Is it specified any where in ASME Sec VIII that no CA is required for the Heat Exchanger Tubes in line with TEMA and API 661 which require no CA on the tubes.

Can we get an exchanger stamped provided with CS tubes (with no CA on tubes) and CA specified as xx mm for both shell and tube side??

Regards

"those aspects which are not specifically addressed should not be considered prohibited". I mean, there's no authority to say such a design violates the code, but:
1. your AI will have to make you aware that the design is not consistent
2. your client will probably reject it
3. if you do it deliberately you can be in real trouble if it causes a catastrophe

Otherwise- I hope your heat exchanger will not work anywhere near my house

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Konrad Anikiel

Akonrad,

Its nothing unusual to provide heat exchanger tubes with zero CA. Please refer to API 661 and TEMA;





I think this is sufficient to convince client.

Its not a delibrate attempt to ignore effect of CA but just to understand whether ASME permits CS tubes with no CA even if shell and tube sides are requiring CA since TEMA/ API 661 will require CA for all other CS components even if corrosion is not a real concern.

In case corrsion is a concern, material selection for the tubes shall be given due consideration.

Regards

Sanjeev, I agree with you. But I was always under impression that these provisions for not specifying CA for tubes and flanges mean you can't use material that corrodes in service. And now, if you use the same material for tubes and for the shell and you assume some CA for the shell- how can you prevent your tubes from corrosion? This is the inconsistency I was talking about.

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Konrad Anikiel

Akonard,

Take the example of heat exchanger in a service which is non corrosive (for eg Hot Oil) and if you select TEMA R type heat exchanger then as per TEMA a min 3.2 mm CA for tube and shell side is required with an exception to tubes.

If CA is to be added on tubes a CA of 6.4 mm will be required (for CS tubes) which is never a case for heat exchanger tubes which are generally in 10/ 12/ 14/ 16 gauge (1.65 to 2.5 mm or may be slightly more).

Considering a non corrosive service, CS tubes are definitely a suitable and economical choice and is widely followed in Industry.

Requirement of no CA on tube is very well defined in TEMA and API 661 but not clear when it comes to ASME Sec VIII as could not locate any such requirement or am I missing any thing.

Whether ASME require any min CA for CS equipment if nothing is specified by purchaser, I remember some requirement of 1.5 mm but not able to locate the same now.

Regards

OK, I'm with you now. No, SecVIII-1 does not have any compulsory CA values. See UG-16(e) and UG-25.
Regards

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Konrad Anikiel