refer to ASME Section IX)

c) A change from one P-No. to any other P-No. or to a base metal not listed in QW-

422 (Refer to ASME Section IX), except as permitted in QW-423, (Refer to ASME Section IX)

d) Qualification with an F-No. 4X nickel or nickel alloy filler metal shall qualify to

weld with any other F-No. 4X filler metal.

e) The deletion or addition of filler metal.

f) Qualification with an F-No. 2X aluminum filler metal shall qualify to weld with any other F-No. 2X filler metal.

g) The omission or addition of consumable inserts. Qualification in a single-welded butt joints, with or without consumable inserts, qualifies for fillet welds and single-welded butt joints with backing or double-welded butt joints.

h) A change from one F-No. in QW-432 to any other F-No. or to any other filler

metal not listed in QW-432 (Refer to ASME Section IX), except that deposited weld metal using a bare rod not covered by an SFA specification, which conforms to an analysis listed in QW-(Refer to ASME Section IX), shall be considered to be classified as F-No. 6.

i) A change in deposited weld metal thickness beyond the range qualified in QW-

452 (Refer to ASME Section IX) for performance qualification, except as otherwise permitted in QW-303.1 and QW-303.2 . (Refer to ASME Section IX) When a welder is qualified using radiography, the thickness ranges of QW-452.1 apply. (Refer to ASME Section IX)

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j) The addition of other welding positions than those already qualified. (See ASME Section IX, QW-120, QW-130 and QW-303)

k) A change from upward to downward, or vice versa, in the progression specified

for any pass of a vertical weld, except that the cover or wash pass may be up or down. The root pass may also be run either up or down when the root pass is removed to sound weld metal in the preparation for welding the second side.

l) The omission of inert gas backing except that requalification is not required

when welding a single-welded butt joint with a backing strip or a double-welded butt joint or a fillet weld. This exception does not apply to P-No. 5X, P-No. 6X and P-No. 10I metals.

m) A change from ac current to dc current or vice versa; and in dc current welding,

a change from straight polarity to reverse polarity, or vice versa.

7. Materials 7.1 Base metals

The types of base metals to be welding in accordance with this specification are shown in Table 1. 7.2 Welding consumable 7.2.1 Consumables for ferrous metals

Consumable electrodes / filler rods for SMAW and GTAW shall be in accordance with Table 2. 7.3 Consumable storage Conventional welding electrodes may not be suitable where X-ray quality is required, where the base metal has a tendency to crack, where thick sections are to

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the welded, or where base metal has an alloy content higher than that of mild steel. In these applications, a low-hydrogen electrode may be required. Low -hydrogen electrodes are shipped in hermetically sealed containers, which normally can be stored indefinitely without danger of moisture pick up. But once the container is opened, the electrodes should be used promptly or stored in a heated cabinet at 120 to 150C. Supplying welders with electrodes twice a shift - at the start of the shift and at lunch, for example - minimizes the danger of moisture pick up. Return electrodes to the heated cabinet for overnight storage. When containers are opened so that the electrode is exposed to the air for a few days, or when containers are stored under unusually wet conditions, low-hydrogen electrodes pick up moisture. The moisture, depending upon the amount absorbed, impairs weld quality. Re- drying completely restores ability to deposit quality welds. The proper re-drying temperature depends upon the type of electrode and its condition. General drying procedures are listed in Table 3, but recommended procedure by manufacturer of electrode shall be noted.

8. Preparation for Welding 8.1 Cleaning Internal and external surfaces of the parts to be welded shall be clean and free of scale, rust, oil, paint, grease and other deleterious foreign material for a distance of at least 1/2 inch from the welding joint preparation for ferrous materials and at least 2 inch for nonferrous materials.

Also, when weld metal is to be deposited over a previously welded surface, all slag shall be removed by a roughing tool, chisel, air chipping hammer, or other suitable means so as to prevent inclusion of impurities in the weld metal.

Cast surfaces to be welded shall be machined, chipped, or ground to remove foundry scale and to expose sound metal. 8.2 End preparation Butt weld end preparation is acceptable only if the surface is reasonably smooth and true and all slag from oxygen or arc cutting is cleaned from flame-cut surfaces.

