API 650 - Vacuum box test Vs PT/MT(Penetrant Test/MPI)

[M S]

Please provide technical support:-

What is the difference between Vacuum box test(for leak detection) and PT(for surface discontinuity detection)?

PT can detect all the surface discontinuity as well and MT can detect surface and slightly subsurface discontinuity also, but why API 650 prefers Vacuum box test instead of PT for Carbon steel-tank bottom plate welding?

[madhan chozhan]

hi

PT and MT can detect surface and sub surface defects whereas vaccum box testing after applying soap water produce bubbles if there is leak (whatever discontinuity it may be crack, porosity) and you can examine the area carefully to find the defect which is more effective.

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Thanks & Regards

Srirammadhan

Piping/painting inspector

Great drill Chaaya

Great Ship

Hamriyah Free zone, UAE

[Karthik]

Hi,

With PT you can find surface discontinuities and Imperfections and MT you can find Subsurface imperfections/Discontinuities also. But Code given some tolerance for the acceptance criteria in these method.

While you do with Vacuum box test you can find Pinholes and small cracks and code doesn't allow any small defect for bottom plate lap welding.

 

Thanks & Regards,

(Karthik)

Karthikeyan.S

QA/QC Manager

German-Thai Boiler Engineering Cooperation Limited.

Rayong Factory ;

379 Moo.6 Soi 8, Tambol Pananikom,

Nikompattana, Rayong 21180 THAILAND

Tel : +66 38 897 035-9 Ext. 137

Fax : +66 38 897 034

Hand Phone: 0066 892512282

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From: M S <str...@gmail.com>
To: material...@googlegroups.com
Sent: Monday, May 7, 2012 5:51 PM
Subject: [MW:14200] API 650 - Vacuum box test Vs PT/MT(Penetrant Test/MPI)

Please provide technical support:-

What is the difference between Vacuum box test(for leak detection) and PT(for surface discontinuity detection)?

PT can detect all the surface discontinuity as well and MT can detect surface and slightly subsurface discontinuity also, but why API 650 prefers Vacuum box test instead of PT for Carbon steel-tank bottom plate welding?

[Karthik]

Hi,

With PT you can find surface discontinuities and Imperfections and MT you can find Subsurface imperfections/Discontinuities also. But Code given some tolerance for the acceptance criteria in these method.

While you do with Vacuum box test you can find Pinholes and small cracks and code doesn't allow any small defect/leaks for bottom plate lap welding.

 

Thanks & Regards,

(Karthik)

Karthikeyan.S

QA/QC Manager

German-Thai Boiler Engineering Cooperation Limited.

Rayong Factory ;

379 Moo.6 Soi 8, Tambol Pananikom,

Nikompattana, Rayong 21180 THAILAND

Tel : +66 38 897 035-9 Ext. 137

Fax : +66 38 897 034

Hand Phone: 0066 892512282

---

From: Karthik <karth...@yahoo.com>
To: "material...@googlegroups.com" <material...@googlegroups.com>
Sent: Tuesday, May 8, 2012 9:21 AM
Subject: Re: [MW:14200] API 650 - Vacuum box test Vs PT/MT(Penetrant Test/MPI)

[rafeeqmahadighar rahman]

Gentleman,

It is my understanding with the code API 650 prefers for the Vaccum box test specially where there is no accessible to other side like tank bottom plate, any linear indication reveal by the PT or MT may subject to re-verification by other method like RT for further assessment to ensure the severity of flaws in such condition where there is no access to perform the RT for further assessment, Hence the Vaccum box test method is best method to identify the any possible leakage on the welded area of tank bottom plate.  

