Carbon steel (0.1 to 0.5 percent carbon) is the workhorse structural material for pump shafts, impellers, and casings in petrochemical, power generation, and process industries where higher mechanical strength than cast iron is required and the liquid handled does not cause significant corrosion at operating temperature.
History
Crucible cast steel for pump components was introduced in Sheffield, England around 1770 by Benjamin Huntsman. However, carbon steel became practical for pump manufacturing only after Henry Bessemer invented the Bessemer converter in 1856, enabling mass production of uniform-quality steel. By 1900, carbon steel had replaced cast iron in high-pressure boiler feed pumps. The introduction of killed (deoxidized) steel grades in the early 20th century allowed reliable casting of pump volutes free from porosity.
Key Properties
- Density: 7.8 g/cm3
- Tensile strength: 400 to 700 MPa depending on carbon content and heat treatment
- Yield strength: 250 to 500 MPa
- Hardness: 120 to 220 HB (annealed to normalized)
- Good machinability and weldability for pump component fabrication
- Magnetic — allows use of magnetic couplings in pump drive systems
Corrosion and Chemical Resistance
- Acceptable for dry petroleum products, non-aggressive oils, and steam condensate
- Rapid corrosion in aqueous environments without inhibitors or coatings
- Suitable for hydrogen sulfide-free hydrocarbon service below 260 degrees C per Nelson curves
- Not suitable for acids, seawater, or chlorinated media
- Internal coatings or cathodic protection required for water service
- Hydrogen embrittlement risk in high-pressure hydrogen service above 200 degrees C
Grades and Standards
- ASTM A216 WCB — most common cast carbon steel pump casing grade for ambient temperature service
- ASTM A105 — carbon steel forgings for pump flanges and impellers
- DIN 1.0619 (GS-C25) — European equivalent cast carbon steel grade
- ASME B31.3 governs piping and connected pump material selection for process plants
Applications
- Petrochemical refinery process pumps handling hydrocarbons
- High-pressure boiler feed pumps in power generating stations
- Steam condensate return pumps
- Hydraulic fracturing pump fluid ends in oil and gas production
- Pipeline booster pump casings for long-distance transport
- Mining dewatering pumps with non-corrosive groundwater
Advantages
- Significantly higher strength than cast iron — enables thinner walls and lighter casings
- Readily weldable — facilitates repair and modification in the field
- Suitable for low-temperature cryogenic applications with low-carbon grades
- Lower cost than stainless or alloy steels for moderate service conditions
- Wide global supplier base for forgings and castings from multiple foundries
Limitations
- Corrodes rapidly in water, acids, and chloride environments without surface protection
- Carbon steel impellers erode quickly in slurry or abrasive liquid service
- Limited use above 425 degrees C due to carbide precipitation embrittlement
- Requires surface protection (paint, zinc coating, or lining) for most water service
- Not suitable for aqueous process streams without demonstrated corrosion inhibition
Selection Criteria
- Specify ASTM A216 WCB for ambient-temperature hydrocarbon pump casings
- Use ASTM A352 LCB or LCC for low-temperature service down to -46 degrees C
- Apply NACE MR0175/ISO 15156 for sour (H2S) hydrocarbon service requirements
- Not suitable for aqueous process streams without demonstrated corrosion inhibition
- Consider stainless steel upgrade for any liquid containing dissolved chlorides
Top 10 Manufacturers
- 1. Flowserve Corporation (USA) — ~15% of carbon steel pump market; API 610 process pump casings
- 2. Sulzer Ltd. (Switzerland) — ~12%; high-pressure multistage carbon steel pump bodies
- 3. ITT Inc. Goulds Pumps (USA) — ~10%; ANSI and API carbon steel process pump casings
- 4. KSB SE (Germany) — ~9%; carbon steel centrifugal pumps for petrochemical industry
- 5. Weir Group PLC (UK) — ~8%; carbon steel pump casings for oil and gas upstream operations
- 6. CIRCOR International (USA) — ~6%; carbon steel high-pressure pump components and assemblies
- 7. Ebara Corporation (Japan) — ~6%; carbon steel boiler feed and process pump casings
- 8. Baker Hughes (USA) — ~5%; carbon steel ESP and surface pump components for oilfield service
- 9. SPX Flow Inc. (USA) — ~5%; carbon steel centrifugal and positive displacement pump casings
- 10. Ruhrpumpen GmbH (Germany) — ~4%; carbon steel API 610 centrifugal pump casings