What Does MSS Mean in Piping Industry? List of MSS Standards

MSS Standards

If you work in the piping industry, chances are you’ve heard of MSS standards. But what do they mean? In this blog post, we’ll explore what MSS stands for and list out some of the most important MSS standards that every professional in the piping industry should know.

What Does MSS Stand For?

MSS stands for Manufacturers Standardization Society, which is an American-based trade organization founded in 1933 to promote standardization among manufacturers. It was originally known as the Valves and Fittings Committee but changed its name to the Manufacturers Standardization Society (MSS) in 1957. The organization has over 6,000 members worldwide and is responsible for creating numerous standards for piping products, components, and systems.

List of Important MSS Standards            

The following is a list of some of the most important MSS standards that apply to the piping industry:

  • MSS SP-6 – Standard Finishes for Contact Faces of Pipe Flanges and Connecting-End Flanges of Valves and Fittings
  • MSS SP-25 – Standard Marking System for Valves, Fittings, Flanges & Unions
  • MSS SP-43 – Wrought Stainless Steel Butt-Welding Fittings
  • MSS SP-58 – Quality Standard for Steel Castings & Forgings Used in Piping Applications
  • MSS SP-97 – Integrally Reinforced Forged Branch Outlet Fittings – Socket Welding & Threaded Types
  • MSS SP-114 – Quality Standards for Steel Castings & Forgings Used in Piping Applications with Supplementary Requirement S1
  • MSP SP-134 – Qualification Procedure for Carbon & Low Alloy Steel Butt Welder Operators

These are just a few examples; there are many more specific standards depending on your application. It’s important to become familiar with these standards so you can ensure your products meet them when designing or manufacturing components or systems within the piping industry. 


In conclusion, understanding MSS standards is essential if you work in the piping industry. It ensures that your products meet safety requirements and regulations as set forth by the Manufacturers Standardization Society. This blog post introduced two key concepts related to MSS—what it stands for and a list of key standards—that every professional working in this field should be aware of. By familiarizing yourself with these concepts, you can ensure that your products are up to code!

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