Hollow Specimen

When performing SCC or HE tests, the tensile specimen is conventionally a solid piece of metal surrounded by a 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 be first 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.