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- since 1996 -

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Technical Discussions
daniel iordache
daniel iordache
06:36 Feb-06-2006
underground pipe

have anyone a procedure for inspection of underground pipe---gas line ..depth 1-1.5 metre
thanks


    
 
 
Michael Trinidad
Consultant,
LMATS Pty Ltd , Australia, Joined Jan 2003, 138

Michael Trinidad

Consultant,
LMATS Pty Ltd ,
Australia,
Joined Jan 2003
138
03:17 Feb-19-2006
Re: underground pipe
I see this post has had no response so I'll put my 2 cents in.

You could dig it up or use a pig on it. The first item I would be interested in is the line cathodically protected. If it is has it been operated the whole lifetime of the pipeline and how often was cathodic surveys carried out. This way you can get some idea of risk.

There are a few methods being developed as alternatives to pigging but have numerous known and unknown variables.


Kindest Regards


Mike Trinidad


----------- Start Original Message -----------
: have anyone a procedure for inspection of underground pipe---gas line ..depth 1-1.5 metre
: thanks
------------ End Original Message ------------




    
 
 
John O'Brien
Consultant, -
Chevron ETC , USA, Joined Jan 2000, 278

John O'Brien

Consultant, -
Chevron ETC ,
USA,
Joined Jan 2000
278
06:53 Feb-19-2006
Re: underground pipe
Daniel

you do not state the length or pipe material.

Assuming its carbon steel - there should not be an internal corrosion concern unless you have some form of contamination. That leaves external corrosion or SCC as the deterioration mechanisms of concern. you should be able to do a risk assessment to determine if SCC is an issue.

That leaves external corrosion. How is the external surface coated? Is there CP? Is the CP system working?

You could perform a DCVG and CIPS survey to determine external corrosion condition. If bad then length is an issue. Long lines more than say 10-20 kms intelligent pigs is the option. Shorter you may be able to do a dig at identified sites from the DCVG/CIPS and use Long Range UT to screen the extent of problems.

Beyond this quick repsonse you probbaly need to hire a consultant.


    
 
 
Godfrey Hands
Engineering,
PRI Nadcap, United Kingdom, Joined Nov 1998, 287

Godfrey Hands

Engineering,
PRI Nadcap,
United Kingdom,
Joined Nov 1998
287
01:21 Feb-20-2006
Re: underground pipe
----------- Start Original Message -----------
: have anyone a procedure for inspection of underground pipe---gas line ..depth 1-1.5 metre
: thanks
------------ End Original Message ------------

Daniel,
John has suggested Long Range Ultrasonics.
NDT Consultants Ltd. in the UK have the MsS Long Range Guided Wave system, which can be ued if your pipe cannot be pigged. (Pigging is the obvious solution, but not always possible).

Our MsS system (unlike other commercially available LRUT systems) uses low cost transducers, so is ideal for permanent installation of the transducers to facilitate regular condition monitoring (perhaps on an annual basis).
Our system, like all LRUT systems has a limited test range on buried pipelines, with a minimum test length in the order of 20 metres in each direction. This means that access every 40 metres (or longer if we have a greater range) is required ONCE only to install our sensors, after which it can be filled and the cables to the sensors left accessible to the surface.

Typical detection on a first test with any guided wave system is about 3 to 8% or pipe cross section (depending on pipe condition), and with our system, we regularly detect 2%. In condition monitoring mode, we are able to detect changes in the order of 1% or less.

Please contact me for more details.
Regards,

Godfrey Hands


    
 
 
Mike Trinidad
Consultant,
LMATS Pty Ltd , Australia, Joined Jan 2003, 138

Mike Trinidad

Consultant,
LMATS Pty Ltd ,
Australia,
Joined Jan 2003
138
03:46 Feb-20-2006
Re: underground pipe
Granted there has been some success with LRUT in underground applications, however there has been more failures and too much hype.

I say this as a user of the technology and a proponent. LRUT is an ultrasonic wave and the basic fundementals for the wave motion is to have particle motion, in more simpler terms like a bell ringing, 'sound and vibration'.

Now if we bury the bell under 2m of dirt how well does the bell ring? Ok we are using low frequencies but the difference between signal response in a buried section of line and an aboveground section of line is a lot.

Some factors involved and to this point I have not seen adequate research done on the consequences are:
1. Soil depths i.e. external pressure
2. Internal pressure of the pipe
3. Moisture content of the soil
4. Types of coating especially HDPE in buried lines
5. In homogenous backfill

Again not saying it cannot be done but from my experience buried sections should be approached as a pilot study and see what is achievable. Many clients have been misinformed and think the technology can go 100's of meters underground.

