Ammonia compressor overhaul

Hour meters are a starting point, not a verdict. Reciprocating NH₃ machines commonly reach a major strip between 15,000 and 25,000 hours; oil-injected screws often sit in the 30,000–50,000 hour band. Condition monitoring should beat the calendar: rising discharge temperature, metallic oil, shaft-seal weep, knock, or a slide valve that hunts at part load.

Overhaul during a low-load window — winter, a planned holiday, or a second machine covering the room. Emergency rebuilds cost more because rotors, valve-plate sets, and bearings have lead time. If repair quotes approach half the cost of a sound replacement frame, we say so before you open the casing.

Piston work covers valve plates as a set, liners, pistons and rings, connecting rods, crank journals, gaskets, and shaft-seal housing. Screw work covers male/female rotors, bearings, mechanical shaft seals, slide-valve travel, oil-system flush, and coupling alignment.

We isolate, pump down, lock out, and photograph the nameplate before tools come out. Clearances go on a sheet. After reassembly we laser-align the motor-compressor train — a few tenths of a millimetre of offset will destroy a new seal in days.

Plants use these words interchangeably. In our workshop an overhaul is a full inspection and renewal of wear parts to a documented fit. A rebuild usually means selected failed items plus the seals and gaskets that must come off to reach them. Replacement is for cracked housings, scored rotors beyond grind limits, or frames where parts cost more than a remanufactured machine.

If you searched “ammonia compressor rebuild” or “compressor overhauling,” you are on the right job — the decision is condition, not vocabulary. Send hours, make/model, and a photo of the nameplate and we will say which path is honest.