Marine Stainless Steel Cargo Oil Pump

I. Product Overview

Marine stainless steel cargo oil pumps are core equipment in the cargo conveying systems of liquid cargo ships, specifically designed for loading, unloading, and inter-tank transfer of liquid cargo such as crude oil, refined oil, and chemicals. Constructed with 316L ultra-low carbon stainless steel (022Cr17Ni12Mo2) or duplex stainless steel (2205) as the main material, they achieve efficient transportation of high-viscosity, volatile, and micro-impurity-containing liquid cargo through screw pump or centrifugal pump principles. Their working principle involves a power source (electric motor or steam turbine) driving rotors to mesh and rotate, generating pressure through volume changes in chambers to draw liquid cargo from tanks, pressurize it, and convey it to shore tanks (during unloading) or into tanks from shore (during loading). Safety is ensured throughout via explosion-proof control systems. The pump body undergoes solution treatment and oil-resistant passivation, with a corrosion-resistant service life of ≥15 years in sulfur-containing crude oil and aromatic chemicals. It meets IMO International Code for the Construction and Equipment of Ships Carrying Dangerous Chemicals in Bulk (IBC Code) and liquid cargo pump certification requirements of classification societies such as LR and ABS, and is mandatory for liquid cargo ships including oil tankers, chemical tankers, and liquefied gas carriers.

II. Core Technologies and Material Characteristics

1.Stainless Steel Material Selection and Performance

2.Key Technical Parameters

Flow range: 50-1000m³/h, suitable for ships of 5000-300,000 deadweight tons (e.g., 100,000-ton oil tankers require single pump flow ≥300m³/h)

Head coverage: 20-80m, meeting long-distance conveying pressure requirements from cargo tanks to shore tanks (including pipeline losses)

Medium compatibility: Capable of conveying crude oil, diesel, gasoline, alcohol, ethylene glycol with viscosity 5-1000cSt, and chemicals with pH 2-12

Explosion-proof rating: Motor explosion-proof grade Ex d IIC T3, suitable for Zone 0 hazardous areas (near cargo tanks) to prevent oil-gas ignition

Temperature adaptability: Wide-temperature operation from -40℃ to 150℃; duplex stainless steel withstands short-term high temperatures up to 200℃ (e.g., hot oil cargo)

3.Safety and Anti-Pollution Design

Equipped with double mechanical seals + barrier fluid systems, with leakage ≤0.1mL/h and barrier fluid pressure always 0.1MPa higher than cargo oil pressure

Integrated emergency shutdown device (ESD) to cut connection between the pump and cargo tank within 1 second when overpressure, overheating, or fire signals are detected

Surface roughness of flow-through components Ra≤0.8μm to avoid cross-contamination from residual media (e.g., when switching from gasoline to diesel)

III. Technical Advantages and Innovative Design

1. High-Viscosity Liquid Cargo Conveying Capacity

Twin-screw forced conveying: Adopts male-female screw meshing structure with clearance ≤0.02mm, maintaining volumetric efficiency ≥92% at 1000cSt (50℃) — 25% higher than centrifugal pumps — suitable for heavy oil and high-viscosity chemical conveying.

Staged heating system: Integrates steam heating jackets (working pressure 0.6MPa) to heat high-viscosity cargo oil (e.g., asphalt) from ambient temperature to 120℃ (viscosity reduced to 200cSt), avoiding medium decomposition from local overheating.

2. Adaptability to Highly Corrosive Environments

All-stainless steel flow components: Pump body, rotors, and seal chambers are forged from homogeneous stainless steel to avoid galvanic corrosion from contact between dissimilar metals, showing no significant corrosion after 1000-hour immersion in 5% sulfuric acid solution.

Anti-cavitation design: Inlet is equipped with an inducer to reduce net positive suction head (NPSH) by 30%, ensuring stable operation at low liquid levels (remaining tank bottom ≤500mm) to minimize cargo oil residue.

