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ASME B31.8 VS CSA Z662

ASME B31.8 VS CSA Z662 by Meena Rezkallah, P.Eng. for engineering Services across Canada and USA.

This Article focuses on the comparison of the American Society of Mechanical Engineers (ASME) B31.8, Gas Transmission and Distribution Piping Systems and the Canadian Standards Association (CSA) Standard Z662, Oil and Gas Pipeline Systems. Significant issues which are expected to be the basis of continued discussion include:

  • Increasing the design factor in Class 1 locations in the US to the Canadian value of 0.80

  • Allowing additional flexibility in valve spacing

  • Normalizing requirements for pressure testing, especially hydrostatic testing

  • IM requirements.

There are also differences in depth-of-cover requirements, although they do not appear to be a critical factor.

Both standards incorporate concepts of strain-based design and reliability approaches, although no consensus has been reached on a standard approach for pipeline design or operations. In this regard, a prescriptive approach would likely be counterproductive and an application methodology might be a better option. CSA Z662 Annex O provides a reliability-based methodology that can be applied to both design and operating scenarios for gas pipelines. The methodology establishes definitive target levels of reliability. ASME B31.8 is expected to publish Reliability Based Design and Assessment methodology in December 2008 which is reportedly based on the same reference material as Annex O; however, detailed information was unavailable at the time of this report.

Table below provides a tabulated version of comparisons between US and Canadian gas transmission pipeline design.

ASME B31.8

CSA Z662-15

ASME B31.8 is an American Society of Mechanical Engineers (ASME) standard that covers the design, installation, operation, and maintenance of gas transmission and distribution systems. It provides requirements for the design, fabrication, testing, and inspection of gas pipelines, components, and related equipment for the safe and reliable transport of natural gas. The standard includes requirements for the design, operation, and maintenance of gas distribution systems, including systems operated at pressures of 7 psi or greater.

CSA Z662-15, Oil and Gas Pipeline Systems, is a Canadian standard that outlines the design, construction, operation, and maintenance of oil and gas pipelines. It is published by the Canadian Standards Association and has been in effect since 2015. It is intended to provide a comprehensive framework for the safe and responsible operation of oil and gas pipelines. The standards outlined in this document are designed to ensure the safe and efficient transport of oil and gas and to protect the public, workers, and the environment. The standard covers topics such as pipeline installation, operation and maintenance, integrity management, and emergency preparedness and response. It also provides guidance on the requirements for pipeline-related activities such as welding, testing, inspections, and repairs.

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