Section 56(8) in The West Bengal Factories Rules, 1958
(8)(a)In respect of any pressure vessel or plant of thin walls such as sizing cylinder made of copper or any other non-ferrous metal the maximum permissible working pressure shall be reduced at the rate of 5 per cent of the original maximum permissible working pressure for every year of its use after the first five years and no such cylinder shall be allowed to continue to be used for more than twenty years after it was first taken into use.(b)If any information as to the date of construction, thickness of walls, or maximum permissible working pressure is not available, the age of such pressure vessel or plant shall be determined by the competent person in consultation with the Chief Inspector from the other particulars available with the manager.(c)Every new and second hand pressure vessel or plant of thin walls to which repairs likely to effect its strength or safety have been carried out, shall be tested before use to at least 1.5 times its maximum permissible working pressure.
