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4838 views
04:22 Sep-05-2007

Florin Turcu

R & D
Dept. of Electrical Systems and Automation - University of Pisa,
Italy,
Joined Jul 2007
9
Guided Waves on PE coated Pipes

Hello everybody,
Does any of you have experience with Ultrasonic Guided Waves applied on pipelines with PE (Polyethylene) coating? Did you get any good result, or very high attenuation instead?
Thank You for your time.

Florin Turcu



 
04:42 Sep-05-2007

Godfrey Hands

Engineering,
PRI Nadcap,
United Kingdom,
Joined Nov 1998
286
Re: Guided Waves on PE coated Pipes ----------- Start Original Message -----------
: Hello everybody,
: Does any of you have experience with Ultrasonic Guided Waves applied on pipelines with PE (Polyethylene) coating? Did you get any good result, or very high attenuation instead?
: Thank You for your time.
: Florin Turcu
------------ End Original Message ------------


Hi Florin,
It depends on the thickness of the coating.
I have tested pipes with a thin layer (typically 1mm) and seen "normal" results, but coatings of many mm will cause great attenuation.
This is my personal experience. maybe other people have other experiences.
Godfrey Hands



 
05:35 Sep-06-2007

John O'Brien

Consultant, -
Chevron ETC ,
USA,
Joined Jan 2000
278
Re: Guided Waves on PE coated Pipes We have just done some trials on external PE coating.

Thin Films less than 2 mm most systems performed reasonably 80' transmission length with good detection. As the thickness increases above 2 mm and becomes multi layer performance dropped dramatically - MSS could not see beyond 3 feet nor could the SE16 Wavemaker or G3 with standard rings. GUL G3 with new style rings 40' transmission typically with good detection and resolution. Operator experience also becomes critical.




 
07:49 Sep-06-2007

Sang Kim

Consultant, NDT Trainer
Guided Wave Analysis LLC,
USA,
Joined Feb 2008
44
Re: Guided Waves on PE coated Pipes ----------- Start Original Message -----------
: We have just done some trials on external PE coating.
: Thin Films less than 2 mm most systems performed reasonably 80' transmission length with good detection. As the thickness increases above 2 mm and becomes multi layer performance dropped dramatically - MSS could not see beyond 3 feet nor could the SE16 Wavemaker or G3 with standard rings. GUL G3 with new style rings 40' transmission typically with good detection and resolution. Operator experience also becomes critical.
------------ End Original Message ------------

We tested PE-coated pipe with MsS system and found that the inspection range was about 120 ft with 10 and 16 kHz frequency. Also, MsS system can inspect about 500 ft for above ground pipeline of good condition for finding 2 or 3 percent cross-sectional-area defect [See paper-- Guided wave fills inspection gap, Pipeline and Gas Technology, August, 2006, page 30]. If the equipment generates strongly generate guided wave in pipe, theinspection range is mostly decided by attenuation of the pipeline and the operating frequency. If the attenuation is very high with the PE coating of 2 mm or higher, the guided wave inspection range should be shortened.


 
07:22 Sep-11-2007

Florin Turcu

R & D
Dept. of Electrical Systems and Automation - University of Pisa,
Italy,
Joined Jul 2007
9
Re: Guided Waves on PE coated Pipes Thank You everyone for sharing you experience with PE pipelines inspection. I will let you the results of our tests on PE coated pipes using guided waves.

----------- Start Original Message -----------
: : We have just done some trials on external PE coating.
: : Thin Films less than 2 mm most systems performed reasonably 80' transmission length with good detection. As the thickness increases above 2 mm and becomes multi layer performance dropped dramatically - MSS could not see beyond 3 feet nor could the SE16 Wavemaker or G3 with standard rings. GUL G3 with new style rings 40' transmission typically with good detection and resolution. Operator experience also becomes critical.
: We tested PE-coated pipe with MsS system and found that the inspection range was about 120 ft with 10 and 16 kHz frequency. Also, MsS system can inspect about 500 ft for above ground pipeline of good condition for finding 2 or 3 percent cross-sectional-area defect [See paper-- Guided wave fills inspection gap, Pipeline and Gas Technology, August, 2006, page 30]. If the equipment generates strongly generate guided wave in pipe, the inspection range is mostly decided by attenuation of the pipeline and the operating frequency. If the attenuation is very high with the PE coating of 2 mm or higher, the guided wave inspection range should be shortened.
------------ End Original Message ------------




 
06:39 Sep-27-2007

Florin Turcu

R & D
Dept. of Electrical Systems and Automation - University of Pisa,
Italy,
Joined Jul 2007
9
Re: Guided Waves on PE coated Pipes: test done Hello everybody,

We have finally tested a PE coated 10'' pipe. We maneged to perform a Long Range inspection of 25m (in one direction) pipeline with good detection. The system used was MsS with a 16kHz pulse.

