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Hydro Test of Replacement Tube Bundle for Shell & Tube Heat Exchanger:- 2

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Dec 7, 2020
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Hi..

Refer to the subject, our client have requirement for Tube Bundle Replacement for Shell & Tube Heat Exchanger..

Our scope includes Hydro test of tube bundle on Shell Side only, for the same we have to design a dummy shell, Test Flange, Test Ring & Packing Gland to complete the hydro on shell side since TEMA type is AES(H), we have identical 4 Tube bundles to be hydro tested using dummy shell, so that i can use one testing fixtures for all (4) bundles.
My question is since the purpose of dummy shell & testing fixtures is to complete shop hydro test to check the integrity of joints & Tube to T/S joint leaks. In such case hope i don't have to consider Corrosion Allowance for any of the accessories like dummy shell & testing fixtures.
Also should i consider 90% of yield stress as allowable stress to arrive the thickness of dummy shell, test flange & test rings ? in these way i can optimize the thickness of dummy shell & testing fixtures which will give commercial advantage. Is there any other optimization is possible to have commercial advantage since these dummy shell & testing fixtures will go scrap once shop test is done.

Requesting experts & experienced persons advice in this regards..
 
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Corrosion = 0 and YS 90% is OK.

Regards
 
You did not mention the tube sizes. However, it looks to me pressurising tubes externally only for test does not make sense if the tube diameters are small, I would say the same for up to 2 inches. I do not expect the shell internal pressure/tube external pressure is very high.
It can be done by retest the shell in place, I guess that will solve problem in case your client expect some leakages, I do not think they are looking for buckling on tubes.

You have not mention the thickness of the tube plate and the connection types. If the tubes rolled perhaps what you are doing is right. If the welded in addition to rolling you could not get any indication in the test at room temperature.
 
What you also want to check is if the tubes are strong enough for the shell test pressure which in this case would be External for them.
 
This is the pressure test performed with a new HE. What is the problem now?.
The Cliente is right.

Regards
 
Thank you all for the time inputs.
As per the client requirement shell side Pressure (Design Pressure is 11.7 Kg/cm2) which is higher than the Tube Side Pressure (8.4 Kg/cm2), so that our client want's the tube bundle to be tested on shell side by using dummy testing fixtures at manufacturer shop to check the integrity and leaks of Tube to Tube Sheet joints.
Prior to hydro test, we have also to carry-out Pneumatic test of Tube to Tube Sheet joints @ 1.25 Kg/cm2.
Also the seamless tubes will be procured with 100% Hydro test at vendors work hope this & above tests will make sure the bundles will operate well once back in to the service.
For information the Tube size is 1" inch & 2.5 mm WT. CS moc.
 
You do not have consider CA for dummy one time use components. You can use 90% yield criteria for all welded components but not on gasketed joints. 90 % yield criteria allows certain deformation and gasket joints requires a limit on deformation for leak tightness.
 
@ Some Curious Guy
Do not consider gasket leaks, this pressure test is for tube to tubesheet leaks.
Did you ever see this pressure test?

Regards
 
@ Venkatachalam Ponnusamy
I forgot to say that the pneumatic test must be done after the hydrostatic test. Sorry

Regards
 
@ r6155
Thanks for the responses.
As in client QAP(Quality Assurance Plan) it is specified that Pneumatic test of Tube to Tube Sheet joints @ 1.25 kg/cm2 will be done before final inspection.
In QAP hydro will be done during Final inspection, Since it is a replacement tube bundle the QAP given is existing Job.
Any specific reason that we have to perform the Pneumatic test after Hydro.
If you share your experience then it will be really helpful.
 
@ Venkatachalam Ponnusamy
Precautions shall be taken to protect against the consequences of catastrophic failure when pressure testing,. Pressurizing
under pneumatic conditions is not recommended .
Special safety precautions shall be taken when pneumatic testing is required; for example, safety valves, etc.

I don't know the extent of the NDE you're thinking of for the dummy shell.

The hydraulic test is to verify structural integrity. If you do the pneumatic leak test before the hydraulic test, you are in the risk zone.
All parts must be dry before pneumatic leak testing.

See ASME VIII-1 UW-50

Regards
 
ASME PCC-2 gives an explicit detail on doing a pneumatic test.

GDD
Canada
 
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