ANSI MSS SP-25:2018 pdf free download – Standard Marking System for Valves, Fittings, Flanges, and Unions
6. HEAT NUMBER
If part size permits and when required by the product or material’s specification standard, carbon, alloy, and stainless-steel castings and forgings used for fittings, flanges, union components, valve bodies, bonnets, and covers shall be marked with a heat number and material symbol from the Mill Test Report, also known as the Material Test Report (MTR). Heat number is not required for materials identified in Sections 5.3 and 5.4. TERMINOLOGY NOTE: The term “heat” is also known as “melt” and the term “number” was previously known as “identification”, as in “heat identification” or “melt identification. Current terminology is “heat number”.
7. VALVE TRIM IDENTIFICATION
7.1 Trim identification marking is required on the identification plate for all flanged end and butt-welding end steel or flanged-end ductile iron body valves having trim material which is different than the body material. Symbols for material identification can be found in Tables A1 and A2 of this Standard Practice. If all trim materials are the same, the identification plate may be marked with the word “TRIM”, followed by the appropriate material symbol.
7.1.1 When required, trim identification marking for gate, globe, angle, and cross valves or valves with similar design characteristics shall consist of three material symbols. The symbols may either be preceded by the words “STEM”, “DISC”, “SEAT”, or used alone. If used alone, the symbols shall appear in the following order: (1) the first symbol shall indicate the material of the stem, (2) the second shall indicate the material of the disc or wedge face, and (3) the third shall indicate the material of the seat face.
7.1.2 When required, the trim identification marking for check valves, as they do not have a stem, shall consist of two material symbols. The symbol may either be preceded by the words “DISC”, “SEAT”, or if used alone, the first symbol shall indicate the material of the disc face, and the second shall indicate the material of the seat face.
7.1.3 Plug, ball, and butterfly valves or other quarter-turn valves require no trim identification marking unless the plug, ball, disc, or closure member, or stem, or both are different material than the body. In such cases, trim identification symbols on the nameplate will first indicate the material of the stem, and secondly indicate the material of plug, ball, disc, or closure member. When required, valves with seating or sealing materials different than the body material shall add a third symbol to indicate the material of the seat. In these cases, the seat symbol identification shall be preceded by the word “SEAT”. If used alone, the material symbols must appear in the order given.
7.1.4 When specified, API steel valves built to specific standards that list Trim Numbers shall be marked with the API Standard Number (e.g., “API 600”), the word “TRIM”, and the API Trim Number (e.g., 1,2,3, etc.) on the valve’s Identification Plate. See Section B18.5.5 Example.