Air bottle stores compressed air at high pressure. Any leakage in the air bottle may jeopardize the safety of the ship itself as main engine and many safety devices need compressed air for their operation.
SOLAS Requirements for air bottle
- SOLAS states that the total capacity of air bottles must be enough to provide at least 12 starts for a reversible engine and 6 starts for a non-reversible engine without refilling.
- SOLAS prescribes that there must be at least two identical main air bottle and one emergency bottle on every vessel.
Material
- It is generally made up of cast iron.
- Internal surface is coated with anti-corrosive, anti-toxic and anti-oxidant substances.
Maintenance on air bottle
- Regularly drain the bottle of water and oil
- Regular inspection should be carried out to ensure that the internal condition of the bottle is good
- Check for corrosion both internally and externally.
- Inside coating, COPAL varnish condition to be checked to ensure that it is unbroken and no peeling is taking place
- Welding seams to be checked, carry out dye-penetrant test at suspected areas
- The tell tale hole between the lap welding seams of the doubler plate / ring to be checked for leaks in service to ensure that the internal welding is intact
- Face of the man hole is to be checked for pitting marks
- Drain should be clear
- All points of high stress and corrosion are to be thoroughly checked viz. welds, supports braces, the bottom of the bottle where water/oil is collected. Pay attention to the zone of water line.
- Check for leaks at the mounted valve glands/flanges, carry out inspection of the valve face and seat for wire drawing effect
- A timing check with the air bottle completely charged and isolated will give a good idea of the intactness of the pressure vessel
- The safety/relief valve setting to be inspected as per the class requirement
- Regularly check the alarms and monitoring equipment for proper functioning
