Marine Cast Steel Cargo Oil Pump

I. Product Overview

Marine cast steel cargo oil pumps are core conveying equipment for liquid cargo ships, designed specifically for loading, unloading, transferring, and inter-tank of cargo oils such as crude oil, diesel, heavy oil, and chemicals. Constructed with high-strength alloy cast steel (WC6/WC9) or carbon cast steel (WCB), they achieve efficient transportation of high-viscosity, high-sulfur media through centrifugal or screw pump principles. Their working principle involves a power source (electric motor or steam turbine) driving an impeller or screw to rotate, generating negative pressure to draw cargo oil from shore tanks into ship's tanks, or conversely, discharge oil from ship's tanks to shore tanks. The entire process controls conveying flow and pressure via frequency conversion speed regulation to ensure loading/unloading efficiency and safety. The pump body undergoes integral forging and anti-sulfur corrosion treatment, with a corrosion-resistant service life of ≥15 years in crude oil with sulfur content ≤5%. It meets the IMO International Convention for the Prevention of Pollution from Ships (MARPOL) and liquid cargo pump certification requirements of classification societies such as LR and ABS, widely used in oil tankers, chemical tankers, LNG carriers, and multi-purpose liquid cargo ships.

II. Core Technologies and Material Characteristics

1.Cast Steel Material Selection and Performance

2.Key Technical Parameters

Flow range: 100-2000m³/h, suitable for ship tonnages 1000-300000 DWT (e.g., single pump flow for 300,000-ton VLCCs can reach 1500-2000m³/h)

Head coverage: 20-100m, meeting multi-level pressure requirements from shore to ship's tanks and between tanks

Medium compatibility: Capable of conveying crude oil, diesel, fuel oil with viscosity 5-5000cSt, and cargo oil with sulfur content ≤5% (WC9 material can withstand crude oil with sulfur content ≥3%)

Corrosion resistance design: Inner walls undergo aluminizing + nitriding treatment, with sulfur ion corrosion rate ≤0.1mm/year, passing 2000-hour salt spray test without rust

Temperature adaptability: Wide-temperature operation at -20℃~250℃ (WC9 material can withstand high-temperature cargo oil up to 250℃)

3.Safety and Explosion-Proof Design

The pump body and drive end adopt flameproof structure with explosion-proof grade Ex d IIC T4, suitable for Zone 0 hazardous areas (cargo oil tanks and adjacent zones)

Equipped with overspeed protection (1.1 times rated speed), overpressure protection (1.2 times rated pressure), and leakage detection system, automatically shutting down when leakage ≥5mL/h

III. Technical Advantages and Innovative Design

1. Efficient Cargo Oil Conveying Capacity

Twin-screw + centrifugal pump composite structure: Low-viscosity cargo oil (e.g., diesel) is conveyed efficiently by centrifugal pumps (efficiency ≥85); high-viscosity cargo oil (e.g., heavy oil) switches to twin-screw mode, pushing media through volume changes in meshing chambers, maintaining efficiency ≥80% even at 5000cSt viscosity.

Frequency conversion speed regulation and load adaptation: Integrated PLC control system automatically adjusts rotation speed (500-3000r/min) according to cargo oil viscosity, with flow fluctuation ≤±5% during loading/unloading to avoid pipeline impact.

2. Adaptability to Extreme Conditions

Enhanced sulfur corrosion resistance: WC9 alloy cast steel forms a passive film by adding Cr and Mo elements, improving stress corrosion cracking resistance in H₂S-containing crude oil by 3 times compared to ordinary cast steel, with leak-free operation cycle exceeding 10,000 hours.

Resistance to inclination and vibration: The pump body and base adopt hydraulic shock absorbers with vibration value ≤2.8mm/s, ensuring no attenuation in suction performance when the ship heels 25° or trims 10°, meeting continuous operation requirements under harsh sea conditions.