3. Safe and Efficient Operation

Variable frequency speed regulation system: Links with cargo oil loading/unloading progress, enabling stepless speed adjustment within 500-3000r/min with flow control accuracy ≤±2% to avoid pipeline impact.

Online flushing function: After conveying different cargo oils, built-in flushing channels allow automatic cleaning with solvents (e.g., kerosene), leaving residual media ≤0.1%, meeting cleanliness requirements for food-grade chemicals (e.g., edible oil).

IV. Typical Application Scenarios

1. Crude Oil and Refined Oil Transportation

Crude oil tanker cargo oil conveying: 300,000-ton VLCCs are equipped with duplex stainless steel cargo oil pumps (flow 800-1000m³/h, head 60m) to convey crude oil with 3.5% sulfur from cargo tanks to shore tanks, maintaining stable outlet pressure at 2.5±0.1MPa, with single-pump unloading of one tank taking only 2 hours.

Product oil tanker inter-tank transfer: 100,000-ton product oil tankers use 316L stainless steel screw pumps (flow 300-500m³/h) to achieve pollution-free transfer of gasoline and diesel between tanks via reversing valves, with switching and cleaning time ≤30 minutes.

2. Chemicals and Special Liquid Cargo

Aromatic chemical transportation: Chemical tankers are equipped with duplex stainless steel cargo oil pumps (flow 100-300m³/h) to convey volatile chemicals such as benzene and toluene, with pump shaft seals using "metal bellows + silicon carbide" structures to resist strong medium permeability.

Food-grade liquid cargo conveying: Edible oil tankers use 316L stainless steel centrifugal pumps (flow 50-150m³/h) with flow-through components meeting FDA food contact standards, ensuring no metal ion contamination of oil (heavy metal content ≤0.001mg/kg).

3. Extreme Environment Operations

Polar crude oil transportation: In -50℃ environments, pump bodies with hot oil tracing and insulation heat crude oil from a freezing point of -35℃ to 50℃ (viscosity reduced to 150cSt) with flow 200-400m³/h, powering ice-breaking oil tanker cargo oil systems.

High-temperature asphalt conveying: Asphalt tankers use twin-screw cargo oil pumps (flow 50-150m³/h) with heating jackets maintaining asphalt at 180℃ (viscosity 300cSt) and outlet pressure 2.0MPa to ensure no solidification or blockage during unloading.

V. Selection and Maintenance Specifications

1. Key Selection Parameters

Cargo oil type: 316L stainless steel for sulfur-containing crude oil and weakly corrosive chemicals; duplex stainless steel (2205) for highly corrosive chemicals (e.g., acids, chlorinated hydrocarbons)

Transport volume: Configure flow at 1/3 of the maximum single-tank volume per hour; e.g., 5000m³ tank capacity requires pump flow ≥1700m³/h

Safety level: Ex d IIC T3 explosion-proof type for flammable and explosive goods (e.g., gasoline); heat-resistant seal type for high-temperature cargo oil (≥150℃)

2. Maintenance Points

Daily monitoring: Check outlet pressure (fluctuation ≤±0.2MPa), bearing temperature (≤80℃), and mechanical seal chamber pressure (0.1MPa higher than cargo oil pressure) every 1000 hours

Regular maintenance: Replace mechanical seals every six months (Hastelloy for duplex stainless steel pumps); calibrate flowmeters annually (accuracy ≤±0.1%)

Overhaul maintenance: Conduct water pressure tests (1.5 times rated pressure) every 5 years; re-passivate 316L components; inspect rotor wear (allowable clearance ≤0.05mm)

VI. Compliance and Certification

International standards: Complies with IMO IBC Code and MARPOL Annex I safety requirements for liquid cargo pumps

Classification society certifications: Passed type approval for cargo oil pumps by LR, ABS, and CCS (including 1000-hour operation tests with sulfur-containing media)

Explosion-proof certification: Ex d IIC T3 Gb explosion-proof grade, meeting ATEX 137 requirements for equipment in hazardous areas