Maintenance precautions for gear pumps transporting heavy oil

For the maintenance of gear pumps transporting heavy oil (such as fuel oil, residual oil, asphalt, etc.), special attention should be paid to the following aspects. Heavy oil has high viscosity, impurities, is prone to solidification, and sometimes requires

The heating and other characteristics pose special requirements for the maintenance of heavy oil pumps.

The following are detailed maintenance precautions, which can be divided into three parts: daily operation precautions, regular maintenance, and long-term pump shutdown maintenance.

1、 Daily operation precautions (during each start stop and operation)

Correct operating habits can greatly extend the lifespan of a pump.

1. Preheating pump body: extremely important!

Before starting, the pump and inlet and outlet pipelines must be fully preheated. Heavy oil may solidify at room temperature, and starting it directly can cause motor overload, damage to pump shafts, seals, and even the gears themselves.

Usually, the temperature of the pump body is heated above the flow temperature of the heavy oil by steam or electric heating (the specific temperature depends on the oil product). Touch the pump body with your hand and feel it warm evenly before starting.

Absolutely prohibited: Forcefully start when the medium inside the pump is in a cold state of solidification!

2. Turning gear:

After preheating and before starting, use tools or manually rotate the pump shaft several times to feel whether it is flexible, uniform, and free of jamming. This ensures that there is no solidified material inside the pump and provides initial lubrication to all lubrication parts.

3. On/off sequence:

Start sequence: First open the inlet and outlet valves of the pump (ensure smooth pipeline), then start the motor.

Shutdown sequence: Stop the motor first, then close the inlet and outlet valves.

Long term shutdown: After shutdown, the heavy oil pump and pipelines must be flushed with light oil (such as diesel) or specialized cleaning solution to completely replace heavy oil and prevent blockage and solidification in the pump after cooling. This is the most important shutdown step.

4. Monitoring during operation:

Pressure: Pay close attention to whether the outlet pressure gauge reading is stable. Abnormal increase in pressure may indicate outlet blockage or filter blockage; A decrease in pressure may indicate inlet blockage, intake of air, or

Increased internal leakage.

Abnormal sound: Monitor the sound of the pump running. Abnormal noise or impact sounds may indicate gear wear, bearing damage, or air intake (cavitation).

Leakage inspection: Check whether the shaft seal (mechanical seal or packing seal) has serious leakage. Slight leakage may be allowed for certain packing seals, but dripping leakage must be addressed.

Temperature: Check if the temperature of the pump body and bearings is within the allowable range to avoid overheating.

2、 Regular maintenance (planned maintenance)

Develop maintenance plans based on frequency of use and operating conditions.

1. Maintenance of filtration system:

Impurities in heavy oil, such as asphaltene, carbon particles, and mechanical impurities, are the main cause of wear on gear pumps.

Regularly clean the inlet and outlet filters (filter screens or basket filters). The frequency depends on the cleanliness of the oil, and may be weekly, per shift, or even more frequent.

Check if the filter is damaged, and replace it immediately if it is damaged.

2. Shaft seal inspection and replacement:

Mechanical seal: Check the wear of the sealing surface. If there is any leakage or the service life is reached, replace the dynamic and static rings and O-rings in a timely manner. Be sure to clean thoroughly when replacing.

Packing seal: Regularly adjust the tightness of the gland to maintain a small amount of leakage for lubrication and cooling. When the packing wears out, it should be replaced with new packing in a timely manner.

3. Inspection of clearance between gears and side plates (lining plates):

The efficiency and pressure of a gear pump mainly depend on the clearance between the gear and the pump body, as well as between the gear and the side plate. With wear and tear, the gap will increase, leading to an increase in internal leakage and a decrease in volumetric efficiency (output flow rate)

Reduce).

Regularly disassemble the pump (such as every year or every few thousand hours of operation) and measure the clearance of key components. If the clearance exceeds the maximum allowable value specified by the manufacturer, the gear or side plate should be replaced in a timely manner.

4. Bearing inspection and lubrication:

Check the bearings for wear, looseness, or abnormal noise.

For bearings that require lubrication, regularly add high-temperature grease of the specified grade (note: high-temperature grease should be selected for heavy oil working conditions with high temperatures). For bearings lubricated with engine oil, regularly check the oil

Location and oil quality.

5. Coupling alignment inspection:

Regularly check the alignment of the pump and motor coupling. Misalignment can lead to premature damage of vibration, bearings, and shaft seals.

3、 Long term pump shutdown maintenance

If the pump needs to be stopped for a long time (more than a week), the following steps must be performed:

1. Thoroughly rinse: Use light oil (diesel) or specialized cleaning solution to run the pump for a period of time until the discharged liquid is completely clear, ensuring that all heavy oil in the pump and pipeline is completely replaced.

2. Emptying: After flushing, empty all liquids from the pump chamber and pipeline.

3. Rust prevention: If necessary, a small amount of rust prevention oil can be injected into the pump chamber and manually turned several times to cover the inner wall with an oil film.

4. Isolation: Close all valves to prevent impurities and moisture from entering.

5. Marking: Hang the signs of "maintained, ready for use" or "long-term disuse".

The most important points are "preheating" and "rinsing". By doing these two things well, 80% of common faults can be avoided. Strictly follow the product manual of the gear pump for maintenance, and according to the delivery you provide

Adjust maintenance strategies based on specific characteristics of heavy oil, such as viscosity, sulfur content, and impurity content.