Hollow Specimens

When performing SCC or HE tests, the tensile specimen is conventionally a solid piece of metal surrounded by the corrosive environment. If the testing environment is corrosive, poisonous or explosive, special attention must be paid to the safety features.

In some cases, these challenges can be avoided by using a hollow tensile specimen pressurized internally with gas, usually hydrogen. The specimen will first be rinsed with nitrogen to reduce the oxygen content of the gas phase to a low level. Finally, the hollow space is pressurized using hydrogen, after which the mechanical testing is started. Even if the specimen is filled with high-pressure hydrogen, the effective volume practically never exceeds 1 Nl. In case of a specimen rupture, such a low hydrogen volume dilutes in the lab room, especially if it is effectively ventilated.