Industrial Pump Materials: Selection and Use（II）

3. High-Alloy Materials & Nickel-Based Alloys

Used for extremely corrosive environments.

Hastelloy (e.g., C-276/C-22):

Characteristics: Excellent corrosion resistance to both oxidizing and reducing media, particularly resistant to wet chlorine, hypochlorite, sulfuric acid, and hydrochloric acid.

Applications: Hydrometallurgy, absorber circulation pumps in Flue Gas Desulfurization (FGD), strong acids (hydrochloric acid, sulfuric acid).

Monel (400/K-500):

Characteristics: Primarily nickel-copper, excellent corrosion resistance to hydrofluoric acid, seawater, and alkaline solutions.

Applications: Hydrofluoric acid transfer, seawater pumps, caustic pumps.

Titanium & Titanium Alloys (e.g., Gr.2):

Characteristics: Low density, high strength, extremely strong corrosion resistance to chlorides (e.g., seawater, brine), excellent pitting resistance.

Applications: Seawater desalination pumps, marine pumps, chlor-alkali industry, oxidizing media (e.g., wet chlorine).

Zirconium (702):

Characteristics: Excellent corrosion resistance to sulfuric and hydrochloric acids, especially at medium concentrations and temperatures.

Applications: Concentrated sulfuric acid pumps, certain harsh chemical processes.

4. Non-Metallic Materials

Used for highly corrosive but relatively mild (temperature, pressure) conditions.

Plastics (e.g., PP Polypropylene, PVDF Polyvinylidene Fluoride):

Characteristics: Excellent corrosion resistance, low cost, light weight. But strength and temperature resistance are poor.

Applications:

PP: Resistant to acids and alkalis, used in electroplating, scrubbers, wastewater treatment.

PVDF: Stronger corrosion resistance, better temperature resistance, can be used for halogens, strong oxidizing acids.

Fluoroplastics (e.g., FEP, PFA):

Characteristics: Resistant to almost all chemical media, known as "plastic kings."

Applications: Lining or full plastic construction for magnetic drive pumps, centrifugal pumps, used for high-purity, highly corrosive chemicals like hydrochloric, sulfuric, nitric acids, and mixed acids.

Ceramics (e.g., Alumina, Silicon Carbide):

Characteristics: Extremely high hardness, exceptional wear resistance, excellent corrosion resistance, but brittle.

Applications:

Alumina Ceramic: Mechanical seal rings.

Silicon Carbide Ceramic: The preferred choice for wear and corrosion-resistant pumps, used for slurries with sharp particles, e.g., power plant FGD slurry pumps, mining slurry pumps. Also used as friction pairs for mechanical seals.

Rubber Lining (e.g., Natural Rubber, Neoprene, Butyl Rubber):

Characteristics: Utilizes the elasticity of rubber to resist particle impact and wear, while providing good corrosion resistance.

Applications: Slurry Pumps. Different rubbers are selected based on the medium, e.g., natural rubber has good wear resistance, butyl rubber has excellent acid resistance.

Summary

The selection of materials for water pumps in industrial production is a complex systems engineering task. A typical pump may use different material combinations for its casing, impeller, shaft, and seals. For example, a pump handling concentrated brine in seawater desalination might use a duplex stainless steel casing and impeller, paired with silicon carbide mechanical seals and a titanium alloy shaft sleeve.

Core Recommendation: When selecting a pump, always provide complete and accurate information about the fluid composition, concentration, temperature, pressure, pH value, solid content, and particle size. Consult with professional pump manufacturers or materials engineers and conduct necessary corrosion tests to finalize the safest, most economical, and most durable material solution.