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VALVE MATERIALS SPECIFICATION
2024.08.06
1. General requirements for materials
The materials of the valve body, bonnet and flange should be selected according to the conditions of use and manufacturing requirements, and should comply with the provisions of GB 12228, GB 12229, GB 12230 and GB 3077.
Nuts, bolts, studs can be made of A5, 25, 35, 30CrMoA and 40MnVB, etc., which should be selected according to the pressure and temperature of use, and should comply with the provisions of GB 700, GB 699 and GB 3077.
Precision castings must not be used in valves with nominal pressure PN > 10.0MPa.
Attention should be paid to the possibility of graphitization of the material in the following situations:
Carbon steel at about 425°C;
Carbon-molybdenum steel at approximately above 470°C;
Chromium-molybdenum steel (less than 0.6% chromium) at approximately above 525°C.
Attention should be paid to possible peroxide reactions (descaling) in the following situations:
1Cr-0.5Mo steel, 1.25Cr-0.5Mo steel, 2Cr-1Mo steel, and 3Cr-1Mo steel approximately above 565°C
Approximately 595Mo above 595°C for 5Cr-0.5Mo steel
Second, the main parts and materials selection regulations
The main parts and materials of carbon steel valves used for conveying medium temperature of -20~425°C shall comply with the provisions of Table 1.
The main component material of the alloy steel valve used for conveying medium temperatures below or equal to 540°C shall comply with the provisions of Table 2.
The main material of alloy steel valves used for conveying medium temperatures below or equal to 550°C shall comply with the provisions of Table 3.
The main component materials of stainless acid-resistant steel valves used for conveying medium temperatures below or equal to 200°C shall comply with the provisions of Table 4.
The sealing surface material of the wedge gate valve used for Class A and B pipelines and frequently opened and closed should be made of cemented carbide.
If there are special requirements for the main parts and materials of the pipeline valve for transporting corrosive media, it should be put forward at the time of ordering.
Alloy steel, stainless steel valve bracket material separated from the bonnet, should be carbon steel or according to the order requirements.
The manufacturer of valve packing and gasket must be tested for the performance of its products by the relevant sealing testing unit, and the technical performance shall meet the following requirements:
There should be no defects such as scars, unevenness and rust spots on the surface of the gasket body;
The non-metallic belt should be evenly protruding from the metal belt and should be smooth and flat;
The gasket shall not be pre-pressed or otherwise processed, and the solder joints shall not have defects such as false welding and overburning.
(表格）
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