API 610 Pump Material Selection: Corrosion and Erosion Guide

Material selection is critical for API 610 pump reliability in corrosive, high-temperature, and abrasive refinery and chemical service. This guide covers common materials, selection criteria, and compatibility for API 610 pumps.

API 610 Material Requirements

API 610 Standards

• Material class: specified per fluid (API 610 Annex materials)
• Wetted parts: casing, impeller, shaft, wear rings, seal faces
• Certification: material test reports (MTR), PMI verification
• Compatibility: verified per fluid, concentration, temperature
• Consider: corrosion, erosion, temperature, pressure, cost

Common API 610 Materials

Carbon Steel and Low Alloy

Carbon Steel (WCB)

• General hydrocarbon, non-corrosive, low temp
• Advantages: low cost, good strength, readily available
• Limitations: poor corrosion resistance, limited temp (≤425°C)
• Use: crude oil, diesel, gasoline, water (non-corrosive)
• Consider: sour service (H2S) requires NACE MR0175

12% Chromium (CA6NM)

• API 610 standard material (most common)
• Advantages: good corrosion resistance, high strength, castable
• Limitations: not for severe chloride, acid, high temp
• Use: general refinery, hydrocarbon, moderate corrosive
• Consider: hardened for wear rings, impellers

Low Alloy Steel (1.25Cr-0.5Mo)

• High temperature hydrocarbon, hydrogen service
• Advantages: high temp strength, hydrogen resistance
• Limitations: limited corrosion resistance, expensive
• Use: hydrocracker, high-temp refinery, hydrogen
• Consider: temper embrittlement, post-weld heat treatment

Stainless Steel

316SS (CF8M)

• General chemical, caustic, food, pharmaceutical
• Advantages: good corrosion, castable, widely available
• Limitations: chloride pitting (≤500 ppm), not for strong acid
• Use: caustic soda, solvents, water treatment, food
• Consider: 316L (low carbon) for welding, intergranular corrosion

304SS (CF8)

• Mild corrosive, water, food
• Advantages: lower cost than 316, good general corrosion
• Limitations: less corrosion resistance than 316, chloride sensitive
• Use: water, mild chemical, food, beverage
• Consider: 304L for welding

Duplex Stainless Steel

Duplex 2205 (CD4MCu / 4A)

• High chloride, sour service, seawater, mixed acid
• Advantages: high strength (2× 316), excellent chloride resistance, good weldability
• Limitations: high cost, temp limit (≤300°C), complex casting
• Use: seawater, oil & gas (sour), chemical (chloride), desalination
• Consider: PREN ≥35 for seawater, NACE MR0175 for sour

Super Duplex 2507 (5A/6A)

• Severe chloride, high temp sour, extreme corrosive
• Advantages: superior chloride resistance, high strength, good at moderate temp
• Limitations: very expensive, temp limit (≤280°C), difficult to cast/weld
• Use: deepwater oil & gas, severe sour, high chloride chemical
• Consider: PREN ≥40, sigma phase embrittlement (temp control)

Nickel Alloys

Alloy 20 (CN7M)

• Sulfuric acid, chemical processing, mixed acid
• Advantages: excellent sulfuric acid resistance, good general corrosion
• Limitations: expensive, not for hydrochloric, temp limit
• Use: sulfuric acid (all concentrations), chemical, pharmaceutical
• Consider: concentration/temp curve (verify compatibility)

Hastelloy C-276 (CW2M)

• Severe corrosive, mixed acid, oxidizing/reducing
• Advantages: excellent broad corrosion resistance, high temp
• Limitations: very expensive, difficult to cast/machine
• Use: chemical (mixed acid), flue gas desulfurization, waste treatment
• Consider: C-22 for better oxidizing, C-2000 for improved

Monel (M35-1 / N-24M)

• Hydrofluoric acid, seawater, alkaline
• Advantages: excellent HF resistance, seawater, high strength
• Limitations: expensive, not for oxidizing acid
• Use: HF acid, alkylation, seawater, caustic
• Consider: mercury, ammonia (stress corrosion)

Non-Metallic Linings

Fluoroplastic (PTFE/PFA/FEP)

• Severe corrosive acid, high purity, chemical
• Advantages: excellent broad chemical resistance, high purity
• Limitations: temp limit (≤150°C PTFE, ≤200°C PFA), permeation, mechanical damage
• Use: sulfuric, hydrochloric, nitric, mixed acid, pharmaceutical
• Consider: lining thickness, spark test, vacuum resistance