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Discoloration which remain on a flame-cut surface is not considered to be detrimental oxidation. 8.3 Cutting, fitting & alignment

Components that are being welded shall be fitted, aligned and retained in position during the welding operation. Bars, jacks, clamps, tack welds or other appropriate means may be used to hold the edges of parts in alignment. The inside diameters of piping components to be butt welded shall be aligned as accurately as is practicable. The internal misalignment of the ends to be joined shall not exceed 2.0 mm. 8.4 Tack welding

Components that are being welded shall be accurately matched and retained in position during the welding operation. One of the method that is used for this purpose is tack welding.

The tack welds at the root of the joint shall be made with filler metal (or electrode) equivalent to that used in the root pass. Tack welds shall be fused with the root pass weld, except that which have cracked shall be removed.

Tack welds shall either be removed completely when they have served their purpose, or their stopping and starting ends shall be properly prepared by grinding or other suitable means so that they may be satisfactorily incorporated into the final weld.

Tack welds in lap and fillet welded joints need not be removed, provided they are sound and the subsequently applied weld beads are thoroughly fused into the tack welds.

Finally, tack welds, whether removed or left in place, shall be made using a fillet weld or butt weld procedure qualified in accordance with Section IX of the ASME code . Tack welds to be left in place shall be made by welders qualified in accordance with ASME Section IX and shall be examined visually for defects, and if found to be defective, shall be removed.

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9. Preheating & Interpass Temperature 9.1 General The minimum preheat temperature for all materials shall be 10 ºC unless stated

otherwise in WPS. The necessity for preheating prior to welding, and the temperature to be used, shall be established by the engineering design and demonstrated by the procedure qualification. However recommended minimum preheat temperature for the various materials which are used for project are given in Table 4. If the ambient temperature is less than 10°C, the recommended preheats in wps(50 ºC) become mandatory. The base metal temperature prior to welding shall be at or above specified minimum temperature in all directions from the point of welding for a distance of 3 in or 1.5 t, whichever is greater. 9.2 Preheating dissimilar metals When welding dissimilar metals having different preheat recommendations, the preheat temperature shall be established by the engineering design as demonstrated by the qualified welding procedure; however, the higher minimum preheat temperature for the two metals is required. 9.3 Applicability These preheat recommendations apply to all welds including butt welds, fillet welds, socket welds, repair welds, tack welds and seal welds of threaded joints. It may be necessary to avoid cold cracking of certain ferritic steels in the weld and HAZ . 9.4 Lowest permissible temperature for welding It is recommended that no welding of any kind be done when the temperature of the base metal is lower than -18C. At temperatures between 10°C and -18°C, the surface of all areas within 3 in. of the point where a weld is to be started should be heated to at least 50°C before welding .d. It is recommended that no welding be done when surfaces are wet or covered with ice, when snow is falling on the surfaces to be welded, or during periods of high wind, unless the welders or welding operators and the work are properly protected.

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9.5 Preheat requirements For preheating fuel gas / air burner systems, high-velocity gas / oil burners or infrared elements may be employed either locally or in a furnace. For preheating temperatures above 200C electric resistance or induction heating is preferred although infrared radiators are acceptable.

Temperature control may be carried out with tempil stick, digital pyrometers or contact thermometer.

10. Postweld Heat Treatment 10.1 General

Post weld heat treatment is the uniform heating of a structure or portion of a structure to a sufficient temperature, below the critical range. It is used to relieve the detrimental effects of high temperature and severe temperature gradients inherent in welding, followed by uniform cooling. It shall be done after the work, and after confirmation of the following items:

1- Smoothing up after the removal of bridge, overlap, spatters, slag, etc.

2- Visual check, finishing of uneven parts of beads.

3- Radiographic inspection of weld.

4- Any other inspection (NDT) of weld.

5- All repair work (if any) has been completed and nondestructive inspected.

10.2 PWHT methods The operation of PWHT shall be performed in accordance with the requirements given in the para 132 ANSI b 31.1 using one of the following procedures:

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10.2.1 PWHT as a whole

In this method, the equipment is heated as a whole in an enclosed furnace. This procedure is preferable and should be used whenever practicable. The heat treatment in a furnace shall conform to the followings:

1- The holding temperatures and holding times are given in the applicable

welding procedure specification or table 132 of ANSI B 31.1.