----------- Start Original Message -----------
: We have just done some trials on external PE coating.
: Thin Films less than 2 mm most systems performed reasonably 80' transmission length with good detection. As the thickness increases above 2 mm and becomes multi layer performance dropped dramatically - MSS could not see beyond 3 feet nor could the SE16 Wavemaker or G3 with standard rings. GUL G3 with new style rings 40' transmission typically with good detection and resolution. Operator experience also becomes critical.
------------ End Original Message ------------




 
01:36 Oct-09-2007

Thomas Vogt

R & D, - -
Guided Ultrasonics Ltd,
United Kingdom,
Joined Apr 2007
22
Re: Guided Waves on PE coated Pipes: test done Hi,

I would prefer that the claims of such test results are substantiated.

Please state what the general conditions were:
- was it a blind witnessed test on an independent specimen?
- what was the thickness of the pipe and the thickness of the PE coating?
- and most importantly: what was the sensitivity at the test range? What size of defects were you able to find at the test range?

Regards,
Tom


----------- Start Original Message -----------
: Hello everybody,
: We have finally tested a PE coated 10'' pipe. We maneged to perform a Long Range inspection of 25m (in one direction) pipeline with good detection. The system used was MsS with a 16kHz pulse.
: : We have just done some trials on external PE coating.
: : Thin Films less than 2 mm most systems performed reasonably 80' transmission length with good detection. As the thickness increases above 2 mm and becomes multi layer performance dropped dramatically - MSS could not see beyond 3 feet nor could the SE16 Wavemaker or G3 with standard rings. GUL G3 with new style rings 40' transmission typically with good detection and resolution. Operator experience also becomes critical.
------------ End Original Message ------------




 
07:31 Oct-13-2007

Sang Y. Kim

Consultant, NDT Trainer
Guided Wave Analysis LLC,
USA,
Joined Feb 2008
44
Re: Guided Waves on PE coated Pipes: test done Hello!

"MSS could not see beyond 3 feet nor could the SE16 Wavemaker or G3 with standard rings. GUL G3 with new style rings 40' transmission typically with good detection and resolution. Operator experience also becomes critical."

The above statement is not correct. Please read the inspection range definition of guided wave at this website (http://www.gwanalysis.com/inspectionrange.html) and check how far these guided wave systems inspect.

Thanks,

Sang

----------- Start Original Message -----------
: Hi,
: I would prefer that the claims of such test results are substantiated.
: Please state what the general conditions were:
: - was it a blind witnessed test on an independent specimen?
: - what was the thickness of the pipe and the thickness of the PE coating?
: - and most importantly: what was the sensitivity at the test range? What size of defects were you able to find at the test range?
: Regards,
: Tom
:
: : Hello everybody,
: : We have finally tested a PE coated 10'' pipe. We maneged to perform a Long Range inspection of 25m (in one direction) pipeline with good detection. The system used was MsS with a 16kHz pulse.
: : : We have just done some trials on external PE coating.
: : : Thin Films less than 2 mm most systems performed reasonably 80' transmission length with good detection. As the thickness increases above 2 mm and becomes multi layer performance dropped dramatically - MSS could not see beyond 3 feet nor could the SE16 Wavemaker or G3 with standard rings. GUL G3 with new style rings 40' transmission typically with good detection and resolution. Operator experience also becomes critical.
------------ End Original Message ------------




 
07:07 Oct-16-2007

Thomas Vogt

R & D, - -
Guided Ultrasonics Ltd,
United Kingdom,
Joined Apr 2007
22
Re: Guided Waves on PE coated Pipes: test done Dear Sang

I just had a look at this website. Instead of underlining your response, it throws up some interesting points.

