Common WPS Issues

A well written welding procedures specifications (WPS) is the basis of a successful welding management program. It is the main reason why the quality welds are made along with production rates. Surprisingly enough there are many fabrication shops that do not have written WPS’s or even worse, incorrect WPS’s. Those shops do not understand the importance of this document, which is one of the main factors as to why they cannot maintain a quality system and productivity rates. Below are the 8 issues that I see over and over.

1)   A one off WPS – Several of my clients are looking to satisfy only one client for one product, which might be necessary in certain cases. But when this happens, you lose the benefits of standardization. If everyone is welding to the same WPS no matter what the product is, welders become interchangeable. Projects that need more welds to make an extreme deadline or a major project can seamlessly have welders added to the project without losing quality. Productivity improves without retraining or qualifying welders and quality improves since the welders know the standards of welds they are creating.

2)   WPS’s that are not available to welders during fabrication or production. This one is a pet peeve of mine, if we are taking the time to create a road map to make a quality weld, then why wouldn’t you give the map to the person driving the car? An approved WPS’s for the job should be with every welder for reference and review during construction or manufacturing. On a side note, training of the proper method to read a WPS is essential for production of quality welds.

3)   Essential variables ranges are too wide – what is the point of writing a WPS when the amps are from 40-400? Like discussed in item 1 some shops take standardization to the extreme, like having one WPS for everything. They want to give the welders such a broad range that they can weld in every position and thickness. These WPS are written in such a manner that it is almost impossible to weld outside of the parameters of the WPS. Of course, this will lead to poor quality with the loss of control since a welder can weld with whatever they feel is necessary.  Some welds will be running cold and others to hot, but they are welded within the parameters of the WPS.

4)   Prequalified WPSs – some structural welding codes like AWS D1.1, allow the use of prequalified welding procedures, but these procedures can be improperly implemented. Prequalified procedures are meant to be a cost savings and standardization of WPSs across multiple industries. Because of this, prequalified procedures have a very strict guidelines on how to write them. By following the strict guidelines AWS allow you to not qualify the WPS by testing. There are still many violations to rules that govern prequalified welding procedures including:

a.    Use of GMAW short circuit transfer

b.    Incorrect material groups

c.    Exceeding single pass weld size

d.    Exceeding single pass weld width

e.    Exceeding filler metal manufacturers recommended settings

f.     Exceeding joint tolerances

The proper use of prequalified welding procedures in accordance with AWS D1.1 requires that you obey the specified joint tolerances. Having errors in prequalified welding procedure specifications is one of the easiest ways to fail an audit. 

5)   Poorly written welding procedures – a WPS should be a document that provides clear instructions to the welders on how to make a weld. In many cases we see values for certain variables that are just unrealistic and which may be confusing to the welders. This often happens when engineers or other professionals that do not understand the welding process are tasked with developing or simply documenting welding procedures.

6)   WPS written that are not balanced, what do I mean by this? A balanced WPS is written with both quality and production in mind. Production is how you meet schedules but quality is how you keep customers. So, a proper WPS will need to be written to allow the welder to maximize production while still producing a quality weld. There is no reason to have the welder’s deposition rate at 3 inches per minute when welding at 9 inches per minute will still produce the same weld quality. Always try to maximize productivity as long as you don’t compromise quality. 

7)   PQR that are not referenced on the WPS – unless you are using prequalified welding procedures all WPSs need to be qualified by testing. If the procedure is a prequalified then state that in the PQR line of the WPS. The qualification tests are documented in a procedure qualification record (PQR) if the procedure successfully meets the qualification requirements. This PQR must be referenced in the WPS, even Standard Welding Procedures Specifications (SWPSs) provide the PQRs that back them up. Make sure you state the supporting PQRs in your WPSs.

8)   WPS’s without an approval signature. When you write and qualify a procedure, someone else will need to review and approve the WPS. This is really just a second pair of eyes to make sure that all information that is required on a WPS are present and that the procedure meets code. The same person can NOT write and review their own procedures but rather someone with experience with welding, codes and materials. This signature is not stating that all welds will be correct as to many factors play into that, but rather says this document is correct and meets code.

There are plenty of other errors that I have seen over the years, but these are eight of the most common ones that I have seen. If you need help or maybe do not understand something, ask someone or you can email me at randall@pmet-inc.com. Poorly written WPS can impact the quality of the welds and productivity. Rework will drive up the cost of manufacturing with poor quality driving away customers.