2- The temperature of the furnace shall not exceed 315°C at the time of putting in and taking out parts to be heated. 3- The rate of heating and cooling in excess of 315C shall be not more than 335C

per hr divided by 1/2 the maximum thickness of material in inches at the weld, but in no case more than 335C/hr.

4- During the heating and holding periods, the furnace atmosphere shall be so controlled as to avoid excessive oxidation of the surface of the material being treated. The furnace shall be of such design as to prevent direct impingement of the flame on the material. 5- When it is impracticable to heat treatment at the temperature range specified in

table 132 of ANSI B31.1 , it is permissible to carry out the heat treatment operation at lower temperatures for longer periods of time in accordance with the following table:

Decrease in temperature (°C)

Minimum holding time at decreased temperature

28 2 56 4 84 10

112 20

Note: For intermediate temperatures, the time of heating shall be determined by straight-line

interpolation.

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10.2.2 Local PWHT

The local operation of PWHT can be performed using one of the following procedures:

1- Heating the equipment in more than one heat in a furnace, provided the overlap of

the heated sections of the equipment is at least 150 cm. 2- Locally heating of any circumferential joints by any appropriate means that will

assure the required uniformity. The width of the heated band on each side of the greatest width of finished weld shall be not less than two times the shell thickness. This procedure may also be used to postweld heat treatment portions of new equipments after repair.

3- Heating a circumferential band containing nozzles or other welded attachments

that require PWHT in such a manner that the entire band shall be brought up uniformly to the required temperature and held for the specified time.

4- Heating the circumferential joints of pipe or tubing by any appropriate means over

a band having a width on each side of the center line of not less than three times the greatest width of the finished weld.

Note: In all of the above procedures other than the first procedure, the portion outside of the heating

band shall be protected so that the temperature gradient is not harmful.

10.3 Postweld heat treatment requirements

Postweld heat treatment shall be in accordance with the material groupings and thickness ranges according to ANSI B31.1. Postweld heat treatment to be used after production welding shall be specified in the WPS and shall be used in qualifying the welding procedure.

The engineering design shall specify the examination and/ or other production quality control to ensure that the final welds are of adequate quality. Hardness testing is used to check of the postweld heat treatment quality.

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10.4 Welds of dissimilar metals Heat treatment of welded joints between dissimilar ferritic metals or between ferritic metals with dissimilar ferritic weld metal, shall be at the higher temperature range of those ranges required in Table-5 for each material joined. Dissimilar joints including both a ferritic and an austenitic weld or component shall be heat treated according to the requirements for the ferritic material, unless otherwise specified by the engineering design.

10.5 Welds of components with different thickness

When components with different thickness are joined by welding, the thickness to be used in applying the postweld heat treatment requirements shall be that of the thicker component measured at the joint. 10.6 Temperature measurement Heat treatment temperature shall be checked by the use of thermocouple pyrometers or other suitable methods to ensure that the requirements stated in the procedure specification are accomplished. 10.7 Hardness test Hardness tests of production welds and of hot formed and hot bent piping are intended as a check to determine if heat treatment has been performed satisfactorily. Where a hardness limit is specified, a minimum of 10% of welds and of hot formed and hot bent materials in each heat treatment batch which are furnace heat treated, and 100% of those which are locally heat treated shall be hardness tested. The hardness limit applies to the weld and the heat affected zone. Hardness tests of the heat affected zone shall be made at a point as near as practicable to the edge of the weld.

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When dissimilar metals are joined by welding, the hardness limits specified for the base and welding materials shall be met for each material.

11. Welding of Stainless Steels During welding of austenitic stainless steel, heat input per weld pass shall be kept to a minimum and the interpass temperature shall not exceed 150 C. Weldability of stainless steels takes into account not only the usual mechanical properties, but also the chemical characteristics that affect corrosion resistance. Thus, the choice of welding processes is limited because of possible reactions of chromium with carbon and oxygen at welding temperatures.

