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- since 1996 -
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Technical Discussions
Dent McIntyre
Consultant, NDE Manager NDELevel III/3
NDT Consultant, Canada, Joined Nov 1998, 248

Dent McIntyre

Consultant, NDE Manager NDELevel III/3
NDT Consultant,
Canada,
Joined Nov 1998
248
05:46 Dec-04-2002
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.


    
 
 Reply 
 
James
James
07:17 Dec-04-2002
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.



    
 
 Reply 
 
Jim Knowles
Jim Knowles
00:33 Dec-05-2002
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.



    
 
 Reply 
 
Dent McIntyre
Consultant, NDE Manager NDELevel III/3
NDT Consultant, Canada, Joined Nov 1998, 248

Dent McIntyre

Consultant, NDE Manager NDELevel III/3
NDT Consultant,
Canada,
Joined Nov 1998
248
04:55 Dec-05-2002
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.
.



    
 
 Reply 
 
Matthias Block
Matthias Block
04:16 Dec-06-2002
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.
.



    
 
 Reply 
 
S.V.Swamy
Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex , India, Joined Feb 2001, 787

S.V.Swamy

Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex ,
India,
Joined Feb 2001
787
09:17 Dec-09-2002
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.
: .
.



    
 
 Reply 
 
Kamola Zygmunt
Kamola Zygmunt
07:31 Dec-31-2002
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.
.



    
 
 Reply 
 
Tushar vaghela
Tushar vaghela
23:24 Mar-23-2018
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.

    
 
 Reply 
 
Michel
Michel
06:07 Mar-24-2018
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

    
 
 Reply 
 
tushar vaghela
tushar vaghela
21:17 Mar-24-2018
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.


    
 
 Reply 
 
Dent
Consultant, NDE Manager NDELevel III/3
NDT Consultant, Canada, Joined Nov 1998, 248

Dent

Consultant, NDE Manager NDELevel III/3
NDT Consultant,
Canada,
Joined Nov 1998
248
16:15 Mar-26-2018
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.

    
 
 Reply 
 

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