Abstract: An apparatus for stopping the flow of gas under pressure from a relief valve comprises an elongated tube which fits around a flue secured to a tank. The apparatus has means for maintaining the tube in this position. An elongated rod is extended through the tube and secured into a load-transferring position so that it rests on the pressure valve assembly, thus preventing the assembly from opening.The method for sealing off a leaky safety valve has a first step of placing a tube over a flue for a safety valve. This tube has a bar adjustably secured within and generally coaxial with it. The bar is lowered until it sits on the valve head so as to restrain the valve from leaking.