A successful welding management program is based on well-written welding procedure specifications (WPS). It is the main reason the quality welds are made along with production rates. Surprisingly enough, many fabrication shops do not have written WPSs or, even worse, incorrect WPS. Those shops do not understand the importance of this document, which is one of the main reasons they cannot maintain a quality system and productivity rates. Below are the eight issues that I see over and over.
- A one-off WPS – Several of my clients are looking to satisfy only one client for one product, which might be necessary for some instances. 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 significant project can seamlessly have welders added to the project without losing quality. Productivity improves without retraining or qualifying welders, and quality improves since they know the standards of welds they create.
- WPS is not available to welders during fabrication or production. This one is a pet peeve of mine; if we create a road map to make a quality weld, why wouldn’t you give the map to the person driving the car? An approved WPS for the job should be with every welder for reference and review during construction or manufacturing. On a side note, training the proper method to read a WPS is essential for producing quality welds.
- Essential variables ranges are too wide – what is the point of writing a WPS when the amps are 40-400? As discussed in item 1, some shops take scandalization to the extreme, like having one WPS for everything. They want to give the welders such a broad range that they weld in every position and thickness. These WPS are written so that it is almost impossible to weld outside 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 too hot, but they are welded within the parameters of the WPS.
- Prequalified WPS – 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 a cost-saving and standardization of WPSs across multiple industries. Because of this, prequalified procedures have stringent guidelines on how to write them. By following the strict guidelines, AWS allows you not to qualify the WPS by testing. Unfortunately, there are still many violations of rules that govern prequalified welding procedures, including:
- Use of GMAW short circuit transfer
- Incorrect material groups
- Exceeding single pass weld size
- Exceeding single pass weld width
- Exceeding filler metal manufacturers’ recommended settings
- Exceeding joint tolerances
The proper use of prequalified welding procedures per 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.
- Poorly written welding procedures – a WPS should be a document that provides clear instructions to the welders on making a weld. Unfortunately, in many cases, we see values for certain variables that are just unrealistic and may confuse 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.
- WPS wrote that they 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 the quality keeps customers. So, a proper WPS will need to be written to allow the welder to maximize production while still producing a quality weld. For example, 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.
- PQR is not referenced on the WPS – unless you use prequalified welding procedures, all WPS need to be qualified by testing. If the procedure is prequalified, 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 WPS.
- WPSs without an approval signature. Someone else must review and approve the WPS when you write and qualify a procedure. This is just a second pair of eyes to ensure that all information required on a WPS is present and that the procedure meets the code. The same person can NOT write and review their procedures but someone with experience with welding, codes, and materials. This signature is not stating that all welds will be correct as many factors play into that but instead says this document is accurate 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 email@example.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.