What are the Reasons for Excessively High Mechanical Seal Oil Consumption?

In process industries such as petrochemicals, oil refining, and ethylene production, abnormal consumption of seal oil in the mechanical seal systems of centrifugal compressors or pump units not only leads to a sharp rise in operating costs but may also cause equipment shutdowns, medium contamination, and even safety accidents. So, which links have problems causing excessive seal oil consumption? And how to accurately investigate and address them? Today, combining API standards and frontline on-site practical experience, I will break down the six core reasons for abnormal seal oil consumption and their corresponding solutions.

1. Seal Oil Leaks Outward Through the Floating Ring Seal

This is the most deceptive loss path. In the floating ring seal structure, if seal oil leaks outward through the floating ring, it can easily enter the lubricating oil tank axially.

Diagnostic Logic: 

Observe the state of the external oil return. If the oil return volume increases abnormally, the oil temperature fluctuates, or the color of the lubricating oil changes, it can basically be determined that "oil channeling" has occurred.

Solutions:

• Optimize the control logic of seal oil and injection gas pressure, and appropriately reduce the seal oil pressure;
• Add a balance pipe to balance the pressure difference between the front and rear injection gas chambers;
• Modify the floating ring structure if necessary to improve the precision of the seal gap.

2. Poor Internal Oil Return of Seal Oil

When there is a problem with the internal oil return system, the seal oil will enter the process medium and be discharged along with the gas compression.

Diagnostic Logic: 

Close the liquid level control valve and bypass of the oil-gas separator, record the liquid level drop slope, calculate the actual internal oil return volume based on the inner diameter of the container, and compare it with the normal value.

Solutions:

• Rapid Venting Method: Fill the oil-gas separator and empty it quickly. The instantaneous pressure difference impact can often restore the normal liquid level balance.
• Bypass Transformation: Improve the pipeline pressure difference, or realize rapid oil-gas separation under high pressure difference through dual air extraction means.

3. Leakage Points Exist in Equipment Belonging to the Seal Oil Process

Although this is the most basic problem, it is also the easiest to be ignored in complex petrochemical pipe networks.

Key Inspection Points: Various pumps, filters, heat exchangers, flanges, valves, and instrument interfaces involved in the seal oil process.

Treatment Suggestions: Establish a regular inspection system. Many times, a loose flange or a slightly cracked instrument tube is the culprit consuming several liters of oil every day.

4. Blocked Oil Discharge from the Oil-Gas Separator

If the oil discharge pipeline of the oil-gas separator is blocked, the liquid level control valve is stuck, or the instrument malfunctions, the liquid level will be too high, and the seal oil will flow from the gas return pipeline to the machine body.

• Emergency Measure: Immediately switch to bypass operation and manually control the liquid level.
• In-depth Cleaning: Inspect and unblock the pipeline of the seal oil return degassing tank. If scaling is severe, the pipeline must be disassembled and cleaned to ensure "smooth" oil return.

5. Backflow in the Pressure Tap Pipe of the High-Level Tank

The seal oil high-level tank is crucial for maintaining the pressure difference. Once the hydraulic control fails, the seal oil will directly flow into the machine body along the reference gas pressure tap pipe.

Solutions:

• Immediately inspect and repair the liquid level control system of the high-level tank;
• Temporarily close the pressure tap pipe valve or stop the seal oil pump, and resume operation only after the liquid level of the high-level tank is stable.

6. Problems with the Nitrogen Agitation System of the Seal Oil Degassing Tank

This is the most dangerous situation, often involving cross-system contamination.

Phenomenon Description: If media such as kerosene or gasoline are mixed into the nitrogen system, entering the degassing tank will cause the liquid level to soar and flow back into the main oil tank. This is not only an oil consumption problem but also dilutes the seal oil, leading to the rapid failure of the lubrication performance of the entire system.

Emergency Measures:

• Immediately cut off the contaminated nitrogen source;
• Gradually drain the oil, add new oil, and perform cyclic replacement until the oil quality is qualified;
• Strengthen the monitoring of nitrogen purity to avoid the entry of cross media.

Core Summary

Four Main Causes: Seal performance, installation quality, operating condition fluctuations, cooling/vibration.

Treatment Logic: First accurately locate the cause, then take targeted measures.

Prevention Strategy: Purchase high-quality components + control installation precision + conduct regular parameter inspections.

Expert Advice: Solving small hidden dangers ensures major safety. For targeted technical support or high-performance seal accessories, please contact the Teffiko expert team to obtain customized solutions.