Section 56(5)(b) in The U.P. Factories Rules, 1950
(b)To further protect the pressure vessel in the event of failure of the reducing valve device, at least one safety valve having capacity sufficient to release all the steam, vapour or gas without undue pressure rise as determined by the pressure at the source of supply and the size of the pipe connecting the source of supply, shall be fitted on the low pressure side of the reducing valve.