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The philosophical differences between welder qualifications and welding procedure qualifications are quite similar around the globe. In this article, when examples are required, we will use Canadian Standards such as CSA W47.1/.2 for structural steel and aluminum and ASME Section IX for pressure welding qualifications听

Welder Qualification

In general, regardless of the Standard, welders are required to perform tests to qualify using an individual welding process, type of base metal, electrode, thickness range and position. Basically, there are two types of welds to be tested, either a fillet weld or a groove weld.

As an example, for qualifying to CSA W47.1, there are standard test assemblies that are used. One test assembly is used for fillet weld qualifications and one can be used for just a groove qualification. There is also an optional joint configuration that qualifies for both fillet and grooves. For differing welder classifications for a groove, the welder will weld on test assemblies with backing or without backing, which will result in differing qualifications (S vs T)听听

Once the welder has completed welding, visual inspection is performed to check the weld for profiles and size and for groove welds to check for reinforcement above the base material shall not exceed 3mm. Specimens are then cut from the test assembly for the following tests:

1. Root bend test

2. Face bend test

3. Fracture test for fillet welds and aluminum

4. Marco-etch test for fillet welds and aluminum

5. Optional Radiography test depending on welding process and material.

From the above it can be noted that the testing does not include any information of the strength or other physical properties of the weld. The welder鈥檚 test is simply to check whether the person has the skills to deposit molten metal under a certain set of conditions. It gives absolutely no information for the designer as to whether a certain metal welded by a certain process will give a certain strength etc.

In addition, a welder鈥檚 test approval usually expires after two years. At the end of this period, depending on the code, tests may have to be retaken or proof of welders continued use of the process etc. presented to the relevant authorities.

So, a welder鈥檚 test has an expiry date and only ascertains the ability of a person (the welder) but does not ascertain the properties of the joint welded.

Procedure Qualifications

Welding procedures are required for welding under all Standards and Codes. They are a recipe for making welds with known properties and must be proven by performing a procedure qualification test and recording the parameters used on a Procedure Qualification Record (PQR) form*.

When qualifying a welding procedure and preparing the PQR, some of the data recorded include, but are not limited, to the following variables:

1. base material specification

2. current and its characteristics (direct, alternating, polarity)

3. voltage (if applicable)

4. welding speed听

5. type of welding materials or shielding gas, or both, and the gas flow

6. joint configuration听

7. position of welding and direction in vertical welding

8. number of arcs, spacing, and angular position

9. method of preparing second side after welding first side

10. preheat and interpass temperature

11. post weld heat treatment if required

CSA W47.1 and ASME Section IX have standard test assemblies for testing welding procedures for fillet welds and groove welds on both plate and pipe and, with specific joint configurations to cover all possible weld joints.

Once the test assembly has been completed and all the data recorded on the PQR, visual inspection is performed for weld bead profile, reinforcement, and size for fillet weld. Acceptable tests will then have specimens removed for evaluation.

The minimum requirements for evaluating procedure tests are bend tests and tensile tests, the following are the required evaluation tests plus optional testing required by design:

1. Bends.............satisfactory results indicate a welder can handle the procedure parameters

2. Reduced tensile test...........gives tensile information of the weldment.... its strength, and ductility

3. Macro-etch...........gives information on fillet welds

4. Impacts (optional, gives toughness measurement of joint and HAZ and is dictated by design)

5. Hardness (optional and dictated by design)

6. Corrosion (optional and dictated by design)

If tests are satisfactory, the welding procedure may be accepted by a third party, the CWB for CSA Standards, or the Provincial Regulatory Authorities for the ASME Code. The approved procedure is then available to be used when metal A is to be joined using consumables B and with parameters C. The welding procedure can be used forever as long as it is applied using the recorded parameters within tolerance.

So, in summary: The difference between welder and procedure qualifications are that one gives critical information on the welded joint and has no end date (PQR) whilst the welder tests give no numbers, just pass or fail and has an expiry date.

* Some standards, e.g., CSA W 59, include some prequalified joints which have been deemed so by the Standard Committees based on accumulated data over the years. They are only deemed prequalified if welded within strict tolerances over joint geometry and welding parameters as dictated in the Standard.

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