Marine Cast Steel Sewage Pump

I. Product Overview

Marine cast steel sewage pumps are core equipment in ship sewage treatment systems, designed specifically to handle complex media such as domestic sewage, engine room wastewater, and oily wastewater. Constructed with high-strength alloy cast steel (WC6) or carbon cast steel (WCB), they achieve efficient transportation of high-concentration, high-viscosity sewage through centrifugal or screw pump principles. Their working principle involves a power source (electric motor or diesel engine) driving an impeller or screw to rotate, generating negative pressure to draw sewage from collection tanks, pressurize it, and deliver it via pipelines to sewage treatment devices (e.g., biochemical reactors, oil-water separators) or discharge it overboard after meeting standards. This prevents direct discharge of ship sewage from polluting marine environments. The pump body undergoes integral forging and anti-corrosion treatment, with a corrosion-resistant service life of ≥10 years in acidic and alkaline sewage environments (pH 4-10). It meets the requirements of IMO MARPOL Annex IV (domestic sewage) and Annex I (oily sewage) conventions, widely used in passenger ships, cargo ships, oil tankers, and offshore platforms.

II. Core Technologies and Material Characteristics

1.Cast Steel Material Selection and Performance

2.Key Technical Parameters

Flow range: 20-200m³/h, suitable for ships with 50-3000 passengers and engine room sewage production

Head: 10-50m, meeting the transportation height and distance requirements from sewage collection tanks to treatment devices

Medium compatibility: Capable of transporting domestic sewage, oily sewage, gray water, and small amounts of chemical wastewater (pH 4-10) with solid content ≤8% and particle diameter ≤20mm

Corrosion resistance design: Inner walls adopt vinyl ester resin coating (thickness ≥300μm), resisting oil, acid, and alkali immersion for 10,000 hours without peeling

Temperature adaptability: Stable operation at -10℃~80℃, capable of handling high-temperature engine room wastewater (≤80℃)

3.Anti-Clogging and Safety Design

Impellers adopt non-clogging flow channel design, capable of passing long fibrous impurities (e.g., hair, fabric fragments), reducing clogging rate by 90%

Explosion-proof motors comply with ATEX Zone 2 standards, suitable for sewage tank environments containing flammable and explosive gases

III. Technical Advantages and Innovative Design

1. Complex Sewage Treatment Capability

Twin-screw conveying structure: Adopts male-female screw meshing design, capable of transporting high-concentration sewage with 30% oil content and 5000cSt viscosity, achieving pulse-free transportation to avoid pipeline vibration, with efficiency ≥85%.

Cutting-type impeller: Domestic sewage-specific pumps are equipped with tungsten carbide alloy cutting blades, capable of shredding solid impurities (e.g., food residues, plastic fragments) with diameters ≤50mm before discharge, reducing the load on subsequent treatment devices.

2. Anti-Pollution and Corrosion Resistance

Fully enclosed shaft seal system: Uses double-end mechanical seals (material: silicon carbide + nickel-based alloy), with clean water introduced into the seal cavity to isolate sewage, ensuring leakage ≤3mL/h and preventing shaft corrosion.

Anti-biofouling coating: Inner walls are sprayed with low surface energy fluorocarbon coating to reduce microbial growth and dirt deposition, extending the cleaning cycle to 6 months, twice that of traditional coatings.

3. Intelligent Operation and Low Maintenance

Sewage concentration adaptability: Integrates infrared concentration sensors to automatically adjust pump speed (30%-100% of rated speed) – reducing speed to prevent clogging in high-concentration sewage and increasing speed to save energy in low-concentration sewage, cutting energy consumption by 20%.

Modular quick-release structure: Pump casing and drive end adopt flange quick connections, allowing replacement of core components without disassembling pipelines, with single maintenance time ≤1.5 hours, 60% shorter than traditional structures.

IV. Typical Application Scenarios

1. Domestic Sewage Treatment

Black water treatment for large passenger ships: 3000-passenger cruise ships are equipped with alloy cast steel twin-screw sewage pumps, with flow 100-150m³/h and pressure 2.5MPa, transporting toilet sewage to biochemical treatment devices. Cooperating with grinding systems, solid particles are crushed to ≤5mm.

Gray water treatment for cargo ships: 500-passenger cargo ships use carbon cast steel sewage pumps, with flow 20-50m³/h, treating gray water from washing and kitchens. After filtration, it is reused for deck flushing, achieving a water-saving rate of 30%.

2. Engine Room and Industrial Sewage

Oily sewage treatment in oil tanker engine rooms: Equipped with WC6 alloy cast steel sewage pumps, with flow 50-100m³/h, transporting oily sewage (oil content ≤1500ppm) to oil-water separators. Heating to 60℃ improves separation efficiency, ensuring outlet oil content ≤15ppm.

Construction wastewater from engineering ships: Dredgers use wear-resistant sewage pumps, capable of transporting construction wastewater with 15% sand content, with flow 80-150m³/h and pressure 3.0MPa, preventing pipeline clogging from sediment deposition.

3. Special Vessels and Platforms

Low-temperature sewage from polar research ships: In -20℃ environments, pump bodies are equipped with electric tracing and insulation designs to prevent domestic sewage from freezing, with start-up time ≤30 seconds and flow 30-80m³/h.

Drilling wastewater from offshore platforms: Offshore platforms use high-temperature sewage pumps to treat wastewater containing drilling fluids (temperature ≤80℃), with flow 50-120m³/h and pressure 4.0MPa, cooperating with chemical treatment systems to meet discharge standards.

V. Selection and Maintenance Specifications

1. Key Selection Parameters

Sewage type: Alloy cast steel (WC6) + anti-adhesive coating for oily sewage; carbon cast steel (WCB) + cutting impeller for domestic sewage

Treatment scale: Configure according to 150L/person/day of domestic sewage + 0.5m³/100kW of engine room sewage; for example, 1000-passenger ships recommend flow ≥30m³/h

Medium characteristics: Cutting-type for long fibers; twin-screw type for high solid content; heat-resistant type (≤100℃) for high-temperature sewage

2. Maintenance Key Points

Daily monitoring: Check outlet pressure (fluctuation ≤±0.1MPa), bearing temperature (≤75℃), and impeller vibration (≤3.5mm/s) every 300 hours

Regular maintenance: Clean inlet grilles (aperture ≤10mm) monthly; flush seal cavities quarterly; replace mechanical seals and lubricating oil (oil-resistant ISO VG32) annually

In-depth maintenance: Disassemble and inspect impeller wear (allowable loss ≤1mm) every 5 years; check coating integrity and re-spray anti-corrosion layers

VI. Compliance and Certification

International standards: Complies with IMO MARPOL Annex IV (domestic sewage), Annex I (oily sewage), and MEPC.227(64) discharge standards

Classification society certifications: Passed type approval for sewage pumps by LR, ABS, CCS, and other institutions (including anti-clogging and corrosion resistance tests)

Environmental certifications: Flow-through components meet IMO MEPC.107(49) anti-pollution requirements, with discharged sewage oil content ≤15ppm