Sunday, February 15, 2009

Arc Welding 101
May/June PWT 2008
Title: A WPS lesson for beginners

Recently I was given a weld procedure specification (WPS) from a contractor to review. It’s still lying on my desk. Do you have any tips for a beginner like myself on how to review a WPS?
Habeeb Rahman
TPI Welding Inspector


It's time to pick up that WPS off your desk and give it a good, hard look. The first thing you need to arm yourself with is the correct code or standard. The WPS is going to state which code or standard it complies with. You most likely need to get familiar with ASME Section IX or AWS D1.1 Sections 3 and 4, or both.

Does it reference a procedure qualification report (PQR), or is it considered prequalified? It is important to make sure that the WPS states how it was qualified.

Review the joint design. Does the joint on the WPS match the joint referenced? Is backing required? Is the joint within the stated tolerances?
Ensure the base metal of the joint matches the base metals listed on the WPS, which may require a little homework. Your code should list materials by group or P-numbers. Also review the filler metal/flux/shielding listed and witness which is used.

Are there preheat or postweld heat-treat requirements? How will you measure them? Are the welding parameters such as current, voltage, travel speed, and number of passes being used within the range of the ones that are listed? How will you measure them?

A WPS is really a recipe for how a particular weld is going to be made. All the ingredients need to match, and when they don't, even beginners need to stand up and get the attention of someone who will get your welding back on track. Don't be intimidated by a WPS. Break it down section by section, and simply ensure that what is noted matches what is being done on your project.

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