Tube leak detection on Shell & Tube Heat Exchangers 1

[Hansac]

Has anyone done a tube leak detection on shell and tube heat exchangers? The procedure is like this:

1. Pressurized shell side with pneumatic up to 4 barg, depending on your comfort level in handling pneumatic test.

2. Cover one tubesheet with masking tape, ensuring every tube hole is covered by the masking tape. An alternative with be to plug individual tube with rubber bunk.

3. Apply soapy liquid (Snoopy, for example) on the OTHER tubesheet, by hand application or by applying with paint brush.

4. Leaking tubes will create bubble on the tube hole.

Anyone has photos or videos of the above in action? I checked youtube and could not find any.

I use to do this procedure numerous times as a young engineer more than 2 decades back.

Thank you, everyone.

 

[Alpha Charlie]

Exchanger soap film test is a common practice to identify the leaky tubes.
Instead of masking tape use rubber corks which are available in the market to cover each tube hole. If exchanger is fixed tubesheet then you need not to use the test ring for fixing the tubesheet but you have to use test rings for floating tubesheet exchangers. Shell side is pressurized with air preferably up to 1-2 kg/cm2 but you can consult equipment manufacturer recommendations for shell side pressure. Apply soapy liquid on all the tubes to check leaky tube. (

https://www.youtube.com/watch?v=RxdQ4SfPZpc)

Apart from above, exchanger hydraulic test is recommended to check health of tubes after cleaning activity.

You can look API 660 (Sec 7) and API RP-586 Sec I
Regards,

 

[r6155]

Depends of the allowable leakage rate.
See ASME V

Regards

 

[EdStainless]

Or forget the plugs and pressurize the shell and listen with an ultrasonic detector.
Or make a stable foam (looks like shaving cream) and smear it across the tube ends. You either have to plug one end or foam both ends.
I have also seen this done with foam (they actually used cans of shave cream) and a vacuum on the shell side. In this case you plug the other ends with plastic wrap film. Though with vacuum you just use plastic film on both ends.

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P.E. Metallurgy, consulting work welcomed

 

[CuMo]

r6155 - what is the allowable leakage rate for soapy liquids and how do you measure it?

 

[EdStainless]

You don't want to be mixing these yourself, you want to buy actual leak test solutions.
Soaps that are generally available are very high in Chlorides and residue can cause serious corrosion issues.
The commercial solutions also have controlled properties.
There is an old NASA paper that discusses the sensitivity of these test solutions on small leaks. As I recall they were down in the 10E-5 std cc/sec range.

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P.E. Metallurgy, consulting work welcomed

 

[r6155]

CuMo
The allowable leak rate is defined by the user, and then you must select the proper test to check it.
For example (my experience in nuclear) leak rate 10-3 mbar- dm3 /S is with air test, and
10-6 mbar- dm3/S with Helium test.

Regards

 

[EdStainless]

With large steam condensers they sometimes start with a simple soap test, then move to SF6, and then He. Each step is 1 to 2 orders of magnitude more sensitive.

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P.E. Metallurgy, consulting work welcomed