What is welding procedure specification (wps)
A Welding Procedure Specification (WPS) is the formal written document describing welding procedures, which provides direction to the welder or welding operators for making sound and quality production welds as per the code requirements . The purpose of the 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. Specific codes and/or engineering societies are often the driving force behind the development of a company’s WPS. A WPS is supported by a Procedure Qualification Record (PQR or WPQR). A PQR is a record of a test weld performed and tested (more rigorously) to ensure that the procedure will produce a good weld. Individual welders are certified with a qualification test documented in a Welder Qualification Test Record (WQTR) that shows they have the understanding and demonstrated ability to work within the specified WPS.
According to the American Welding Society (AWS), a WPS provides in detail the required welding variables for specific application to assure repeatability by properly trained welders. The AWS defines welding PQR as a record of welding variables used to produce an acceptable test weldment and the results of tests conducted on the weldment to qualify a Welding Procedure Specification. For steel construction (civil engineering structures) AWS D1.1 is a widely used standard. It specifies either a pre-qualification option (chapter 3) or a qualification option (chapter 4) for approval of welding processes.
The American Society of Mechanical Engineers (ASME) similarly defines a WPS as a written document that provides direction to the welder or welding operator for making production welds in accordance with Code requirements.ASME also defines welding PQR as a record of variables recorded during the welding of the test coupon. The record also contains the test results of the tested specimens.
What is WPS :
“Welding Procedure Specifications is a form that contains details of welding groove, welding method to be employed, electrode and/or welding rod type and diameter, current, voltage, welding position, welding run number and similar information prepared in accordance with its codes relevant Project standard (ASME and/or EN Standards).
WPS is prepared by Manufacturer / Sub-Contractor and approved by Authorized Inspection Body before the start of job.”
It contains sufficient details to enable any competent person to apply the information and produce a weld of acceptable quality. The amount of detail and level of controls specified on a WPS is dependant on the application and criticality of the joint to be welded.
Typical Items That Should Be Recorded On W.P.S:-
- Procedure number
- Process type
- Consumable Size, Type and full Codification.
- Consumable Baking Requirement if applicable
- Parent material grade and spec.
- Thickness range.
- Plate or Pipe, Diameter range
- Welding Position
- Joint Fit Up, Preparation, Cleaning, Dimensions etc.
- Backing Strip, Back Gouging information.
- Pre-Heat (Min Temp and Method)
- Interpass If Required (Maximum Temperature recorded )
- Post Weld Heat Treatment. If Required (Time and Temp)
- Welding Technique (weaving,max run width etc.)
- Arc Energy Limits should be stated if impact tests are required or if the material being welded is sensitive to heat input.
A sketch of the joint configuration is required which should include the basic dimensions of the weld preparation.
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