Cast Steel Screw Cargo Oil Pump

I. Product Overview

Cast steel screw cargo oil pumps, with high-strength cast steel as the core material, adopt the double-screw meshing transportation principle, specially designed for efficient loading/unloading and transportation of cargo oils such as crude oil, heavy oil, and diesel. They are suitable for scenarios like shipping, ports, and petrochemical storage. The cast steel material, combined with precision casting technology, offers excellent resistance to fuel scouring, wear, and high pressure, enabling stable operation under high-viscosity and high-temperature conditions to meet the reliability and safety requirements of cargo oil transportation systems.

II. Core Materials and Characteristics

1.Carbon Cast Steel (ZG)

Characteristics: Carbon content 0.15%–0.60%, tensile strength 400–700MPa, compressive strength 500–850MPa. With mature casting technology and good weldability, it can withstand impact vibration under medium loads, but strength decline and corrosion easily occur in high-temperature (>200℃) or corrosive cargo oils.

Applications: Suitable for manufacturing non-high-pressure components such as pump bodies and non-precision screws, commonly used in low-pressure cargo oil transportation scenarios, such as cargo oil transfer in small tanker tanks and fuel boiler refueling systems.

2.Low-Alloy Cast Steel

Characteristics: Added with alloy elements like manganese, silicon, and chromium, tensile strength increases to 500–900MPa, yield strength is 20%–30% higher than carbon cast steel, cargo oil scouring corrosion resistance is improved by 30%, and it can work stably under 3MPa high pressure, improving the transportation efficiency of cargo oil with viscosity ≤300cSt by 15%.

Applications: Used for key components such as screws and bearing seats of high-pressure cargo oil pumps, commonly found in cargo oil loading/unloading systems of large tankers and long-distance oil pipelines in petrochemical storage areas.

3.High-Alloy Cast Steel

Characteristics: Contains elements such as nickel, chromium, and molybdenum, with 5–8 times higher cargo oil corrosion resistance (especially to sulfur-containing crude oil and ethanol gasoline) than carbon cast steel. It can operate in 300℃ high-temperature cargo oil, with screw surface hardness reaching HRC50–55, featuring outstanding anti-seizing and cavitation resistance, suitable for cargo oil media with fine particle impurities.

Applications: Suitable for special working conditions, such as sulfur-containing crude oil transportation in ocean-going tankers, cargo oil loading/unloading systems with corrosive additives in the chemical industry, or high-temperature cargo oil (e.g., heavy oil heated to 280℃) transportation scenarios.

III. Technical Advantages

1. High-Viscosity Cargo Oil Transportation Efficiency

Low-alloy cast steel screws achieve a transportation efficiency of 82%–88% in 200cSt heavy oil, 12% higher than cast iron screw pumps, with pressure pulsation ≤±0.08MPa to ensure stable oil supply in cargo oil systems.

The screw meshing clearance is controlled at 0.02–0.05mm, maintaining leakage ≤8mL/min in high-viscosity (≤500cSt) cargo oil, suitable for cargo oil loading/unloading scenarios requiring precise metering (e.g., tanker cargo oil metering).

2. Wear Resistance and Long Life

After surface hardening treatment, high-alloy cast steel screws have a wear rate of only 0.005mm per thousand hours in crude oil with 1.5% sulfur content, with a service life exceeding 28,000 hours—3.5 times longer than gray cast iron screw pumps.

The pump body uses wear-resistant alloy linings (such as tungsten carbide coatings) to resist scouring from rust, sand, and other particulate impurities in cargo oil, suitable for long-term continuous operation in port cargo oil loading/unloading systems.

3. Low Noise and Stability

Smooth screw meshing movement with operation noise ≤68dB, 7–10dB lower than gear cargo oil pumps, complying with port operation noise control standards.

The cast steel pump body has good rigidity, with vibration amplitude ≤0.03mm. Combined with fluororubber seals, cargo oil leakage is ≤5mL/h, meeting MARPOL anti-pollution sealing requirements.

IV. Application Scenarios

1. Marine Cargo Oil Systems

Suitable for loading/unloading and transfer operations of tanker cargo oil tanks, capable of transporting media such as crude oil and heavy oil (viscosity 380cSt). Paired with deck cargo oil pipelines and heating systems, it enables efficient loading/unloading in low-temperature environments (temperature range: -10℃–250℃).

2. Petrochemical Storage Transportation

Used for cargo oil transfer in petrochemical storage areas, achieving long-distance pipeline transportation under high pressure (≤2.8MPa), such as crude oil intake pumps in refineries and refined oil outbound pump groups, supporting continuous transportation of large-flow cargo oil (e.g., 120m³/h).

3. Special Media Transportation

High-alloy cast steel pumps can resist corrosion from sulfur-containing crude oil (sulfur content >2%) and ethanol gasoline (ethanol content ≤15%), suitable for corrosive cargo oil transportation scenarios in chemical tankers and special oil depots.

V. Precautions

1. Working Condition Limitations

Carbon cast steel pumps are unsuitable for cargo oil containing >10% ethanol or high sulfur (sulfur content >0.5%); high-alloy cast steel or corrosion-resistant linings must be selected (cost increases by 15%–20%).

When cargo oil viscosity >500cSt, a preheating device (such as steam tracing) should be paired to reduce viscosity; otherwise, pump efficiency drops by 10%–15%, and increased starting load may damage the screws.

2. Maintenance Recommendations

Regularly inspect screw meshing clearance; replace screw components when the clearance exceeds 0.08mm to avoid flow attenuation (allowable deviation ≤7%).

When cargo oil contains >0.2% moisture, separate the moisture in a timely manner and clean the pump cavity to prevent corrosion of cast steel components (especially carbon cast steel materials).

3. Energy Efficiency and Environmental Protection

The hydraulic efficiency of cast steel screw pumps is 4%–6% lower than stainless steel pumps. Variable frequency motors are recommended for large-flow scenarios (e.g., ≥100m³/h) to save energy, reducing annual energy consumption by 10%–15%.

Casting carbon emissions are 38% higher than aluminum alloy. Attention should be paid to green manufacturing upgrades under the "dual-carbon" policy, and low-alloy cast steel is preferred to reduce material consumption.