Welding procedure specification (WPS) and their Process
Welding Procedure specification is a written qualified welding procedure document that is prepared to provide direction for making production sound weld as per code requirement, which is mention in ASME Section-IX of the boiler and pressure vessel code (BPVC).
The welding procedure specification is supported by a number of documents which together comprise a welding approval records termed the welding procedure approval record (WPAR, in BS EN ISO 15614 ) and procedure qualification record (PQR), in American society of mechanical engineers, ASME).
The welding procedure specification or other documents may be used to provide direction to the welder or welding operator to assure compliance with the code requirement. Because of the large number of variables involved in welding, so knowledge of the welding engineer and skills of the welder needs to be validated by the seriousness of the test.
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A WPS is supported by a Procedure Qualifications Record (PQR). A PQR is a record of a test weld perform and tested to ensure that the procedures will produce a good weld. or PQR is a record of variables that are recorded during the WPS or test coupon welding. An individual welder is certified with a qualification test documented in a Welder Qualification Test Record (WQTR) which shows they have the understanding and demonstrated ability to work within the specified WPS.
Purpose
* The purpose of the Welding procedure specification document is to guide welders to the accepted procedures so that repeatable and trusted welding techniques are used. A WPS is developed for each material alloy and for each welding type used, or each and every welding process has a different Welding procedure specifications (WPS).
* The construction is capable of providing the required properties for its intended applications.
* Welding procedure specification (WPS) intended to provide direction for weld and list of the variables, according to the ASME section ix there are three types of variables like essential variables, nonessential variables, and supplementary essential variables, and the acceptable range of these variables when using the WPS.
* WPS is presumed that the welder and welding operator performing the welding procedure qualification test is a skilled workman so that the welding procedure qualification test established and the properties of the weldment are not the skill of the welder.
* WPS is also used to determine the welder is able to deposit sound metal or the welding operator is able to operate welding equipment properly.
* According to international standard welding procedure specification is required to ensure stable welding.
* Under the work health and safety act of 2011, business owners have obligations and duties of care of the constructed and safe plant and worker's health.
Procedure qualification record (PQR) or Procedure qualification test (PQT):-
PQR is a part of the WPS which is recorded all real-time data values during the test coupon welding, data may be essential variables and supplementary essential variables, and also the nonessential variables this is depending on the client or job requirement. And destructive test report or radiography test report data ( Real-time data observe during test coupon welding and their lab test report DT and NDT ) these two things compile together and it is called procedure qualification record.
Also, Read
Parameter or content details are used in welding procedure specification (WPS) which are called variables. These variables are three types-
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more about variables click these link variables
Contents which are mentioned in WPS -
1.1 Joint.
1.2 Base metal.
1.3 Filler metal.
1.4 Positions.
1.5 Preheat.
1.6 PWHT (Post weld heat treatment).
1.7 Electrical characteristics./ Gas characteristics.
1.8 Technique.
Process of Welding procedure specification.
* Proposed/Preliminary welding procedure specification (PWPS):-
The preliminary welding procedure specification is a proposal document that provides directions of the welder on what is needed as joint details, welding parameters, preheat, positions, filler metals, base metals, techniques. etc. In this principle, it is prepared in the same way as the welding procedure specification (WPS), but it may be necessary to calculate various weldings data in advance to ensure that the requested material property in the welded joint and the parent metal materials will be attained.
* Test coupon:-
Then after selecting the test material which is to tested and then after use in the project. material Grade and property thickness range which is mention in the ASME section ix should be the same as used in future work.
* Welding:-
Welding is a fabrication process or technique that joins materials parts with help of filler metal or direct by high heat and pressure.
*Destructive test (DT) or non-destructive test (NDT):-
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Welding procedure specification
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After the successful completion of the welding of a test coupon, visually done by the authorized person, it may be a client or third party inspector after satisfaction. Persons who are successfully qualified will be assigned an identifying number, letters, or symbols by the organization, which shall be used to identify their work. Then Coupon sends to the lab, where a destructive test performs as per API 1104.
*PWPS=WPS:-
After successful completion and satisfaction of destructive and nondestructive test, or test report acceptable as per code standard, that time actually proposed welding procedure specification (PWPS) is called welding procedure specification (WPS). so PWPS=WPS.
After satisfactory and accepted welding procedure specification (WPS) we can perform the welder qualification test (WQT).
Stages of qualified welding procedure specification (WPS Flow Chart).
1. PWPS
2. TEST COUPON
3. WELDING OF TEST COUPON
4. DT/NDT
5. PWPS=WPS
6. WQT
Quick links for more details-
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