Basic rule of thumb if there is no weld on the test shot then there is nothing there.


Regards

Mike

----------- Start Original Message -----------
: : have anyone a procedure for inspection of underground pipe---gas line ..depth 1-1.5 metre
: : thanks
: Daniel,
: John has suggested Long Range Ultrasonics.
: NDT Consultants Ltd. in the UK have the MsS Long Range Guided Wave system, which can be ued if your pipe cannot be pigged. (Pigging is the obvious solution, but not always possible).
: Our MsS system (unlike other commercially available LRUT systems) uses low cost transducers, so is ideal for permanent installation of the transducers to facilitate regular condition monitoring (perhaps on an annual basis).
: Our system, like all LRUT systems has a limited test range on buried pipelines, with a minimum test length in the order of 20 metres in each direction. This meansthat access every 40 metres (or longer if we have a greater range) is required ONCE only to install our sensors, after which it can be filled and the cables to the sensors left accessible to the surface.
: Typical detection on a first test with any guided wave system is about 3 to 8% or pipe cross section (depending on pipe condition), and with our system, we regularly detect 2%. In condition monitoring mode, we are able to detect changes in the order of 1% or less.
: Please contact me for more details.
: Regards,
: Godfrey Hands
------------ End Original Message ------------




    
 
 
Paul Robertson
,
Netherlands, Joined Jun 2003, 12

Paul Robertson

,
Netherlands,
Joined Jun 2003
12
04:25 Feb-20-2006
Re: underground pipe
Daniel,

Without wishing to turn this into an LRUT/Guided Waves only discussion, I tend to support Mike's views. Certainly as part of an inspection regime - ILI verification and/or inspection of high consequence areas then LRUT can really play it's part.
Sensitivity/distance must be considered regarding inspection requirements on buried pipelines, and as Mike says - if you don't see weld features can you be confident of finding areas of wall loss?
If there's a potential for a lot of LRUT/Guided Waves then a couple of days pilot project is certainly something we would recommend, resulting in an open evaluation.
If you feel SCC is a potential issue - then I am yet to see/hear of LRUT/Guided Waves being able to detect this problem due to lack of real cross sectional area change in the pipe wall.

Regards
Paul


----------- Start Original Message -----------
: Granted there has been some success with LRUT in underground applications, however there has been more failures and too much hype.
: I say this as a user of the technology and a proponent. LRUT is an ultrasonic wave and the basic fundementals for the wave motion is to have particle motion, in more simpler terms like a bell ringing, 'sound and vibration'.
: Now if we bury the bell under 2m of dirt how well does the bell ring? Ok we are using low frequencies but the difference between signal response in a buried section of line and an aboveground section of line is a lot.
: Some factors involved and to this point I have not seen adequate research done on the consequences are:
: 1. Soil depths i.e. external pressure
: 2. Internal pressure of the pipe
: 3. Moisture content of the soil
: 4. Types of coating especially HDPE in buried lines
: 5. In homogenous backfill
: Again not saying it cannot be done but from my experience buried sections should be approached as a pilot study and see what is achievable. Many clients have been misinformed and think the technology can go 100's of meters underground.
: Basic rule of thumb if there is no weld on the test shot then there is nothing there.
:
: Regards
: Mike
: : : have anyone a procedure for inspection of underground pipe---gas line ..depth 1-1.5 metre
: : : thanks
: : Daniel,
: : John has suggested Long Range Ultrasonics.
: : NDT Consultants Ltd. in the UK have the MsS Long Range Guided Wave system, which can be ued if your pipe cannot be pigged. (Pigging is the obvious solution, but not always possible).
: : Our MsS system (unlike other commercially available LRUT systems) uses low cost transducers, so is ideal for permanent installation of the transducers to facilitate regular condition monitoring (perhaps on an annual basis).
: : Our system, like all LRUT systems has a limited test range on buried pipelines, with a minimum test length in the order of 20 metres in each direction. This means that access every 40 metres (or longer if we have a greater range) is required ONCE only to install our sensors, after which it canbe filled and the cables to the sensors left accessible to the surface.
: : Typical detection on a first test with any guided wave system is about 3 to 8% or pipe cross section (depending on pipe condition), and with our system, we regularly detect 2%. In condition monitoring mode, we are able to detect changes in the order of 1% or less.
: : Please contact me for more details.
: : Regards,
: : Godfrey Hands
------------ End Original Message ------------




    
 
 
David Forsyth
R & D
TRI/Austin, USA, Joined Nov 2001, 41

David Forsyth

R & D
TRI/Austin,
USA,
Joined Nov 2001
41
02:01 Feb-20-2006
Re: underground pipe
I agree that validation of new techniques is important. The former Nondestructive Testing Information Analysis Center (NTIAC), now part of the Advanced Materials, Manufacturing & Testing IAC, has a facility for development/testing of NDT for piping (but nothing underground at this time). See
http://www.ntiac.com/stand.php for details.

