While WPS and PQR are used to define and prove the welding process.
WQT/WPQ is used to test the actual welder. Is the welder able to produce a sound weld;
- With a particular welding process ie. GMAW or GTAW
- In a given position Horizontal, Vertical or Overhead
- On a particular joint configuration Butt weld or Fillet weld.
A WQT does not test the mechanical properties, it looks at weld soundness only in most cases.
A Welder Qualification Test is recorded on documentation known as a test certificate that details the ranges that welder is qualified. Ranges or essential variables for WQT are not always the same as those for a WPS. An example would be that is a welder can weld in the overhead position (more difficult) it is logical they be qualified in the flat position (less difficult).
The welder completes a test coupon under supervision following a WPS. The weld is then tested using the method prescribed in the relevant standard.
The testing always includes as a minimum visual examination but may also require;
- Bend tests – root/face or sides
- Macro test – cross section view of weld
- Fillet weld break test
- Nick Break
- Radiographic examination
- Ultrasonic examination
The type and number of tests required are detailed in the relevant standard. The most common standards are for WQT are;
- AS/NZS 1554
- AS/NZS 2980
- AS NZS ISO 9606
- AS/NZS 3992
- AWS D1.1
- ASME IX
Some of these standards like AS/NZS 2980 and ISO 9606 have an optional knowledge which can be used to help understand the level of your welders knowledge. Being able to weld and understanding welding are two different things. Someone that has a proven ability to understand what affects the outcome will always be a better option.
If you are looking to hire a welder, you can ask about previous WQT before hiring them. Generally companies pay for the WQT so it remains the companies property not the welders, So welders will not always have them. Certain standards do not allow the transfer of the qualifications. If you are looking for some assistance there are a number of providers that can assist with WQT online that will help you develop your welding management system.
It should be noted that qualification and certification are different things, the differences between the two will be explained in a different blog.
If the welding world confuses you, hopefully this has gone some way to demystifying it.
The terms may seem overwhelming, but the documents these acronyms represent are extremely important to the welding industry.