GB772207A - Improvements in or relating to venting means - Google Patents

Abstract

772,207. Locking valves. SHELL RESEARCH, Ltd. April 29, 1955, No. 12538/55. Class 135. In a fluid venting means in which fluid is vented through a group of two or more relief valves 2, 3 each in fluid connection with a space to be vented and in which there is associated with each relief valve on the upstream side thereof an externally operable valve, 4 or 5, capable of isolating the associated relief valve from the group, a movable locking element or bar 15 co-operates with the operating elements of the externally operable valves 4, 5 to prevent more than one such valve being closed at one time. The venting flow can be accommodated by one less than the number of relief valves provided so that one relief valve may be isolated for repair or inspection. The valves 4, 5 are connected to a pressure vessel 1 by a common header 6 and the relief valves to a common outlet 8. The valves 4, 5 have spindles operated by hand wheels and each spindle has a reduced part. The locking bar 15 has a handle 24 and slots 16, 19 co-operating with fixed pins to limit its movement. The bar also has keyhole slots 17, 18 each having relatively narrow parts and relatively wide parts, respectively. The main or wide parts of the valve spindles can only pass through the wide parts of the respective slots 17, 18 and the valves 4, 5 can only be closed when the spindles are respectively aligned with the wide parts. The latter are, however, arranged so that when one spindle is aligned with the wide part of the slot 17, the other spindle engages the narrow part of the other slot 18 with its reduced part and so cannot be moved to the closed position until the other valve (4 or 5) has been re-opened. The locking bar 15 may then be moved so that the narrow part of the slot 17 engages the reduced part of the spindle of the valve which has been re-opened. The locking bar may be modified to accommodate more than three spindles. The locking element may alternatively have a rotary or swinging movement. Where the relief valves are connected to a common outlet or disposal point and the pressure at this point has to be taken into account when isolating any relief valve for inspection or repair, an externally-operable valve is provided on the downstream side of each relief valve and a similar locking element or bar is provided to prevent more than one of the downstream valves from being closed at one time.