It claims that MSS has better range because its SNR is better. I tried hard, but I cannot find a comparison of the SNR between GUL, MSS and Teletest to sustain this statement (and in fact it is wrong).

Furthermore, it only talks about the coherent noise from flexural modes but neglects the coherent noise caused by the geometry and small variations of the pipe. In the practical world, this definition of SNR is misleading as it does not take into account local pipe conditions.

Most importantly, it makes it look like as if it is an advantage that MSS cannot work with flexural guided wave modes, but in fact this is the major flaw of the magnetostrictive system.

Best regards,
Tom

----------- Start Original Message -----------
: Hello!
: "MSS could not see beyond 3 feet nor could the SE16 Wavemaker or G3 with standard rings. GUL G3 with new style rings 40' transmission typically with good detection and resolution. Operator experience also becomes critical."
: The above statement is not correct. Please read the inspection range definition of guided wave at this website (http://www.gwanalysis.com/inspectionrange.html) and check how far these guided wave systems inspect.
: Thanks,
: Sang
: : Hi,
: : I would prefer that the claims of such test results are substantiated.
: : Please state what the general conditions were:
: : - was it a blind witnessed test on an independent specimen?
: : - what was the thickness of the pipe and the thickness of the PE coating?
: : - and most importantly: what was the sensitivity at the test range? What size of defects were you able to find at the test range?
: : Regards,
: : Tom
: :
: : : Hello everybody,
: : : We have finally tested a PE coated 10'' pipe. We maneged to perform a Long Range inspection of 25m (in one direction) pipeline with good detection. The system used was MsS with a 16kHz pulse.
: : : : We have just done some trials on external PE coating.
: : : : Thin Films less than 2 mm most systems performed reasonably 80' transmission length with good detection. As the thickness increases above 2 mm and becomes multi layer performance dropped dramatically - MSS could not see beyond 3 feet nor could the SE16 Wavemaker or G3 with standard rings. GUL G3 with new style rings 40' transmission typically with good detection and resolution. Operator experience also becomes critical.
------------ End Original Message ------------




 
02:27 Oct-17-2007

Florin Turcu

R & D
Dept. of Electrical Systems and Automation - University of Pisa,
Italy,
Joined Jul 2007
9
Re: Guided Waves on PE coated Pipes: test done We simply wanted to test the GW attenuation in the case of PE coating. For this purpose we used a new pipe with PE coating.
Pipe diameter: 10"
Pipe wall thickness: 5mm
coating thickness: 3mm
Pipe length: 12 m
Being a new pipe, it had both ends uncoated for about 10cm so we could place the MsS transducers.
We didn't have defects on this pipe, but we had an important reflection of the pipe end even at 36 m (3rd reflection). From our experience, considering the pipe-end as a symmetrical 100% defect, a 30% metal loss defect could be identified at 36 m, and a much smaller one (10%) at 24m.
If anybody needs more details, please send me an e-mail and I'll send back some pictures.
Anyway, we shall proceed with tests on defects, in order to establish the sensitivity on this type of coating.

----------- Start Original Message -----------
: Hi,
: I would prefer that the claims of such test results are substantiated.
: Please state what the general conditions were:
: - was it ablind witnessed test on an independent specimen?
: - what was the thickness of the pipe and the thickness of the PE coating?
: - and most importantly: what was the sensitivity at the test range? What size of defects were you able to find at the test range?
: Regards,
: Tom
:
: : Hello everybody,
: : We have finally tested a PE coated 10'' pipe. We maneged to perform a Long Range inspection of 25m (in one direction) pipeline with good detection. The system used was MsS with a 16kHz pulse.
: : : We have just done some trials on external PE coating.
: : : Thin Films less than 2 mm most systems performed reasonably 80' transmission length with good detection. As the thickness increases above 2 mm and becomes multi layer performance dropped dramatically - MSS could not see beyond 3 feet nor could the SE16 Wavemaker or G3 with standard rings. GUL G3 with new style rings 40' transmission typically with good detection and resolution. Operator experience also becomes critical.
------------ End Original Message ------------




 
06:46 Oct-21-2007

Sang Kim

Consultant, NDT Trainer
Guided Wave Analysis LLC,
USA,
Joined Feb 2008
44
Re: Guided Waves on PE coated Pipes: test done Dear Tom,

