MSS piping standards
Manufacturers Standardization Society (USA): Practices for valves, fittings, flanges and pipe supports. 10 standards most used in piping, flanges, fittings, valves and materials.
| Standard | Covers | Category | On this site |
|---|---|---|---|
| MSS SP-25 | Standard marking system for valves, fittings, flanges and unions | Fittings | Open → |
| MSS SP-43 | Wrought and fabricated buttwelding fittings for low pressure, corrosion-resistant service | Fittings | Open → |
| MSS SP-44 | Steel pipeline flanges | Flanges | Open → |
| MSS SP-55 | Visual quality standard for steel castings | Castings | – |
| MSS SP-58 | Pipe hangers and supports | Supports | – |
| MSS SP-75 | High-strength wrought buttwelding fittings | Fittings | Open → |
| MSS SP-79 | Socket-welding reducer inserts | Fittings | Open → |
| MSS SP-83 | Class 3000 and 6000 pipe unions | Fittings | Open → |
| MSS SP-95 | Swaged nipples and bull plugs | Fittings | Open → |
| MSS SP-97 | Integrally reinforced forged branch outlet fittings (weldolet, sockolet, threadolet) | Fittings | Open → |
Subjects are short summaries, not official titles. Always buy the current edition from the issuing body; check which edition your project specification names.
Frequently asked questions
Which MSS standards cover piping?
MSS SP-25 (standard marking system for valves); MSS SP-43 (wrought and fabricated buttwelding fittings for low pressure); MSS SP-44 (steel pipeline flanges); MSS SP-55 (visual quality standard for steel castings); MSS SP-58 (pipe hangers and supports); MSS SP-75 (high-strength wrought buttwelding fittings) and others listed on this page.
Last updated 2026-11-02