What are some commonly used materials for high-flow, high-head multistage pumps?

2025-06-23

High-flow, high-head multistage pumps must withstand high pressure, high-speed flow, and potentially corrosive and abrasive conditions. Material selection must balance strength, corrosion resistance, and wear resistance. The following are some commonly used materials and their applications.

1. Flow Component Materials (Impellers, Guide Vanes, Pump Casings, etc.)

Stainless Steel Series

304/316 Stainless Steel: Used for general corrosive media (such as clean water, weak acids and alkalis). 316, due to its molybdenum content, offers stronger resistance to chloride corrosion and is suitable for seawater or media containing chlorides.

Duplex Stainless Steel (such as 2205, 2507): Combines the advantages of austenitic and ferritic stainless steels, offering high strength and stress corrosion resistance. Suitable for harsh environments with high salinity, high temperature, or hydrogen sulfide (such as petroleum, chemical processing).

Super Austenitic Stainless Steel (such as 904L): Resistant to strong acids (sulfuric acid, phosphoric acid) and high-temperature corrosion, but it is more expensive.

Cast Iron Series

Ductile Iron (QT500-7): Low cost, good pressure resistance, suitable for non-corrosive media (such as clean water, industrial circulating water).

High-Nickel Cast Iron (Ni-Resist): Resistant to alkaline and some acidic media, used in special corrosive environments.

Special Alloys

Hastelloy (C276, B2): Resistant to strong acids (hydrochloric acid, sulfuric acid), high temperatures, and localized corrosion. Used in extreme conditions in the chemical and metallurgical industries.

Titanium Alloy (Gr.2/5): Resistant to seawater and chloride corrosion; the preferred choice for seawater desalination or marine engineering.

2. Shaft and Bearing Components

Martensitic Stainless Steel (such as 2Cr13, 17-4PH): High strength, resistant to slight corrosion, and exhibits good wear resistance after tempering. Suitable for pump shafts.

Precipitation Hardening Stainless Steel (such as 630/17-4PH): Achieves higher strength through heat treatment, used in high-load or fatigue-resistant applications.

Carbon Steel (42CrMo): Chrome or nitride plating enhances wear resistance. Used in non-corrosive media.

3. Sealing Rings and Wear Rings

Silicon Carbide (SiC): High hardness, wear and corrosion resistance. Commonly used in high-speed, high-pressure sealing pairs.

Cemented Carbide (WC-Co): Extremely wear-resistant, used in media containing solid particles (such as slurry pumps).

Bronze (Aluminum Bronze, Tin Bronze): Used in low-load or well-lubricated applications; relatively low cost.

4. Other Key Materials

Rubber/Polymer Linings: Such as EPDM (acid and alkali resistant), fluororubber (high-temperature corrosion resistant), used for lining pump casings containing corrosive media.

Ceramic Coating: Sprayed onto metal surfaces to improve wear resistance. Suitable for media containing particles.

5. Material Selection Influencing Factors

Media Characteristics: Corrosiveness, particle content, temperature (high-temperature applications require consideration of thermal stability).

Pressure Rating: High-pressure applications require high-yield strength materials (such as duplex steel, alloy steel).

Cost and Lifespan: Hastelloy offers superior performance but is expensive; a cost-benefit analysis is necessary.

6. Typical Application Examples

Seawater Desalination Pump: Titanium alloy or super duplex steel (2507).

Oilfield Injection Pump: 316L or Hastelloy (hydrogen sulfide resistance).

Mine Dewatering Pump: High-chromium cast iron impeller + silicon carbide sealing ring.

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