Yes, the website (www.gwanalysis.com) claims that MsS system has better range than teletest and GUL.
The claim of comparison was based on the following sources:
1) The generated signal with MsS probe is 50 dB (300 times) higher than the coherent noise of unwanted modes.
(Source: http://www.gwanalysis.com/capabilities.html and Pipeline and Gas Technology, August (2006) pp 28-31)
2) The generated signal leaving the transducer ring was more 40 dB (100 times) higher than the coherent noise of unwanted modes caused by imperfections of the transducers.
(Source: "Long Range Guided Wave Inspection Usage -- Current Commercial Capabilities and Research Directions," M.J.S. Lowe and P. Cawley, Imperical College London, 29 March 2006 ----- available in website search).

You claims it is wrong. Would you please show me the evidence?

Since MsS technology uses bonded ferromagnetic strips that cover almost 360 degree around the pipe circumference, the axial symmetry of probes limits the generation of flexural mode and the probes does not sensitive to asymmetric mode (flexural mode).
The generation and receiving of flexural mode are problem of only GUL and Teletest system that use discretely tightened piezoelectric array. The flexural mode is generated due to non-uniform contact of transducers as well as discrete distribution of probes. If you use continuously covering probes along the circumference of pipe, the flexural mode due to the geometry and small variations of the pipe cannot be observed.

Yes, MsS does not use flexural mode because the probe is axially symmetric. However, we are using phase of signals to differentiate defects from geometric features
because MsS system detects strong rf-signal of high S/N ratio. Since the flexural mode is dispersive, its application has limitation in lenghth. How long does it works? Since the fundamental torsional mode is not dispersive, the phase comparison of signals worked
for weld signal received at 460 ft.

Best regards,

Sang

---------- Start Original Message -----------
: Dear Sang
: I just had a look at this website. Instead of underlining your response, it throws up some interesting points.
: It claims that MSS has better range because its SNR is better. I tried hard, but I cannot find a comparison of the SNR between GUL, MSS and Teletest to sustain this statement (and in fact it is wrong).
: Furthermore, it only talks about the coherent noise from flexural modes but neglects the coherent noise caused by the geometry and small variations of the pipe. In the practical world, this definition of SNR is misleading as it does not take into account local pipe conditions.
: Most importantly, it makes it look like as if it is an advantage that MSS cannot work with flexural guided wave modes, but in fact this is the major flaw of the magnetostrictive system.
: Best regards,
: Tom
: : Hello!
: : "MSS could not see beyond 3 feet nor could the SE16 Wavemaker or G3 with standard rings. GUL G3 with new stylerings 40' transmission typically with good detection and resolution. Operator experience also becomes critical."
: : The above statement is not correct. Please read the inspection range definition of guided wave at this website (http://www.gwanalysis.com/inspectionrange.html) and check how far these guided wave systems inspect.
: : Thanks,
: : Sang
: : : Hi,
: : : I would prefer that the claims of such test results are substantiated.
: : : Please state what the general conditions were:
: : : - was it a blind witnessed test on an independent specimen?
: : : - what was the thickness of the pipe and the thickness of the PE coating?
: : : - and most importantly: what was the sensitivity at the test range? What size of defects were you able to find at the test range?
: : : Regards,
: : : Tom
: : :
: : : : Hello everybody,
: : : : We have finally tested a PE coated 10'' pipe. We maneged to perform a Long Range inspection of 25m (in one direction) pipeline with gooddetection. The system used was MsS with a 16kHz pulse.
: : : : : We have just done some trials on external PE coating.
: : : : : Thin Films less than 2 mm most systems performed reasonably 80' transmission length with good detection. As the thickness increases above 2 mm and becomes multi layer performance dropped dramatically - MSS could not see beyond 3 feet nor could the SE16 Wavemaker or G3 with standard rings. GUL G3 with new style rings 40' transmission typically with good detection and resolution. Operator experience also becomes critical.
------------ End Original Message ------------




 
08:27 Oct-25-2007

Thomas Vogt

R & D, - -
Guided Ultrasonics Ltd,
United Kingdom,
Joined Apr 2007
22
Re: Guided Waves on PE coated Pipes: test done Dear Sang

I do not think an argument between manufacturers of GWUT equipment is a good idea in a technical forum like this, however I must respond to this.

