On Canadian structural steel jobs, every weld is made to a written procedure: a welding procedure specification (WPS) that sets the company's general rules for a process, and welding procedure data sheets (WPDSs) that give the exact joint, position, consumable and settings for each weld. A company certified by the Canadian Welding Bureau submits these to the CWB Group for review and acceptance before using them. Welders on the floor work from the WPDS.
This post explains how the WPS and WPDS system works, where prequalification and procedure testing come in, and what contractors and engineers should ask for. For the code itself, see our overview of CSA W59, the structural welding code.
Three layers of welding qualification
People often say "structural welding qualification" when they mean one of three different things. A Canadian fabricator needs all three.
| Layer | What it proves | Governing standard |
|---|---|---|
| Company certification | The company has the organization, people and quality system to weld | CSA W47.1 (CSA W186 for rebar welding, CSA W47.2 for aluminum) |
| Welding procedures (WPS and WPDS) | The way each weld is made has been documented and reviewed | Set out under the certification standard, with technical rules from CSA W59 |
| Welder qualification | Each welder can make sound welds in the processes and positions they use | Tested under the CWB system |
Company certification is explained in why hire a CWB-certified fabricator, and welder tickets in CWB vs AWS certification. This post is about the middle layer.
What a WPS is
The welding procedure specification is the company's general procedure for a welding process. Broadly, it describes things that apply to every weld made with that process at that company:
- The welding process (for example flux cored or shielded metal arc).
- The base metals and grades it covers.
- The type and classification of filler metal and any shielding gas.
- General requirements for joint preparation and cleaning.
- Preheat and interpass temperature practice, tied to the code.
- Technique, repair and other workmanship rules.
A WPS is not something a welder reads before each weld. It is the framework that the more specific data sheets sit under.
What a WPDS is
The welding procedure data sheet is where the details live. According to the CWB Group, a WPDS sets out the type of joint, joint geometry, welding position, welding symbol, welding consumables, gas mixture and welding parameters used to make the weldment.
In practice a shop has many WPDSs: one for a fillet weld in the flat position with a given wire, another for the same weld vertical up, another for a single bevel groove weld on backing, and so on. Each is a single sheet the welder can work from, with a sketch of the joint and a table of settings for each pass.
| WPS | WPDS | |
|---|---|---|
| Scope | A welding process, company wide | A specific joint and set of conditions |
| Level of detail | General rules and ranges | Joint sketch, passes, settings |
| Used by | Welding engineer and supervisor | Welders and supervisors on the floor |
| Reviewed by CWB | Yes | Yes |
| Number per shop | A few, one per process | Many |
The Canadian approach differs from the US one here. Under AWS D1.1 the term WPS covers the joint-specific document a welder uses. In the CWB system, the general specification and the joint-specific data sheet are separate documents, and both go to the CWB for independent review before they are used.
Prequalified and qualified procedures
CSA W59 lists prequalified joints and conditions: common joint geometries, processes and consumables with a long track record. A procedure that stays inside those limits can be accepted on review without testing.
When a procedure goes outside the prequalified limits, for example an unusual joint geometry, a different process variant or a material the prequalified rules do not cover, it has to be qualified by testing. The company welds a test plate following the proposed procedure, and the plate is tested. The results are recorded on a procedure qualification record (PQR).
The CWB Group's procedure review has three possible outcomes:
- Accepted: the procedure can be used.
- Requires revision: the company corrects it and resubmits.
- Requires qualification: a test is needed first. Once the PQR results are confirmed, the procedure is revised to match the test and returned for final acceptance.
This is why a fabricator with a broad set of accepted procedures can take on a wider range of work quickly. A job that needs a new procedure qualified needs extra time before welding starts.
Who writes and controls the procedures
Under CSA W47.1, the division a company is certified in reflects its engineering resources for welding. In Division 1 and Division 2 companies, a professional engineer is responsible for the company's welding, including the procedures. Every certified company also has a qualified welding supervisor who makes sure welders follow the procedures on the floor.
In a typical shop:
- The welding engineer prepares or approves the WPSs and WPDSs and submits them to the CWB.
- The welding supervisor assigns the right WPDS to each job and checks that welders work within it.
- The welder is qualified for the process and position on the WPDS and follows its settings.
- Quality control checks the work against the shop drawings and the WPDS.
The detailer and the engineer of record are part of the chain too. The weld symbols on the shop drawings say what weld is needed; the WPDS says how the shop will make it.
What contractors and engineers should ask for
For most structural steel work, a few simple checks cover welding:
- Company certification. Confirm the fabricator, and the erector if there is field welding, are certified to CSA W47.1 in a division that meets the project specification. Our guide on how to check CWB certification shows how.
- Procedures for the job's welds. Many specifications ask the fabricator to submit its CWB-accepted WPDSs with the shop drawings, especially for groove welds, moment connections and anything unusual. If the drawings call for a weld the fabricator does not have a procedure for, find out early.
- Field welding. Field welds need their own procedures and qualified welders on site, plus weather protection and preheat where required.
- Rebar welding. Welding reinforcing bar falls under CSA W186, with its own procedures. Only weldable grades should be welded.
- Inspection. Welding procedures do not replace inspection. See structural weld defects and inspection for how welds are checked.
Why the system matters on site
Written, reviewed procedures are what make welding repeatable. They mean that two welders on two different days make the same weld the same way, with the right preheat, consumable and settings for the steel. When something does go wrong, the procedure is the first thing an inspector or engineer checks: was the weld made to an accepted WPDS, by a welder qualified for it?
For owners and contractors, the short version is that a CWB-certified fabricator brings this system with it. You do not need to read the data sheets yourself, but you should know they exist and ask for them when the specification calls for them.
CWB-certified welding at Procut
Our shop welding is certified by the Canadian Welding Bureau, and we fabricate structural steel to the approved shop drawings, from posts and base plates to beams, connections and full frames. Send us your drawings for a free take-off and quote, and tell us about any welding requirements in your specification, or see our fabrication and welding services.
Frequently asked questions
What is the difference between a WPS and a WPDS?
In the Canadian system, the welding procedure specification (WPS) is the company's general written procedure for a welding process, and the welding procedure data sheet (WPDS) gives the specific joint, position, consumable, gas and settings for a particular weld. Welders work from the WPDS.
Who approves welding procedures in Canada?
A CWB-certified company prepares its procedures and submits them to the CWB Group, which reviews them against the governing standard. Procedures are accepted, sent back for revision, or flagged as needing qualification testing before they can be used.
What is a PQR?
A procedure qualification record documents a test weld made to prove a procedure that falls outside the prequalified limits, along with the results of the tests on it. Once the results are confirmed, the procedure is revised to match and accepted.
Is a welder qualification the same as a welding procedure?
No. The procedure defines how the weld is made. The welder qualification shows that a person can make it, for a given process and position. A CWB-certified company needs both, along with its company certification to CSA W47.1.
Can I ask a fabricator for its WPDSs?
Yes. Many project specifications require the steel fabricator to submit its CWB-accepted welding procedures, often with the shop drawings, so the engineer can see which procedures cover the welds on the job.
