1. Valve body material:
(1) Metals:
1. Cast iron (FC), high hardness, poor corrosion resistance, low cost, easy to form and process, often used as the valve body of butterfly valve to reduce cost.
2. The performance of ductile iron (FCD, GGG40) is slightly better than that of cast iron, and the use is the same as above.
3. Carbon steel is divided into cast steel (WCB) and forged steel (A105). It belongs to the steel category. It is resistant to sulfuric acid, will rust, and has better corrosion resistance than cast iron. It is often used in butterfly valve body, valve plate, ball valve body, etc. .
4. Stainless steel 304 (SUS304, CF8), with good performance and corrosion resistance, is often used in high-demand butterfly valve bodies and valve plates, valve cores of ball valves, and other valves.
5. Stainless steel 316 (SUS316, CF8M), high nickel content, better corrosion resistance than 304, but softer than 304, other properties are equivalent.
6. Duplex steel (2520), high temperature resistance, super corrosion resistance, commonly used in strong corrosive media such as sea water.
7. Aluminum bronze, especially strong resistance to seawater corrosion.
8. Alloy steel is a complex mixture of various components. It is made according to different requirements. At present, there are nearly a thousand different formulas in the world, which are unknown.
9. Brass is also used to make valves, but because of its poor strength and corrosion resistance, it is mostly used by civilians.
(2) Plastics:
1. PVC (polyvinyl chloride), which is the most commonly used plastic valve material, and PVC with increased hardness is often called UPVC, with little difference. The temperature resistance is about 0-65 degrees, and the corrosion resistance is relatively good, but the pressure resistance of plastic valves can only be less than 10 kg.
2. CPVC has better temperature resistance than PVC, can reach 95 degrees, and slightly stronger corrosion resistance.
3. PP, the temperature resistance is stronger than PVC, and other properties are equivalent.
4.PVDF has the best heat resistance and corrosion resistance among plastics, but the price is relatively high.
2. Sealing material:
PTFE, the chemical name is polytetrafluoroethylene, referred to as tetrafluoroethylene, because it has particularly good corrosion resistance (most acid-base salts are suitable, sulfuric acid resistance), temperature resistance (-20 degrees --- 150 degrees), the most common Used for sealing rings and gaskets of ball valves, and also used as sealing rings for butterfly valves that require corrosion resistance.
RPTFE, chemical name enhanced tetrafluoroethylene, can withstand temperature 180 degrees (RPTFE+carbon fiber: temperature resistance, RPTFE+glass fiber: wear-resistant)
3. PPL, its temperature resistance is super strong, and can withstand up to about 230 degrees. Because PPL has relatively high hardness, it is often used as a sealing ring on high-temperature ball valves, especially suitable for steam-over-steam ball valves. It can withstand high temperatures and has good sealing performance , the corrosion resistance is equivalent to PTFE, and the price is relatively high.
4. EPDM, the chemical name is EPDM rubber, which has general corrosion resistance (weak acid and weak alkali can be used), good temperature resistance (applicable within 100 degrees), and is a common sealing ring for valves passing through gas, water, oil and other media. EPDM can be used for butterfly valves in most occasions.
5. NBR, the chemical name of nitrile rubber, except for very good oil resistance, other properties are equivalent to EPDM, and can be used in general. It is generally believed in the industry that the temperature resistance of NBR is slightly worse than that of EPDM (selected within 85 degrees).
6. VITON, often called fluorine rubber, also called FKM, has very good temperature resistance (within 250 degrees), because the material is soft and the hardness is similar to EPDM, it is only suitable for sealing rings of butterfly valves, not suitable for ball valves The seal is similar to the PPL seal of a ball valve.
7. PEEK, the chemical name is polyether ether ketone, with a temperature resistance of 250 degrees. Due to its non-deformable characteristics, it is often used as a sealing ring for high-pressure ball valves, but it is afraid of concentrated sulfuric acid and is expensive.
8. TFM, the chemical name is reinforced polytetrafluoroethylene, TFM1600, suitable for subzero low temperature ball valve temperature resistance -100℃---160℃, TFM4215, suitable for subzero low temperature ball valve temperature resistance -200℃---230℃
9. PCTFE, chemical name polytrifluorochloroethylene, can reach minus 190 degrees without deformation.
10. Alloy, 304/316/Statite alloy (better wear resistance), the ball valve with alloy as sealing ring is called hard-sealed ball valve, the main purpose of hard-sealed ball valve is to use the medium as powder, granules, or Viscous and other occasions with serious wear, and high temperature resistance, basically suitable for below 500 degrees.
11. Ceramics, ceramics have the characteristics of ultra-high temperature resistance, and are the sealing materials for ultra-high temperature resistant valves.