Cast Steel Gear Fuel Oil Pump

I. Cast Steel Material Classification 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 maintains stable mechanical properties at room temperature and withstands impact vibration under medium loads, but its strength declines significantly at high temperatures (tensile strength decreases by 15% when >200℃).

Applications: Suitable for manufacturing fuel pump housings, non-precision gears, and other components, commonly used in low-pressure fuel transportation scenarios (e.g., diesel engine fuel supply systems, small fuel boiler oil supply).

2.Low-Alloy Cast Steel

Characteristics: Added with alloy elements such as manganese, silicon, and chromium, the tensile strength increases to 500~900MPa, and the yield strength is 20%~30% higher than that of carbon cast steel. It features significantly enhanced wear resistance and fatigue resistance, outstanding anti-deformation capability in high-pressure (≤3MPa) fuel media, and 30% improved resistance to fuel scouring corrosion.

Applications: Used for key components such as gears and bearing seats of high-pressure fuel pumps, commonly found in marine main engine fuel systems and high-pressure common rail fuel supply systems of heavy machinery diesel engines.

3.High-Alloy Cast Steel

Characteristics: Contains elements such as nickel, chromium, and molybdenum, with excellent fuel corrosion resistance (5~8 times higher tolerance to sulfur-containing fuel and ethanol gasoline than carbon cast steel). It can operate stably in high-temperature fuel environments of 300℃, significantly improves cavitation resistance caused by fuel gasification, and the gear surface hardness can reach HRC50~55 with outstanding anti-seizing performance.

Applications: Suitable for special working conditions, such as aviation fuel transfer pumps, fuel transportation systems with corrosive additives in the chemical industry, or scenarios requiring resistance to high-temperature fuel carbonization (e.g., gas turbine fuel supply systems).

II. Technical Advantages and Limitations of Cast Steel Gear Fuel Oil Pumps

(1) Core Advantages

1.High Strength and Fuel Scouring Resistance

Under high-pressure fuel (pressure ≤4MPa) scouring, the wear rate of low-alloy cast steel gears is only 0.01mm per thousand hours (when the medium contains impurities ≤0.2%), with a service life exceeding 25,000 hours, 3 times longer than gray cast iron gear pumps.

After carburizing quenching treatment, the surface hardness of cast steel gears is high, effectively resisting wear from tiny particles (such as rust and impurities) in fuel, suitable for heavy-load fuel transportation.

2.Good High-Temperature Resistance and Sealing Performance

High-alloy cast steel pump bodies can operate in 280℃ high-temperature fuel, with a thermal deformation rate <0.3%, avoiding pump body expansion and leakage caused by increased oil temperature, suitable for aero-engines and high-temperature fuel heating systems.

The pump body and gears of cast steel have high matching accuracy, with a fit clearance controlled at 0.02~0.05mm. Combined with fluororubber seals, the fuel leakage is ≤5mL/h, meeting the sealing requirements of high-pressure fuel systems.

3.Balance of Cost and Reliability

The cost of cast steel materials is 1/3~1/2 of that of stainless steel, and the single-piece production cost is 40% lower than that of forged alloy steel, suitable for mass production. The casting process can form complex structures (such as pump bodies with heat dissipation ribs).

Gear pumps have a simple structure and convenient maintenance (such as replacing gears and cleaning filters), with maintenance costs 60% lower than screw fuel pumps, suitable for long-term continuous operation in industrial fuel systems.

(2) Main Disadvantages

1.Weight and Installation Accuracy Requirements

Cast steel has a density of 7.8g/cm³, 3 times higher than aluminum alloy. For example, a 3-inch diameter fuel pump weighs about 40kg, requiring special brackets for installation. The coaxiality error between the pump shaft and motor shaft must be ≤0.03mm; otherwise, seal failure is likely to occur due to vibration, with installation costs 20%~30% higher than plastic pumps.

2.Corrosion Resistance Limitations (for Special Fuels)

Cabon cast steel is prone to electrochemical corrosion in fuels containing ethanol (>10%) or high sulfur (sulfur content >0.5%), relying on inner surface nickel plating or PTFE coating protection, increasing costs by 15%~20%, and regular maintenance is required after coating wear.

Although high-alloy cast steel is resistant to general fuel corrosion, in environments with strongly oxidizing fuel additives (such as peroxides), tooth surface oxidation wear may still occur, shortening the service life to less than 10,000 hours.

3.Energy Efficiency and Environmental Challenges

The hydraulic efficiency of cast steel gear pumps is 5%~8% lower than that of stainless steel pumps. In large-flow fuel systems (such as ≥200L/min), the annual energy consumption cost increases by about 8,000 RMB, and the viscosity decrease caused by fuel temperature rise further reduces efficiency.

Carbon emissions from casting are 45% higher than aluminum alloy, facing the pressure of green manufacturing under the "dual-carbon" policy. It is necessary to optimize the casting process (such as using lost foam casting) to reduce energy consumption and minimize harmful gas emissions from resin sand molding.