where expertise comes together - since 1996 -

The Largest Open Access Portal of Nondestructive Testing (NDT)

Conference Proceedings, Articles, News, Exhibition, Forum, Network and more

where expertise comes together
- since 1996 -

1501 views
Technical Discussions
Ramakrishnan Muruganantham
Ramakrishnan Muruganantham
09:02 Jun-16-2000
Radiography vs High Pressure Helium Leak Test

One Specification calls for the following testing for high pressure valves used on HYDROGEN service.

Specification:

“All class 900 or greater cast valve bodies and integral flanges in hydrogen services shall be examined in accordance with ASME Sec VIII Div 1 paragraphs 7.2 and 7.3 of Appendix 7 regardless of casting quality factor. Repairs and identification shall meet the requirements of paragraphs 7.4 and 7.5 of Appendix-7.

For sizes 2” (50 mm) or less where radiography is impractical, the following examination shall be performed.

1. 100% magnetic particle or liquid penetrate examination

2. A high pressure leak test of the valve body using helium at a minimum of 1.5 times design pressure/rated working pressure at 100 deg F (38 deg C) for a minimum of ten minutes. No leakage is permitted.”

Related Details:

1. This specification is applicable for valve made of cast material.
2. This rated working pressure and the required test pressure of different classes are given below.

Pressure Rating Working Pressure Test Pressure
psi (bar) psi (bar)
Class 900 2250 (155) 3375 (233)
Class 1500 3750 (259) 5625 (389)
Class 2500 6250 (431) 9375 (647)

Questions:

1. How does high pressure helium test help detect casting defects for small size valve?
2. Since helium test by evacuation method or with a pressure of 15 psi (1 bar) gives good results, Why such a high pressure test is required?



    
 
 
David Hermanutz
Consultant,
Hbndt.com, China, Joined Jul 2012, 85

David Hermanutz

Consultant,
Hbndt.com,
China,
Joined Jul 2012
85
02:53 Jun-16-2000
Re: Radiography vs High Pressure Helium Leak Test
w.

: Pressure Rating Working Pressure Test Pressure
: psi (bar) psi (bar)
: Class 900 2250 (155) 3375 (233)
: Class 1500 3750 (259) 5625 (389)
: Class 2500 6250 (431) 9375 (647)

: Questions:

: 1. How does high pressure helium test help detect casting defects for small size valve?
: 2. Since helium test by evacuation method or with a pressure of 15 psi (1 bar) gives good results, Why such a high pressure test is required?

Some basic answers:

1.0 Helium is a slightly larger gas molecule than Hydrogen which is known to travel in an intergranular mode through many cast materials. The helium test at 1.5 times operating pressure would allow the integrity of the valve to be tested similar to the expected in service conditions.

A 15 PSI test gives good results but when dealing with hydrogen perfect results are a must. I have seen the results of two failures due to hydrogen seepage through a valve body. One failure killed an operator as he tried to close a suspecting leaky valve (the ignition source was suspected to be the snipe he was using on the valve handle).

He died while trying to remove his plastic hard hat from his head...


    
 
 
Dent McIntyre
Consultant, NDE Manager NDELevel III/3
NDT Consultant, Canada, Joined Nov 1998, 247

Dent McIntyre

Consultant, NDE Manager NDELevel III/3
NDT Consultant,
Canada,
Joined Nov 1998
247
05:20 Jun-16-2000
Re: Radiography vs High Pressure Helium Leak Test
lated Details:

: : 1. This specification is applicable for valve made of cast material.
: : 2. This rated working pressure and the required test pressure of different classes are given below.

: : Pressure Rating Working Pressure Test Pressure
: : psi (bar) psi (bar)
: : Class 900 2250 (155) 3375 (233)
: : Class 1500 3750 (259) 5625 (389)
: : Class 2500 6250 (431) 9375 (647)

: : Questions:

: : 1. How does high pressure helium test help detect casting defects for small size valve?
: : 2. Since helium test by evacuation method or with a pressure of 15 psi (1 bar) gives good results, Why such a high pressure test is required?

: Some basic answers:

: 1.0 Helium is a slightly larger gas molecule than Hydrogen which is known to travel in an intergranular mode through many cast materials. The helium test at 1.5 times operating pressure would allow the integrity of the valve to be tested similar to the expected in service conditions.

: A 15 PSI test gives good results but when dealing with hydrogen perfect results are a must. I have seen the results of two failures due to hydrogen seepage through a valve body. One failure killed an operator as he tried to close a suspecting leaky valve (the ignition source was suspected to be the snipe he was using on the valve handle).

: He died while trying to remove his plastic hard hat from his head...




    
 
 

Product Spotlight

Spot weld inspection with Phased Array – PHAsis.one

The first PAUT spot weld inspection device offering a physical resolution of the spot weld diamete
...
r better than 0.35mm. Precise: more than 700 real UT measurements per spot weld. Easy to go: minimal training required due to the user friendly inspection software. Be sure: safe evaluation due to the imaging result display and automated creation of an evaluation proposal for the spot weld quality.
>

ISAFE3 Intrinsically Safe Sensor System

ISAFE3 intrinsically safe sensor system of Vallen Systeme is especially targeted at the petrochemica
...
l - as well as oil and gas transportation industry. The sensor system is designed for permanent monitoring or periodic inspection tasks. Sensors are available for different AE-frequency ranges optimized for corrosion and fatigue crack detection and other applications. The ISAFE 3 sensor system consists of an AE-sensor (model ISAS3) certified according to ATEX/IEC for installation in zone 0, gas group IIC, IP68, 20 to +60 °C, and a signal isolator (model SISO3) certified for installation in zone 2. An ISAS3 sensor can be mounted in atmosphere or submerged, e.g. in water or crude oil. It is supported by mounting tools for temporary (magnets) or permanent (welded) installation. ISAFE3 supports automatic sensor coupling test and can be used with any AE signal processor supporting 28V supply at 90 mA peak, e.g. Vallen Systeme ASIP-2/A.
>

EPOCH 6LT

The EPOCH 6LT flaw detector is optimized for one-handed operation in rope access and high-portab
...
ility applications. Lightweight with a grip-oriented weight distribution, the instrument fits securely in a user’s hand or can be strapped to their leg using the rope access accessory kit. The clear, bright screen makes A-scans readable in any light while the intuitive software enables fast navigation.
>

Research and Applications Development For NDT

The Research and Applications Development (RAD) group is a newly formed team within Acuren dedicat
...
ed to tackling challenging inspection problems. Our focus is the development of novel, field deployable, advanced inspection techniques for use in cases where standard NDT methods are ineffective. We don't wait for new innovations, we engineer them. From concept to commissioning.
>

Share...
We use technical and analytics cookies to ensure that we will give you the best experience of our website - More Info
Accept
top
this is debug window
s