How to deal with abnormal noise and high vibration from oil and gas recovery equipment? The straightforward answer is: first classify and then dispose of the issue - sharp whistling noises are often caused by bearings or surge, dull impacts are often due to looseness or foreign objects, and continuous buzzing accompanied by high current is often due to abnormal load; before disposal, shut down the machine and cut off the power. If the problem is with rotating parts, replace them; if it's looseness, tighten them; if it's flow issues, adjust the operating conditions. The cost of operating with defects is the expansion of faults: bearing disassembly and impeller shelling all develop from small abnormal noises. This article clarifies the judgment methods, inspection points, and procedures for resuming operation.
Identifying the source of abnormal noise
Judgment relies on listening, observation, and measurement: Listen to the tone of the sound. A continuous sharp sound indicates bearing oil shortage or blade rubbing, while an intermittent impact sound indicates loose parts or foreign objects. A low-frequency buzz indicates load or surge; observe the vibration by feeling the intensity with your hand on the shell and bearing position, and measure the amplitude to see the trend; measure the current to check whether the three-phase current is balanced and whether it climbs synchronously with the abnormal sound. The role of judgment is to grade: minor abnormalities that can be observed in the trend are included in the planned maintenance, while those with rapidly increasing intensity should be stopped immediately. Do not use the old method of knocking and listening to sound to deal with equipment in explosion-proof areas. Judgment should mainly rely on appearance, temperature, and current data.
Fan and bearing inspection
Fans are prone to producing abnormal noises: a lack of oil or early wear in the bearings will result in a continuous screeching sound, which will evolve into a rough friction noise as it progresses, accompanied by an increase in the temperature of the bearing area; uneven fouling of the impeller causes imbalance, which manifests as more pronounced vibration at higher speeds, and key positions can be felt when turning the fan after it has stopped. The inspection process consists of three steps: using a temperature gun to measure the temperature of the bearing area and compare it with historical values; using a listening needle or vibration meter to measure the vibration at the bearing area; and turning the fan to feel whether the rotational force is uniform. When replacing the bearing, check the model number and heat it in place during installation without forcefully knocking; after cleaning the impeller, a balance check must be performed, as simply replacing the bearing without cleaning will still result in vibration.
Inspection of pump body and connecting pipe
There are two most common types of abnormal noises from pump bodies: one is cavitation, which occurs when the inlet resistance is high or the liquid level is insufficient, causing the pump to evacuate internally, producing a sound like throwing stones, accompanied by significant fluctuations in the inlet pressure gauge. Check the inlet filter and liquid level; the other is stagnation, which occurs when crystals or foreign objects enter the cavity, causing the turning gear to feel rough or even get stuck. This requires dismantling the cavity for cleaning. Pipe vibration is a collateral issue: if the inlet and outlet of the pump and fan are not connected with soft connectors to absorb forces, vibration will be transmitted along the rigid pipes, and there are many examples of weld cracks on the support welds caused by vibration. During inspection, feel along the pipeline section by section. The location where vibration suddenly amplifies is often the point of failure in fixation. Don't just focus on the equipment body for inspection.
Pipe fixation and flexible connection
The pipeline fixation inspection focuses on three types of defects: loose supports or sealing off, manifested as resonance in the entire pipeline segment; overly tight pipe clamps that crush the insulation layer, losing its cushioning effect and actually amplifying vibrations; and insufficient reinforcement and fixation at turning points and valve sections, which become areas of vibration amplification. For soft connections, inspect the corrugations and flanges: fatigue cracking in the corrugations can lead to air leaks, while loose flange bolts can turn soft connections into hard ones. Both issues can be identified by oil stains and traces at the joints. Tightening operations should follow torque requirements, and bolt replacements in explosion-proof areas must be of the same specification, avoiding substitution with ordinary parts.
Disposal and operation recovery
| Abnormal noise characteristics | Possible root cause | Priority check-in position | disposal method |
|---|---|---|---|
| Continuous shrill sound | Bearing wear due to lack of oil | Temperature and vibration at the bearing position | Refill oil or replace bearing |
| Intermittent impact | Loose parts or foreign objects | Support bolt impeller | Fasten or remove foreign objects |
| Low-frequency buzzing | Abnormal surge under load | Three-phase current damper | Adjust operating conditions and check load |
| The higher the rotational speed, the greater the vibration | Uneven fouling of the impeller | Impeller balance | Remove dirt and achieve balance |
| Like throwing pebbles | Pump cavitation and evacuation | Inlet pressure level | Check filtration and liquid level |
| The gears are stiff and difficult to turn | Cavity crystallization jamming | Pump chamber turning gear | Disassemble and clean |
Disposal steps
- Record the characteristics of abnormal sound and the location of vibration;
- Decide whether to shut down or monitor the operation based on the classification;
- After disconnecting the power and tagging out, inspect the bearings and impellers;
- Inspect the pump body for cavitation and the cavity for any blockage or seizure;
- Secure the bracket and repair the flexible connection;
- After recovery, measure the current vibration and temperature trend.
Frequently Asked Questions
What is considered an abnormal bearing temperature?
Looking at trends is more reliable than looking at individual values: Using the historical data of this station as a baseline, if the temperature continues to rise or exceeds the manufacturer's specified value during steady-state operation, it should be treated as abnormal; when there is no baseline, comparing the rate of temperature rise with adjacent bearings is a practical criterion. Don't wait until it smokes before shutting down.
What if the vibration persists even after replacing the bearing?
First, inspect the balance of the impeller and the fixation of the pipeline: if the impeller with uneven scale buildup is not cleaned, no matter how many times the bearing is replaced, vibration will persist; loose supports and failed soft connections can cause vibration to flow back from the pipeline into the equipment. If these two items are not inspected, the effectiveness of component replacement will be compromised.
Can we wait until the maintenance period for the slight abnormal noise?
Hierarchical treatment: For those with stable intensity and no trend change in temperature and current, they should be included in the planned maintenance and have more frequent records; for those with increased intensity or accompanied by abnormal temperature and current, they should be shut down immediately. The basis for judgment is trend data, not just a casual remark on site that it seems fine.
This article is compiled by Luoyang Wohong Petrochemical Equipment Co., Ltd. The company provides design and manufacturing, skid-mounted customization, installation and commissioning, as well as after-sales operation and maintenance services for three-time oil and gas recovery equipment to gas stations and oil depots. If you need on-site inspection or scheme configuration, please feel free to contact us for discussion.