Note: Information in this article is subject to changes as ASME Standards and Codes are “living documents” and are constantly reviewed and revised. For current information on the standards and codes, visit: www.asme.org.
Some customers request that their equipment meet ASME code or standards, but what does that really mean?
The American Society of Mechanical Engineers (ASME) is a not-for-profit organization that promotes interdisciplinary engineering “collaboration, knowledge sharing, career enrichment, and skills development” with the “goal of helping the global engineering community develop solutions to benefit lives and livelihoods.” It serves this community by offering “quality programs in continuing education, training and professional development, research, conferences and publications, government relations and development of codes and standards.”
ASME is renowned for defining standards as a set of “technical definitions and guidelines” that can become the instructions for constructing products or buildings. Specifically in the cryogenic delivery industry, the ASME code outlines engineering requirements deemed for safe design and construction of the vacuum jacketed piping used in cryogenic applications. The Code is not an engineering design manual or handbook. Standards outlined are considered voluntary and are not mandated by law per se. However, if a standard or group of standards is adopted by a government entity such as city, county, state or province, it can be considered code and incorporated into the standards according to ASME. Many companies or firms, as well as states and provinces, specify ASME codes as a requirement in purchase and installation of cryogenic systems.
States in which ASME Code is mandatory:
Provinces in which ASME Code is required:
Prince Edward Island
Code requirements and laws change. It is wise to check your state and local requirements when considering a cryogenic pipe project and installation.
Common ASME Codes for cryogenic projects:
Two of the most familiar codes used in cryogenic equipment applications are the ASME Boiler and Pressure Vessel Code (BPVC Section VIII) and the Pressure (process) Piping Code (ASME B31.3). Some industries that may require B31.3 pipe include food and beverage, pharmaceutical, biological research, chemical, refineries, steel, offshore offloading, electronics and semiconductor.
“The ASME BPVC Certification Program establishes rules governing the design, fabrication, assembly, and inspection of boiler and pressure vessel components during construction.” Certification stamps are available for some standards like BPVC. They indicate compliance and verify an acceptable maintenance program to ensure the quality. For other codes, like ASME B31.3, certification stamps are not used and code compliance becomes more complex and more self-regulated.
The standards are very long (BPVC is over 700 pages and B31 over 450 pages) and following the process correctly can be arduous. The Code is not an engineering design manual or handbook. Its purpose is to establish engineering requirements for the safe design and fabrication of pipe systems. The code does not address operation, maintenance, or repair of in service vacuum jacketed pipe systems.
Per ASME B31.3 code, the owner has the overall responsibility for code compliance even though tasks for a cryogenic delivery system project may be distributed among several companies. For example, a designer specifies the piping requirements, the manufacturer fabricates the pipe, and the mechanical contractor installs the system; the ultimate adherence responsibility resides with the owner. Note: The pipe manufacturer may fabricate in accordance with the standards for the pipe in a system, but if the sections of pipe are welded together onsite, then, those joints and welds also need to be to be made to ASME standards. It is the owner’s duty to ensure that they hire reputable companies. The owner’s responsibility consists of the design, construction, examination, inspection and testing of the entire fluid delivery or process installation including the pipe. A simplification of the advantages of code compliance is listed below. For additional information, visit https://www.asme.org/products/codes-standards/b313-2016-process-piping.
By complying with ASME B31.3, the owner/buyer is assured of the following:
- Designer qualifications: The Designer is the person in charge of the engineering of the piping system. He must hold an accredited engineering degree, or be a P.E., hold a 2-year engineering technician’s degree plus 10 years of relevant experience, or have 15 years of design experience that includes pressure calculations, load calculations, and pipe flexibility calculations.
- Material traceability all the way back to the mill.
- Certified welders with appropriate documentation.
- Certified weld procedures for every ASME weld.
- Inspected welds examined to the customer’s pre-determine requirements, including optional procedures such as visual, radiographic or penetrant examination.
- All examinations performed by a Level II Weld Inspector or Certified Weld Inspector (CWI)
- All components, including valves, meet the requirements of B31.3 or referenced codes and are plainly labeled as such.
- Functional pressure testing with written certification.
- Piping designed to meet the owner’s thermal cyclic requirements.
- Code compliant written certifications for file.
- Copies of all calculations including MAWP and the pipe support system stresses.
Another ASME standard used in the cryogenic piping industry is B16.34.
ASME B16.34 is a standard that covers detailed requirements on design, manufacture, and testing of valves. The standard outlines procedures for rating valves, material compliance, and test validation. Like the codes above, this code promotes safety by minimizing risk through design principles and construction of valves used in cryogenic temperatures.
The ASME Codes promote conformity through standards publication, manufacturer accreditation, and product validation. Standard fabrication processes vary from manufacturer to manufacturer. Reputable manufacturers incorporate ASME guidelines into the normal product design as well as the production of the vacuum jacketed pipe and cryogenic components, fabrication processes, quality procedures and final inspection. However, this does not mean that the products are ASME certified. No marks or labels are required by ASME to identify adherence on vacuum jacketed pipe and accessories. Conversely, valves require identification. Only a Certificate of Authorization issued to the manufacturer from ASME ensures conformance to the safety and performance established.
To find out more about the American Society of Mechanical Engineers and the standards and codes, visit www.asme.org.
The author wishes to thank Philip Redenbarger P.E. for his hard work and collaboration on this article.