This is the third edition of CSA B341, UN pressure receptacles and multiple-element gas containers for the transport of dangerous goods. It supersedes the previous editions published in 2015 and 2009. This Standard is one of a series of Standards adopted by reference by the Transportation of Dangerous Goods Regulations. Because the Regulations might adopt this Standard with certain exceptions or additional requirements, they should be consulted to determine where they differ from the requirements of this Standard. Notwithstanding the provisions of this Standard, compliance with the provisions of the Transportation of Dangerous Goods Act and the Regulations thereto can call for additional requirements due to particular characteristics or properties of individual dangerous goods. Any requirements of the Transportation of Dangerous Goods Regulations regarding the handling, the offering for transport, and the transportation of dangerous goods in cylinders, spheres, and tubes are to be fully complied with. It should be emphasized that this Standard was not prepared with the intention of removing existing requirements for specification gas containers authorized by CSA B340; rather, it was developed to incorporate the ISO standards as referenced in the United Nations' Recommendations on the Transport of Dangerous Goods - Model Regulations, 19th edition (2015) ("UN Model Regulations") as an optional means of compliance and hence to provide for a broader selection of authorized pressure receptacles and facilitate international transport. The following requirements have been included in this Standard for consistency with North American practice: a) manufacturers, inspection bodies, periodic inspection and test bodies, and design review agencies need to be registered with Transport Canada; b) UN pressure receptacles and multiple-element gas containers manufactured in accordance with this Standard are marked with the letters "CAN" to denote the country of approval; and c) an inspection body is not authorized to delegate its inspection functions to inspectors of the manufacturer. The Technical Committee on Cylinders, Spheres, and Tubes for the Transportation of Dangerous Goods, which is responsible for this Standard, has maintained close links with Transport Canada to ensure compatibility of the new edition of this Standard with the amended Transportation of Dangerous Goods Regulations. The Technical Committee has also reviewed and made extensive use of the UN Model Regulations. This edition of CSA B341 incorporates numerous amendments and refinements to the previous edition, while retaining the same basic format.