Scope 1.1 This Standard provides uniform test methods for evaluating material compatibility in compressed hydrogen applications. The results of these tests are intended to provide a basis for comparison of materials performance in applications using compressed hydrogen. 1.2 This Standard applies to polymer materials only. Note: In this Standard, the term "polymer" refers to synthetic polymers, such as thermoplastics and elastomers, that have been manufactured for liner or sealing applications. 1.3 This Standard is not intended to replace sound engineering judgment or component testing in hydrogen applications; additional testing considerations based on applicable standards and relevant failure modes should be conducted to fully qualify the polymer in the design of a component manufactured for use in certain hydrogen applications. 1.4 In this Standard, "shall" is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the Standard; "should" is used to express a recommendation or that which is advised but not required; and "may" is used to express an option or that which is permissible within the limits of the Standard. Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material. Notes to tables and figures are considered part of the table or figure and may be written as requirements. Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application. 1.5 All references to pressure throughout this Standard are to gauge pressures, unless otherwise specified.