There are a variety of things to consider when ensuring a quality welding process during a capital project. Some of these items include client requirements, environmental considerations like cold temperatures, the sophistication of materials, code and governmental compliance, and planning and preparation. In this article, I will discuss the basic, yet important, components of a system to ensure quality welding.
As early as the pre-contract and pre-mobilization phase, setting clear expectations is crucial. Contractors must be provided a clear technical scope, alongside relevant specifications, inspection and test plan (ITP) and nondestructive examination (NDE) requirements, before welding begins. This upfront exercise helps keep the overall cost down. To keep the direction on track, it is recommended clients fully review the request for proposal with the contractor, communicate their desired process and subcontract list, providing desired project formats for documents like procedure qualification records (PQRs) and welding procedure specifications (WPSs), along with anything else specific to the project.
With most EPC projects, welding is a major part of completing the venture. There are a variety of welding processes that can be utilized, with each process varying when it comes to the skillset needed. Deciding which welding process to use is based on several factors, such as deposition rate, efficiency and equipment costs. Welding procedures and welder qualifications are also essential to providing quality welds. These elements should not be overlooked and must be taken seriously and done correctly in order to prevent potential failures.
The main code surrounding this is ASME Section IX. Across the industry, this is the most prevalent code that governs qualifications for welding, brazing and fusing procedures. Broken into five articles, the code was made to be easily interpreted and understood by end-users. This code is dedicated solely to qualifying procedures and qualifying welders/fusers; it does not have inspection call-outs for the field.
I will take one part of the code and cover PQR and WPS development. ASME Section IX does not allow the contractor to subcontract oversight of either of these critical operations.
Jim Huges, H+M Industrial EPC
A PQR creates a record of variables (essential and nonessential) taken during the welding of the test coupons that demonstrates the contractor's ability to make a sound weld. It also contains the test results of the selected specimens. For ASME Section IX, the minimum mechanical tests are bend and tensile. There are other tests that can be done if required by contract or code. The recorded variables normally fall within a small range of the actual variables that will be used in production welding. This is the proof to ASME that we, as the end-user, can make sound welds, and forms the foundation of a WPS. Ultimately, the end goal of this is to replicate from the PQR and test what the expectation in the field is going to be. Other considerations in determining the PQR capabilities include line list, temperature, materials and the materials' thickness.
A WPS is a written set of instructions for the welder to follow. Think about it like a cake recipe. To have a good-tasting cake, you must follow the instructions. To have a weld that a welder can replicate, he or she must follow the instructions. Qualified welding procedures are prepared to provide direction for making production welds to meet code requirements. The WPS or other documents may be used to provide direction to the welder or welding operator to ensure compliance with the code requirements. A welder should be able to repeatedly replicate welds per the procedures. It is essential the welder sees the procedure and understands it. The WPS is not for the foreman or superintendent, although they also need to understand the procedure. If the welder follows it, a good, sound welding operation should follow.
The next time you're traveling somewhere, look around: Chances are the skyscrapers or industrial plants you see followed these same principles in building.
For more information, contact Robyn Hall at (281) 930-8750 or rhall@hm-ec.com.