First regarding to your comparison, source 2).
Let me publish here the ENTIRE unchanged paragraph found in the source you quoted:

"Initial site trials of the technique carried out in the research phase in the mid 1990s achieved propagation distances approaching 50 m and by using multiple rings of transducers it was shown to be possible to obtain uni-directional propagation (Alleyne et al, 1997; Alleyne and Cawley, 1997). Signal to coherent noise ratios of better than 40 dB were obtained on site (ie the generated signal leaving the transducer ring was more 40dB higher than the coherent noise of unwanted modes caused by imperfections of the transducers), approaching 50 dB being obtained on clean pipe in the laboratory."

Your quote was a shortened version, withholding important information (including cutting out the 50dB statement and stating that these were initial trials in the mid 90s). Why is anyones guess...

Most importantly what MSS is claiming to achieve today was basically already achieved more than 10 years ago! Even then you could almost get to 50dB on a clean pipe, prooving that the discrete system works. The GUL system, which resulted from this research, has without doubt evolved enourmously since then.

Now in response to your other point, phase "vs" flexural:

1. Getting the phase right on isolated welds is one thing, getting it right on corrosion is quite another! Could you let us know how good the phase is at finding defects in welds? Or at supports? Or on generally corroded pipe work? Or where there is interference between pipe features (incl. corrosion)? Or in bends? Or where there is high ambient noise? In other words, on real pipework? I agree phase is an important tool (which is why GUL have it too), but stand-alone it is unreliable.

2. Once you found a defect, you must be able to at least give an estimate of severity, ie classify it! With flexural you can, without it you cannot.

3. Dispersion of the flexural mode can be compensated for.

Regards,
Tom

----------- Start Original Message -----------
: Dear Tom,
: Yes, the website (www.gwanalysis.com) claims that MsS system has better range than teletest and GUL.
: The claim of comparison was based on the following sources:
: 1) The generated signal with MsS probe is 50 dB (300 times) higher than the coherent noise of unwanted modes.
: (Source: http://www.gwanalysis.com/capabilities.html and Pipeline and Gas Technology, August (2006) pp 28-31)
: 2) The generated signal leaving the transducer ring was more 40 dB (100 times) higher than the coherent noise of unwanted modes caused by imperfections of the transducers.
: (Source: "Long Range Guided Wave Inspection Usage -- Current Commercial Capabilities and Research Directions," M.J.S. Lowe and P. Cawley, Imperical College London, 29 March 2006 ----- available in website search).
: You claims it iswrong. Would you please show me the evidence?
: Since MsS technology uses bonded ferromagnetic strips that cover almost 360 degree around the pipe circumference, the axial symmetry of probes limits the generation of flexural mode and the probes does not sensitive to asymmetric mode (flexural mode).
: The generation and receiving of flexural mode are problem of only GUL and Teletest system that use discretely tightened piezoelectric array. The flexural mode is generated due to non-uniform contact of transducers as well as discrete distribution of probes. If you use continuously covering probes along the circumference of pipe, the flexural mode due to the geometry and small variations of the pipe cannot be observed.
: Yes, MsS does not use flexural mode because the probe is axially symmetric. However, we are using phase of signals to differentiate defects from geometric features
: because MsS system detects strong rf-signal of high S/N ratio. Since the flexural mode is dispersive, its application has limitation in lenghth. How long does it works? Since the fundamental torsional mode is not dispersive, the phase comparison of signals worked
: for weld signal received at 460 ft.
:
: Best regards,
: Sang
: ---------- Start Original Message -----------
: : Dear Sang
: : I just had a look at this website. Instead of underlining your response, it throws up some interesting points.
: : It claims that MSS has better range because its SNR is better. I tried hard, but I cannot find a comparison of the SNR between GUL, MSS and Teletest to sustain this statement (and in fact it is wrong).
: : Furthermore, it only talks about the coherent noise from flexural modes but neglects the coherent noise caused by the geometry and small variations of the pipe. In the practical world, this definition of SNR is misleading as it does not take into account local pipe conditions.
: : Most importantly, it makes it look like as if it is an advantage that MSS cannot work with flexural guidedwave modes, but in fact this is the major flaw of the magnetostrictive system.
: : Best regards,
: : Tom
: : : Hello!
: : : "MSS could not see beyond 3 feet nor could the SE16 Wavemaker or G3 with standard rings. GUL G3 with new style rings 40' transmission typically with good detection and resolution. Operator experience also becomes critical."
: : : The above statement is not correct. Please read the inspection range definition of guided wave at this website (http://www.gwanalysis.com/inspectionrange.html) and check how far these guided wave systems inspect.
: : : Thanks,
: : : Sang
: : : : Hi,
: : : : I would prefer that the claims of such test results are substantiated.
: : : : Please state what the general conditions were:
: : : : - was it a blind witnessed test on an independent specimen?
: : : : - what was the thickness of the pipe and the thickness of the PE coating?
: : : : - and most importantly: what was the sensitivity at the test range? What size of defects were you able to find at the test range?
: : : : Regards,
: : : : Tom
: : : :
: : : : : Hello everybody,
: : : : : We have finally tested a PE coated 10'' pipe. We maneged to perform a Long Range inspection of 25m (in one direction) pipeline with good detection. The system used was MsS with a 16kHz pulse.
: : : : : : We have just done some trials on external PE coating.
: : : : : : Thin Films less than 2 mm most systems performed reasonably 80' transmission length with good detection. As the thickness increases above 2 mm and becomes multi layer performance dropped dramatically - MSS could not see beyond 3 feet nor could the SE16 Wavemaker or G3 with standard rings. GUL G3 with new style rings 40' transmission typically with good detection and resolution. Operator experience also becomes critical.
------------ End Original Message ------------




