What’s The Deal With SA-105?
Understanding Material Selection For Tube Plug Welding
Welding has become fairly common practice in pressure vessel fabrication and maintenance. From tube ends to plugs, welding can provide additional strength or sealing coverage if done correctly. When it comes to tube plugging, many customers are facing questions about plug materials and special requirements to ensure vessel specifications are met. In this article we will discuss the changes to the ASME code, material types and nomenclature, and impacts to the welding process.
Selecting The Right Material
When plugging a tube, it’s best practice to use the same or a compatible material to the tube to prevent corrosion. Using a dissimilar metal will cause the tube and plug to corrode, resulting in a leak and plug failure. Generally, in most cases it’s easy to match the tube material to the plug without any special material designations. However, there are a few materials that can have several grades or uses depending on the application.
Different grades of Carbon Steel have become more popular, due to specifications set by ASME and other standards for welding.
One method to identify materials is based on the organization that specifies it. The American Society for Testing and Materials (ASTM) and the American Society for Mechanical Engineers (ASME) often work together to produce material specifications for the pressure vessel industry. As a result, their spec’d materials will often start with ASTM or ASME followed by the material, or an “S” prefix will be added in front of the material number.
The ASTM Grading System will also assign a letter prefix to a metal based on the category. For example, ‘A’ typically refers to ferrous materials (contains iron), where ‘B’ refers to nonferrous materials (does not contain iron). Combined with the organization prefix, materials may read ASTM A105 or simply SA-105.