Marine Screw Cargo Oil Pump

I. Product Overview

Marine screw cargo oil pumps are the "efficient conveying core" of ship cargo oil transportation systems, designed specifically for loading, unloading, transferring, and inter-tank transfer of cargo oils such as crude oil, diesel, fuel oil, and lubricating oil. Through volumetric changes in closed chambers formed by screw meshing, they achieve high-pressure, stable cargo oil conveyance, ensuring loading/unloading efficiency and transportation safety. Constructed with cast iron (HT200), bronze alloy (ZCuAl10Fe3), or stainless steel (316L) as the main material, they rely on the synchronous rotation of two or three screws to generate continuous suction and pressure, drawing medium from cargo oil tanks, pressurizing it, and delivering it to onshore storage tanks, barges, or other cargo tanks via pipelines. The pump body undergoes precision machining and anti-corrosion treatment, with a corrosion-resistant service life of ≥8 years in -10℃~150℃ environments. It meets IMO International Convention for the Prevention of Pollution from Ships (MARPOL Annex I) and cargo oil pump certification requirements of classification societies such as RS, LR, ABS, and CCS, widely used in cargo oil conveying systems of oil tankers, chemical tankers, multi-purpose cargo ships, and other transport vessels.

II. Core Technologies and Material Characteristics

1.Material Selection and Performance

2.Key Technical Parameters

Flow range: 5-500m³/h, suitable for ships of 1000-100,000 gross tons (e.g., 50,000 gross ton oil tankers require single pump flow ≥200m³/h)

Pressure coverage: 0.8-5.0MPa, meeting pressure requirements for transportation from cargo oil tanks to target storage tanks (including pipeline elbows, valves, and flowmeter resistance losses)

Medium compatibility: Capable of conveying crude oil, diesel, fuel oil, lubricating oil, etc., adapting to cargo oils with viscosity 5-1500cSt (high viscosity requires heating) and temperature -10℃~150℃

Self-priming performance: Self-priming height ≥3m, priming time ≤60 seconds, suitable for oil suction from low-level cargo oil tanks without external priming devices

Volumetric efficiency: ≥95% under design conditions, 3% higher than gear pumps of the same specification; maintains ≥88% efficiency in heavy fuel oil with 800cSt viscosity

3.Safety and Explosion-Proof Design

Explosion-proof certification: Motors adopt Ex d IIB T4 Gb explosion-proof grade, suitable for Zone 1 hazardous areas in cargo oil tank zones to prevent explosion risks from oil and gas leakage

Overpressure protection: Safety valves automatically relieve pressure (returning oil to cargo oil tanks) when outlet pressure exceeds 1.2 times the rated value, avoiding pipeline rupture due to overpressure

Impurity filtration system: Inlet fitted with 20μm precision filters, cooperating with optimized screw tip clearance (≤0.04mm) to intercept metal debris, sediment, and other impurities, protecting screw meshing surfaces

III. Technical Advantages and Innovative Design

1. High-Viscosity Cargo Oil Conveying Capacity

Twin-screw meshing structure: Uses 40° helix angle twin-screw design, increasing meshing overlap coefficient by 60% compared to single-screw pumps. In heavy crude oil with 1500cSt viscosity, pressure fluctuation ≤±0.05MPa, with operating noise ≤85dB (at 1 meter).

Integrated heating jacket: Pump bodies and screw boxes are externally wrapped with heating jackets (working pressure 1.0MPa), allowing steam or hot oil to heat high-viscosity cargo oil (e.g., crude oil) from ambient temperature to 90℃, reducing viscosity to below 100cSt and ensuring smooth conveyance.

2. Wear and Corrosion Resistance Enhancement

Stainless steel screw surface treatment: 316L screws undergo nitriding treatment, achieving surface hardness HV600, improving resistance to sediment wear in cargo oil by 50% compared to ordinary stainless steel, and extending service life to 12,000 hours.

Bronze pump anti-adhesion design: Bronze alloy screw tooth surfaces undergo mirror polishing (Ra≤0.8μm), reducing adhesion and deposition of high-viscosity cargo oil, extending cleaning intervals to 600 hours, and reducing maintenance frequency by 40% compared to ordinary screw pumps.

3. Adaptability to Ship Operating Conditions

Vibration-resistant structure: Pump units and bases adopt damping shock absorbers + steel spring composite damping, with vibration acceleration ≤5m/s², ensuring stable operation in high-vibration main engine room environments (flow fluctuation ≤2%).

