Preface This is the sixth edition of CSA G401, Corrugated steel pipe and buried structures . It supersedes the previous editions published in 2014, 2007, 2001, 1993, and 1981 under the title Corrugated steel pipe products. Changes have been made to this Standard to permit materials, manufacturing methods, and inspection procedures that meet appropriate, current, and projected industry practices. These changes include the following: a) changed standard name to Corrugated steel pipe and buried structures; b) removed spiral rib pipe Type II; c) added profile structural plate Type III; d) expanded tunnel liner plate to Types I and II; e) added zinc flake coated bolts and nuts; f) added alternative coating for structural plate and deep corrugated structural plate; g) added clause for helical welded lockseam; h) added requirements in Clause 6, Quality of work and repair; i) rewrote Clause 8, Handling, transport, storage and repair; j) removed Tables 10 and 11 for minimum outside circumference; k) updated bolt tables to imperial dimensions only, as metric is not available; and l) added Annex C (informative), Sustainability. This Standard is considered suitable for use for conformity assessment within the stated scope of the Standard. CSA Group acknowledges that the development of this Standard was made possible, in part, by the financial support of the Corrugated Steel Pipe Institute (CSPI). Such support does not indicate endorsement of the contents of this Standard. This Standard was prepared by the Technical Committee on Corrugated Steel Pipe and Buried Structures, under the jurisdiction of the Strategic Steering Committee on Construction and Civil Infrastructure, 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. Scope 1.1 This Standard specifies material and fabrication requirements for corrugated steel pipe, spiral rib pipe, structural plate, and two-flange tunnel liner plate. 1.2 This Standard applies to corrugated steel pipe and buried structures for applications such as culverts, storm sewers, storm water management systems, subdrains, hydraulic structures, grade separations, and tunnels. 1.3 This Standard does not include requirements for hydraulic design, service life, structural design, construction, or installation. For the structural design of products less than 3.0 m in span, refer to ASTM A796. The structural design of corrugated steel pipe and buried structures greater than or equal to 3.0 m in span is included in CSA S6. 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.