Section 18(1) in The Static and Mobile Pressure Vessels (Unfired) Rules, 2016
(1)General-(i)Fittings. - Each vessel shall be provided with each of the following fittings all of which should be suitable for use with the gas at pressures not less than the design pressure of the vessel to which they are fitted and for temperatures appropriate to the characteristics of the gas and operating conditions, namely,-(a)Pressure relief valve connected to the vapour space;(b)Drains;(c)Contents gauge or maximum level indicator;(d)Pressure gauge connected to the vapour space;(e)Means of measuring the temperature of the contents of the vessel.(ii)Vessel connections. - Connections of vessels shall be designed and attached to the vessels in accordance with the design code referred to in rule 13. All static vessels for storage of corrosive, flammable or toxic gas in liquefied state shall not have more than one pipe connection to the bottom for inlet or outlet, apart from the drainage. The drainage pipe, if provided, shall be extended beyond the shadow of the vessel and provided with two shut-off valves. No drainage pipe shall be provided direct from spherical vessel. The bottom inlet or outlet pipe for spherical vessel or for any vessel intended for storage of flammable or toxic or corrosive gas exceeding 50 tonnes or 100 M3 water capacity shall be integrally welded to the vessel and extended up to three metres beyond the shadow of the vessel, at the end of which, combination of manually operated valve for positive isolation and quick shut-off remote operated valve shall be provided.
