Cylinder Lubrication in Reciprocating Compressors: Too Much, Too Little

Lubrication of the cylinders and packing is one of the cheapest things to get right on a reciprocating compressor, and one of the most expensive to get wrong. In the EFRC's 2019 survey of compressor users, piston rings, valves, packing and rider bands were the wear parts behind most unscheduled shutdowns, and all four depend on the right amount of the right oil reaching the cylinder.

Signs of too little oil

• Fast wear of piston rings, rider bands and packing rings

• Scoring of the cylinder liner or the piston rod

• Rising packing case temperature and packing leakage

• Dry or polished areas on the liner when the cylinder is opened

Signs of too much oil

• Valve plates sticking and breaking, with oil collecting in valve pockets

• Carbon and deposits on valves, especially at high discharge temperatures

• Oil carried downstream into coolers, scrubbers and the process

• Oil consumption well above the expected daily volume

What sets the right rate

The manufacturer's lubrication rate depends on cylinder bore, stroke, speed and pressure. The gas matters too: wet, sour or heavy hydrocarbon gas usually needs a different oil, and often a higher rate, than dry sweet gas. The oil grade matters as much as the quantity, so check both whenever the gas or the operating pressures change.

How to check it on site

1. Compare the lubricator pump setting and the divider block cycle time with the manufacturer's rate.

2. Confirm that no-flow alarms and divider block indicators actually work.

3. At every opening, look at the liner: it should carry a thin, even oil film. Pools of oil mean too much; dry or polished areas mean too little.

4. Look at the valves: wet, sticky valves with deposits point to over-lubrication.

5. Track oil consumption against the expected daily volume.

Short Way checks lubrication systems as part of every reciprocating compressor inspection and overhaul. If valves or rings on one of your units keep failing early, talk to our engineers. For valve problems, see our guide to compressor valve failure.