What is Pressure Vessel, Safety requirements for Pressure Vessels

Pressure Vessel means:  any vessel subjected to or operated at a pressure greater than the atmospheric pressure.

1)       Safety requirements for Pressure Vessels as per factories act are as follows - 

a.             Every pressure plant or pressure vessel shall be fitted with-
 a suitable safety valve or other effective device, conveniently located to ensure that the maximum safe working pressure of the vessel shall not be exceeded at any time;
b.             a suitable pressure gauge with a dial range not less than 1.5 times and not exceeding twice the maximum safe working pressure, easily visible and designed to show, at all times, the correct internal pressure in kilograms per square centimetre and marked with prominent red mark at the maximum safe working pressure of the pressure plant or pressure vessel;
c.             a suitable stop valve or valves by which the pressure vessel or the system of pressure vessels may be isolated from other vessels or source of supply of pressure;
d.            a suitable nipple and globe valve connected for the exclusive purpose of attaching a test pressure gauge for checking the accuracy of the pressure gauge referred to in clause (b) of the sub-rule;
e.             a suitable drain cock or valve or a plug at the lowest part of a pressure vessel so as to ensure effective draining of liquid that may be collected in the pressure vessel.
2)       Every pressure gauge, stop valve, nipple and globe valve, shall be mounted at a height not more than 1.5 metres from the working level.
3)       Every pressure plant or pressure vessel not constructed to withstand the maximum possible working pressure at the source of supply or the maximum pressure which can be obtained in the pipe connecting the pressure vessel with any other source of supply shall be fitted with a suitable reducing valve or other suitable automatic device to prevent the safe working pressure of the vessel being exceeded. Suitable pressure guages shall be provided close to the reducing valve to show the high pressure and reduced pressure.
4)        In case of a jacketted vessel in which heat is transmitted by means of steam or other media in the jacket causing pressure rise in the vessel, the heat input in the jacket shall be so controlled by a suitable device as not to allow the safe working pressure of the vessel being exceeded.
5)       To further protect the pressure vessel in the event of failure of reducing valve or the control device mentioned in clauses (3) and (4) an additional safety valve having a capacity to release all steam, vapour or gas without under pressure rise shall be provided in addition to the one referred to in clause (1)(a).
Provided that it shall be sufficient for the purposes of this sub- rule if the safety valve, pressure guage and stop valve or other suitable effective device are mounted on a pipeline immediately adjacent to the pressure vessel and where there is a range of two or similar pressure vessels in a plant served by the same pressure load, only one set of such mountings need be fitted provided that those cannot be isolated from any of the pressure plant or pressure vessels.

6)       Ever pressure plant in service shall be thoroughly examined by a competent person,-
(a)  externally once in every period of six months;
(b)  internally, once in every period of twelve months, and
(c)  hydraulic test once in a period of four years.