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05:46 Dec-04-2002

Dent McIntyre

Consultant, NDE Manager NDELevel III/3
NDT Consultant,
Canada,
Joined Nov 1998
247
Helium Leak Test vs Hydrostatic Test

Does anyone have experience or information on correlation of these tests?
What will leak at hydro test vs what leaks need to be found at helium test.

Any guidance would be appreciated.



    
 
07:17 Dec-04-2002
James
Re: Helium Leak Test vs Hydrostatic Test : Does anyone have experience or information on correlation of these tests?
: What will leak at hydro test vs what leaks need to be found at helium test.
.
: Any guidance would be appreciated.
.
The helium leak detection system can/should-be much, much more sensitive than the
hydro/proof testing.




    
 
00:33 Dec-05-2002
Jim Knowles
Re: Helium Leak Test vs Hydrostatic Test : Does anyone have experience or information on correlation of these tests?
: What will leak at hydro test vs what leaks need to be found at helium test.
.
: Any guidance would be appreciated.
.Dent
You really need to assess the final application of the component.
Hydrostatic will reveal relatively large through wall leak paths. There are limitations to this technique as water is quit viscous, and tight cracks can be missed.
Helium on the other hand providing the potential through leak path is clear of DPI and the like is capable of detecting the smallest through leak.
Figures for this are depending on the vacuum and time are as low as 1 x 10-8 mbar litres per second.
Generally are in the region of 10-4-10-6 mbar/lt/sec.




    
 
04:55 Dec-05-2002

Dent McIntyre

Consultant, NDE Manager NDELevel III/3
NDT Consultant,
Canada,
Joined Nov 1998
247
Re: Helium Leak Test vs Hydrostatic Test Thanks. It is interesting to note that you mentioned DPI as a possible obstruction to the leak path.

We suspected that this may be part of our problem since we did do PT before helium test.

Do you have any experience with this? How would you remove PT materials from the leak path?

: : Does anyone have experience or information on correlation of these tests?
: : What will leak at hydro test vs what leaks need to be found at helium test.
: .
: : Any guidance would be appreciated.
: .Dent
: You really need to assess the final application of the component.
: Hydrostatic will reveal relatively large through wall leak paths. There are limitations to this technique as water is quit viscous, and tight cracks can be missed.
: Helium on the other hand providing the potential through leak path is clear of DPI and the like is capable of detecting the smallest through leak.
: Figures for this are depending on the vacuum and time are as low as 1 x 10-8 mbar litres per second.
: Generally are in the region of 10-4-10-6 mbar/lt/sec.
.




    
 
04:16 Dec-06-2002
Matthias Block
Re: Helium Leak Test vs Hydrostatic Test Based on several applications we see gas leak rates around 1x10-3 mbarl/s as an equivalent for water tightness. In such cases it is often not necessary to use helium as tracer gas. We would recommend the use of hydrogen containing tracer gas instead. For more detailed informnation please have a look at our website www.sensistor.com


: Does anyone have experience or information on correlation of these tests?
: What will leak at hydro test vs what leaks need to be found at helium test.
.
: Any guidance would be appreciated.
.




    
 
09:17 Dec-09-2002

S.V.Swamy

Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex ,
India,
Joined Feb 2001
785
Re: Helium Leak Test vs Hydrostatic Test Yes, presence of any liquid like water, oil (penetreants are oil based!), will affect the helium leak test results.

It is always better to do helium leak test after a very thorough cleaning. If required, spray the area with volatile organic solvents and allow the part to dry thoroughly. If needed, use a hot air blower and heat the part slightly (Keep the safety aspects in mind!!!). Helium leak testing is best done under a good pressure differential. You are wlecome to discuss your requirements in more detail.


: Thanks. It is interesting to note that you mentioned DPI as a possible obstruction to the leak path.
.
: We suspected that this may be part of our problem since we did do PT before helium test.
.
: Do you have any experience with this? How would you remove PT materials from the leak path?
.
: : : Does anyone have experience or information on correlation of these tests?
: : : What will leak at hydro test vs what leaks need to be found at helium test.
: : .
: : : Any guidance would be appreciated.
: : .Dent
: : You really need to assess the final application of the component.
: : Hydrostatic will reveal relatively large through wall leak paths. There are limitations to this technique as water is quit viscous, and tight cracks can be missed.
: : Helium on the other hand providing the potential through leak path is clear of DPI and the like is capable of detecting the smallest through leak.
: : Figures for this are depending on the vacuum and time are as low as 1 x 10-8 mbar litres per second.
: : Generally are in the region of 10-4-10-6 mbar/lt/sec.
: .
.




    
 
07:31 Dec-31-2002
Kamola Zygmunt
Re: Helium Leak Test vs Hydrostatic Test : Does anyone have experience or information on correlation of these tests?
: What will leak at hydro test vs what leaks need to be found at helium test.
.




    
 
23:24 Mar-23-2018
Tushar vaghela
Re: Helium Leak Test vs Hydrostatic Test In Reply to S.V.Swamy at 09:17 Dec-09-2002 .

please do needful.

Recently we did the hydro test in stack heat exchanger and we were identified leak from bottom heat exchanger welded diaphragm gasket joint at differential test pressure Shell side: 94 Kg/cm2(g) & Tube side: 82 Kg/cm2(g).

we did helium leak test at 2 kg/cm2 (g) to identified and confirmed the leak as per the procedure but we are not able to identify the leak in the helium leak test.

please help me to identify the root cause: why are we not able to identify leak in helium leak test? which leak was already identified in hydro test.

History:- Exchanger is under the shutdown condition and it was under the operation since more than four year.


    
 
06:07 Mar-24-2018
Michel
Re: Helium Leak Test vs Hydrostatic Test In Reply to Tushar vaghela at 23:24 Mar-23-2018 .

to find the cause, one would have to look at the conditions of implementation. (exchanger preparation, pressurization scheme, test duration) and find out which technique you have chosen for the detection of helium


    
 
21:17 Mar-24-2018
tushar vaghela
Re: Helium Leak Test vs Hydrostatic Test In Reply to Michel at 06:07 Mar-24-2018 .

Thank you Michel for your replay.

Actually we are using Helium mass spectrometer test with traceable probe technique. First we were pressured heat exchanger by 1 kg of N2 then we were achieved 2 kg/cm2 pressure with the help of Helium. Holding time is 2 hour.

Is there any minimum test pressure requirement for the helium leak test?

As per ASME Section V article 10 T-1044 test pressure shall not be more than 25% of the design pressure and we are using 2 kg/Cm2 pressure condition. Is it acceptable? or I have to revise my test pressure.



    
 
16:15 Mar-26-2018

Dent

Consultant, NDE Manager NDELevel III/3
NDT Consultant,
Canada,
Joined Nov 1998
247
Re: Helium Leak Test vs Hydrostatic Test In Reply to tushar vaghela at 21:17 Mar-24-2018 .

What sensitivity level are you trying to achieve?

If you can send me your procedure I can have a look for you. No charge.


    
 


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