CSA/ANSI CHMC 1:2026

Preface This is the third edition of CSA/ANSI CHMC 1, Test methods for evaluating material compatibility in compressed hydrogen applications — Metals . It supersedes the previous editions published in 2014 and 2012. The major changes to this edition are as follows: a) Environmental requirements have been updated to reflect state-of-the-art understanding, including emphasis on role and control of oxygen impurities, modification of the standard test temperature (testing at an alternative temperature was moved to the informative annex), and addition of guidance on soak time. b) The fracture test method has been updated to include a definition of the fracture initiation threshold and of the testing rate. c) The fatigue test methods have been generalized, such as allowance for testing at different force ratios. d) Clause 6 on material qualification has been deleted. The screening test has been maintained in Annex I. e) Annex D on test temperature has been expanded with guidance formerly in the main body of the standard. f) A new annex (Annex E on additional information of frequency dependence) has been added. g) Annex I has been added to maintain the screening test for aluminum alloys and austenitic stainless steels. CSA Group acknowledges that the development of this Standard was made possible, in part, by the financial support of Natural Resources Canada. This Standard is considered suitable for use for conformity assessment within the stated scope of the Standard. This Standard was prepared by the Subcommittee on Material Compatibility for Compressed Hydrogen Applications, under the jurisdiction of the Technical Committee on Hydrogen Transportation and the Strategic Steering Committee on Transportation, and has been formally approved by the Technical Committee. This standard has been developed in compliance with Standards Council of Canada requirements for National Standards of Canada. It has been published as a National Standard of Canada by CSA Group. This Standards has been approved by the American National Standards Institute (ANSI) as an American National Standard. Scope 1.1 Inclusions This Standard provides uniform test methods for evaluating material performance in compressed hydrogen applications. The results of these tests are intended to provide basic materials performance in applications utilizing compressed hydrogen. This Standard is not intended to replace sound engineering judgment; additional testing considerations might be necessary to fully qualify the design of a component manufactured for use in certain hydrogen applications. This Standard applies to metallic materials only. 1.2 Conflict with government requirements In the case of conflict between this Standard and federal, provincial/territorial, state, or local requirements, the governmental requirements take precedence. 1.3 Gauge pressure All references to pressure throughout this Standard are to be considered gauge pressures, unless otherwise specified. 1.4 Terminology 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 Units of measurement The values given in SI units are the units of record for the purposes of this Standard. The values given in parentheses are for information and comparison only.