Technical Articles
Materials of Valve Body and Components
Posted: 2014-06-05 10:39:25 Hits: 766
1. Materials of valve body: Grey cast iron has been weeded out. Body is mainly made of nodular cast iron and should be given clear indication of the name of a product and physical or chemical data of casting.
2. Materials of stem: Stem is made of stainless steel (2CR13), including large caliber valve.
3. Materials of nut: Nut is made of casting aluminum brass or casting aluminum bronze and the strength and hardness is higher than stem.
4. Materials of bush for stem: The hardness and strength is lower than stem. Bush cannot cause electrochemical corrosion to stem or body.
5. Materials of seal face:
(1) Different valves require different seal and materials;
(2) Materials of copper collar, methods of fasten or grind should be shown;
(3) For soft seal gate valve, physical and chemical data of rubber lining of disc should be shown;
(4) For butterfly valve, the materials of seal face and disc should be shown. Generally, disc and seal face is made of nitrile rubber or ethylene propylene terpolymer. Reconverted rubber is not allowed.
6. Packing in shaft:
(1) Valves in pipe do not open or close frequently. For that, valves should have excellent aging resistance and keep good seal for a long time.
(2) Packing in shaft should keep good seal when valve opens or closes frequently.
(3) Packing can be irreplaceable forever or at least ten years.
(4) When packing needs to be replaced, it should be carried out under water pressure.
