The complete air compressor body was broken due to pressurized crankcase. Fortunately no one was injured by this incident. However repairs are estimated beyond economical and new compressor unit installed.

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Possible scenario of trouble:

During operation, the compressor crankcase turned in pressurized condition due to following reasons –

1) Air leaking from second stage (High pressure side), where the piston gudgeon pin is located protected with seal ring and disc arrangements.

2) Hairline cracks or pit holes developed on piston crown, possibly due to cylinder lubrication insufficient or failure. Pressurized air can be discharged into Crankcase chamber.

3) Seized or broken piston rings and scratched liners allowed high pressure air to leak in the crankcase.

4) Inadequate crankcase breathing due to restricted or clogged breather caps disabled the venting systems.

Admission of the high pressure air into crankcase can lead to interrupt the lubrication and develop hot spots. Air compressor at this stage will be vulnerable to develop explosive atmosphere. If the crankcase breathing or venting system is not adequate or restricted the explosion may occurre.

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Countermeasures/ conclusion


  • 1) Breather cap observation ensures breather cap venting effectively and no high pressure air releasing with sound from the crankcase. Crankcase oil condition and oil splashing from the breather cap to be observed in running condition.
  • 2) Cylinder lubricators to be ensured working satisfactorily in all running conditions.

Whenever pressurizing of crankcase noticed
- 1) Perform pressure test for seal disc of piston pin and discard the defective seals. ( For tandem compounding through 2nd stage side)
- 2) Piston top on LP side can also be tested with compressed air for leaks through piston cracks or pitting holes.

At every overhaul
Check the piston crown or top for cracks, holes if any disorders. Replace seal disc and seal rings of piston pin for all units.

Overhaul of seal discs (if applicable) must be included in the PMS system.

posted 15 Jun '17, 23:23

June 15, 2017, 11:23 p.m.
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edited 16 Jun '17, 00:47

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