Common materials for national standard valves

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I. General requirements for materials: The materials for the valve body, valve cover, and flanges should be selected based on the operating conditions and manufacturing requirements, and must comply with the provisions of GB 12228, GB 12229, GB 12230, and GB 3077. Materials for nuts, bolts, and studs can include A5, 25, 35, 30CrMoA, and 40MnVB, etc. The choice should be based on the operating pressure and temperature, and they must comply with the requirements specified in GB 700, GB 699, and GB 3077. Precision cast parts shall not be used in valves with a nominal pressure of PN > 10.0 MPa. Attention should be paid to the potential graphitization of materials in the following situations: for carbon steel, above approximately 425°C ； Carbon-molybdenum steel above about 470°C ； Chromomolybdenum steel (with less than 0.6% chromium) above about 525°C. In the following situations, attention should be paid to the possible occurrence of peroxide reactions (which lead to the formation of oxide scales): 1Cr-0.5Mo steel, 1.25Cr-0.5Mo steel, 2Cr-1Mo steel, and 3Cr-1Mo steel at temperatures above approximately 565°C; 5Cr-0.5Mo steel at temperatures above approximately 595°C. II. Specifications for selecting materials for key components The materials used for the key components of carbon steel valves designed to handle media at temperatures ranging from -20 to 425°C must comply with the requirements specified in “Table 1”. The material of the main components of alloy steel valves used for transporting media with a temperature of 540°C or lower shall comply with the provisions of \"Table 2\". The main materials for alloy steel valves used to transport media at temperatures of 550°C or lower shall comply with the provisions of \"Table 3\". The material of the main components of stainless acid-resistant steel valves used for transporting media with a temperature of 200°C or lower shall comply with the provisions of \"Table 4\". For wedge gate valves used in Class A and B pipelines and subjected to frequent opening and closing, the material of the sealing surface should be cemented carbide. If there are special requirements regarding the material of the main components of valves in pipes transporting corrosive media, they should be specified at the time of ordering. The valve support material, made of alloy steel or stainless steel and separate from the valve cover, shall be carbon steel or as specified in the order. Manufacturers of valve packing and gaskets must have their products tested for performance by designated sealing inspection agencies, and their technical specifications must meet the following requirements: The surface of the gasket itself shall be free from defects such as scratches, unevenness, and rust spots ； The non-metallic strip should protrude evenly from the metallic strip, and it should be smooth and even ； Gaskets shall not be pre-pressed or otherwise processed, and welds must be free from defects such as weak soldering or over-burning. **Table 1** Materials for main components of carbon steel valves
Component name | Material name | Grade | Standard
---|---|---|---
Valve body, valve cover | Carbon cast steel | WCB | GB 12229
Opening/closing parts, brackets | High-quality carbon steel | 20, 25 | GB 699
Valve stem | Chromium stainless steel | 2Cr13, 1Cr13 | GB 1220
Valve stem nut | Aluminum bronze | Cast aluminum bronze QA19-4, ZCuA110Fe3 | GB 4429, GB 1176
Seals for valve seat and opening/closing parts | Chromium stainless steel | – | GB 1220
| Cobalt-chromium-tungsten alloy | – | GB984
| Polytetrafluoroethylene | – | ZBG33002, ZBG33003
Bolts | Alloy structural steel | 35CrMo | GB 3077
Nuts | High-quality carbon steel | 35, 45 | GB 699
Gaskets | Stainless steel strip | – | Flexible graphite wound gasket; technical requirements per SHJ407
| Special graphite wound gasket | – | Flexible graphite composite gasket; technical requirements per HGJ70
Packing | Flexible graphite packing ring | – | JB/T 6617
| Flexible graphite braided packing | – |
Handwheel | Malleable cast iron, ductile iron | KTH330-08, KTH350-10; QT400-15, QT450-10 | GB 9440, GB 12227

Note: Gaskets and packing can also be selected according to user requirements. When other non-metallic sealing materials are used for the sealing surfaces of valve seats and opening/closing parts, this must be specified. The flexible graphite packing ring must be assembled together with flexible graphite braided packing.