 
02:58 Oct-26-2007

Sang Kim

Consultant, NDT Trainer
Guided Wave Analysis LLC,
USA,
Joined Feb 2008
44
Re: Guided Waves on PE coated Pipes: test done Dear Tom,

I also agree that it is not a good idea to discuss this in a technical forum. But I'd like to finish this talk after correcting your statement about MsS. In 1990s MsS system also achieved S/N ratio better than 40 dB with longitudinal mode, L(0,2) like Teletest system. My comparison of systems is about torsional mode that is really non-dispersive mode in a pipe. So, your statement of "Most importantly what MSS is claiming to achieve today was basically already achieved more than 10 years ago!" is wrong.

If defect is close from probe, our system can estimate severity using MsS sector probes. In most cases, we recommend using monitoring technique that allows detecting a small defect initiation and growth in the geometric features.

Best regards,

Sang Kim

----------- Start Original Message -----------
: Dear Sang
: I do not think an argument between manufacturers of GWUT equipment is a good idea in a technical forum like this, however I must respond to this.
: First regarding to yourcomparison, source 2).
: Let me publish here the ENTIRE unchanged paragraph found in the source you quoted:
: "Initial site trials of the technique carried out in the research phase in the mid 1990s achieved propagation distances approaching 50 m and by using multiple rings of transducers it was shown to be possible to obtain uni-directional propagation (Alleyne et al, 1997; Alleyne and Cawley, 1997). Signal to coherent noise ratios of better than 40 dB were obtained on site (ie the generated signal leaving the transducer ring was more 40dB higher than the coherent noise of unwanted modes caused by imperfections of the transducers), approaching 50 dB being obtained on clean pipe in the laboratory."
: Your quote was a shortened version, withholding important information (including cutting out the 50dB statement and stating that these were initial trials in the mid 90s). Why is anyones guess...
: Most importantly what MSS is claiming to achieve today was basically already achieved more than 10 years ago! Even then you could almost get to 50dB on a clean pipe, prooving that the discrete system works. The GUL system, which resulted from this research, has without doubt evolved enourmously since then.
: Now in response to your other point, phase "vs" flexural:
: 1. Getting the phase right on isolated welds is one thing, getting it right on corrosion is quite another! Could you let us know how good the phase is at finding defects in welds? Or at supports? Or on generally corroded pipe work? Or where there is interference between pipe features (incl. corrosion)? Or in bends? Or where there is high ambient noise? In other words, on real pipework? I agree phase is an important tool (which is why GUL have it too), but stand-alone it is unreliable.
: 2. Once you found a defect, you must be able to at least give an estimate of severity, ie classify it! With flexural you can, without it you cannot.
: 3. Dispersion of the flexural mode can be compensated for.
: Regards,
: Tom
: : Dear Tom,
: : Yes, the website (www.gwanalysis.com) claims that MsS system has better range than teletest and GUL.
: : The claim of comparison was based on the following sources:
: : 1) The generated signal with MsS probe is 50 dB (300 times) higher than the coherent noise of unwanted modes.
: : (Source: http://www.gwanalysis.com/capabilities.html and Pipeline and Gas Technology, August (2006) pp 28-31)
: : 2) The generated signal leaving the transducer ring was more 40 dB (100 times) higher than the coherent noise of unwanted modes caused by imperfections of the transducers.
: : (Source: "Long Range Guided Wave Inspection Usage -- Current Commercial Capabilities and Research Directions," M.J.S. Lowe and P. Cawley, Imperical College London, 29 March 2006 ----- available in website search).
