Heat Exchanger Industry Codes and Practices

The Company uses Heat Transfer Research Inc. (HTRI) technology, supplemented by Company experience, for design and evaluation of thermal and hydraulic performance of heat exchangers. HTRI conducts large scale tests of heat exchangers and incorporates the results into reports and computer programs. HTRI has tested extensively shell and tube exchangers in boiling, condensing and single phase service, and completed limited testing of air coolers and plate and frame exchangers. HTRI information is contract confidential and should not be disclosed outside of the Company.

Mechanical design of exchangers is based on standards developed by the American Society of Mechanical Engineers (ASME), Tubular Exchanger Manufacturers Association (TEMA), American Petroleum Institute (API), and Chevron.

ASME covers mechanical design of pressure vessel components (shells, channels, tubesheets, headers and some aspects of large flanges), and imposes restrictions on piping, instrumentation and inspection of steam boilers.

TEMA addresses shell and tube heat exchangers only, and covers nomenclature, fabrication tolerances, standard tube sizes, standard clearances, minimum plate thickness, and minimum tie rod requirements. TEMA also provides tubesheet design rules that differ from ASME tubesheet design rules.

TEMA tubesheet rules are used for most shell and tube exchangers. ASME tubesheet rules are used for stayed fixed tubesheet steam boilers, and air cooler headers. API standards address mechanical design criteria of shell and tube exchangers, and air-cooled exchangers.

There are no industry standards for double pipe, multitube hairpin or plate and frame heat exchangers.