A device for controlling the release of gas from a pressurised container, the device comprising a plug comprising a passage therethrough, a diaphragm within said passage, wherein said diaphragm is configured to initially prevent flow of gas through said passage, and is rupturable or displaceable to allow gas to flow through said passage once said diaphragm is ruptured or displaced. The device further comprises a screw located within said plug and comprising a lance configured to move towards said diaphragm upon rotation of said screw, wherein said lance is configured to rupture or displace said diaphragm so as to allow flow of gas through said passage and out of said plug, once said screw is rotated a predetermined amount.

A pressure cylinder made of thin-walled welded stainless steel vessel fitted with a composite shell and a neck with an external and/or internal thread, where the neck is attached to the thin-walled vessel by a circular welded seam with a hermetic seal and containing a flange which is fitted circumferentially with a pair of tapered grooves on its outer surface whose adjacent sides meet on an annular ridge on which there are locking teeth in the direction of the longitudinal axis of the neck and composite fibers are placed in inter-tooth spaces. The method of producing a pressure cylinder includes the welding of a neck to the thin-walled vessel with a hermetic seal, whereupon composite fibers with stress less than the total force acting on the fiber bundle are wound into additional grooves between the teeth and further winding of the fiber around the neck is carried out while simultaneously moving bilaterally along the axis of the shell to position the fiber between the teeth, whereupon fibers with a nominal stress value are wound and final winding of the reinforced composite shell is carried out.