: : You claims it is wrong. Would you please show me the evidence?
: : Since MsS technology uses bonded ferromagnetic strips that cover almost 360 degree around the pipe circumference, the axial symmetry ofprobes limits the generation of flexural mode and the probes does not sensitive to asymmetric mode (flexural mode).
: : The generation and receiving of flexural mode are problem of only GUL and Teletest system that use discretely tightened piezoelectric array. The flexural mode is generated due to non-uniform contact of transducers as well as discrete distribution of probes. If you use continuously covering probes along the circumference of pipe, the flexural mode due to the geometry and small variations of the pipe cannot be observed.
: : Yes, MsS does not use flexural mode because the probe is axially symmetric. However, we are using phase of signals to differentiate defects from geometric features
: : because MsS system detects strong rf-signal of high S/N ratio. Since the flexural mode is dispersive, its application has limitation in lenghth. How long does it works? Since the fundamental torsional mode is not dispersive, the phase comparison of signals worked
: : for weld signal received at 460 ft.
: :
: : Best regards,
: : Sang
: : ---------- Start Original Message -----------
: : : Dear Sang
: : : I just had a look at this website. Instead of underlining your response, it throws up some interesting points.
: : : It claims that MSS has better range because its SNR is better. I tried hard, but I cannot find a comparison of the SNR between GUL, MSS and Teletest to sustain this statement (and in fact it is wrong).
: : : Furthermore, it only talks about the coherent noise from flexural modes but neglects the coherent noise caused by the geometry and small variations of the pipe. In the practical world, this definition of SNR is misleading as it does not take into account local pipe conditions.
: : : Most importantly, it makes it look like as if it is an advantage that MSS cannot work with flexural guided wave modes, but in fact this is the major flaw of the magnetostrictive system.
: : : Best regards,
: : : Tom
: : : : Hello!
: : : : "MSS could not see beyond 3 feet nor could the SE16 Wavemaker or G3 with standard rings. GUL G3 with new style rings 40' transmission typically with good detection and resolution. Operator experience also becomes critical."
: : : : The above statement is not correct. Please read the inspection range definition of guided wave at this website (http://www.gwanalysis.com/inspectionrange.html) and check how far these guided wave systems inspect.
: : : : Thanks,
: : : : Sang
: : : : : Hi,
: : : : : I would prefer that the claims of such test results are substantiated.
: : : : : Please state what the general conditions were:
: : : : : - was it a blind witnessed test on an independent specimen?
: : : : : - what was the thickness of the pipe and the thickness of the PE coating?
: : : : : - and most importantly: what was the sensitivity at the test range? What size of defects were you able to find at the test range?
: : : : : Regards,
: : : : : Tom
: : : : :
: : : : : : Hello everybody,
: : : : : : We have finally tested a PE coated 10'' pipe. We maneged to perform a Long Range inspection of 25m (in one direction) pipeline with good detection. The system used was MsS with a 16kHz pulse.
: : : : : : : We have just done some trials on external PE coating.
: : : : : : : Thin Films less than 2 mm most systems performed reasonably 80' transmission length with good detection. As the thickness increases above 2 mm and becomes multi layer performance dropped dramatically - MSS could not see beyond 3 feet nor could the SE16 Wavemaker or G3 with standard rings. GUL G3 with new style rings 40' transmission typically with good detection and resolution. Operator experience also becomes critical.
------------ End Original Message ------------




