Marine Cast Iron Sewage Pump

I. Product Overview

Marine cast iron sewage pumps are core equipment for ship sewage discharge systems, constructed with high-strength ductile iron (QT400-18) or gray cast iron (HT250), enabling efficient pumping and treatment of ship sewage (containing oil, solid particles, fibrous impurities, etc.) through centrifugal or positive displacement pump principles. The working principle utilizes centrifugal force from impeller rotation or volume changes from pistons/gears to draw sewage from bilges, engine rooms, or living areas through the suction pipe, pressurize it, and deliver it to wastewater treatment units or compliant discharge areas via the discharge pipe. The pump body undergoes integral casting and epoxy resin heavy anti-corrosion coating, with a corrosion-resistant service life ≥8 years in seawater with Cl⁻≤20,000ppm, complying with IMO MARPOL Annex IV anti-pollution conventions and classification society certifications (LR, ABS, etc.), widely used in sewage discharge for merchant ships, engineering vessels, and offshore platforms.

II. Core Technologies and Material Characteristics

1.Cast Iron Material Selection and Performance

2.Key Technical Parameters

Flow range: 20-300m³/h, suitable for 500-30,000-ton vessels

Head: 15-50m, meeting long-distance transportation and lifting requirements for sewage

Impurity passing capacity: Centrifugal pumps pass ≤5mm solid particles; positive displacement pumps pass ≤8mm fibrous impurities

Corrosion resistance design: Epoxy resin coating thickness ≥250μm, 1,500-hour salt spray test passed without rust

Temperature adaptability: Stable operation at -20℃~70℃

III. Technical Advantages and Innovative Design

1. Efficient Sewage Disposal and Anti-Clogging Capacity

No rotating parts design: Some models adopt ejector pump principles, free of vulnerable parts like impellers and shafts, passing ≤10mm solid particles and reducing clogging risk by 95%.

Anti-winding structure: Positive displacement pumps use open impellers or cycloidal gears with spiral guide groove design, reducing fibrous impurity winding probability by 90%, suitable for complex impurities like rags and cable debris.

2. Complex Condition Adaptability

All-attitude operation: Axial force balancing technology ensures stable drainage under ship heel 25° and trim 12°, meeting emergency discharge needs in critical conditions.

Low-temperature start-up resistance: With electric tracing systems at -20℃, start-up response time ≤15 seconds, preventing pump damage from sewage freezing.

3. Long Life and Low Maintenance

Wear-resistant and corrosion-resistant process: Impeller surface treated with supersonic sprayed tungsten carbide (thickness 150μm), wear rate ≤0.03mm/1000h in wastewater with sediment content ≤500ppm, service life exceeding 40,000 hours.

Modular quick-release structure: Flange quick-connect design for pump cover and body reduces single-component replacement time by 60%, lowering life-cycle maintenance costs by 35%.

IV. Typical Application Scenarios

1. Merchant Ship Sewage Discharge

Cargo ship engine room sewage pumping: Equips 100,000-ton cargo ships with ductile iron centrifugal pumps, flow 80-150m³/h, pumping engine room sewage containing lubricating oil and metal debris, achieving compliant discharge with oil-water separators.

Passenger ship domestic sewage treatment: Inland cruise ships use gray cast iron positive displacement pumps, flow 30-80m³/h, negative pressure pumping of toilet and kitchen sewage to prevent odor diffusion.

2. Engineering Vessels and Special Ships

Dredger bilge sediment discharge: Engineering vessels equipped with wear-resistant ductile iron pumps pass ≤8mm sediment particles, flow 150-250m³/h, adapting to high-sediment sewage discharge in dredging operations.

LNG ship low-temperature sewage discharge: Polar LNG ships equipped with low-temperature resistant cast iron pumps operate stably at -15℃, rapidly pumping bilge condensate and low-temperature sewage.

3. Offshore Platforms and Ports

Drilling platform sewage systems: Offshore platform sewage pumps, flow 100-200m³/h, head 35m, treating domestic and industrial wastewater, adapting to complex offshore conditions.

Port tugboat sewage cleaning: Tugboats use self-priming cast iron pumps, self-priming height ≥8m, quickly cleaning residual ballast water and oil from bilges to improve operation efficiency.

V. Selection and Maintenance Specifications

1. Key Selection Parameters

Sewage type: Centrifugal pumps for oily sewage; positive displacement pumps for fibrous impurities; wear-resistant ductile iron pumps for high-sediment sewage

Ship conditions: Ductile iron for ocean-going vessels; gray cast iron for inland vessels; insulated pump bodies for cold seas

Flow matching: Configure at 1.8x maximum sewage generation, e.g., 8,000-ton cargo ships recommend flow 120-200m³/h

2. Maintenance Key Points

Daily monitoring: Inspect bearing temperature (≤70℃) and vibration value (≤4.5mm/s) every 400 hours

Regular maintenance: Clean suction filters (accuracy ≤15mm) monthly; inspect coating integrity quarterly; replace mechanical seals annually

In-depth maintenance: Hydraulic pressure test (1.2x rated pressure) every 3 years; replace impellers with wear exceeding 25%

VI. Compliance and Certification

International standards: Complies with IMO MARPOL Annex IV Regulations for the Prevention of Pollution by Sewage from Ships and ISO 15085 ship drainage system specifications

Classification society certifications: Passed class certifications by LR, ABS, DNV GL, etc.

Environmental requirements: Sewage discharge complies with MEPC.279(70) standards; 100% recyclable material