What a Korean refinery learned about reciprocating compressor monitoring
A Bently Nevada case study shows why frame vibration alone cannot diagnose a reciprocating compressor — and what changes when cylinder pressure and rod position are added.
Bently Nevada's Orbit journal published a case from SK Energy's Ulsan refinery that is worth reading if you run reciprocating machines. Three booster compressors in the catalytic reforming unit were eating roughly 90% of the maintenance budget across a fleet of a hundred machines. Valves failed, pistons cracked, and nobody could say why.
The short version: contamination in the process gas formed sticky residue in the cylinders. Valves stuck, effective compression ratio climbed, discharge temperatures rose, and components failed. The fix combined process changes, stronger valve and piston designs, and — the part that interests us — a rebuilt monitoring system.
Why the monitoring part matters
The original system measured frame and crosshead vibration plus basic process values. That is enough to know a machine is unhappy. It is not enough to know why.
Adding cylinder pressure transducers and rod position probes changed that. With pressure and crank angle together, System 1 builds P-V diagrams — and a P-V diagram shows a sticking valve directly, as a distortion in the compression curve, before anything breaks.
Our take
We see the same gap on plants across the region. Reciprocating compressors are often instrumented like centrifugal ones: a couple of vibration channels on the frame and nothing inside the cylinder. That setup protects the machine from catastrophic failure but tells you almost nothing about valve condition, and valves are what actually fail.
If you are budgeting an upgrade for a reciprocating machine, cylinder pressure is where the diagnostic value is. It is the difference between scheduling a valve change and discovering the problem when the piston cracks.
The full case study, including the failure analysis and results, is published by Baker Hughes: https://www.bakerhughes.com/bently-nevada/orbit-home/orbit-article/reliability-improvement-reciprocating-compressor-ccr