11.1 Effects of ferrite content Fully austenitic stainless steel weld deposits have a tendency to develop small fissures even under conditions of minimal restraint. These small fissures tend to be located transverse to the weld fusion line in weld passes(and base metal) that were reheated to near the melting point of the material by subsequent weld passes. Cracks are clearly injurious defects and can not be tolerated. On the other hand, the effect of fissures on weldment performance is less clear, since these micro-fissures are quickly blunted by the very tough austenitic matrix. However, a tendency to form fissures generally goes hand-in-hand with a tendency for larger cracking, so that it is often desirable to avoid fissure-sensitive weld metals. It has been recognized that the presence of a small fraction of the magnetic delta ferrite phase in an otherwise austentic (non magnetic) weld deposit has a pronounced influence in the prevention of both centerline cracking and fissuring. The amount of delta ferrite in as-welded material is largely, but not completely, controlled by a balance in the weld metal composition between the ferrite - promoting elements (Cr, Si, Mo and Cb are the most common) and the austenite - promoting elements (Ni, Mn, C and N are the most common). Excessive delta ferrite, however, can have adverse effects on weld metal properties. The greater the amount of delta ferrite, the lower will be the weld metal ductility and toughness. Delta ferrite is also preferentially attacked in a few corrosive environments (such as urea). And in extended exposure to temperatures in the range

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of 480 to 930C ferrite tends to transform in part to a brittle intermetalliic compound (sigma phase) that severely embrittles the weldment.

However, for the reasons previously mentioned, control over ferrite content in austenitic stainless weld metal is often required. This , in turn, requires a method of measurement. Estimation of ferrite content can be performed by three methods; metallographic examination, magnetic response of material and chemical composition through a constitution diagram (the Schaeffler diagram is the most popular and is given in Appendix E) . Estimation of ferrite content by the third method has been more common, but it is subject to analytical errors and uncertainties concerning alloying influences. The ferrite content recommended in weld filler metal is usually between 3 and 20 percent. A minimum of 3 percent ferrite is desirable to avoid microfissuring in weld. Up to 20 percent ferrite is permitted when needed to offset dilution losses. Excessive delta ferrite has been shown to be detrimental to both high-temperature creep strength and low temperature toughness.

12. Reinforcement on Welds Butt joints hall have complete joint penetration and complete fusion for the full length of the weld and shall be free from undercuts, overlaps, or abrubt ridges or valleys. The ensure that the weld grooves are completely filled so that the surface of the weld metal at any point does not fall below the surface of the adjoining members, weld metal may be built up as reinforcement on each side of the member of joint. The thickness of the reinforcement on each side of the member of joint shall not exceed the thickness listed in the following table.

Thickness of Base metal[1] (mm)

Maximum Weld Reinforcement Height (mm)

Up to 3.0 2.5

>3.0, 5.0 3.0

>5.0, 13.0 4.0

>13.0, 25.0 5.0

>25, 50 6.0

>50 The greater of 6 mm or 1/8 times the width of the weld

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13. Surface Weld Metal Buildup Construction in which deposits of weld metal are applied to the surface of base metal for the purpose of: a) restoring the thickness of the base metal for strength consideration or b) modifying the configuration of weld joints shall be performed in accordance with the following rules:

1- A butt welding procedure qualification in accordance with provisions of ASME

Section IX must be performed for the thickness of weld metal deposited, prior to production welding.

2- All weld metal buildup must be examined over the full surface of the deposit by

either magnetic particle examination or by liquid penetrant examination. When such surface weld metal buildup is used in welded joints which require

full or spot radiographic examination, the weld metal buildup shall be included in the examination..

14. Manufacturer Quality Control

14.1 General The Manufacturer or Assembler shall have and maintain a quality control system which will establish that all Code requirements including the following: Material, design, fabrication, examination (by the Manufacturer or Assembler) and inspection (by the Inspector). Provided that Code requirements are suitably identified, the system may include provisions for satisfying any requirements by the Manufacturer, Assembler or user which exceed minimum Code requirements and may include provisions for quality control of non-Code work. The necessary scope and detail of the system shall depend on the complexity of the work performed and on the size and complexity of the Manufacturer’s organization. The complexity of the work includes the following: Design simplicity versus complexity, the type of materials and welding procedures used, the thickness of materials, the types of nondestructive examinations applied and whether heat treatments are applied.

