The ASME B31 Code is one of the most demanded for industries which depend on the appropriate design of pressure piping. 

Cryospain, with our experience in compliance with this standard for pressure equipment, shares some of the keys to understanding the ASME B31 Code and some of the subcodes, such as ASME B31.1 and ASME B31.12.

What is the ASME B31 Code and what does it regulate?

The ASME B31.1 Code regulates all aspects related with pressure piping: from its correct installation and design to adequate inspection and maintenance methods.

It is an international standard created by the American Society of Mechanical Engineers, which since 1922 has focused on the safety of piping and the creation of strict codes for its construction.

The code prescribes the minimum requirements for guaranteeing safety in the design, materials, manufacturing, verification, inspection, operation and maintenance of pressure piping. 

In this way, it affects a wide variety of industries which depend on accessing this type of equipment of the highest quality, including power stations, industrial plants, district heating projects and vacuum insulated piping for the transport of cryogenic materials. 

You may be interested in: Why thermal shields are important in cryogenic pipes

Additionally, both manufacturing companies, and designers and operators follow the rules prescribed by ASME B31.

The code is made up of seven sections and each one is oriented toward describing the requirements for a type of piping (design, materials, manufacturing, tests and inspection of piping). These seven sections are:

  • ASME: B31.1: Power piping for the thermoelectric industry.
  • ASME-B31.2: Piping for combustible gas, including natural gas and LPG (liquefied petroleum gas)
  • ASME-B31.3: Piping for chemical plants and oil refineries
  • ASME-B31.4: System for transporting liquid petroleum by piping
  • ASME-B31.5: Refrigeration piping working at temperatures under -196°C (-320°F)
  • ASME-B31.8: Piping systems for gas distribution and transmission.
  • ASME-B31.9: Services piping for factories, industries, commerce and multi-family units.

Additionally, since the 2020 version on the official ASME page, some significant revisions have been made in the latest version of the ASME B31 Code. Notable, among others, are:

  • New figures for limits in piping in accordance with the jurisdictional code
  • Modifications in the stress equations 
  • Update of the design conditions for alignment with ASME B31.3

How must piping be, according to the ASME B31 Code?

The full ASME B31 Code is a text of 200 pages plus appendices, setting out precise specifications on how pressure piping must be to offer guarantees. 

As a summary, we cite some of the content that the code includes as part of the requirements:

  • A series of design conditions appear, which must be observed, regarding issues such as pressure, minimum temperature, design temperature, components without insulation and externally and internally insulated piping.
  • Among the design criteria, elements must be observed such as the pressure-temperature rating for piping components, ratings in normal operating conditions and tolerance for variation with regard to normal operation, rating in transitions, allowable stresses and other limits and excess thicknesses.
  • It also specifies requirements for the pressure design for straight pipes under internal pressure, under external pressure, curved pipes and segments, branched, closed or tapped connections, design pressure of Flanges and Blanks, reducers and other components. 
  • It applies criteria for components and their fluid requirements.
  • It defines the flexibility and support that pressure piping must be capable of providing. 
  • It details the conditions of the materials to use.
  • It includes the testing methods and acceptance, inspection and examination criteria.

Keep reading: Cryogenic piping: a brief on sizing, materials, insulation and hazards

Appendices of the ASME B31

A series of appendices complement the information set out in the ASME B31 Code, some of the most recent being: 

  • Appendix P in ASME B31.3, which was introduced to incorporate new rules for analysis of flexibility in piping in accordance with computerised models. 
  • Appendix B31.3 W, added in new editions on the evaluation of piping systems in high cycle fatigue.
  • Appendix B31.3 X, which includes rules for expansion joints.

Exceptions to the code

  • Condensate piping designed for 15 (psig) or less
  • Heating systems for buildings or hot water heating systems designed for 30 (psig) or less
  • Structures for steam distribution
  • Piping for hydraulic or pneumatic tools
  • Piping for marine installations or installations under federal control
  • Construction elements of non-structural piping

Cryospain pressure piping

At Cryospain we offer our range of vacuum insulated Cryoline pressure piping in accordance with the ASME Code. 

Designed and manufactured by our expert cryogenic engineering team, it has been developed for transport of LIN, LOX, LAR, GNL, LHe, LH2 and LNG. 

We therefore offer an optimal solution for insulation of cryogenic materials and their transport, guaranteeing quality thanks to verification in accordance with the ASME B31 Code and others, such as directives 2014/68/EU and TR CU 032/2013. Additionally, our piping is compliant with the EN13480 and ASME B31.3 design codes.

Cryoline piping has formed part of dozens of successful projects, including the transformation of ships to Liquefied Natural Gas and the design of VIP (vacuum insulated piping) in Huelva.

Contact us to find out more about ASME B31 and how our pressure piping ensures compliance with these requirements. 

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