The welding process is part of a special process, i.e. a product manufacturing process, the validity of which cannot be completely verified once a final inspection has been carried out.

For a "normal" process, such as cold cutting a profile, checking the correct execution and result can be done by carrying out a dimensional inspection. For a welding, a visual check and even a radiographic check can verify the correct geometry and highlight the absence or presence of any surface and internal defects of the joint, but not its mechanical and chemical properties, detectable only by destructive tests.

Therefore, it is necessary to carry out the welding in accordance with specific procedures, the results of which have already been verified by process qualification tests, according to recognised international standards. One or more tests are performed together with a designated examiner, recording all the parameters used, and then performing the non-destructive and destructive tests required by the reference standard on these tests.

The conformity of the test results makes it possible to use the qualified process in production, applying welding parameters that are consistent with the parameters applied to the test assays

The current legislative framework requires the qualification of welding processes used by manufacturers in various areas, such as: pressure equipment, machinery, railway construction, structural carpentry, among others.

Update

In July 2017, UNI, the Italian Organization for Standardization, published the new edition of the international standard UNI EN ISO 15614.1 ed. 2017; it replaced the previous UNI EN ISO 15614.1, ed. 2012.

The new standard fully complies with the structure and requirements of the PED Directive and became part of the national regulatory framework on July 26, 2017.

Europe and America are more aligned in terms of standards due to the publication of EN ISO 15614-1 "Specification and Qualification of Welding procedures for Metallic Materials - Welding Procedure Test".

This update is a world-wide milestone in the historical dualism between the American and European approaches to the qualification of welding procedures.

The new edition contains an element of innovation. The standard has been divided into two parts that describe two alternative approaches to each other:

• one very close to the traditional philosophy that is reflected, as an example, in the ASME code
• another that continues and updates the European approach already present in the previous edition of EN ISO 15614
   

The innovative elements covered by the new standard and the possible consequences on the quality control of welding production are various.

The certification service according to the international standards ISO 15613 and ISO 15614 and the national American standards ASME and AWS, includes the following steps:

 

DOCUMENT VERIFICATION

Verification of the technical documentation of the tests being carried out: welding procedure specification (WPS), basic material certificates, filler material certificate (if applicable).

 

MONITORING DURING THE PERFORMANCE OF THE TESTS

Verification, by qualified inspectors of a Certification Body, the correct application of the specification of the welding process (WPS), during the testing, and joint inspection.

 

SUPERVISION OF LABORATORY TESTS AND ISSUE OF CERTIFICATION

Laboratory monitoring during the tests, and issue of the Certificate of qualification of the welding process (WPQR).