Gearbox inspection and test-run for Kuwait oil company

Challenge

Stork Diagnostic Services was invited by a Kuwaiti oil company for the complete inspection of a damaged vertical offset speed-increasing gearbox, type Rademakers. The gearbox is part of a Ruston TB5000 driven sour gas compressor train. The aluminum frame of the gearbox including the primary and secondary gears had been removed from the unit and brought to a local workshop in Kuwait for further inspection (picture 1). During inspection all bearing pocket diameters and all bearing journal diameters were measured and the damage was summarized in a diagnostic report. For a brief impression of the damage, please view the summary and photogallery below.

Solution

The aluminum gearbox frame (the cradle) had one bearing pocket that was badly worn out (picture 2). The radial and axial bearings were in very bad condition, and showed signs of a chemical reaction, which might have been caused by oil starvation. The worst damage was caused by the output shaft coupling end bearing failure, which was completely destroyed. The white metal from this bearing was totally wiped out (picture 3), resulting in significant damage on the shaft journal (picture 4), the bearing pocket of the aluminum frame and teeth of the gearwheel and bull gear. The pinions showed signs of overheating, most likely related to bearing failure. Renewal of the primary gears including the cradle and bearings was recommended.  

Benefit

• Renewal of the cradle, primary and secondary gears

• Alignment check between gas turbine and load gearbox

• Mounting and adjusting of the secondary gears

• Installing (temporarily) proximity probes and thermal couples

• Witness test run (see below)

• Record and analyse shaft vibrations

• Dynamic tooth contact pattern check

• Diagnostic report

Witness test-run 

During the witness test-run the following critical running parameters were recorded:

• Revolutions of the input shaft

• Casing and shaft and vibrations

• Oil inlet temperature and pressure

•Oil outlet and bearing temperatures

Location: Kuwait

Market segment: Oil & Gas