 

Warm Regards'

Rafeeq Ur Rahman

From: M S <str...@gmail.com>
To: material...@googlegroups.com
Sent: Monday, 7 May 2012 1:51 PM
Subject: [MW:14200] API 650 - Vacuum box test Vs PT/MT(Penetrant Test/MPI)

[pradeep kumar hormis]

Dear

In my experience , it seems CHEAPER AND MORE EFFECTIVE FINDINGS WITHOUT MORE CONCENTRATED VISUAL INSPECTION. imagine how much penetrant and developer use for a small tank. same thing in MT also. material which using for test is costly. but If we use Vacuum box testing, at least we can cover nearly 1 meter length and minimum 5 inch width both sides of weld. and if a hole opening o both side in the weld( even in multi run weld)  air bubbles comes continuously, it is visible easily in sunlight glare also.not expensive with compare to  other PT & MT. normal soap water or any approved liquid using for the test. that is not much expensive.

On Mon, May 7, 2012 at 4:21 PM, M S <str...@gmail.com> wrote:

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The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.

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Thanks & Regards

PRADEEPKUMAR HORMIS
Mob: +91-0-9496754791

[deva m]

Vacuum box test is mean to find the air leak where PT/MT mean to find the defects...

Assume minute  a pin hole on the weld thorough the weld thickness,where in vacuum box test it can be traced easily and where PT/MPT,sometimes it may not be able to trace the minute defects.

And in MPT/PT,pin holes, porosity are acceptable up to certain size so when the pin hole is throught the plate thickness,it may cause leak..

As we know the tanks are for storage purpose,even a minute leak causes big problems..

Tats why Vacuum box test is preferred.

On Mon, May 7, 2012 at 4:21 PM, M S <str...@gmail.com> wrote:

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[Fred Majdnia]

Dear All

Vacuum Box is used to test for pin holes on the weld as well as bottom plates. Plate damage is common in construction of the Tank due to falling objects or sparks made by welders. Floating roof tanks have a lot of pantoons which are also leak tested by Vacuum Boc and air leak testing. The Roof lap- joints are also tested by Vacuum Box for the same reason. It is not meant for welds only and can cover plates as well. I have used it for leak detection of pontoons of a floating roof while resting on its support. DPT or MPI are meant for a limitted area for their cost as explained by other friends.

Shell fillet weld to the annular plate is also tested normally by special Vacuum Box (to fit the 90 angle) and in its absence a penetrant materials such as diesel oil is applied to the corner weld from inside surface and a white powder( not commercial developer) sprayed to the weld from outside, giving them 24 hours to detect the hole or crack. DP or MPI is used when such method detects a defect.

Hope this helps

 

 

 

 

    

-----material...@googlegroups.com wrote: -----

To: material...@googlegroups.com
From: M S
Sent by: material...@googlegroups.com
Date: 05/07/2012 10:12AM

Subject: [MW:14200] API 650 - Vacuum box test Vs PT/MT(Penetrant Test/MPI)

Please provide technical support:-

What is the difference between Vacuum box test(for leak detection) and PT(for surface discontinuity detection)?

PT can detect all the surface discontinuity as well and MT can detect surface and slightly subsurface discontinuity also, but why API 650 prefers Vacuum box test instead of PT for Carbon steel-tank bottom plate welding?

--

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To unsubscribe from this group, send email to materials-weld...@googlegroups.com
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The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.

 
 
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[Doni Afrizal]

What about the edge of joint which can not vacuum? Do we just only PT
or PT for leak through testing?

[madhan chozhan]

you can design and make a vacuum box according to the area where the weld is located to be tested..........

On Sat, May 12, 2012 at 7:51 PM, Doni Afrizal <doni.a...@gmail.com> wrote:

What about the edge of joint which can not vacuum? Do we just only PT
or PT for leak through testing?

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The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.

[Guoliang Xue]

Dear Sir,
you can find surface discontinuities and Imperfections by PT and you
can find Subsurface imperfections/Discontinuities by MT also. But Code

given some tolerance for the acceptance criteria in these method.
While you do with Vacuum box test you can find Pinholes and small
cracks and code doesn't allow any small defect for bottom plate lap

welding and access to the all corner of the vessel or tank.

--
George Xue (Xue Guoliang)
Suzhou CXGL Mechanical Engineering Co., Ltd.
China
Tel: +86-512-68639769 Fax: +86-512-68639492
Email: cxuegu...@gmail.com
Skype: xuegl2001

2012/5/8 deva m <devm...@gmail.com>: