heat exchanger leakage

[mec5216]

hello

I'm facing a situation at work with heat exchanger in a pump sealing plan.
It's a coil heat exchanger, wich runs with fluid to be cooled at 260ºC (500°F) in the coil and water at 25ºC (77ºF) at the shell. But it doesn't even last 3 weeks running properly. There's always a hole that appears on the coil, allowing the water to get mixed to the hot fluid
We think this problem is due to the high difference temperature between the fluids, undergoing hence the coil to stress and failure.
Would this be the main root cause of the problem? There's no sight of corrosion around, thus this possibility could be scratched out.

cheers

 

[Compositepro]

Is it a "hole" or a crack? Cracking due to thermal stress is very likely. Thermal cycling over time will make the problem more difficult. Such a high temperature difference requires careful design and construction of the heat exchanger.

 

[MintJulep]

So, you are asking the internet to guess at the root cause of your vaguely described failure.

And even if we guess correctly, how will that help you?

 

[IRstuff]

Instead of posting a drawing, a picture of the "hole" would have been infinitely more useful and informative

TTFN
faq731-376

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[racookpe1978]

3 weeks?

One hole or many? Or are there many holes that "almost didn't go through", but only one that did cause the leak you found?

Always at the same place? Same supplier/repair method each time?

 

[Sam654]

Is it a pit, crack or general erosion?
Where is the location of the hole? middle of the tube or at the tube sheet?
Can you tell the direction of corrosion, process to water or water to process? Cutting the tube in half at the hole may reveal something.
Is it a helical coil in the HX? Usually they are much more forgiving for high temp differences.
Are there compatibility issues with the hot medium and the metallurgy of the coil?
What is the cooling medium? Treated water or a waste stream that may have contamination.
What pressure is the coil subjected to?
Is the coil designed for the pressure or temperature it's seeing?
How is the heat exchanger put on line? Is there a written procedure?
Is there too much flow on the water side? vibration will obviously fatigue a tube especially at the tube sheet.

The best advice I can give is to contact your seal/HX vendor and show him the problem. You'll find they are usually more than willing to help since they don't want you to get the impression that their product is junk (which may be the case).

 

[EdStainless]

This looks similar to the sample coolers that people like Sentry make.
There are probably better ways to handle this.
You need to get the manufacturer involved.
It could be material selection, operating conditions, or just the basic design is wrong.

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