(1)Every plant or machinery other than the working cylinders of prime movers used in a factory and operated at a pressure greater than atmospheric pressure shall be -(a)of good construction, sound material, adequate strength and free from any patent defect;(b)properly maintained in a safe condition;(c)fitted with -(i)a suitable safety valve or other effective device to ensure the maximum permissible working pressure of the vessel shall not be exceeded;(ii)a suitable pressure gauge easily visible and designed to show, at all times, the correct internal pressure in kilogram per square centimetre and marked with a prominent red mark at the safe working pressure of the vessel;(iii)a suitable stop valve or valves by which the vessel may be isolated from other vessels or source of supply of pressure; and(iv)a suitable drain cock or valve at the lowest Part of the vessel for the discharge of connected liquid;(d)thoroughly examined by a competent person -(i)externally, once in every period of six months, to ensure general condition of the vessel and the working of its fittings;(ii)internally, once in every period of twelve months, to ensure condition of the walls, seams and dies both inside and outside of the vessels, soundness of the Parts of the vessel, and the effects of corrosion. If by reason of construction of the vessel thorough internal examination is not possible, this examination may be replaced by a hydraulic test which shall be carried out once in every two years; provided that for the vessels in continuous processes which cannot be frequently opened, the period of internal examination may be extended to four years; and(iii)hydraulically tested at intervals of not more than four years; provided that in respect of pressure vessels with thin walls such as sizing cylinders made of copper or any other non-ferrous metal periodic hydraulic test may be dispensed with on the condition that the requirements laid down in clause (2) are fulfilled:Provided further that it shall be sufficient for the purposes of clause (c) if the safety valve, pressure gauge and stop valve mounted on a pipeline immediately adjacent to the vessel and where there is a range of two or more similar vessels in a place served by the same pressure load only one set of such mountings need be fitted provided they cannot be isolated.
