The TEMA classes — R, C, and B — define the construction standards for shell and tube heat exchangers published by the Tubular Exchanger Manufacturers Association, and picking the right class affects mechanical design margins, materials, and ultimately cost. Choosing a class that doesn’t match your actual service either overspends on unnecessary robustness or undersizes the design margin for a demanding process.
TEMA Class R: Refinery and Severe Service
Class R covers the most demanding requirements, generally applied to petroleum and related processing applications where safety, reliability, and long service life under severe conditions are the priority. This class specifies the largest mechanical design margins of the three.
TEMA Class C: General Commercial and Process Service
Class C is intended for generally moderate requirements of commercial and general process applications, offering a more economical design than Class R while still meeting sound engineering practice. It is a common choice where the service is not chemically or mechanically severe.
TEMA Class B: Chemical Process Service
Class B is specifically intended for chemical process service, with materials and design details oriented toward the corrosion and cleanliness demands typical of chemical plants rather than refineries. It sits between R and C in terms of design conservatism, tuned for chemical rather than petroleum duty.
Choosing the Right Class for Your Application
The correct TEMA class depends on the process fluid, pressure, temperature, and the plant’s own engineering standards, not on cost alone. GreyTec’s shell and tube heat exchangers are built to the TEMA class your process actually requires, with support from our engineering and consultancy team to confirm the right classification before fabrication begins.