3. Safety and Maintenance Optimization

Dry running protection system: Equipped with infrared liquid level sensors, shutting down within 3 seconds when no medium is detected in the pump to avoid damage from dry friction of mechanical seals (traditional designs require over 10 seconds).

Online maintenance structure: The bearing housing and pump casing are connected by quick-opening flanges, allowing replacement of mechanical seals without disassembling inlet/outlet pipelines, with single maintenance time ≤4 hours, 60% shorter than traditional structures.

IV. Typical Application Scenarios

1. Oil Tanker Cargo Oil Conveying

VLCC crude oil loading/unloading: 300,000-ton ultra-large oil tankers are equipped with 3 WC9 alloy cast steel cargo oil pumps, with single pump flow 1500-2000m³/h and head 60m. Parallel operation achieves 40,000 tons of oil loading per hour, meeting rapid loading/unloading requirements, with outlet pressure stable at 5.0±0.2MPa.

Product oil tanker multi-tank conveying: 100,000-ton product oil tankers use WCB carbon cast steel cargo oil pumps with flow 500-800m³/h, realizing multi-tank conveying of different grades of diesel through multi-outlet pipelines, with switching time ≤30 seconds and no medium mixing.

2. Special Liquid Cargo Ship Adaptation

Chemical tanker compatible conveying: Adopts WC6 alloy cast steel pump body with PTFE anti-corrosion lining, capable of conveying corrosive chemicals such as formic acid and ethanol, with flow 200-500m³/h, meeting IMDG code requirements for hazardous cargo conveying.

LNG carrier fuel oil supply: When supplying heavy oil to LNG carrier main engines, cargo oil pumps cooperate with heating jackets to control oil temperature at 120℃, reducing viscosity to 380cSt, with flow 100-300m³/h and pressure 4.0MPa, ensuring continuous combustion.

3. Port and Emergency Scenarios

Offshore oil depot connection: Offshore single-point mooring systems are equipped with self-priming cast steel cargo oil pumps, with self-priming height ≥6m and flow 800-1200m³/h, completing cargo oil transfer between oil tankers and storage tanks in deep-sea areas without terminal facilities.

Cargo oil leakage emergency: Equipped with portable diesel-driven cargo oil pumps, with flow 100-300m³/h, capable of quickly pumping leaked cargo oil from tanks to emergency treatment tanks, reducing marine pollution risks.

V. Selection and Maintenance Specifications

1. Key Selection Parameters

Cargo oil type: WC9 alloy cast steel for high-sulfur crude oil (S≥1%), WCB carbon cast steel for light oil/low-sulfur oil, WC6 + anti-corrosion lining type for chemicals

Conveying scale: Configure single pump flow according to 1/8 of the ship's deadweight tonnage; e.g., 100,000-ton oil tankers recommend single pump flow ≥1200m³/h (loading/unloading time ≤8 hours)

Environmental conditions: -30℃ start-up type for polar navigation, forced cooling type for tropical routes (activated when oil temperature ≥150℃)

2. Maintenance Key Points

Daily monitoring: Check outlet pressure (fluctuation ≤±0.1MPa), bearing temperature (≤80℃), and seal chamber temperature (≤90℃) every 1000 hours

Regular maintenance: Clean suction filters (precision ≤2mm) monthly, replace mechanical seals (using silicon carbide-nickel-based alloy material) every six months, and inspect pump body wall thickness annually (corrosion amount ≤0.2mm/year)

In-depth maintenance: Conduct water pressure tests (1.5 times rated pressure) every 6 years, and perform dynamic balance correction on impellers (allowable deviation ≤0.05mm)

VI. Compliance and Certification

International standards: Complies with IMO MARPOL Annex I and MEPC.145(54) liquid cargo pump safety specifications

Classification society certifications: Passed type approval for cargo oil pumps by LR, ABS, CCS, and other institutions (including sulfur resistance, explosion-proof, and performance tests)

Environmental requirements: Pump body materials 100% recyclable, with seal leakage collection systems meeting IMO anti-pollution requirements