The ship’s main engine comprises of several bearings, which assist the moving parts such as crankshaft, connecting rod, crosshead etc. The bearings supports the journal pin to avoid metal to metal contact, to reduce the rotational friction, and to transfer the load through lubricants.
Main engine bearings are opened up for inspection or renewal if their is a breakdown in the rotating equipment, grounding/accident of the ship, or for routine maintenance and survey.
While doing inspection of bearings, following steps must be considered:
Prior to Opening Bearing for Repair/ Survey:
– Ensure to check the previous bearing opening/ survey report
– Check details of the records and clearances
– Check all bearing related service letters from the manufacturer
– Check shore lube oil analysis record
– Perform onboard lube oil test and note down the results
– Check work done report or log book for any important points on the bearings (grinding or pin/ under or oversize bearing etc.)
– Check all the photographs of the last opened bearing
– Perform tool box and risk assessment of the job
– Take immobilization permission from port authority
During Bearing Repair/ Survey
– Ensure crankcase is properly ventilated and proper personal protective equipment (PPE’s) like helmet and safety harness are worn by those working
– Check and record clearance of the bearing
– Check the condition of bearing metal
– Check for signs of squeezing, scoring, cracking, pitting etc.
– Check the surface shine of the pin – it should be shiny in appearance
– If scoring, pitting, cracks etc. exist in the pin, same to be polished, grinded, or reconditioned
– Replacement of bearings to be be done as per maker’s instruction. For e.g. if overlay alloy is wiped out or oil wedge in the bearing is reduced in dimension etc.
– The pin and the bearing to be thoroughly cleaned and lube oil to be put before fitting
– Take enough photographs while doing the maintenance or survey
– Ensure the bearing and other parts are secured as per manual instructions
– The tightening value of the hydraulic bolts to be crosschecked and it is to be done in the presence of senior engineer officer
– Engine to be turned by turning gear for at least 10 minutes with lube oil pump on and oil pressure recorded
– The turning gear current to be observed during this process
– Once the engine is closed and ready, running-in to be performed as per makers instructions
– Record all the parameters
– Prepare the maintenance/ survey report
– File the report in ship’s record and send the complete work with photo proof to the office. This can be used as a reference during continuous machinery survey and the concerned bearing need not to be opened.
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