Abstract: A pressure relief valve adapted in use to relieve excess pressure within a vessel. The valve comprises a valve seat (20) and a moveable valve member (28) which is resiliently biased towards the valve seat (20) by coil springs (30) to maintain the valve in a normally closed position. A valve seal (52) is carried by the moveable valve member (28), between the moveable valve member (28) and the valve seat (20), to seal the gap therebetween when the valve is closed. The valve seal (52) has an annular pressure sealing face (54) which in the valves normally closed position sealingly co-operates with the valve seat (20).