General

This standard establishes a test method to measure the ability of elastomeric materials to withstand static exposure to vapor phase sour gas environments (e.g., gaseous hydrocarbons with hydrogen sulfide [H2S]) at elevated pressure. This test method is not designed to be an immersion or a functional test. It is designed for testing standard O-rings or test specimens of elastomeric vulcanites cut from standard sheets (see ASTM D31822). This test method is not applicable to testing cellular rubber or porous materials.

This standard recommends the procedures for preparation of test specimens, the test equipment to be used, the test procedures to be followed, and the reporting of test results. The standard also discusses test conditions, test media, and reagents. In summary, the standard specifies conditions of temperature, exposure time, and pressure for the exposure of test specimens to the influence of a gaseous environment that contains H₂S, carbon dioxide (CO₂), methane (CH₄), water vapor, and hydrocarbon vapor. The results are determined by monitoring changes in physical and mechanical properties (i.e., mass, volume, compression set, hardness, tensile strength, ultimate elongation, and modulus), as well as changes in appearance after exposure to the selected test medium.

In view of the wide range of service conditions, this test method is intended only to be a means of initial material evaluation and is not intended to provide any direct correlation with service performance. No attempt is made or implied to establish any pass/fail criteria for materials tested by this method. The change in properties of an elastomeric material is indicative of its resistance to the specific environment. This test method should be regarded only as a measure of the resistance of a material under the conditions of this particular test—test results do not necessarily have any direct relation to service performance. The significance of the test results should be determined only by each laboratory for its particular application. The precision of this test method and reproducibility within and among laboratories has not been established. Test specimens being tested using this method may be different in performance or alike within test error. The user of this test method should establish statistical significance of the data resulting from use of this test method.

Safety Precautions: H2S is an extremely toxic gas that must be handled with care. See Appendix A (nonmandatory) for safety considerations and information on toxicity of this gas.

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