TL;DR
High main bearing temperature means the bearing oil film is breaking down. Check oil supply, quality, and crankshaft alignment before the bearing fails.
What you might see
- main bearing temperature alarm active
- bearing temperature above 75 degrees C at normal load
- crankcase oil temperature rising
- bearing metal particles in oil analysis
Likely causes
Oil supply flow reduced from a clogged filter or failing oil pump
Oil viscosity incorrect for the ambient temperature or contaminated with process gas
Crankshaft misalignment increasing bearing load
Bearing clearance worn beyond specification
Required tools
- Calibrated lube oil pressure gauge
- Oil sample kit
- IR thermometer
- LOTO kit
Safety first
- Lock out the compressor drive motor and close and lock the suction and discharge block valves before accessing the crankcase.
- Compressor crankcase gas may be present if packing is leaking. Verify the crankcase vent is clear and the area is ventilated before opening the crankcase cover.
- Hot oil from the crankcase can cause burns. Confirm oil temperature is at a safe level before draining or sampling.
Procedure
- 1
Log the main bearing temperatures from the panel and compare to the normal operating profile.[1]
- 2
Check the lube oil supply pressure at the main oil gallery. Low pressure indicates pump or filter problem.[1]
- 3
Inspect the lube oil filter differential pressure. A high pressure drop across the filter means restricted flow.
- 4
Take a crankcase oil sample for analysis. Check viscosity, particle count, and water content.
- 5
Review the alignment records. If the compressor was recently moved or the foundation has settled, a crankshaft alignment check is warranted.
- 6
If oil pressure is low, replace the filter element and re-check. If pressure remains low, inspect the oil pump pressure relief valve.
- 7
If bearing temperature continues to rise despite normal oil conditions, plan an outage for bearing clearance measurement and replacement.
Sources
Ariel Corporation Ariel JGC / KBV / KBZ Reciprocating Gas Compressor general technical documentation, Ariel Corporation
Ariel JGC / KBV / KBZ reciprocating compressor general main bearing and lubrication system procedures (general)
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