For Mr. Stremmel, inspecting welded assets takes attention to detail and thorough testing, no matter the material of construction. But in working with clients and end users as they alternate between projects that involve stainless steel and materials like carbon steel, Mr. Stremmel has come to observe a persistent problem that can affect quality control. “One of the big challenges in welding stainless steel has always been with ‘weldability,’” Mr. Stremmel said. “By that I mean that many clients I work with approach stainless steel welding in the same way they approach carbon steel—and this leads to problems.”
For example, in welding carbon steel, the underlying characteristics of the pieces that will be welded and the welding wire itself do not have as big of an impact as they do in stainless steel. With carbon steel you can take just about any other kind of carbon steel and weld them together, and you will be okay. But you can’t do that with stainless.
When you go and start welding stainless steel, you have to make sure that grades are compatible. After all, I don’t want to weld 304 to 316. On top of that, you have to make sure the welding wire is not going to adversely affect the quality of the weld. One of the biggest challenges I face is teaching people about the diversity of stainless steel as compared to a material like carbon steel.”
“The diversity across stainless steels is reflected in the standards,” Mr. Stremmel continued. “A look through the American Society of Mechanical Engineers guidelines, specifically section 9, will bring up standards for welding procedures. In that section, they list materials under different numbers. Now carbon steel is listed in a high level of detail, but it isn’t broken down nearly as fine as stainless steel is. Inside of the material numbers for stainless steel there are even further distinctions of group numbers—covering characteristics such as austenitic, martensitic, high magnesium, high molybdenum etc.”
“What the standards are saying here is that in technical welding, you need to break down your procedure to a high degree of specificity with stainless steel, as the diversity of the material is such that careful attention must be paid to underlying properties. That means if I want to weld 304 to 310, for example, I will need to do destructive testing to verify the mechanical properties of the weld. Stainless steel is a great material, and when welded properly, it can make an excellent material for any asset, but you have to ensure the materials being welded together are compatible. What I commonly see is that welders tend to approach stainless steel like carbon steel, but a look at the regulations will show why this is not a good idea.”
The situation, however, is slowly improving. “Thanks to standardization and quality control on the end of stainless steel manufacturers, along with knowledge sharing and the passing on of experience, welders are getting better at working with stainless steel. Welding has this element of black magic to it, and when you start welding, there is a lot of trial and error. In many cases you are mixing and matching, and human error enters into a lot of what we do. But just as steel production has standardized and improved, so too is welding developing into a more refined, regulated task. And as we go forward, that will mean that stainless steel will become less mysterious and better understood by welders.”
Meet Mr. Stremmel
Many welding inspectors begin their careers working on manufacturing lines or in construction. Mr. Randall Stremmel began with aircraft carriers and submarines. After leaving the Marine Corps. in 2001, Mr. Randall Stremmel’s still-active security clearance granted him access to an exciting subset of the welding world: inspecting welds on aircraft carriers and submarines. But after a few years carrying out ultra-sonic, radiographic, and penetrant tests for the armed forces, Mr. Stremmel began to have aspirations outside the military. He applied for and received a coveted welding inspector certification, and from there opened his own firm, RPS Welding Consultants in Ohio. At the start of 2020, Mr. Stremmel merged his company with another outfit in the Houston area to become Oso Partners, a consulting firm that assists in the development of large-scale energy projects.