Weldtest NZ Limited

The Importance Of Welding Personnel Operating Under Qualified Weld Procedures

This time we look at the importance of welding personnel operating under qualified weld procedures and as importantly, demonstrating their competence to those procedures by way of mechanical or non-destructive volumetric testing.
The advantage with having welding personnel qualified to a specific weld procedure, is that it can then be proven that the welder has demonstrated competence to make that particular weld on that particular joint.
The basis of any generic welder qualification is that the welder is able to follow a verbal or written instruction ( in the form of a weld procedure specification – WPS ) of how to make a defect free weld. Virtually all welder qualification standards allow to a certain degree (in some cases a very high degree) wide range qualified by the welding of only one type of joint and one weld type. For example, in many cases a butt weld will qualify a fillet weld.
This is allowed under the standard due to the expectation that the welder has suitable expertise with all other positions, joint and weld types.
However, in reality this is not always the case. There are many examples in the structural steel welding industry were welders may have the qualification range to say, make single and multi-pass fillet welds but yet still lack the skills and technique to lay a fillet weld that would pass a macro (destructive) examination.
As approx. 85% of welds laid on production pieces in this industry are fillet welds, this is particularly concerning when welders have not been tested by way of a separate test piece to the welding procedure used by the manufacture. There are many cases where the fillet weld will comply to a visual or magnetic particle test but internally the weld is seriously defective.
As there is no practical non-destructive test method to test small leg fillet welds volumetrically, it is essential that a test piece should be made under the parameters of the weld procedure and a destructive test by way of at least one macro, be carried out to ensure the internal integrity of the weld.
It is also a requirement under the welding standard of AS/NZS 1554.1:2014 that ‘welders shall be suitably qualified to carry out the welding procedures for which they will be employed’. See clause 4.12.2.1.
In short, once a weld procedure specification is qualified, regardless of what generic qualifications welders may have, quality of production welds could be left to chance if each welder does not qualify by way of a test piece to that particular procedure.
Remember, a weld procedure specification is specific to that particular type of weld and that particular type of joint. And a test piece made under that procedure, will ensure the competence of personnel to make welds of acceptable quality for your products.
In a sense, welds are like people. Its what’s on the inside that counts! ?
Next time we will discuss the difference between surface and volumetric test methods, where and why both should be carried out to maintain your quality control programmes. Have a great couple of weeks and until next time!
Next update 18/5/18.