Preface This is the fourth edition of CSA B622, Selection and use of highway tanks, TC portable tanks, and ton containers for the transportation of dangerous goods, Class 2. It supersedes the previous editions published in 2003, 1998, and 1987, under the title Selection and use of highway tanks, multi-unit tank car tanks, and portable tanks for the transportation of dangerous goods, Class 2. Scope 1.1 This Standard details the requirements for the selection and use, handling, filling, and unloading of highway tanks, TC portable tanks, and ton containers used as means of containment for the transportation of dangerous goods of Class 2. 1.2 This Standard sets out certain minimum requirements for the selection of the appropriate means of containment for the transportation of dangerous goods. This Standard does not, however, prescribe selection of the materials of construction of the means of containment to ensure chemical compatibility with the dangerous goods. Consequently, it is essential to exercise competent technical and engineering judgment in conjunction with this Standard. 1.3 Where any requirement of this Standard differs from the Transportation of Dangerous Goods (TDG) Regulations, the requirements of the TDG Regulations apply. 1.4 This Standard does not apply to tubes for the transportation of gases. Requirements for these tubes are provided in CSA B340. 1.5 In CSA Standards, "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; "may" is used to express an option or that which is permissible within the limits of the standard; and "can" is used to express possibility or capability. 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. 1.6 The values given in SI (metric) units are the standard. The values given in parentheses are for information only. Units for pressure refer to gauge pressure unless otherwise noted.