Welding quality rests on two things being proven before production starts: that the welding procedure produces sound welds, and that the people using it can follow it. Procedure qualification tests the recipe; welder qualification tests the person. In Canada, structural steel fabricators are also commonly required to hold company certification, which ties both together under an audited quality system.
The welding procedure: WPS and PQR
A welding procedure specification (WPS) is the written recipe for making a particular weld. It sets out the essential variables, such as:
- Welding process (for example stick, MIG, flux-cored, TIG or submerged arc).
- Base metal type and thickness range.
- Filler metal and, where used, shielding gas.
- Joint design and welding positions.
- Preheat and interpass temperatures.
- Electrical settings and travel speed ranges.
- Post-weld heat treatment, if required.
To prove a WPS works, a test weld is made following it and then tested, usually with mechanical tests such as bend, tensile and sometimes impact tests, and often with non-destructive testing. The results are recorded in a procedure qualification record (PQR). The PQR is the evidence; the WPS is the instruction that welders follow on the job.
Some codes allow prequalified joints and procedures, where the code itself has established that a joint design and set of conditions produce acceptable welds. The procedure still has to be written down and followed within the stated limits.
Canadian terminology
Under the Canadian Welding Bureau (CWB) system used for structural steel, you will see welding procedure specifications and welding procedure data sheets (WPDS). Broadly, the WPS describes the general procedure and the data sheet gives the specific details for a joint. These documents are reviewed and accepted as part of company certification.
Welder qualification
A welder qualifies by making a test weld under controlled conditions, which is then examined, often by bend testing or radiography. The test covers a specific process, position, and in some codes a range of thicknesses and material types. A welder qualified in the flat position with one process is not automatically qualified for overhead work with another.
Points to understand:
- Qualifications are tied to the process, position and other variables tested.
- Qualifications normally need to be maintained, for example by welding with the process regularly and renewing at set intervals as the governing code or certification body requires.
- Welding operators running automated or mechanized equipment have their own qualification.
- Tack welders may also need qualification under some codes.
Company certification in Canada
For structural steel, CSA W47.1 sets out requirements for companies doing fusion welding of steel, and CSA W47.2 does the same for aluminum. Certification is administered by the Canadian Welding Bureau. A certified company has accepted procedures, qualified welders, and designated welding engineering and supervisory staff, and is subject to audits. Building codes and project specifications commonly require structural welding to be done by a company certified to the right division of W47.1.
Welding for steel structures is then done to CSA W59, which sets design and workmanship requirements. Check the current editions and what your project specification calls for.
Pressure equipment and piping
Boilers, pressure vessels and pressure piping follow a different path. Procedures and welders are typically qualified to ASME Section IX, and registration and oversight are handled by the provincial safety authority, which differs by province. If your work involves pressure equipment, the provincial requirements apply, and the provincially mandated inspections must be done by the authorized body. An independent inspector can help you prepare for those inspections but does not replace them.
Paperwork is part of the weld. A sound-looking weld made by an unqualified welder, or outside the limits of the procedure, may still be rejected. Records that show who welded what, with which procedure, are what let an owner accept the work.
What owners and contractors should ask for
- Proof of the fabricator's company certification, where the project requires it, and its scope.
- The accepted WPS and data sheets covering each joint type on the job.
- Current qualification records for each welder, matching the processes and positions they will use.
- The name of the welding supervisor and the welding engineer or designated person responsible.
- Consumable handling and storage practices.
- The fabricator's inspection and test plan, including what NDT will be done and by whom.
- A system for identifying which welder made which weld.
Reviewing these before work starts avoids rejected welds later. Understanding common welding defects also helps make sense of why procedure limits matter, and non-destructive testing methods explains how finished work is checked.
How ehZee can help
ehZee can review welding procedures, welder qualifications and fabricator documentation against your project specification before work begins, then inspect the work as it proceeds. Our welding inspections service gives owners and contractors an independent check on both the paperwork and the welds.
Common questions
Is a welding ticket the same as being qualified for my job?
Not necessarily. A trade certificate shows training and experience, but qualification under a code is specific to a process, position and other variables. Check that the welder's qualification matches the work.
Can a fabricator use a procedure from another company?
Generally, procedures are qualified and accepted for the company that uses them, under that company's quality system. Rules vary by code, so check with the certification body or the governing code.
Who checks that a fabricator follows its procedures?
The fabricator's own quality control staff, the certification body through audits, and, on many projects, an independent inspector working for the owner.