Weldtest NZ Limited

The main differences between a PQR and a WPS

Further to our last article where we discussed what a PQR and WPS is: This week we wanted to delve a little deeper and discuss the main differences. In case you are wondering, a WPS stands for ‘welding procedure specification’ and a PQR is ‘procedure specification record’.

A WPS and PQR are mandatory documents when welds need to comply to a standard. Both documents are closely related, but they are not the same.

The PQR is a standard document, but the people who use it may not necessarily come from the same background. Welders and engineers who create the welded product develop a WPS to make the product comply with the standard quality.
In contrast, the PQR is often associated with inspectors, manufacturers, or contractors who use the document for testing and verification purposes.

An added variance is the orientation of the document’s contents. A WPS is usually filled with numerous texts, images, and sentences in accordance to its being an instructional guide. On the other hand, a PQR is like a checklist with blank lines and spaces for written notes that will be filled out by the inspector during the inspection.

Before the inspection, the WPS document is the object of attention of the welders. Meanwhile, during and after the inspection, the PQR is the document of concern for inspectors, contractors/manufacturers, and welders.?
Each document has a different purpose. A WPS serves as a blueprint for a written instruction and a PQR checks whether the standard is being followed by inspecting and answering the document regarding specific areas and tests. ?The PQR acts as the evidence that the testing of the piece, that was used to write the WPS, was carried out and complied to the standard.

A WPS has the welding parameters explained in the context of instructions to allow for the welder to reproduce the product with a particular quality and standard.
A PQR uses these welding parameters as a checklist to see if the standard is met or not.

In case you missed the last article, we think the following sums it up well:

In simple terms:

The WPS is written from the PQR.
A PQR comes before a WPS.
A PQR is needed to do a WPS.
The PQR is specific while the WPS is generic.