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The size and complexity of the organization includes the following: The number of employees, the experience level of employees, the number of Code items produced and whether the factors defining the complexity of the work cover a wide or narrow range. 14.2 Description of the quality control system The following is a guide to outline of features to be included in the written description of the quality control system, which is equally applicable to both shop and field work. a) Authority & Responsibility: The authority and responsibility of those in charge of the quality control system

shall be clearly established.

Persons performing quality control functions shall have sufficient and well - defined responsibility, the authority and the organization freedom to identify quality control problems and to initiate, recommend and provide solutions.

b) Organization: An organization chart showing the relationship between management and

engineering, purchasing, manufacturing, construction, inspection and quality control is required to reflect the actual organization.

The purpose of this chart is to identify and associate the various organizational groups with the particular function for which they are responsible.

c) Drawings, Design Calculations & Specification Control: The manufacturer’s or assembler’s quality control system shall provide

procedures which will ensure that the latest applicable drawings, design calculations, specifications and instructions, required by the Code, as well as authorized changes are used for manufacture, examination, inspection and testing.

d) Material Control: The Manufacturer or Assembler shall include a system of receiving control

which will ensure that the material received is properly identified and has documentation including required Certificates of Compliance or Material Test Reports to satisfy Code requirements as ordered.

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e) Examination & Inspection Program: The Manufacturer’s or Assembler’s quality control system shall describe the

fabrication operations, including examinations, sufficiently to permit the Inspector to determine at what stages specific inspections are to be performed.

f) Welding: The quality control system shall include provisions for indicating that welding

parameters conforms to requirements of ASME Section IX.

g) Nondestructive Examination: The quality control system shall include provisions for identifying

nondestructive examination procedures.

h) Heat Treatment: The quality control system shall provide controls to insure that heat treatments

as required are applied. This may be by review of furnace time - temperature records or by other methods as appropriate.

i) Calibration of Measurement & Test Equipment: The Manufacturer or Assembler shall have a system for the calibration of

examination and test equipment used in fulfillment of requirements. j) Records Retention: The Manufacturer or Assembler shall have a system for the maintenance of

radiographs and Manufacturer’s Data Reports as required.

k) Sample Forms: The forms used in the quality control system and any detailed procedures for

their use shall be available for review. The written description shall make necessary references to these form.

15. Test & Inspection Examination , inspection and testing activities , the type and degree of nondestructive examination and the acceptance standards are given in" NDT SPECIFICATION " of project.

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Inspection applies to functions performed for the owner by the owner’s Inspector or the Inspector’s delegates. It is the owner’s responsibility, exercised through the owner’s Inspector, to verify that all required examinations and testing have been completed and to inspect to the extent necessary to be satisfied that if conforms to all applicable examination requirement of the Code and of the engineering design. These examinations includes verification of Code and engineering design requirements for materials, components, dimensions, joint preparation, alignment, welding, bonding, brazing, bolting, threading or other joining method, supports, assembly and erection. The owner’s Inspector shall at all times have free entry to all parts of the job while work under the contract is being performed. This includes manufacture, fabrication, heat treatment, assembly, erection, examination and testing of the piping or equipment. However, it is to be noted that the owner’s Inspector shall be designated by the owner and shall be the owner, an employee of the owner, an employee of an engineering or scientific organization or of a recognized Insurance or inspection company acting as the owner’s agent. Therefore, the owner’s Inspector shall not represent nor be an employee of the manufacturer, fabricator or erector unless the owner is also the manufacturer, fabricator or erector.

16. Miscellaneous Welding Requirements - The reverse side of double - welded joints shall be prepared by chipping, grinding

or melting out, so as to secure sound metal at the base of weld first deposited, before applying weld metal from the reverse side.

- If the welding is stopped for any reason, extra care shall be taken in restarting to get the required penetration and fusion.

- Where single-welded joints are used, particular care shall be taken in aligning and

separating the components to be joined so that there will be complete penetration and fusion at the bottom of the joint for its full length.

- In welding plug welds, a fillet around the bottom of the hole shall be deposited

first.

