The technical suitability of the steel grades L80 and 42CrMo4 (UNS G41400) for the application in an underground gas production facility is investigated. Therefore, the materials are tested with respect to their susceptibility to embrittlement by hydrogen gas, up to a maximum H2-partial pressure of 20 bar (290 psi), by means of constant load tests (CLTs) and immersion tests with subsequent hydrogen analysis.

The tests are carried out within a specially developed and constructed autoclave setup, which enables rotation and heating of the vessels. Each autoclave holds 3 specimens: a coupon for measuring the mass loss, an immersion specimen for hydrogen analysis and a small tensile specimen under constant load (CLT).

Tests are done under realistic field conditions and hence samples are periodically wetted by the aqueous part of the test medium, which contains chloride in a concentration of 15 000 mg/L. The gaseous part of the medium consists of H2 and/or CO2. Tests are performed with or without a corrosion inhibitor and last 30 days. In general, the examined steel grades show a good resistance to hydrogen embrittlement.