Page 350 - Reciprocating Compressors Operation Maintenance

Troubleshooting Compressor Problems 335

CASE HISTORIES FROM SERVICE TECHNICIAN REPORTS

Service technicians compiled examples of problems that could have been
prevented by more-detailed or careful examination of early symptoms.
The following are some of the typical problems they described.

Symptom: Compressor would not unload, pumping until safety valve
blew. Excessive blow-by existed at the piston rod packing.
Findings; The unloader piston was found to have rusted in its cylinder due
to excessive condensation. Jacket water temperature at 50°F was
increased to 100°F outlet, Unloader piping cleaned of dirt and moisture.
Symptom and Problem: Compressor forced shutdown due to extreme
knocking. Found wiped crank pin bearing that had been recently
installed.
Findings: Damaged parts were checked and crankpin was found to be
.007" out of round.
Symptom: Two-stage compressor developed a knock. Preliminary
inspection showed no apparent cause.
Findings: Cylinder heads of both stages were removed. Clearances of
crosshead and rod were checked. Found piston rod nut of high pres-
sure cylinder lacked cotter pin, allowing it to turn, loosening the piston
and causing the knock.
Symptom and Problem: Horizontal non-lube compressor would not unload.
Diaphragm unloader was "chattering," caused by diaphragms failing.
Findings: Diaphragm stem travel was insufficient to correctly unload.
Symptom: Single-stage, vertical-type compressor cylinder was worn
excessively; piston was scored and machine was out of service.
Findings: Since all valve passages were found dry, it indicated lubricator
was also dry, causing piston failure.
Symptom: Compressor piston rod was scuffed. Packing was worn and
cylinders showed pitting from moisture.
Findings: Found piston rod packing cocked, impairing lubrication of the
rod.
Symptom: Water leaking from the air side of the intercooler. Traps were
bypassed to handle drain.
Findings: A number of tubes were corroded through from the water side
due to improper water treatment.