Talk:Heat exchanger/TEMA
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.
Eight 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 (American Society of Mechanical 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.
Which type of TEMA Heat Exchanger?
[edit]All the types shown in the table can be designed in accordance with TEMA B, C and R codes. The table is intended as a general guide only and does not purport tocover all aspects of design. Full technical advice can be given by a heat exchanger applications engineer.
Another question that is often asked is ‘what is the difference between the three types of TEMA B, C and R codes?’ To answer that in detail would require a full 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.
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.
| Typical TEMA type heat exchanger | Description of TEMA type heat exchanger | Removable tube bundle | Tubes can be cleaned internally by rodding | Non-hazardous liquids and gases below 40 barg | Non-hazardous liquidsand gases above 40barg | Hazardous liquids and gases | No gaskets in contact with process side | Ability to resist thermal shock | |
|---|---|---|---|---|---|---|---|---|---|
| Below 190 ºC | Above 190 ºC | ||||||||
| AEW / BEW | Externally sealed Floating tube sheet | Yes | Yes | Yes | No | No | No | No | No |
| AEP / BEP | Outside packed floating head | Yes | Yes | Yes | Yes | Yes2 | No | No | No |
| AEL / BEM | Fixed tube sheet | No | Yes | Yes1 | Yes1 | Yes | Yes | Yes3 | No |
| NEN | Fixed tubesheet, channel integral with tubesheet | No | Yes | Yes1 | Yes1 | Yes | Yes | Yes3 | No |
| AEU / BEU | U tube | Yes | No | Yes | Yes | Yes | Yes | Yes4 | Yes |
| AET / BET | Pull-through floating head | Yes | Yes | Yes | Yes | Yes | Yes | No | Yes |
| AES / BET | Floating head with backing device | Yes | Yes | Yes | Yes | Yes | Yes | No | Yes |
| 1. Expansion bellows may be required. 2. Tube side only. 3. Shell side only. 4. Shell side only if tube bundle welded into shell and therefore not removable. | |||||||||