»
Standards review of TEMA standards , but the following guide lines may be useful :
• TEMA B — generally for chemical process services , more stringent than TEMA C , but not as stringent as R ;
• TEMA C — for generally moderate commercial and process application requirements . Probably the most commonly used in our industry ;
• TEMA R — the highest integrity design .
Front end stationary head types
The decision as to which class of TEMA to use does not lie with the heat exchanger manufacturer , but with the design authority responsible for that part of the project . The manufacturer must then consider all the thermal and mechanical requirements of the requested design code when making the selection .
L - Fixed tubesheet like “ A ” stationary head
Rear end head types
A - Channel and removable cover
M - Fixed tubesheet like “ B ” stationary head
B - Bonnet ( integral cover )
N - Fixed tubesheet like “ N ” stationary head
P - Outside packed floating head
N - Channel integral with tube-sheet and removable cover
S - Floating head with backing device
Shell types
E - One pass shell
T - Pull through floating head
The standard-setting TEMA team
TEMA , the Tubular Exchanger Manufacturers Association , is a US trade association of leading manufacturers of shell and tube heat exchangers , which has pioneered the research and development of heat exchangers since its foundation in 1939 . TEMA standards and software are now accepted worldwide as the authoritative source on shell and tube mechanical design . Ten editions of TEMA standards have been published over the years , each one updating the industry on the latest developments in technology . The standards have been developed with input from the likes of the API ( American Petroleum Institute ) and ASME ( the American Society of Mechnical Engineers ), both standard-setting organisations in their own right . TEMA has also developed engineering software products which complement the TEMA standards in the areas of flexible shell elements ( expansion joints ) analysis , flow induced vibration analysis and fixed tubesheet design and analysis . The software programs feature a materials databank of 38 materials of construction .
U - U-tube bundle
W - Externally sealed floating tubesheet
The typical TEMA type heat exchangers listed in the table can be visualised from the diagrams shown here ( right and left ). From the three-letter coding for each type of exchanger ( AEW , BEW , AEP and so on , as listed in the table ) a picture can be built up of the final shell and tube assembly of front- end stationary head , shell type , and rear-end head
62 Heat Exchanger World September 2022 www . heat-exchanger-world . com