Modular assembly: Screws, bearings, and seals feature a modular design, reducing replacement time to ≤4 hours, supporting emergency repairs at sea, and minimizing ship port stay time.

IV. Typical Application Scenarios

1. Cargo Oil Loading and Unloading Operations

Crude oil loading: 100,000 gross ton crude oil tankers use stainless steel screw cargo oil pumps (flow 300-500m³/h, pressure 2.5MPa) to heat crude oil to 70℃ (120cSt viscosity) via heating jackets, cooperating with flowmeters for precise loading, with a single pump capable of loading 5000 tons of crude oil per hour.

Product oil unloading: 5000 gross ton product oil tankers use bronze alloy screw pumps (flow 50-100m³/h, pressure 2.0MPa) to deliver diesel from cargo oil tanks to onshore storage tanks, with volumetric efficiency ≥96% and ensuring unloading loss rate ≤0.1%.

2. Inter-tank Cargo Oil Transfer

Oil tanker cargo tank balancing: When large oil tankers need to adjust oil levels in various tanks during navigation, screw cargo oil pumps (flow 100-200m³/h, pressure 1.5MPa) transfer cargo oil from full tanks to empty tanks via cross-tank pipelines, completing 1000m³ oil transfer within 20 minutes to ensure ship stability.

Chemical tanker compartmented conveyance: Multi-purpose chemical tankers transporting different grades of diesel use bronze screw cargo oil pumps (flow 30-50m³/h) to achieve independent conveyance of different cargo tanks by quickly switching valves, avoiding oil mixing and contamination.

3. Special Cargo Oil Conveyance

High-sulfur crude oil conveyance: Ocean-going oil tankers use stainless steel screw pumps (flow 200-300m³/h) to deliver crude oil with 3.5% sulfur content, heated to 100℃ via heating jackets to reduce viscosity to 80cSt, meeting low-speed loading/unloading requirements without pump body corrosion.

Low-temperature cargo oil loading/unloading: In -10℃ port environments, cast iron screw pumps with heating jackets (flow 50-80m³/h) convey diesel, maintaining oil temperature above 15℃ through heating to prevent pipeline blockage from diesel wax precipitation at low temperatures.

V. Selection and Maintenance Specifications

1. Key Selection Parameters

Cargo oil type: Cast iron/bronze pumps for light diesel and fuel oil; stainless steel pumps for crude oil and high-sulfur oil; corrosion-resistant bronze or 316L pumps for chemicals

Flow calculation: Configure 1.2 times the maximum loading/unloading rate of the ship; e.g., an oil tanker loading 600 tons of oil per hour (crude oil density 0.9t/m³) requires flow ≥800m³/h

Pressure requirements: 0.8-2.0MPa for short-distance conveyance (inter-tank transfer); 2.0-3.5MPa for onshore loading/unloading; high-pressure models (≥3.5MPa) for high-viscosity cargo oil

2. Maintenance Points

Daily monitoring: Check outlet pressure (fluctuation ≤±0.1MPa), bearing temperature (≤80℃), and mechanical seal leakage (≤5mL/h) every 800 hours

Regular maintenance: Replace mechanical seals (oil-resistant fluoroelastomer) and clean inlet filters (20μm aperture) every 3000 hours; inspect screw wear (tip clearance ≤0.08mm)

Cargo oil switching maintenance: Flush pump chambers and pipelines with low-viscosity diesel before conveying different grades of cargo oil to avoid mixing contamination; fill pumps with anti-rust oil (e.g., No. 20 machine oil) during long-term shutdown

3. Compliance Inspection

Annual classification society inspection, focusing on verification of volumetric efficiency (≥90%), explosion-proof performance, and compatibility with cargo oil systems

Meets MARPOL Annex I requirements for cargo oil loading/unloading systems, ensuring cargo oil leakage rate ≤0.05% and compliance with environmental emission regulations

VI. Compliance and Certification

International standards: Complies with ISO 13709 marine screw pump design standards and IMO MARPOL Annex I cargo oil system specifications

Classification society certifications: Obtained type approval for screw cargo oil pumps from RS, LR, ABS, and CCS (including 3000-hour heavy fuel oil operation tests)

Safety requirements: Overall pump unit explosion-proof grade reaches Ex d IIB T4 Gb, meeting SOLAS Convention requirements for equipment in hazardous areas