Stainless Steel Gear Cargo Oil Pump

I. Product Overview

Stainless steel gear cargo oil pumps are designed based on the gear meshing volume transportation principle, using austenitic stainless steel (316/316L) or duplex stainless steel (2205). They provide efficient solutions for loading/unloading and transfer of cargo oil media such as crude oil, refined oil, and sulfur-containing heavy oil. The all-stainless-steel gears and pump body, combined with anti-corrosion structural design, integrate excellent resistance to fuel sulfide corrosion and high-viscosity media wear, enabling stable transportation of cargo oil with viscosity 10-500cSt under 0.5-2.0MPa pressure. They meet the strict requirements of the International Maritime Organization (IMO) anti-pollution conventions and classification societies (CCS/ABS).

II. Core Materials and Performance Adaptation

1.316 Stainless Steel (Medium-Sulfur Cargo Oil Scenarios)

Characteristics: Contains 2-3% molybdenum, corrosion rate <0.01mm/year in crude oil with sulfur content ≤1%, tensile strength ≥520MPa, can withstand cargo oil temperatures of -20℃~120℃, surface hardness reaches HRC30-35 after nitriding treatment, and fuel scouring wear resistance is 3 times higher than cast iron.

Applications: Transporting light refined oils such as diesel and kerosene, or medium-sulfur crude oil (API gravity >20), suitable for coastal tankers and port loading/unloading systems.

2.316L Stainless Steel (Low-Sulfur/High-Purity Cargo Oil)

Improved Design: Carbon content ≤0.03%, excellent intergranular corrosion resistance after welding, gear surface boronized (hardness HRC45-50), wear rate 40% lower than 316 stainless steel in ultra-low sulfur crude oil with sulfur content ≤0.5%, suitable for clean cargo oil transportation such as food-grade vegetable oil.

Typical Scenarios: Diesel auxiliary cargo oil pumps for LNG-powered ships, or palm oil and rapeseed oil loading/unloading systems for edible oil tankers, meeting food hygiene requirements (FDA certification).

3.Duplex Stainless Steel (2205/2507)

High-Strength Corrosion Resistance: Ferritic-austenitic duplex structure, pitting corrosion resistance index (PREN) ≥40, stress corrosion resistance 2 times higher than 316L in high-sulfur heavy oil with sulfur content 1-3%, tensile strength ≥620MPa, can withstand 2.0MPa high-pressure cargo oil impact, and resist acidic substances (pH≤3) from cargo oil high-temperature cracking.

Special Applications: High-sulfur crude oil (such as Middle Eastern crude oil) loading/unloading pumps for ocean-going tankers, or sulfur-containing residue oil transport pumps in refineries, resisting composite corrosion from asphaltenes and sulfides in cargo oil.

III. Technical Advantages and Application Limitations

Core Technical Advantages

1. High-Viscosity Cargo Oil Adaptability and Sealing Performance

Duplex stainless steel gears achieve a volumetric efficiency of 88%-92% in 380cSt heavy oil (preheated to 120℃), with a self-priming height ≥4m. Adopting double sealing of bellows mechanical seal + fluororubber O-ring, cargo oil leakage ≤5 drops/hour, complying with MARPOL Annex I anti-pollution requirements.

2. Wear Resistance and Long-Life Design

316L stainless steel gears undergo ion nitriding treatment, with surface hardness HRC55-60, and a service life of 50,000 hours in media containing 0.2% solid impurities (such as cargo oil sediment and rust), 10 times that of cast iron gears, reducing tanker loading/unloading downtime maintenance frequency.

3. Explosion-Proof Safety and Compliance

The pump body adopts an explosion-proof design (Ex d IIB T4 Gb), and the motor junction box explosion-proof rating meets ATEX certification, suitable for cargo oil tank areas (Zone 0/1), with static grounding resistance ≤1Ω, equipped with pressure sensors for real-time monitoring (accuracy 0.2 class) to prevent leakage caused by overpressure.

Performance Limitations

1. High-Temperature and Impurity Sensitivity Boundaries

When the cargo oil temperature of 316 stainless steel pumps >150℃, fuel carbonization causes gear wear to increase by 60%, requiring a cooling jacket (heat exchange area ≥3m²). When transporting heavy oil with viscosity >500cSt (unpreheated), pump efficiency decreases by 25%, requiring a electric heating device (power configured as 1.5kW/100L/h flow).

