Cast Steel Hand Pumps for Marine Use: Analysis of Structural Characteristics, Application Advantages, and Emergency Condition Adaptability

I. Classification of Marine Cast Steel Materials and Their Adaptability to Hand Pumps

1.Carbon Cast Steel

Carbon cast steel is represented by typical grades such as ZG230-450 and ZG270-500, with a carbon content of 0.12%-0.6%:

Material Characteristics: Tensile strength of 450-600MPa, yield strength of 230-300MPa, excellent weldability, lower cost than alloy cast steel, and suitable for low-pressure conditions.

Marine Applications:

Lifeboat hand pumps: ZG270-500 material has a service life of 10 years in freshwater environments. A lifeboat on a ro-ro passenger ship used this material's hand pump to drain continuously for 60 hours without failure under simulat

d sinking conditions.

Freshwater supply pumps for small ships: Suitable for freshwater transportation with pressure ≤1.0MPa, such as emergency freshwater supply for fishing boat decks.

2.Alloy Cast Steel

Alloy cast steel enhances performance by adding elements such as Cr, Mo, and Ni, excelling in high-pressure and high-temperature conditions:

Cr-Mo series alloy cast steel: Such as ZG20CrMo, containing 1-3% chromium and 0.5-1% molybdenum:

Performance Highlights: 40% increase in high-temperature strength, strength retention rate >80% at 300℃, and excellent hydrogen corrosion resistance.

Core Applications: Emergency fire-fighting hand pumps can withstand 1.6MPa pressure. A cargo ship used a ZG20CrMo hand pump to supply water continuously for 15 hours in a simulated fire scenario.

Ni-Cr series alloy cast steel: Such as ZG340-640, containing 2-4% nickel and 1-2% chromium:

Low-temperature Characteristics: Impact energy ≥27J at -40℃, suitable for emergency drainage of polar ships.

Marine Applications: An Arctic research ship used this material's hand pump to drain stably at -30℃, meeting BV classification society low-temperature certification.

3.Stainless Steel Cast Steel

Stainless steel cast steel is indispensable for seawater and corrosive media due to its corrosion resistance:

Austenitic stainless steel cast steel: 304 (ZG0Cr18Ni9), 316L (ZG00Cr17Ni14Mo2):

Corrosion Resistance Index: Corrosion rate <0.01mm/year in 3.5% sodium chloride solution, with 316L having 50% enhanced chloride ion corrosion resistance compared to 304.

Application Scenarios: Seawater emergency drainage pumps. A 316L hand pump on a cruise ship life raft was used for 8 years in seawater without corrosion.

Duplex stainless steel cast steel: 2205 (ZG0Cr22Ni5Mo3N):

Comprehensive Performance: Strength twice that of 316L, pitting resistance equivalent number (PREN) ≥34, suitable for acidic ballast water.

Typical Applications: Drainage of electrolyzed acidic ballast water (pH <5), with a service life three times longer than ordinary cast steel.

4.Wear-Resistant Cast Steel

Wear-resistant cast steel improves wear resistance through alloying, suitable for particle-containing media:

High-chromium wear-resistant cast steel: Containing 12-18% chromium, hardness HRC55-60:

Wear Resistance: In mud with a sand content of 15%, the wear rate is 50% lower than carbon cast steel.

Special Scenarios: Hand pumps for port 驳运 (port cargo transfer). Sand dredging ships use this material's hand pumps to transport mud, with a piston life of 15,000 operations.

II. Core Technical Advantages of Marine Cast Steel Hand Pumps

1.High-Pressure Heavy-Duty Emergency Reliability

Mechanical Drive Advantage: No need for electrical or hydraulic systems; relies on manual handle operation for medium transportation, still functional in extreme situations such as ship power outages or engine failures:

Deep-sea exploration ship emergency drainage: A deep-sea ship used a ZG340-640 hand pump to achieve 3m³/h drainage with 3 operators under 5,000-meter water depth pressure.

Emergency fuel supply: When small ships have no power, ZG20CrMo hand pumps can supply fuel from storage tanks to the main engine at a flow rate of 25L/min.

2.High-Strength Structure and Long-Life Design

Enhanced by cast steel properties:

Compressive strength 40% higher than cast iron. A cargo ship's QT600-3 hand pump withstood 1.2MPa water pressure without deformation.

Anti-fatigue strength up to 350MPa, rocker arms can withstand 150,000 reciprocating motions. A research ship's hand pump has not replaced core components in 10 years.

3.Extreme Environment Adaptability

Temperature adaptation range:

Alloy cast steel hand pumps can work in environments from -40℃ to 300℃. Arctic route ships use Ni-Cr cast steel hand pumps to drain normally at -35℃.

Stainless steel cast steel hand pumps in tropical seas (water temperature 35℃) have a corrosion rate <0.02mm/year in seawater.

4.Ship Vibration Environment Stability

Vibration damping performance: Cast steel damping coefficient 0.02 (5 times that of steel). In 6-level sea conditions

Bearing amplitude ≤0.05mm. A cruise ship's hand pump worked stably under 1500rpm main engine vibration.

Anti-impact design can withstand 30G impact load, meeting lifeboat airdrop requirements.

III. Application Limitations of Marine Cast Steel Hand Pumps

1.Manpower-Driven Efficiency Bottleneck

Flow and head limitations:

Manual operation flow is usually ≤8m³/h, only 15% of electric pumps. Main drainage for large ships requires 8 people to operate 4 hand pumps.

Maximum head ≤12m, unable to meet deep-sea ship bilge (water depth >20m) drainage needs.

2.Weight and Installation Challenges

Weight disadvantage: DN50 cast steel hand pump weighs 18kg (cast iron pump 12kg), affecting lifeboat center of gravity configuration, requiring additional counterweight.

Installation requirements: Coaxiality requirement ≤0.05mm. A container ship's rocker arm wear due to installation errors increased maintenance costs by 30%.

3.Corrosion Resistance and Medium Limitations

Seawater corrosion: Ordinary carbon cast steel in seawater requires zinc-based epoxy coating (cost increased by 20%). Uncoated pump bodies have a 30% rusting rate within 1 year.

Strongly corrosive media: Forbidden to transport concentrated acids, liquid ammonia, etc. A chemical ship mistakenly using carbon cast steel hand pumps to transport dilute nitric acid caused pump body perforation within 2 months.

IV. Key Points for Marine Selection and Maintenance

1. Material Selection Matrix

2.Key Maintenance Actions

Pressure testing: Conduct 1.5-fold rated pressure testing annually (e.g., 1.5MPa test for 1.0MPa pumps). A cargo ship experienced piston seal failure due to omitted testing.

Rust prevention treatment: Rinse seawater pumps with fresh water after each voyage and apply molybdenum disulfide grease. A fishing boat's untreated 316L pump body developed crevice corrosion.

Rocker arm lubrication: Add lithium-based grease monthly. A research ship's unlubricated ZG20CrMo rocker arm saw a 40% increase in rotation resistance after six months.