A Temperature Controlled Mechanical Test Facility to Ensure Safe Materials Performance in Hydrogen at 1000 Bar-Paper

Increasingly, car manufacturers are turning to high pressure hydrogen storage for on-board powerapplications. Many prototypes use costly materials and fabrication methods, such as Type 316Laustenitic stainless steel and processes such as TIG (GTA) welding. There is a need to move to lessexpensive options without compromising safety to assist in developing economic vehicles. It isimportant that the behaviour of new/modified materials and joints (including those fabricated by newtechnologies) is understood at anticipated service temperatures and hydrogen pressure as theconsequences of poor material choice could be severe. The greatest detrimental effect of gaseoushydrogen on the mechanical properties of metallic materials is commonly observed under conditionsof dynamic plastic strain. Under such conditions , an atomically clean surface is produced, wherehydrogen molecules will dissociate, and penetrate the material. Thus, static load test methods withhydrogen charging are not reliable for engineering data generation. To meet the need for dynamicallystraining material in a pressurised hydrogen environment, TWI has developed a facility to loadspecimens in a high pressure environment for tensile , toughness and fatigue testing. The design of thishas involved a number of innovative steps. This paper outlines the requirements and the design andconstruction issues that were encountered when installing a facility which can not only perform tests atup to 1000bar (100MPa) but also for temperatures between ?150 C to +85 C.