Section 20 in The Merchant Shipping (Cargo Ship Construction And Survey) Rules, 1974
20. Air pressure system.
(1)In every ship in which machinery essential for the propulsion and safety of the ship or persons on board is required to be started, operated or controlled solely by compressed air, an efficient air system shall be provided which shall include a sufficient number of air compressors and compressed air storage vessels so as to ensure that an adequate supply of compressed air is available under all conditions likely to be met in service.(2)(a)Parts of every such compressed air system other than a pneumatic control system which are subjected to air pressure shall be so designed and constructed as to withstand, with adequate factor of safety, the maximum working stresses to which they may be subjected and every air pressure pipe or fitting in such system shall, before being put into service for the first time, be subjected to a hydraulic test to twice its maximum working pressure and be maintained in an efficient condition.(b)Means shall be provided to prevent over-pressure in any part of any such compressed air system and where water jackets or casings of air compressors and coolers might be subjected to dangerous over-pressure due to leakage into them from air pressure parts, suitable and adequate pressure relief arrangements shall be provided.(c)In every such compressed air system provision shall be made-(i)to reduce to a minimum entry of oil into the system;(ii)to drain the system; and(iii)to protect the system from the effects of internal explosion.(d)In every such compressed air system, discharge pipes from starting air compressors shall lead directly to the starting air receivers, and all starting air pipes from the receivers leading to main or auxiliary engines shall be entirely separate from the compressor discharge pipe system.
