Welding Procedures—AEIS can prepare welding procedures for commonly used materials and processes as well as exotic alloys and emerging welding processes. The WPS and PQR can be written to comply with AWS, ASME, API, BIS, NAVSEA, SAE or virtually any code/ specification. Where possible, we recommend the use of AWS SWPSs to provide cost savings to the client by eliminating procedure qualification testing.
Heat treatment procedures—Generic and specific heat treatment guidelines and procedures are written to meet ASME and AWS requirements. This includes pre-heating, post-heating, PWHT and heat straightening procedures.
Welding Procedure Specification (WPS)
A WPS is a document that describes how welding is to be carried out in production. Its purpose is to aid the planning and quality control of the welding operation. They are recommended for all welding operations and most application codes and standards make them mandatory.
Procedure Qualification Record (PQR)
A PQR is required when it is necessary to demonstrate that your company has the ability to produce welds possessing the correct mechanical and metallurgical properties.
A welding procedure must be qualified in accordance with the requirements of an appropriate welding procedure standard, such as ASME Sec IX, as follows:
- Produce a welding procedure specification (WPS) as stated above.
- Weld a test piece in accordance with the requirements of your specification. The joint set up, welding and visual examination of the completed weld should be witnessed by a certified welding inspector such as an AWS certified CWI or an Inspection Body. The details of the test such as the welding current, pre-heat etc., must be recorded during the test.
- Once the welding is complete the test piece must be subject to destructive and non destructive examination such as radiography and mechanical tests as defined by the welding procedure standard. This work must be carried out in a qualified laboratory but the Inspection Body may require witnessing the tests and viewing any radiographs.
- If the test is successful you or the test body completes the appropriate documents which the test body’s surveyor signs and endorses.
What information should WPS and PQR include?
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.
For most applications the information required is generally similar to that recorded on a Procedure Qualification Record (PQR), except that ranges are usually permitted on thicknesses, diameters, welding current, materials, joint types etc.
If a WPS is used in conjunction with an approved procedure qualification record (PQR) then the ranges stated should be in accordance with the approval ranges permitted by the PQR.
However careful consideration should be given to the ranges specified to ensure they are achievable, so that these ranges represent good welding practice.
Prequalified WPS
Some codes, such as AWS D1.1, allow “Prequalified WPS”, whereby it is established that the WPS written per code will produce welds with correct mechanical and metallurgical properties. It is not necessary to prepare a PQR in such cases. However, the pre-qualified WPS have a specified range of parameters under which the weld must be produced. When welding variables fall outside these ranges, a WPS with supporting PQR must be prepared.
SWPS
In an effort to standardize and harmonize the process of WPS approvals, AWS started writing “Standard Welding Procedure Specifications (SWPSs)” with input from the pioneers and experts in the welding industry. An extensive testing program was undertaken whereby; these SWPSs were then supported by numerous PQRs.
When the use of SWPSs is permitted by referencing code section, your company does not have to perform one or more procedure qualification tests. You can simply purchase the applicable SWPS for unlimited intra-company use from the American Welding Society (www.aws.org).
