Nonmetals can pose a fire risk in oxygen systems. Therefore, nonmetals should be tested to qualify their use in oxygen. ISO 21010:2017 provides test methods for qualifying a nonmetal's use in oxygen, which includes the oxygen pressure surge test. Nonmetals not meeting the oxygen pressure surge testing requirements can be tested in their actual operating configuration. This additional testing option (oxygen pressure surge testing) can be performed on the component or on a representative assembly that houses the nonmetal(s). Performing this type of testing on a large industrial piping valve is not currently feasible with the test system described in ISO 21010. Therefore, a test fixture was designed to enable oxygen pressure surge testing to be performed on O-rings, in their use conditions, within a partial assembly. One benefit of using a partial assembly is to reduce the cost of larger components. The partial assemblies are more cost-effective than providing three replicate, complete components. The test fixture was designed to permit the application of compression heating consistent with the potential compression heating that the component could experience in service. This oxygen pressure surge testing was successfully performed using the testing fixtures, qualifying the O-rings for use on the component at significantly higher operating conditions than those established by the material version of the oxygen pressure surge test.