Preface 

This is the twentieth edition of CSA B51, Boiler, pressure vessel, and pressure piping code. It supersedes the previous editions published in 2019, 2014, 2009, 2003, 1997, 1995, 1991, 1986, 1981, 1975, 1972, 1969, 1965, 1960, 1957, 1955, 1951, 1945, and 1939. In keeping with CSA Group’s goal of harmonizing its standards with those of other countries to the greatest extent possible, CSA’s Technical Committee on Boilers and Pressure Vessels and its Subcommittees have, in the course of developing this Standard, worked closely with the National Board of Boiler and Pressure Vessel Inspectors in the United States and with the American Society of Mechanical Engineers (ASME) committees responsible for producing the National Board Inspection Code and ASME’s Boiler and Pressure Vessel Code. This Standard contains requirements for boilers, pressure vessels, pressure piping, and fittings. It is intended mainly to fulfill two objectives: first, to promote safe design, construction, installation, operation, inspection, testing, and repair practices; and second, to facilitate adoption of uniform requirements by Canadian jurisdictions. This Standard has undergone substantial technical and editorial revisions since the previous edition in 2019. The requirements in this edition have been reorganized in a lifecycle format, with four new clause titles: Conformity assessment and quality control systems (Clause 4); Classification of equipment (Clause 5); Equipment manufacturing (Clause 6); and Owner’s equipment (Clause 7). Significant changes include the following: a) the requirements of Part 2 in CSA B51:19 have been removed to reflect their inclusion in CSA HGV 2 and CSA NGV 2; b) the requirements of Part 3 in CSA B51:19 have been incorporated throughout this Standard; c) new requirements in Clauses 5.1.1.8 to 5.1.1.10 for boilers in cyclic service have been added; d) a new Clause (Clause 5.2.4.13) with design guidance for superheated steam sources connected to blowoff vessels has been added; e) new definitions and Clauses (Clauses 6.1.1 and 7.1.2) laying out responsibilities for manufacturers have been added; f) new references to ISO 16528-1 have been added to Clause 6.2.1.1; g) references to a CCRN or similar organization have been removed; h) revisions have been made to address carbon steel toughness requirements, now found in Clause 6.2.6, and in a deletion of notes to Clause 5.2.1; i) new test requirements for carbon steel pipe, fittings, and forgings in Clause 6.3.7 have been added; j) requirements for welded staybolts, previously found in Clause 6.8 in CSA B51:19, have been removed; k) additions to the Table 5 Note on in-situ testing have been included; l) Clause C.1.1 has been updated to clarify certificate of authorization requirements for safety, relief, or safety relief valves; m) Clause C.2.2.8 regarding PRD-certified assemblers or distributors has been revised; n) the Statutory Declaration form has been replaced with a new Declaration of Conformity form (see Figure D.6); o) a new CRN application form has been added (see Figure D.9); p) revisions to Annex F including i) replacing references to "statutory declaration" with "declaration of conformity"; ii) new informative clauses for quality programs; and iii) Annex F now titled "Quality programs for manufacturers of boilers, pressure vessels, piping systems and fittings"; q) Annex G has been revised to bring the annex into alignment with CSA B149.5; r) Clause I.6, providing optional requirements for servicing historical boilers, has been revised; s) the Standard has been revised throughout to allow references to ASME Code Section XIII and use of term ASME Code certification mark with designator; t) the addition of new annexes including i) Annex M, "Pneumatic testing of pressure vessels and piping systems"; ii) Annex N, "Quality program requirements for performing new construction inspection"; iii) Annex O, "Guidelines for a quality program for organizations that provide design examination services"; iv) Annex P, "Guidelines for audit programs"; v) Annex Q, "Guidelines for the development and operation of a Pressure Equipment Integrity Management Program (IMP)"; vi) Annex R, "Synopsis of some exemptions in Canadian jurisdictions"; vii) Annex S, "Guidelines for registration documentation and inspections for new construction"; and viii) Annex T, "Recommended safe practices where hydrogen is a constituent of the service fluid". CSA Group acknowledges that the development of this Standard was made possible, in part, by the financial support of Natural Resources Canada. The users of this Standard should note it is a recommendatory document only and does not have the force of law except where it has been officially adopted by a Canadian jurisdiction. Users should also note that adoption does not necessarily mean the Standard has been adopted unchanged. For example, a jurisdiction may decide to make an informative annex normative. The Technical Committee intends to meet periodically to review this Standard and, if necessary, to revise it to meet changing conditions and maintain uniformity of practice throughout Canada. The Technical Committee supports the use of the National Board Inspection Code. It is the responsibility of users of this Standard to be aware that applicable local regulations can take precedence over the requirements of that Code. This Standard was prepared by the Technical Committee on Boilers and Pressure Vessels, under the jurisdiction of the Strategic Steering Committee on Mechanical Industrial Equipment Safety, 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 Equipment within scope 

Except as indicated in Clause 1.2, this Standard applies to all pressure equipment including a) boilers, pressure vessels, pressure piping, and fittings, as provided for by the Act (as defined in Clause 3) and identified in this Standard; and b) compressed natural gas and hydrogen refuelling station pressure piping systems and storage pressure vessels. Notes: 1) It is possible the size limitations specified in provincial/territorial statutes or regulations will differ from those specified in this Standard. The applicable AHJ should be consulted. 2) The pressures specified in this Standard are gauge pressures above atmospheric pressure. 3) This Standard applies to all boilers, pressure vessels, pressure piping, and fittings installed after its adoption. 

1.2 Exclusions 

This Standard does not apply to a) pressure-retaining components in hydraulic elevators; b) pressure-containment devices for gas-filled switchgear and controlgear; c) high-pressure cylinders for the on-board storage of hydrogen as fuel for automotive vehicles (see CSA/ANSI HGV 2); d) high-pressure cylinders for the on-board storage of natural gas as fuel for automotive vehicles (see CSA/ANSI NGV 2); and e) pressure vessels for the transportation of dangerous goods regulated by Transport Canada. 

1.3 Variances with CSA B51 

Where a clause in this Standard is at variance with a code or standard referenced in this Standard, the requirements of this Standard will govern. 

1.4 Exemptions in Canadian jurisdictions 

A synopsis of some exemptions in Canadian jurisdictions is provided in Annex R. 

1.5 Clause numbering between B51:19 and B51:24 

Annex U compares the location of clauses between the 2019 and 2024 editions of this Standard. 

1.6 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. 

1.7 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. Nominal pipe sizes are expressed in non- dimensional terms.