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1836 views
01:06 Jul-25-2005
David
EMAT vs. GUL

Looking into best amethod for corrosion under support skid plates. Used GUL considering EMAT, advantages or disadvantages of EMAT over Guided Wave.


 
09:55 Jul-26-2005

Charlie Jackson

Engineering
MBINSPECTION,
United Kingdom,
Joined Aug 2003
7
Re: EMAT vs. GUL ----------- Start Original Message -----------
: Looking into best amethod for corrosion under support skid plates. Used GUL considering EMAT, advantages or disadvantages of EMAT over Guided Wave.
------------ End Original Message ------------

Dear User
Both Axial directed plate waves generated by LRUT ( GULL/TELETEST)and Circ' plate waves generated by Emat probes have differing benefits, although both have the distinct benefit over contact methods of requiring no couplants, hope the following helps.

1 LRUT it is quite possible to locate anomolies at pipe support zones although quantification is not feasable at the moment ( present developments may give some quantification in the future)Some miscalls will be experienced dependant on support design.

2 CIRC EMAT ( based on Sonic sensors system) Again using plate waves ( lamb type) but the difference(from LRUT) is that the wave generated is aimed to be at a dispersive point on the dispersion curves ( meaning a change in thickness will result in a significant change in sound velocity) therefore the data produced will give both Amplitude and velocity change data and therefore the data can be more quantiative.

3 Contact system considerations
generally if all types of support zones are to be attempted on a plant you may have consider including the following

a testing from top wall through fluid and examinig opposite wall

b circumferential scans using shear waves(useful on small lines) --- care must be taken on fluid filled lines

c longitudinal/circumferential scans using longit+shear waves -- CHIME _On the big diameters + 24" dont know of another system ( EMATS in development for these sizes)

Not knowing your inspection requirements I would say that as a rule of thumb, if the line is lagged use LRUT to sort then strip your anomolies and EMAT if they are over supports. If however you know you have a problem at supports and the rest of the line is relatively unaffected then inspect the support zones with EMAT ( or a contact system if coatings are removable )


Kind Regards Charlie Jackson





 
00:38 Jul-26-2005

Borja Lopez

Director
Innerspec Technologies,
USA,
Joined Jun 2002
35
Re: EMAT vs. GUL Innerspec Technologies has recently developed a system that can perform both circumferential and axial inspection with the same instrument.

- For circumferential inspection it uses plate waves (lamb) that detects defects by means of both reflection and TOF measurements. The main advantage of this system with previous versions is that it can use pulsed magnets thus it is much easier to scan and results are more consistent.
- For axial inspection (for supports or air-to-ground interfaces) it also uses plate waves to perform volumetric inspection in one pass. This configuration can also be used for weld inspection.

Innerspec also offers permanent magnet solutions for non-magnetic pipes (SS, inconel).

For more info, visit www.innerspec.com or e-mail temate@innerspec.com

Best regards,
Borja Lopez

----------- Start Original Message -----------
: : Looking into best amethod for corrosion under support skid plates. Used GUL considering EMAT, advantages or disadvantages of EMAT over Guided Wave.
: Dear User
: Both Axial directed plate waves generated by LRUT ( GULL/TELETEST)and Circ' plate waves generated by Emat probes have differing benefits, although both have the distinct benefit over contact methods of requiring no couplants, hope the following helps.
: 1 LRUT it is quite possible to locate anomolies at pipe support zones although quantification is not feasable at the moment ( present developments may give some quantification in the future)Some miscalls will be experienced dependant on support design.
: 2 CIRC EMAT ( based on Sonic sensors system) Again using plate waves ( lamb type) but the difference(from LRUT) is that the wave generated is aimed to be at a dispersive point on the dispersion curves ( meaning a change in thickness will result in a significant change in sound velocity) therefore the data produced will give both Amplitude and velocity change data and therefore the data can be more quantiative.
: 3 Contact system considerations
: generally if all types of support zones are to be attempted on a plant you may have consider including the following
: a testing from top wall through fluid and examinig opposite wall
: b circumferential scans using shear waves(useful on small lines) --- care must be taken on fluid filled lines
: c longitudinal/circumferential scans using longit+shear waves -- CHIME _On the big diameters + 24" dont know of another system ( EMATS in development for these sizes)
: Not knowing your inspection requirements I would say that as a rule of thumb, if the line is lagged use LRUT to sort then strip your anomolies and EMAT if they are over supports. If however you know you have a problem at supports and the rest of the line is relatively unaffected then inspect the support zones with EMAT ( or a contact system if coatings are removable )
:
: Kind Regards Charlie Jackson
:
------------ End Original Message ------------




 
00:32 Jul-28-2005

Godfrey Hands

Engineering,
PRI Nadcap,
United Kingdom,
Joined Nov 1998
281
Re: EMAT vs. GUL ----------- Start Original Message -----------
: Looking into best amethod for corrosion under support skid plates. Used GUL considering EMAT, advantages or disadvantages of EMAT over Guided Wave.
------------ End Original Message ------------

David,

NDT Consultants Ltd. in the United Kingdom is able to provide a testing service or sales of equipment using LRUT / Guided Wave.
Our equipment is the SwRI equipment, which generates the ultrasound electromagnetically (normally using Magnetostricive methods) and we can steer the equipment to generate waves of a specific frequency and specific wave type (e.g. SH0 for plate inspection, Torsional mode for Pipe inspection etc) without having to manufacture transducers for that specific application and frequency.

We will be pleased to advise if you could provide more information.

As has been mentioned before, LRUT can pinpoint areas of concern at distances, but these areas then need some alternative method to locally evaluate.

Regards,

Godfrey Hands


 
07:09 Aug-01-2005
Geert B
Re: EMAT vs. GUL Inline UT inspection might be a good option if you can take the pipeline offline for a few days. The lines need to be clean on the inside but you do not need to take the insulation off and you can get very good readings for all the areas, save for the bends.
Regards Geert

----------- Start Original Message -----------
: : Looking into best amethod for corrosion under support skid plates. Used GUL considering EMAT, advantages or disadvantages of EMAT over Guided Wave.
: David,
: NDT Consultants Ltd. in the United Kingdom is able to provide a testing service or sales of equipment using LRUT / Guided Wave.
: Our equipment is the SwRI equipment, which generates the ultrasound electromagnetically (normally using Magnetostricive methods) and we can steer the equipment to generate waves of a specific frequency and specific wave type (e.g. SH0 for plate inspection, Torsional mode for Pipe inspection etc) without having to manufacture transducers for that specific application and frequency.
: We will be pleased to advise if you could provide more information.
: As has been mentioned before, LRUT can pinpoint areas of concern at distances, but these areas then need some alternative method to locally evaluate.
: Regards,
: Godfrey Hands
------------ End Original Message ------------




 


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