Common pump materials mainly include: cast iron, cast steel, stainless steel, carbon structural steel, alloy steel, and non-metallic materials.
I. Cast Iron
- Gray cast iron is the most commonly used type of cast iron, with the national standard code HT. Generally, the pump body, impeller, pump cover, suspension, and other components of clean water pumps are made of this material. Three grades are usually used: HT150, HT200, and HT250. HT150 is mostly used for non-critical parts such as bases and base plates; HT200 for pump bodies, pump covers, and suspensions; and HT250 for impellers, wear rings, and shaft sleeves. The designation of gray cast iron varies by country: FC in Japan, GG in Germany, and Class in the United States.
- Ductile iron is a cast iron with excellent comprehensive properties, with the national standard code QT. Its mechanical properties are close to those of steel, while its casting and machining properties are superior to steel, so it is often used as a substitute for cast steel. The most commonly used grades are: QT450-10, QT500-7, and QT600-3. Due to limitations in casting and other factors, it is currently used for pump impellers—especially open-cut impellers—due to their excellent cost-performance ratio. The designation of ductile iron is GGG according to DIN standards and Ductile iron in the United States.
In addition, there are corrosion-resistant cast iron (high-silicon cast iron), wear-resistant cast iron (white cast iron), and high-toughness cast iron (malleable cast iron), etc. Due to certain difficulties in processing, they are not widely used in pump materials.
II. Cast Steel
Cast steel has high strength. Usually, when the pressure > 1.6MPa, pressure-bearing parts are mostly made of cast steel, with the national standard code ZG. The most commonly used grade is ZG230-450. Cast steel is usually designated as CS in Japan and the United States.
III. Stainless Steel
The most widely used stainless steel for pumps is austenitic stainless steel, such as 0Cr18Ni9, 1Cr18Ni9Ti, and 0Cr18Ni12Mo2Ti. Except for a few media such as hydrochloric acid and dilute sulfuric acid, austenitic stainless steel is an excellent corrosion-resistant material and is the most commonly used corrosion-resistant material for chemical pumps. Austenitic stainless steel is usually designated as SS304, SS316, and SS316L in Japan and the United States. Martensitic stainless steel, such as 2Cr13 and 3Cr13, has better mechanical properties than austenitic stainless steel and is usually used as the material for pump shafts and shaft sleeves, with corresponding designations SS420 in Japan and the United States. In addition, high-alloy stainless steel (Alloy 20) and duplex stainless steel are also ideal corrosion-resistant materials.
IV. Carbon Structural Steel
It is usually divided into ordinary carbon structural steel and high-quality carbon structural steel. The most representative ordinary carbon structural steel is Q235, which is widely used for various steel plates and section steels; the most representative high-quality carbon steel is 45# steel, which is extensively used as the material for pump shafts when there are no corrosion requirements.
V. Alloy Steel
The most representative alloy steel is 40Cr, which is usually used as the material for high-strength pump shafts.
VI. Non-Metallic Materials
Non-metallic materials for pumps are mainly used for sealing, such as polytetrafluoroethylene (PTFE), fluororubber, and nitrile rubber.
- PTFE has excellent corrosion resistance and high-temperature resistance, so it is used for gaskets of chemical pumps and static seals of mechanical seals. It is suitable for almost all chemical media within 250℃, but its disadvantage is high hardness and difficulty in assembly.
- Fluororubber is also a good high-temperature and corrosion-resistant material, with a maximum temperature resistance of 160℃. In the absence of special requirements from users, it is recommended to use fluororubber seals for chemical pumps; nitrile rubber is mainly used for static seals in oil-resistant or clean water media.