Rubber Lining

• Abrasive slurry, acid, wastewater
• Types: natural rubber (abrasion), neoprene (acid), EPDM (hot water/acid)
• Advantages: excellent abrasion resistance, good acid, low cost
• Limitations: temp limit (≤80-120°C), oil/solvent attack, mechanical damage
• Use: mining slurry, wastewater, acid (dilute), scrubber liquor
• Consider: lining thickness, bond strength, inspection

Material Selection Factors

Corrosion Compatibility

• Fluid: chemical composition, concentration, impurities
• Temperature: corrosion rate increases with temp (verify at operating temp)
• Concentration: acid/base concentration affects corrosion (non-linear)
• Impurities: chloride, fluoride, oxygen (accelerate corrosion)
• Use: corrosion tables, supplier data, field experience

Erosion/Abrasion

• Solids: particle size, concentration, hardness, velocity
• Wear rate: ∝ velocity³ (minimize velocity for abrasive)
• Materials: high-chrome iron, rubber, ceramic, hardened 12% Cr
• Consider: impeller, volute, wear rings (highest velocity)
• Use: slurry, catalyst, ash, mining

Temperature

• High temp: material strength, creep, oxidation
• Low temp: brittleness (Charpy impact test required)
• Carbon steel: ≤425°C (above, graphitization risk)
• Stainless: ≤400°C (above, sensitization, sigma phase)
• Duplex: ≤300°C (above, 475°C embrittlement, sigma)

Pressure

• High pressure: material strength, wall thickness
• Rating: ANSI 150#, 300#, 600#, 900#, 1500#
• Material: higher strength allows thinner wall (duplex, alloy)
• Consider: flange rating, bolting, gasket
• Use: hydrocracker, boiler feed, high-pressure injection

API 610-Specific Applications

Sour Service (H2S)

• NACE MR0175/ISO 15156: material requirements
• Materials: 12% Cr (controlled hardness), duplex, 316SS (low carbon)
• Avoid: carbon steel (sulfide stress cracking), high hardness
• Consider: H2S partial pressure, chloride, temp (NACE severity)
• Certification: NACE compliance, hardness test, PMI

Hydrocracker (High H2, High Temp)

• Materials: 2.25Cr-1Mo, 3Cr-1Mo, austenitic stainless (overlay)
• Hydrogen: high temp hydrogen attack (HTHA), decarburization
• Consider: temper embrittlement, step cooling test
• Seal: API 682 double seal, Plan 53B
• Use: hydrocracker feed, recycle, high-pressure injection

Sulfuric Acid

• Materials: Alloy 20, Hastelloy, 316SS (concentration dependent)
• Concentration: dilute (corrosive to steel), concentrated (passivates steel)
• Temp: critical (higher temp = more corrosive)
• Consider: velocity (erosion-corrosion), air ingress
• Use: acid transfer, circulation, fertilizer, chemical

Common Issues

• Wrong material: Corrosion, premature failure. Verify compatibility per fluid/concentration/temp.
• Ignoring chloride: Pitting, crevice corrosion in 316SS. Use duplex for >500 ppm chloride.
• Ignoring H2S (sour): Sulfide stress cracking. Follow NACE MR0175, use approved materials.
• Carbon steel for acid: Rapid corrosion. Use stainless, alloy, or lined.
• Ignoring temp limits: Embrittlement, creep, graphitization. Verify material at operating temp.
• No PMI: Wrong material installed. Use positive material identification (PMI).
• Galvanic corrosion: Dissimilar metals in conductive fluid. Use compatible materials, isolate.
• Ignoring erosion: Wear in abrasive service. Use high-chrome, rubber, or ceramic.

Procurement Recommendations

1. Specify material class per fluid (API 610 Annex or custom)
2. For chemical: specify 316SS, duplex, Alloy 20, or Hastelloy per fluid
3. For sour service: specify NACE MR0175 compliance
4. For chloride: specify duplex (2205) or super duplex (2507)
5. For sulfuric acid: specify Alloy 20 or Hastelloy
6. For abrasive: specify high-chrome iron or rubber lining
7. Require material test reports (MTR) for all wetted parts
8. Require PMI verification (critical pumps, alloys)
9. For high/low temp: specify impact testing, temp limits
10. For lined pumps: specify lining thickness, spark test, inspection
11. Verify supplier has material selection and application experience

Related Industries

API 610 material selection applies to oil & gas (refinery, sour service, hydrocracker), petrochemical (ethylene, ammonia), chemical processing (acid/caustic/solvent), power generation (boiler feed, FGD), mining (slurry, abrasive), and desalination (seawater, chloride). The core principle — proper material selection based on fluid chemistry, temperature, pressure, and abrasion for reliable API 610 pump operation — is consistent across all critical pump applications.