2. Impurity and Moisture Tolerance

Gear meshing clearance is 0.05-0.1mm, sensitive to solid particles >20μm, requiring a double-barrel filter (filtration accuracy ≤5μm). When cargo oil water content >1%, it easily causes stainless steel pitting, requiring a water separator (separation efficiency ≥99%) to avoid water-oil emulsification corrosion of the pump body.

3. Cost and Weight Challenges

Duplex stainless steel pumps cost 6-8 times more than cast iron pumps, with a 50% increase in weight (e.g., DN100 pump weighs about 45kg), requiring reinforced ship cargo oil pump cabin foundations. Large-flow models (≥500m³/h) have operation noise ≥85dB, requiring a soundproof cover (noise reduction ≥20dB).

IV. Typical Application Scenarios

1. Marine Cargo Oil Loading/Unloading Systems

Ocean-Going Tanker Crude Oil Transportation: Duplex stainless steel pumps transport high-sulfur crude oil (sulfur content 2.5%) for 300,000 DWT VLCCs, configured with steam tracing jackets (temperature maintained at 120℃), achieving large-flow loading/unloading of 1500m³/h under 1.8MPa pressure to meet port rapid turnover needs.

Product Tanker Compartment Transfer: 316L stainless steel pumps are used for compartment transportation of gasoline and diesel, with electrolytically polished gear surfaces (Ra≤0.8μm) to avoid cargo oil cross-contamination, cooperating with the Oil Management System (OMS) for precise transfer.

2. Ports and Oil Storage Facilities

Onshore Cargo Oil Loading/Unloading Arm Systems: 316 stainless steel pumps connect tankers to storage tanks, transporting sulfur-containing crude oil (API gravity 15-20), equipped with Emergency Shutdown Valves (ESD) to close pump inlets/outlets within 10 seconds in emergencies, complying with OCIMF Tanker Safety Guide.

Bunker Fuel Loading Systems: 316L stainless steel pumps load low-sulfur bunker fuel (sulfur content ≤0.5%) for ported ships, with a flow rate of 200-500m³/h and pressure of 0.6-1.0MPa, meeting IMO 2020 sulfur restriction requirements.

3. Special Cargo Oil Media Transportation

Chemical Tanker Liquid Cargo: Duplex stainless steel pumps transport corrosive chemicals such as phenol and styrene, using perfluororubber seals (FFKM), heat-resistant up to 200℃, resisting cargo oil chemical corrosion, complying with IBC Code requirements for bulk liquid chemical tankers.

V. Usage and Maintenance Specifications

1. Cargo Oil Pretreatment Requirements

High-viscosity heavy oil must be preheated to viscosity ≤150cSt (corresponding temperature ~110-130℃) using steam coils or electric heating. When cargo oil sulfur content >1%, add anti-corrosion additives (dosage 0.1-0.3%) to inhibit stainless steel pitting.

2. Operation Monitoring Key Points

Real-Time Parameters: Monitor inlet and outlet pressure (fluctuation ≤±3%), bearing temperature (temperature rise ≤40℃), cargo oil temperature (not exceeding material tolerance), equipped with vibration sensors (accuracy 0.1mm/s), and automatic alarm for abnormalities (vibration value >0.06mm/s).

Regular Maintenance: Inspect gear meshing clearance every voyage (allowable wear ≤0.02mm), replace mechanical seals every 5000 hours (replace in advance when leakage >10 drops/hour), and flush the pump cavity with fresh water (pressure 0.4MPa) after cargo oil tank cleaning to remove oil sludge deposits.

3. Safety and Compliance Requirements

Marine pumps must pass CCS/DNV classification society certification, providing sulfur corrosion test reports for stainless steel materials (ASTM G35 standard, no pitting after 96-hour immersion). Industrial pumps must comply with API 676 standards, with an explosion-proof rating not lower than Ex d IIB T4, and static grounding systems tested annually (resistance ≤4Ω).

Cargo oil pump cabins must be equipped with combustible gas detection systems (LEL≤10%), and conductive flange gaskets must be used between the pump body and cargo oil pipelines to prevent static electricity accumulation causing cargo oil vapor explosions.