This section introduces you to the general steps of developing a WPS; however, there are many details of WPS development that are beyond the scope of this chapter. It is important to note that this discussion is intended to be generic and not exact since different welding codes and fabrications have different requirements that will make their processes look different. The basic process will be common to what is presented here.

Let’s return to the recipe example that opened this chapter. Imagine you are hungry and want to make a meal, but you want to use the ingredients available to you at home. First you look at the ingredients that are available and form an idea for what to make. You are thinking through what you can cook, how best to cook it, and details about spices to use or processes to employ, such as cooking on the stovetop, oven, or grill.

In welding a similar process occurs for code welds, where a fabrication is made to the requirements of a welding code. Depending upon the complexity of the build and their familiarity with the type of fabrication, an engineer or senior certified welding inspector will develop an initial educated guess as to what welding process, machine settings, and technique will create a successful weld. This information is written down on a preliminary WPS, also called a pWPS. Then a welder or welding operator will try it out while someone records the essential variables, such as the important settings and characteristics of the weld, on a Procedure Qualification Record (PQR). The sample weld is then visually inspected and mechanically tested. If it passes all of the requirements of visual and mechanical testing and the PQR is reviewed and accepted in accordance with the company procedures and the quality program, then the PQR is qualified.

Let’s look at each of these development steps more closely.

Preliminary Welding Procedure Specification

The preliminary welding procedure specification is an initial educated guess at what the welding essential variables are based upon the code being used and the manufacturer’s recommendations and experience welding the same or similar material. If the material or process is not one that is often used by the company, a welding engineer will very likely research the joint design and setting needed to create a successful weld.

Procedure Qualification Record

The research done for a pWPS provides a range for the essential variables that the welder or welding operator uses to create the weld. For example, if welding with SMAW, a range could be 90–110 amps. The welder sampling the weld would use a value within that range to perform the weld. As the welder is welding another person would write down all of the essential information on a PQR to record the inputs used. A single value is typically written down for each essential variable—so this one value might be the average current used. This single value is important because welding codes will provide ranges that are expressed as plus or minus the percentage so that a range can be listed on the final WPS.

It is common for companies to ask a relatively new welder to do the welding for a PQR because a less experienced welder will typically listen more and follow directions more easily than a welder that has been welding for a long time.

If you weld for a PQR and it passes visual and mechanical testing, the related welding codes typically make you a qualified welder for that weld. It is worth asking directly if your welding in support of the PQR has qualified you, as this could be mistakenly overlooked by those asking you to weld.

Welding Procedure Specification

Next the PQR is used to create a WPS. Depending upon the rules of the welding code being applied, a single PQR can be used to create many WPSs. There are various reasons for creating multiple WPSs from one PQR. One is that different alloys might be welded, and creating many WPSs might make the WPS easier to read rather than if there were one that contained many alloy options. However, a willingness to do this will depend upon the welding company’s preferences. Another reason would be finer control of the welder’s machine settings. Recall that the ranges that are developed from the PQR come from single values. If a welder uses the low end of voltage range for GMAW and the high end of the range for wire feed speed, the welder would technically be within the WPS; however, those settings are likely not the best for success. A certain level of common welding sense that is learned by the welder is assumed.

Standard Welding Procedure Specification

Developing a PQR for a WPS is a time-consuming and expensive process. Therefore, the American Welding Society (AWS), American Society of Mechanical Engineers, and others have welding codes that allow for the use of Standard Welding Procedure Specifications (SWPSs), which are developed for common welding configurations of geometry, welding processes, base materials, and filler materials. A company may purchase an SWPS for an application that they wish to create a WPSs for. The SWPS has the advantage of having the backing of the various welding codes and societies that allow them. This reduces liability of the company if something was not 100% accurate with their PQR.