Introduction And Classification Of Water Pump Materials

Jan 18, 2025

Due to the wide range of applications and different working conditions of water pumps, they need to be treated differently according to specific situations. Firstly, it depends on what system engineering it is used for, and the classification of engineering will roughly distinguish the types and materials of pumps. Afterwards, in the individual project, based on the design requirements, the pump will be subdivided according to the pipeline medium, flow rate, head, and power.

Selection method
Temperature of the medium: The brittleness of the material will increase at very low temperatures, but it will undergo creep at high temperatures; A certain material can withstand the corrosion of a certain medium at room temperature, but not the corrosion of that medium at high temperature. When selecting materials, attention should be paid to the temperature requirements and their range of variation of the conveyed medium.

Corrosivity of the medium: The corrosion resistance of materials to the medium is specific to the medium and within a certain range. For example, the acid resistant steel lCr18N19 used in IH chemical centrifugal pumps can withstand corrosion from medium and low concentrations of nitric acid or organic acids, but cannot withstand corrosion from dilute sulfuric acid.

Electrochemical corrosion: To prevent the formation of electrochemical corrosion effects in conductive media due to the different potentials of different materials, it is best to use metal materials with the same potential for all overcurrent components of the water pump.

The economy of materials: It is uneconomical to use high-quality materials with low usage or non corrosion-resistant materials as corrosion-resistant materials in design or use.

Wear resistance of solid particles: When the conveyed medium contains solid particles, the relevant components should be made of wear-resistant materials.

Clamping between materials: For parts that move relative to each other during installation or operation, such as shafts and shaft sleeves, bolts and nuts, impeller sealing rings and pump body sealing rings, balance plates and balance plates, the hardness of the two parts should be slightly different when selecting materials or processing technology to avoid biting or scratching each other during loading, unloading or operation.

The places where high-speed liquid flow passes through: the impeller blades and guide vane inlet edges of high lift pumps, sealing sleeves with high single-stage head, balance sleeves, balance disks, and balance plates of high lift pumps should be made of erosion resistant materials (such as chromium stainless steel or chromium nickel acid resistant steel, etc.).

Introduction to Common Materials for Water Pumps

1, Cast iron
1. Grey cast iron
It is the most commonly used type of cast iron, with the Chinese code name HT. The pump body, impeller, pump cover, suspension, etc. of a general clean water pump are all made of this material, and three grades are usually used: HT150,HT200,HT250. For non essential components such as bases and pads, HT150 is commonly used, while HT200 is commonly used for pump bodies, pump covers, suspensions, etc., and HT250 is commonly used for impellers, mouth rings, shaft sleeves, etc.

The representation of gray iron varies among countries, such as FC in Japan, GG in Germany, and Class in the United States.

2. Ductile iron
It is a type of cast iron with good comprehensive functions, with the Chinese code name QT. Because its mechanical properties are close to steel, and its forging and processing capabilities are superior to steel, it is usually used as a substitute for cast steel. The commonly used grades are: QT450-10,QT500-7,QT600-3.

The representation method for ductile iron in DIN scale is GGG, and the representation method is Ductile iron.

In addition, there are corrosion-resistant cast iron - high silicon cast iron, wear-resistant cast iron - white cast iron, high toughness cast iron - malleable cast iron, etc.

2, Cast steel

Because the strength of cast steel increases, when the pressure is greater than 1.6Mpa, cast steel is often used for pressure bearing parts, and CS is usually used to represent cast steel.

3, Stainless steel

The most commonly used stainless steel is austenitic stainless steel, such as 0Cr18Ni9, 1Cr18Ni9Ti, 0Cr18Ni12Mo2Ti, etc. Except for a few media such as hydrochloric acid and dilute sulfuric acid, austenitic stainless steel is an excellent corrosion-resistant material, usually represented by SS304, SS316, and SS316L.

Martensitic stainless steels such as 2Cr13 and 3Cr13 have better mechanical properties than austenitic stainless steels and are commonly used as materials for pump shafts and shaft sleeves, corresponding to the code SS420.

In addition, high alloy stainless steel (alloy 20) and duplex stainless steel are also ideal corrosion-resistant materials.

4, Alloy steel

The most representative alloy steel is 40Cr, which is commonly used as a material for high-strength pump shafts.

5, Carbon structural steel

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 in various steel plates and sections; The most representative high-quality carbon steel is 45 steel, which is widely used as a pump shaft material when there is no erosion requirement.

6, Non metallic materials

Non metallic materials for pumps are mainly used for sealing, such as polytetrafluoroethylene, fluororubber, nitrile rubber, etc. Among them, polytetrafluoroethylene is used as a sealing gasket for chemical pumps and a static seal for mechanical seals due to its excellent corrosion resistance and high temperature resistance. It is suitable for almost all chemical media within 250 ℃, but its disadvantages are high hardness and difficult assembly.

Fluororubber is also a good material for temperature and corrosion resistance, with a suitable upper temperature limit of 160 ℃. When users have no special requirements, chemical pumps mainly use sealing rings made of this material; Nitrile rubber is mainly used for static sealing in oil or water resistant media.