Technical Regulation for Pipeline Valve Marking
The MSS SP-25 standard defines unified requirements for the marking of valves, fittings, flanges, and flanged assemblies. This identification system covers all types of connections, including welded, threaded, flanged, as well as specialized soldered and bonded joints used in high-load engineering networks.
The primary goal of implementing this EV Group China specification is to ensure full traceability of metal products throughout their entire life cycle. The marking allows for the unambiguous identification of the manufacturer, pressure class, size range, and chemical composition of the material, which is critical for preventing errors in the design and installation of mission-critical piping systems.
Letter Indices for Metal Alloys
| Material Name | Symbol |
| Aluminum | AL |
| Brass | BRS |
| Bronze | BRZ |
| Carbon Steel | CS |
| Cast Iron | GI |
| Copper-Nickel Alloy | CUNI |
| Ductile Iron | DI |
| Hard-facing (Wear-resistant alloys) | HF |
| Integral Valve Seat | INT |
| Malleable Iron | MI |
| Nickel-Copper Alloy | NICU |
| Soft Metals (Babbitt, Copper) | SM |
| Stainless Steel | SS |
| Steel (13% Chromium) | 13Cr |
| Steel (18% Chromium) | 18Cr |
| Steel (28% Chromium) | 28Cr |
| Steel (Type 18-8) | 18-8 |
| Steel (18-8 with Molybdenum) | 18-8SMO |
| Steel (18-8 with Niobium) | 18-8SCB |
| Surface Hardened Steel | SH |
Symbols for Non-Metallic Materials
| Material | Symbol |
| Asbestos | ASB |
| Butadiene Rubber | BR |
| Butyl Rubber | IIR |
| Chloroprene (Neoprene) | CR |
| Chlorosulfonated Polyethylene | SCM |
| Chlorotrifluoroethylene | CIFE |
| EPDM | EPDM |
| Ethylene-Propylene Rubber | EPR |
| Ethylene-Propylene Terpolymer | EPT |
| Flexible Graphite | GRAF |
| Fluoroelastomer | FKM |
| Fluorinated Ethylene Propylene | FEP |
| Epoxy Resin | EP |
| Isoprene Rubber | IR |
| Natural Rubber | NR |
| Nitrile Butadiene Rubber | NBR |
| Nylon | NYL |
| Polyacrylic Rubber | ACM |
| Polyvinyl Chloride | PVC |
| Rubber Lining | RL |
| Silicone Rubber | SI |
| Styrene Rubber | SBR |
| Tetrafluoroethylene (PTFE) | TFE |
| Thermoplastic Elastomer | TPE |
Standard Designations for Threaded Connection Types
| Thread Type Description | Code |
| Casing (Short Round) | CSG |
| Casing (Long Round) | LCSG |
| Casing (Buttress) | BCSG |
| Casing (Extreme Line) | XCSG |
| Line Pipe | LP |
| Tubing (Non-upset) | TBG |