Welding Procedure Specification (WPS) is a written and detailed document for the welding operations. It explains a prescribed description of the welding process, gases and flow rates, the joint design and geometry, the base materials used, welding position including various variables. Each code has a recommended format.
- What is the Welding Procedure Specification?
- Why do We Need a WPS?
- Types of WPS
- WPS Codes
- How to Write A WPS?
- WPS Applications
- Importance of WPS
What is the Welding Procedure Specification?
WPS is a document consisting of welding procedures and guidelines for welders and welding operators. The document mainly suggests welders for accepting it and follow the trusted/proved welding codes and techniques. Look at what two highly popular welding bodies of the USA say about the WPS requirement.
American Welding Society (AWS) defines that WPS is essential welding variables for the specific application.
American Society of Mechanical Engineers (ASME) defines WPS as a written document providing guidelines to welders and welding operators for performing welding production as per welding codes.
Why do We Need a WPS?
We need a welding procedure specification for welders in the industry for the following reasons.
- The procedure is necessary and required by code such as AWS and ASME.
- The WPS explains to engineers and regulators what you are doing on a piece of metal.
- It makes sure that welders can produce quality welds.
Types of Welding Procedure Specification
Welding Procedure Specification is divided into two types. They are as follows.
Prequalified WPS (PWPS)
PWPS a set of written instructions for welders that reveals how should be the production of weld made. According to AWS A3.0, “A welding procedure specification in compliance with the stipulated conditions of a particular welding code or specification and therefore acceptable for use under that code or specification without a requirement for qualification testing.”
Qualified WPS (QWPS)
QWPS is a set of written instructions explaining to welders about how a weld is to be made. According to AWS A3.0, Standard Welding Terms, and Definitions, “A document providing the required welding variables for a specific application to assure repeatability by properly trained welders and welding operators.”
The main governing codes for WPS are as follows.
- AWS B2.1 – Standard for welding procedure and performance qualification
- ASME Code Section IX – Essential variable, non-essential variable, and supplementary essential variable
- API and ISO codes
- Foreign Codes
How to Write A WPS?
Generally, a qualified person can write a welding procedure specification into four steps.
1. Gather basic materials for welding such as tools, metal types, and grades. Welding activity should take place under the supervision of an experienced person.
2. Include information like the welding process, process parameters, governing codes, material parameters, joint design, cleanliness, pre/post-weld heat treatment, filler metals, and joint fit-up. Next, add all the essential information to the preliminary welding procedure specification (PWPS).
3. Procedure Qualification Record consists of lab reports such as materials or parameters, information made for each pass, and ambient conditions. Besides this, it comprises testing reports.
4. Write A Weld Procedure Specification that carries all correct information about making the weld and tools used. While preparing WPS, PQR is considered. Then, the report is subjected to non-destructive and destructive testing. After passing all the tests, a welding procedure specification is written.
The following industries should have had WPS.
- Manufacturing Industry – It includes automotive and heavy equipment
- Construction Industry
- Pipeline Industry
Importance of Welding Procedure Specification
WPS is an important document for welders in the following ways.
- It provides direction to welders and operators for making quality welds as per the code requirements.
- It reinforces applicable welding codes.
- It shows the skills and qualification of welders for performing certain jobs by adhering to special codes and procedures.
Thus, the information on WPS is beneficial to students, welders, and professionals’ careers. It is not developed for a single alloy, rather they are for each material alloy and every welding type performed. Therefore, WPS is an essential requirement for the welding procedures in the USA and outside as well.
Related: Other Welding Certifications