I also agree I would not expect Lamb or SH waves to be very sensitive to any intergranular cracking such as SCC.

Regards, Dave.
dforsyth@tri-austin.com

----------- Start Original Message -----------
: Daniel,
: Without wishing to turn this into an LRUT/Guided Waves only discussion, I tend to support Mike's views. Certainly as part of an inspection regime - ILI verification and/or inspection of high consequence areas then LRUT can really play it's part.
: Sensitivity/distance must be considered regarding inspection requirements on buried pipelines, and as Mike says - if you don't see weld features can you be confident of finding areas of wall loss?
: If there's a potential for a lot of LRUT/Guided Waves then a couple of days pilot project is certainly something we would recommend, resulting in an open evaluation.
: If you feel SCC is a potential issue - then I am yet to see/hear of LRUT/Guided Waves being able to detect this problem due to lack of real cross sectional area change in the pipe wall.
: Regards
: Paul
:


    
 
 
Jim Yukes
Consultant
Canada, Joined Aug 2005, 11

Jim Yukes

Consultant
Canada,
Joined Aug 2005
11
01:25 Feb-25-2006
Re: underground pipe
You should supply the pipe diameter, wall thickness, length, material, and related information to determine if it cold be inspected using a pig. Refer to the panamiris web site for information on an ultrasound In-Line Inspection tool used for measureing wall loss.

Jim Yukes

----------- Start Original Message -----------
: I see this post has had no response so I'll put my 2 cents in.
: You could dig it up or use a pig on it. The first item I would be interested in is the line cathodically protected. If it is has it been operated the whole lifetime of the pipeline and how often was cathodic surveys carried out. This way you can get some idea of risk.
: There are a few methods being developed as alternatives to pigging but have numerous known and unknown variables.
:
: Kindest Regards
:
: Mike Trinidad
:
: : have anyone a procedure for inspection of underground pipe---gas line ..depth 1-1.5 metre
: : thanks
------------ End Original Message ------------




    
 
 
Zahir
Engineering
Universiti Kebangsaan Malaysia,, Malaysia, Joined Jan 2001, 5

Zahir

Engineering
Universiti Kebangsaan Malaysia,,
Malaysia,
Joined Jan 2001
5
05:54 Mar-07-2006
Re: underground pipe
Hi.

Let me add comment based on my experience.
There's several ways you can inspect the pipe.
Either pig it or dig it.

Pigging
If your piping have a launcher & receiver you might as well pig it due to the fact that it is the most accurate tool for detecting wall loss or any discontinuity.

Digging.
How long is the line. If the line is quite long apply DCVG to pin point location of coating degradation. Normally this areas is where external corrosion might be found. Dig the pipe and carried out Corrosion mapping inspection on the surrounding areas. And if you have more budget $$ apply Long Range UT to know the extend of corrosion from that line. Make sure to use LOW Frequency probe due to the soil might interfere the signal.

Good Luck
Rgds
Zahir


----------- Start Original Message -----------
: You should supply the pipe diameter, wall thickness, length, material, and related information to determine if it cold be inspected using a pig. Refer to the panamiris web site for information on an ultrasound In-Line Inspection tool used for measureing wall loss.
: Jim Yukes
: : I see this post has had no response so I'll put my 2 cents in.
: : You could dig it up or use a pig on it. The first item I would be interested in is the line cathodically protected. If it is has it been operated the whole lifetime of the pipeline and how often was cathodic surveys carried out. This way you can get some idea of risk.
: : There are a few methods being developed as alternatives to pigging but have numerous known and unknown variables.
: :
: : Kindest Regards
: :
: : Mike Trinidad
: :
: : : have anyone a procedure for inspection of underground pipe---gas line ..depth 1-1.5 metre
: : : thanks
------------ End Original Message ------------




    
 
 

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