Suitability of soldered and brazed joints in copper pipework for low pressure hydrogen gas installations

With the transition to a hydrogen economy, there are necessary questions relating to the safety of repurposed infrastructure. Here, the impact of hydrogen on lead and lead-free soldered joints, as well as brazed joints, in copper pipework, has been evaluated by the tensile testing of hollow tubular specimens in gaseous hydrogen with supplementary ammonium thiocyanate immersion charging. A consistent ≤5% decrease in tensile strength was observed, which may be interpreted in terms of hydrogen enhanced plasticity in the copper piping. Failure strain decreased by up to 21% in soldered joints, but not brazed joints, indicative of hydrogen-induced reductions in fracture toughness or interfacial cohesion. Considerable scatter was present in the large dataset obtained, with trends in tensile strength and failure strain falling below statistical significance. Regardless, the magnitude of the trends observed, even if induced by hydrogen, indicate soldered and brazed joints are suitable for low-pressure hydrogen installations.