**Table 2** Materials for main components of alloy steel valves
Component | Material name | Grade | Standard
---|---|---|---
Valve body, valve cover | Chromium-molybdenum-vanadium cast steel | ZG15Cr1Mo1V | ZBJ98015
| Chromium-molybdenum-vanadium steel | 12Cr1MoV | GB 3077
Valve seat, opening/closing parts | Chromium-molybdenum-vanadium cast steel | ZG15Cr1Mo1V | ZBJ98015
| Chromium-nickel-titanium cast steel | ZG1Cr18Ni9Ti | GB 2100
| Chromium-nickel-titanium steel | 1Cr18Ni9Ti | GB 1221
| Chromium-molybdenum-vanadium steel | 12Cr1Mov | GB 3077
Valve stem | Chromium-molybdenum-vanadium steel | 25Cr2MoVA | GB 3077
Valve stem nut | Aluminum bronze | Cast aluminum bronze QA19-4, ZCuA110Fe3 | GB 4429, GB 1176
Sealing surfaces of valve seat and opening/closing parts | Cobalt-chromium-tungsten alloy | – | GB 984
Bolts | Chromium-molybdenum-vanadium steel | 25Cr2MoVA | GB 3077
Nuts | Chromium-molybdenum steel | 35CrMo | GB 3077
Gaskets | Stainless steel strip | – | Flexible graphite wound gasket; technical requirements per SHJ407
| Flexible graphite composite gasket | – | Technical requirements per HGJ70
Packing | Flexible graphite packing ring | – | JB/T 6617
| Flexible graphite braided packing | – |
Handwheel | Malleable cast iron, ductile iron | KTH330-08, KTH350-10; QT400-15, QT450-10 | GB 9440, GB 12227

Note: Gaskets and packing can also be selected according to user requirements. The flexible graphite packing ring must be assembled together with flexible graphite braided packing.

**Table 3** Materials for main components of alloy steel valves
Component name | Material name | Grade | Standard
---|---|---|---
Valve body, valve cover | Chromium-molybdenum cast steel | ZC1Cr5Mo | Chromium-molybdenum steel 1Cr5Mo; GB 1221
Valve seat, opening/closing parts | Chromium-molybdenum cast steel | ZG1Cr5Mo | Chromium-nickel-titanium cast steel ZG1Cr18Ni9Ti; GB 2110
| Chromium-nickel-titanium steel | 1Cr18Ni9Ti | GB 1221
Valve stem | Chromium-nickel-titanium steel, chromium-nickel-vanadium steel | 1Cr18Ni9Ti, 25Cr2MoVA | GB 1221, GB 3077
Valve stem nut | Aluminum bronze | Cast aluminum bronze QA19-4, ZCuA110Fe3 | GB 4429, GB 1176
Sealing surfaces of valve seat and opening/closing parts | Cobalt-chromium-tungsten alloy | – | GB 984
Bolts | Chromium-molybdenum-vanadium steel | 25Cr2MoVA | GB 3077
Nuts | Chromium-molybdenum steel | 35CrMo | GB 3077
Gaskets | Stainless steel strip | – | Flexible graphite wound gasket; technical requirements per SHJ407
| Flexible graphite composite gasket | – | Technical requirements per HGJ70
Packing | Flexible graphite packing ring | – | JB/T 6617
| Flexible graphite braided packing | – |
Handwheel | Malleable cast iron, ductile iron | KTH330-08, KTH350-10; QT400-15, QT450-10 | GB 9440, GB 12227

**Table 4** Materials for main components of stainless and acid-resistant steel valves
Component material | Material name | Grade | Standard
---|---|---|---
Valve body, valve cover, opening/closing parts | Chromium-nickel-titanium cast steel | ZG0Cr18Ni9Ti, ZG1Cr18Ni9Ti | GB 2100
| Chromium-nickel cast steel | ZG00Cr18Ni10 |
| Chromium-nickel-titanium steel | 0Cr18Ni9, 1Cr18Ni9Ti | GB 1220
| Chromium-nickel steel | 00Cr19Ni10 |
| Chromium-nickel-molybdenum-titanium cast steel | ZG0Cr18Ni12Mo2Ti, ZG1Cr18Ni12Mo2Ti | GB 2100, CF3M; GB 12230
| Chromium-nickel-molybdenum-titanium steel | 0Cr18Ni12Mo2Ti, 1Cr18Ni12Mo2Ti | GB 1220
| Chromium-nickel-molybdenum steel | 00Cr17Ni14Mo2 |
Valve stem | Chromium-nickel-titanium steel | 0Cr18Ni9, 1Cr18Ni9Ti, 00Cr19Ni10 | GB 1220
| Chromium-nickel-molybdenum-titanium steel | 1Cr18Ni12Mo2Ti, 0Cr18Ni12Mo2Ti |
| Chromium-nickel-molybdenum steel | 00Cr17Ni14Mo2 |
Valve stem nut | Aluminum bronze | Cast aluminum bronze QA19-4, ZCuA110Fe3 | GB 4429, GB 1176
Sealing surfaces of valve seat and opening/closing parts | Base material | – |
| Cobalt-chromium-tungsten alloy | – | GB 984
| Polytetrafluoroethylene | – | ZBG33002, ZBG33003
Bolts | Chromium-nickel steel | 1Cr17Ni2, 1Cr18Ni9 | GB 1220
Nuts | Chromium stainless steel, chromium-nickel steel | 1Cr13, 1Cr18Ni9 | GB 1220