(4)(a)In respect of pressure vessels of thin walls such as sizing cylinders made of copper or any other non-ferrous metal the safe working pressure shall be reduced at the rate of five percent of the original working pressure for every year and no such cylinder shall be continued to be used for more than twenty years after it was first taken into use.(b)If no information as to the date of construction, thickness of walls and safe working pressure is available, the age of the sizing cylinder shall be determined by the competent person in consultation with the Chief Inspector from any other particulars available with the manager.(c)Every new and second hand cylinder of thin walls to which rapairs which may effect its safety, have been carried out, shall be tested before use, to at least one and a half times its working pressure.
