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01:21 Dec-22-2008
youri
NDT gas distribution mains

At the moment I am conducting a literature survey of available NDT techniques for steel gas distribution mains. These mains suffer from general corrosion, pitting corrosion and cracks.

On the internet and in literature I find several NDT methods, but it is unclear to me which are the most suitable.

Possible options are
Remote Field Eddy Current
Ultrasonic Phased Array
Magnetic Flux leakage
Guided Wave Inspection

However, I don't know what can be used best. For example Remote Field and Ultrasonic Phased array seem to have the same capabilities

Can someone explain what the advantages and disadvantages of above techniques are?

Thanks in advance!


 
09:31 Dec-22-2008

Tom Nelligan

Engineering,
retired,
USA,
Joined Nov 1998
390
Re: NDT gas distribution mains In addition to the techniques that you have listed, pulse/echo ultrasonic thickness gaging with a simple hand-held instrument is probably the least expensive, and usually highly sensitive to individual pits. Access to the outside of the pipe is required. See the application note linked below for further details.


 
00:18 Dec-23-2008
youri
Re: NDT gas distribution mains Thank you for your reply.
I forgot to mention that the pipes are buried so the use of a pig is needed.




 
02:50 Jan-09-2009
sreeram srinivas
Re: NDT gas distribution mains ----------- Start Original Message -----------
: At the moment I am conducting a literature survey of available NDT techniques for steel gas distribution mains. These mains suffer from general corrosion, pitting corrosion and cracks.
: On the internet and in literature I find several NDT methods, but it is unclear to me which are the most suitable.
: Possible options are
: Remote Field Eddy Current
: Ultrasonic Phased Array
: Magnetic Flux leakage
: Guided Wave Inspection
: However, I don't know what can be used best. For example Remote Field and Ultrasonic Phased array seem to have the same capabilities
: Can someone explain what the advantages and disadvantages of above techniques are?
: Thanks in advance!
------------ End Original Message ------------
Eddy current is used for small thickness pipes say below 5 mm. Most of the burried pipelines i.e. gas distribution lines have thickness above 6 mm unless one is doing a precision engineering to save costs. the preferred NDT for burried pipelines are Ultrasoni tests using intelligent pigs, which is a costly exercise done once in 5 yrs on average and is based on regulatory guidelines in respective countries.




 
17:08 Mar-12-2009

Jim Yukes

Consultant
Canada,
Joined Aug 2005
11
Re: NDT gas distribution mains In Reply to youri at 01:21 Dec-22-2008 (Opening).

You could also consider the ultrasonic IRIS for wall thickness. It can be used as a free running ILI tool to inspect from the pipe ID. It would require a liquid for propulsion (as do most ILI tools) and for locomotion so may be a difficult choice in a gas distibution system.

See www.panamiris.com

 
17:07 Mar-13-2009
cailean
Re: NDT gas distribution mains In Reply to youri at 01:21 Dec-22-2008 (Opening).

You don't mention pipe diameter's or operating pressure amongst other important information

These will influence what options you have

 


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