Welding Procedure Development: Qualification

Over the past three weeks we covered 3 of the most important aspects of developing welding procedures:

There are many other important considerations when developing a welding procedure such as selection of shielding gases and fluxes, specifying joint details, welding positions, technique, determining preheat and post heat requirements and more.  All of these are covered in fine detail in Welding Procedure Development for Non-Welding Engineers. 

To wrap up our services in welding procedure development we’ll cover the topic of qualification.  Qualification as it pertains to welding procedures is the performance of both destructive and non-destructive testing to provide assurance that the developed welding procedure is capable of producing sound welds. 

Qualification is typically done following the qualification requirements of the code or standards being followed.  For example, in the latest edition of AWS D1.1 Structural Welding Code – Steel you will find all the requirements for qualification in Clause 5.  Testing can include a combination of the following tests:

  • Visual examination (VT)
  • Ultrasonic testing (UT)
  • Radiographic testing (RT)
  • Macroetch examination
  • Bend testing
  • Fillet break test
  • and others

Although these evaluations are typically carried out by a certified welding inspector (CWI), it is not necessary to be one in order to qualify a procedure.  However, all the requirements of the code must be followed.  This is the reason why CWIs are the most indicated to perform qualifications.  Their certification is proof that they have shown competence in reading, interpreting and applying structural welding codes as well as other codes and standards. 

There is an alternative to qualification and that is prequalification.  Certain structural codes allow the use of prequalified welding procedures.  AWS D1.1 (Steel) and AWS D1.6 (Stainless Steel) are two examples of codes that permit prequalification.

Prequalification is simply the option to forgo all destructive and non-destructive testing and still have a welding procedure that is qualified.  In order for prequalification to be valid the person creating the prequalified welding procedures must meet all the requirements of the prequalification clause of the applicable code.  The reasoning behind this is that if all requirements are met then the user can have reasonable assurance that sound welds can be produced with the prequalified welding procedure.  Of course, as is also the case with qualified welding procedures, welder skill is crucial to depositing sound welds.  Because of this reason, welder performance must also be qualified by testing.  There is no option for prequalified welder performance. 

There are cases in which a fabricator does not need to comply with specific codes or standards. In these cases they may have their own internal welding quality standards that dictate the requirements for qualification.  These requirements can be as loose as simply evaluating a weld by its external appearance or can be even more stringent than structural welding codes.  

Whether you are following a code, a standard or your own internal quality requirements, it is always good practice to verify the suitability of any welding procedure that is developed.  This verification should be documented in order to have a record that can be referenced for future jobs, for conducting audits, for conducting failure analysis and for many other reasons. 

Are you performing qualifications in your welding operations?

References:

Welding Procedure Development for Non-Welding Engineers

Qualification of Welding Procedures, Welders and Welding Operators

322 AWS D1.1 Prequalified Welding Procedures for Steel Fabricators

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Categories: Processes, Testing and Inspection
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