- Peening is prohibited on the root pass and final pass of a weld

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17. Welding Sequence Components that are being welded shall be prepared and welded according to drawing(s) and approved welding procedure specification(s) by qualified welder(s). For this purpose the standard forms and procedures shall be used. The standard forms and procedures are the regulations which shall be followed and complied with by all personnel before and during the welding works at shop & site. The below sequences are followed for welding works: 1-Filling & submitting of «Daily Fit-up Inspection report» form to supervisor 2-Fit-up of joints according to drawings & WPS(S) 3-Check and approve of fit-up works by supervisor 4-Filling & submitting of «Daily Welding Inspection report» form to supervisor 5-Welding of components according to drawings & WPS(S) 6-Check and approve of welding works by supervisor

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Table-1: Base Metals P-No. Base Metal Classification

ASTM Spec. No. ( Grade(s) )

1 A-36, St 37-2, A-53 , A-105, A-234 (WPB), A515, A106,A-216 (WCB),

8

A-312 (TP304, TP304L, TP304H, TP310, TP316, TP316H, TP316L), A-182(F304, F304L, F304H, F310, F316, F316L, F316H), A-403(WP304,WP304L,WP304H,WP310,WP316,WP316L,WP316H,)

Table 2: Consumable Electrodes / Filler Rods for Ferrous Metals

Base Metal Classification P-No. AWS (A) Spec. [1]

Classification [2] ;E70XX ASTM Spec. No. ( Grade(s) )

St 37-2, A- 53, A-106 , A36 1 5.1 & 5.18 E60XX;E70XX ER70S

A - 216 (WCB) 1 5.5 & 5.18 E70XX-A1; ER70S A- 105 1 5.5 & 5.18 E70XX; ER70S

A- 234 (WPB)

1 5.5 & 5.1 & 5.18 E60XX; E70XX; ER70S

A- 312 (TP304,TP304H) A-182(F304,F303H), A-403(WP304,WP304H)

8 5.4 & 5.9 ER308

A- 403 (WP304L) A - 312 (TP304L), A-182 (F304L)

8 5.4 & 5.9 ER308L

A-312 (TP310) 8 5.4 & 5.9 ER310

A-312 (TP316, TP316H), A-182(F316,F316H) A-403(WP316,WP-316H)

8 5.4 & 5.9 ER316

A-312 (TP316L),A-182(F316L) 8 5.4 & 5.9 ER316L

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A-403(WP-316L) Table- 3: General Procedures for Drying Low-Hydrogen Electrodes

Drying Temperature (C)

Nature of Moisture Pickup E70XX

E80XX E90XX

E110XX Electrodes exposed to air for less than one week; no direct contact with water. Welds not subject to X-ray inspection.

150 150

Electrodes exposed to air for less than one week; no direct contact with water. Welds subject to X-ray inspection.

370 400

Electrodes have come in direct contact with water or have been exposed to extremely humid conditions as indicated by core wire rusting at the holder end. Before redrying at 370-400C, predry electrodes in this condition at 80C for 1 to 2 hours. This minimizes the tendency for coating cracks or oxidation of the alloys in the coatings.

370

400

Notes:

- Electrode coatings designated XX may be 15, 16 or 18. - One hour at the listed temperatures is satisfactory. Do not dry electrodes at higher

temperatures or for more than 8 hours. Several hours at lower temperature are not equivalent to using the specified temperatures. Remove the electrodes from the can and spread them out in the furnace. Each electrode must reach the drying temperature.

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Table-4: Preheat Temperature

Base Metal Weld Metal Analysis Base Metal Nominal Wall Min. Preheat

Temperature.C P-No.[1] A-No.[2] Group Thickness (mm) 1 1 Carbon steel <25

25 10 80

3 2, 11 Alloy steels (Cr 1/2%)

<13 13

10 80

4 3 Alloy steels (1/2% <Cr 2%)

<13 13

10 120

5 4,5 Alloy steels ( 2

1

4

%<Cr 10%) All 150

8 8, 9 High alloy steels (austenitic)

All 10

Notes: 1) Refer to Table 1 2) A-Number from ASME, Section IX, QW-442.

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APPENDICES- WELDING FORMS & DIAGRAMS Appendix A: - Sample format for Welding Procedure Specification Appendix B: - Sample format for Procedure Qualification Records Appendix C: - Sample format for Welder’s Performance Qualification Appendix D: - Sample format for Welder’s Qualification Card Appendix E: - Schaeffler diagram

Appendix F: - Sample format for Daily Fit-up Appendix G: - Sample format for Daily Welding