 
08:15 Jan-14-2008
Juan Carlos Hernàndez N
Guided Waves by Teletest Focus System ----------- Start Original Message -----------
: Dear Tom,
: Yes, the website (www.gwanalysis.com) claims that MsS system has better range than teletest and GUL.
: The claim of comparison was based on the following sources:
: 1) The generated signal with MsS probe is 50 dB (300 times) higher than the coherent noise of unwanted modes.
: (Source: http://www.gwanalysis.com/capabilities.html and Pipeline and Gas Technology, August (2006) pp 28-31)
: 2) The generated signal leaving the transducer ring was more 40 dB (100 times) higher than the coherent noise of unwanted modes caused by imperfections of the transducers.
: (Source: "Long Range Guided Wave Inspection Usage -- Current Commercial Capabilities and Research Directions," M.J.S. Lowe and P. Cawley, Imperical College London, 29 March 2006 ----- available in website search).
: You claims it is wrong. Would you please show me the evidence?
: Since MsS technology uses bonded ferromagnetic strips that cover almost 360 degree around the pipe circumference, the axial symmetry of probes limits the generation of flexural mode and the probes does not sensitive to asymmetric mode (flexural mode).
: The generation and receiving of flexural mode are problem of only GUL and Teletest system that use discretely tightened piezoelectric array. The flexural mode is generated due to non-uniform contact of transducers as well as discrete distribution of probes. If you use continuously covering probes along the circumference of pipe, the flexural mode due to the geometry and small variations of the pipe cannot be observed.
: Yes, MsS does not use flexural mode because the probe is axially symmetric. However, we are using phase of signals to differentiate defects from geometric features
: because MsS system detects strong rf-signal of high S/N ratio. Since the flexural mode is dispersive, its application has limitation in lenghth. How long does it works? Since the fundamental torsional mode is not dispersive, the phase comparison of signals worked
: for weld signal received at 460 ft.
:
: Best regards,
: Sang
: ---------- Start Original Message -----------
: : Dear Sang
: : I just had a look at this website. Instead of underlining your response, it throws up some interesting points.
: : It claims that MSS has better range because its SNR is better. I tried hard, but I cannot find a comparison of the SNR between GUL, MSS and Teletest to sustain this statement (and in fact it is wrong).
: : Furthermore, it only talks about the coherent noise from flexural modes but neglects the coherent noise caused by the geometry and small variations of the pipe. In the practical world, this definition of SNR is misleading as it does not take into account local pipe conditions.
: : Most importantly, it makes it look like as if it is an advantage that MSS cannot work with flexural guided wave modes, but in fact this is the major flaw of the magnetostrictive system.
: : Best regards,
: : Tom
: : : Hello!
: : : "MSS could not see beyond 3 feet nor could the SE16 Wavemaker or G3 with standard rings. GUL G3 with new style rings 40' transmission typically with good detection and resolution. Operator experience also becomes critical."
: : : The above statement is not correct. Please read the inspection range definition of guided wave at this website (http://www.gwanalysis.com/inspectionrange.html) and check how far these guided wave systems inspect.
: : : Thanks,
: : : Sang
: : : : Hi,
: : : : I would prefer that the claims of such test results are substantiated.
: : : : Please state what the general conditions were:
: : : : - was it a blind witnessed test on an independent specimen?
: : : : - what was the thickness of the pipe and the thickness of the PE coating?
: : : : - and most importantly: what was the sensitivity at the test range? What size of defects were you able to find at the test range?
: : : : Regards,
: : : : Tom
: : : :
: : : : : Hello everybody,
: : : : : We have finally tested a PE coated 10'' pipe. We maneged to perform a Long Range inspection of 25m (in one direction) pipeline with good detection. The system used was MsS with a 16kHz pulse.
: : : : : : We have just done some trials on external PE coating.
: : : : : : Thin Films less than 2 mm most systems performed reasonably 80' transmission length with good detection. As the thickness increases above 2 mm and becomes multi layer performance dropped dramatically - MSS could not see beyond 3 feet nor could the SE16 Wavemaker or G3 with standard rings. GUL G3 with new style rings 40' transmission typically with good detection and resolution. Operator experience also becomes critical.
------------ End Original Message ------------

Have you seen the Results using for Pipeleine Inspection the Teletest Focus System..............do you have some Companies information about this application .....Thanks a will appreciate this favor........................



 


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