How is the better choice between TEMA and ASME tubesheet calc. method?

Dear Sir,

There are many differences between the ASME and TEMA methods for computing required thickness of heat exchanger tubesheets. Generally, the ASME method is more tedious and complicated and will result in a thinner tubesheet required thickness at the cost of a more complicated analysis.

I suggest that you run both calculations using both design methods and compare the results. If there is not a great difference in the requirements, I would go with the thicker value. Also, TEMA calculations have been around for quite a number of years (longer that ASME) and have been used with great success.


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Scott Mayeux
COADE Inc.

The TEMA tubesheet design procedure should be used for TEMA-type shell-and-tube heat exchangers. Also for other applications where there is a concern for potential leakage. The TEMA procedure generally results in a thicker tubesheet which will bend less under the applied loads. The reduced tubesheet bending helps minimize the potential for leakage at the tube/tubesheet joints and at the girth flanges (for exchangers where the fixed tubesheet is clamped between flanges).

Vince Carucci

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Vincent A. Carucci
President
Carmagen Engineering
7 Waverly Place
Madison, NJ 07940

Visit our web site at http://www.carmagen.com

I think we have to go for ASME tubesheet calculation anyhow if you are stick to the ASME sect VIII div1 code. TEMA tubesheet calculation only to be consider as supplement calculation. Please note that TEMA tubesheet calculation (formula) being shift to Appendix in latest TEMA book.

Dear all
Parameter Xa shall be evaluated to decide whether tubesheet thickness as per TEMA is applicable or not.

“TEMA equations are based on asymptotic approximation of certain Bessel Functions which limit there range of validity to xa > 3. In addition a further approximation introduce into TEMA equations neglects an important functional variation of xa and replace this functional variation of xa with a constant depending only on presumed degree of Edge restraint. These approximation taken into, can lead to some discrepancy in result when the calculated unit thickness turn out to imply xa to be on the order of 3 or less”

The above statement is from Mechanical Design of heat exchanger edition 1984 by K P Singh and A L Soler.

This limitation does not exit in ASME Sec VIII Div1 UHX procedure.I hope I have made it clear.

With regards