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Auxiliary Air Compressor Damage Incident: Return To TOC

The auxiliary air compressor on a tanker experienced a breakdown in October 1994 while the ship was anchored. Inspection found the high-pressure piston was fully broken at the neck, with melted areas on the piston. Foreign material like broken fragments from an air valve had likely entered and imposed a load on the piston rings, generating heat that caused seizing and breakage. Rising cooling water temperatures also increased air and oil temperatures, breaking the lubricating oil film and accelerating the seizing. The high-pressure side liner and piston were replaced to repair the compressor.

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53 views2 pages

Auxiliary Air Compressor Damage Incident: Return To TOC

The auxiliary air compressor on a tanker experienced a breakdown in October 1994 while the ship was anchored. Inspection found the high-pressure piston was fully broken at the neck, with melted areas on the piston. Foreign material like broken fragments from an air valve had likely entered and imposed a load on the piston rings, generating heat that caused seizing and breakage. Rising cooling water temperatures also increased air and oil temperatures, breaking the lubricating oil film and accelerating the seizing. The high-pressure side liner and piston were replaced to repair the compressor.

Uploaded by

Rani Nouman
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© © All Rights Reserved
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Return to TOC

ME261
Auxiliary Air Compressor Damage Incident
Technical committee

Ship type Tanker


Date of build March 1990, Mitsui Engineering & Shipbuilding Co., Ltd. Chiba Works
Navigation route Tramper (Japan ~ PG)
Trouble machinery
Category Auxiliary machinery in engine room
Name Auxiliary air compressor
Type Type 2TM68
Date of trouble Around 09:00, October 18, 1994, while anchored

1. Outline of breakdown

Together with abnormal sound of the auxiliary air compressor in operation, blow off from the
low-pressure side safety valve was discovered. The compressor was immediately stopped and the suc-
tion/delivery valves for high/low pressure were detached for inspection. As abnormality of the high
pressure piston was observed, the cylinder cover was overhauled and the piston was pulled out for
further checking. Breakage of the high-pressure piston was found.
1) The high-pressure piston was fully broken at the neck part. The upper part was stuck to the liner and
the lower part alone was moving up/down together with the connecting rod.
2) The piston had melted area, whose widest melted part was above the 1st piston ring and extended
above the upper part of the 3rd piston ring.
3) Traces of hitting were found on the top surface of the piston, which had been caused by falling
foreign matter. Many of the dents were created by melted chips or other kinds of fragments
(probably of an air valve).

2. Probable Cause

1) Foreign substance (broken fragments of an air valve, etc.) entered between the piston ring and the
ring groove, which imposed load to the ring and heating it. The heat was transmitted to the piston,
causing seizure.
2) Further, along with an increase in cooling water temperature, both air and lubricating oil increased
in temperature and breakage of oil film on the cylinder wall occurred, generating heat and accel-
erating seizing.

3. Repair

The high-pressure side liner and the piston were replaced.

1
Fig. Cross section view of Auxiliary air compressor

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