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Quotes - Engineering - SalesU-Tube Heat Exchangers For
TEMA Classes R, C and B
U-Tube Duty
TEMA class is not about geometry. Two exchangers can be identical BEU units and differ substantially in cost because one is Class R and the other Class C.
TEMA publishes mechanical standards for shell and tube exchangers, and divides construction into three classes reflecting service severity. The class affects thicknesses, allowances, clearances and tolerances rather than the fundamental arrangement.
Class R. Intended for the severe requirements of petroleum and related processing applications. The heaviest construction, largest corrosion allowances and tightest tolerances. Specified widely in refining and petrochemical service.
Do Not Specify R by Default. Class R appears in a lot of specifications that were written for refinery service and then reused. On a plant utility heater it adds material, cost and sometimes lead time, and returns nothing the duty will ever use.
Conversely, specifying Class C on genuinely severe service is a false economy, because the smaller allowances and lighter construction shorten the life you get. Match the class to the severity and the decision is straightforward.
Class C. General commercial applications. The lightest of the three and entirely appropriate for utility duty, HVAC, and general industrial service where the severity does not justify more.
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The Three Classes at a Glance
TEMA class affects corrosion allowance, minimum thicknesses, tube pitch, clearances and tolerances rather than the basic geometry. Two BEU units of identical size can sit in diffrent classes and differ substantially in price. Matching the class to the severity of the service is the straightforward way to avoid paying for robustness the duty will never use, or buying too little for a service that will consume it.
Class R
Class B
Class C
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