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Ishbel Macdonald
Consultant, Engineering Consultant - NDT
Subsea 7, Norway, Joined Nov 1998, 11

Ishbel Macdonald

Consultant, Engineering Consultant - NDT
Subsea 7,
Norway,
Joined Nov 1998
11
02:47 May-23-2002
Thickness measurement of GFRP


Can anyone suggest a quick (and preferably cheap) method of measuring the thickness of GFRP in the range of 5 to 25mm? We have conventional UT equipment, with a few low frequency probes(1MHz).

Thanks in advance

Ishbel Macdonald


 
 Reply 
 
Jim Knowles AMI Mar EST
Jim Knowles AMI Mar EST
03:03 May-23-2002
Re: Thickness measurement of GFRP
:
: Can anyone suggest a quick (and preferably cheap) method of measuring the thickness of GFRP in the range of 5 to 25mm? We have conventional UT equipment, with a few low frequency probes(1MHz).
.
: Thanks in advance
.
: Ishbel Macdonald

Ultrasonic through thickness measurements using low frequency compession works well.
There are problems where the density or the fibre wetting by the epoxy is low and the backwall echo falls off and therefore a comparative inspection should be carried out, comparing adjacent areas.

Additionaly magnetic methods can be used.
This employs the use of a target such as a ball bearing or small bar magnet
on the inside of the tank or hull and measure the effective fall off or increase in the magnetic field as the thickness increases or decreases.



 
 Reply 
 
Tom Nelligan
Engineering,
retired, USA, Joined Nov 1998, 390

Tom Nelligan

Engineering,
retired,
USA,
Joined Nov 1998
390
05:34 May-23-2002
Re: Thickness measurement of GFRP

: Can anyone suggest a quick (and preferably cheap) method of measuring the thickness of GFRP in the range of 5 to 25mm? We have conventional UT equipment, with a few low frequency probes(1MHz).


It is usually possible to ultrasonically measure thickness of GFRP in the indicated range in a pulse/echo mode using the right sort of equipment -- a thickness gage or flaw detector with optimized low frequency capability and a 500 KHz broadband delay line transducer. Because of a relatively high level of internal scattering in GFRP, it's very useful to have low-pass filtering capability in the instrument (to filter out scatter noise), and a delay line transducer provides better acoustic coupling in and out of a low-impedance material. We'd be happy to examine samples of your material and recommend specific equipment if you're interested.

--Tom Nelligan
Panametrics, Inc.
www.panametrics.com


 
 Reply 
 
rozaimi
rozaimi
15:05 Feb-12-2012
Re: Thickness measurement of GFRP
In Reply to Tom Nelligan at 05:34 May-23-2002 .

Hi,
i also have problem similar to Ishbel. We are trying to utilize GE DMS 2 with low frequency probe as recommended by our ndt supplier. Is it really work?How about the calibration block?do we need block made of frp?

Can somebody suggest which code outline the guideline of uttm on frp material?is the guideline similar as outline in ASME V. the only difference on the material to be tested. Im i right?

Thanks in advance

 
 Reply 
 

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