where expertise comes together - since 1996 -

The Largest Open Access Portal of Nondestructive Testing (NDT)

Conference Proceedings, Articles, News, Exhibition, Forum, Network and more

where expertise comes together
- since 1996 -

Hi-Spec Systems
we are specialised in the design, development and manufacture of Phased Array and Time-of-Flight Diffraction (ToFD) ultrasonic inspection systems.
821 views
Technical Discussions
Michael Trinidad
Consultant,
LMATS Pty Ltd , Australia, Joined Jan 2003, 138

Michael Trinidad

Consultant,
LMATS Pty Ltd ,
Australia,
Joined Jan 2003
138
03:16 May-09-1998
Ultrasonic coating thickness measurement

We have an engineer doing research for us and is developing some new equipment. A brilliant electronics man however the practical UT side I give him what I want the equipment to do. He has manufactured a prototype ut set from scratch for further research now he has been told that we want the instrument to disregard coating thicknesses.

My understanding of this aspect of ut is that sets capable of doing this gate the multiple back wall echoes and then average out the results. My question is am I basically correct?

Kindest Regards

Michael Trinidad
International Refinery Services Thailand


 
 Reply 
 
Rolf Diederichs
Director,
NDT.net, Germany, Joined Nov 1998, 609

Rolf Diederichs

Director,
NDT.net,
Germany,
Joined Nov 1998
609
09:13 May-11-1998
Re: Ultrasonic coating thickness measurement

: We have an engineer doing research for us and is developing some new equipment. A brilliant electronics man however the practical UT side I give him what I want the equipment to do. He has manufactured a prototype ut set from scratch for further research now he has been told that we want the instrument to disregard coating thicknesses.

: My understanding of this aspect of ut is that sets capable of doing this gate the multiple back wall echoes and then average out the results. My question is am I basically correct?

: Kindest Regards

: Michael Trinidad
: International Refinery Services Thailand

Michael is basically correct.
The evaluation of multiple backwall echoes is commonly used to measure only the
parent material thickness while ignoring the coating thickness.

Many commercial thickness gauges can measure the time interval between the
first (or later) backwall echo (n), thus measuring only the material transit
time. However be aware that this option is mostly provided for other reasons -
the multiple echo measurement is applied for increasing measurement accuracy.

It might be possible to apply those gauges for coated components also.
But there are a lot of problems which can cause error readings (see figure).
For that reason an instrument with A-scan display is recommended to find proper
adjustments for the following situations:

1. Absolute thickness of coating and parent material.
2. Ratio of coating and parent material thickness.
3. Acoustic impedance of the materials.
4. Material attenuation.
5. Interferences caused by multiple reflections of the coating path.

The adjustment of a correct gate position is mainly a problem if the gauge is
applied in a wide range of applications. Adjustment of thresholds, trigger
phase are functions which are needed to consider the specific acoustic situation.

You may find commercial gauges without an A-scan display for this application.
For a limited range of components (applications, geometries) a flexible
instrument adjustment may not be needed.
However, in generally I would prefer the use of an A-scan display for adjustment
an verification of the measurement.

Rolf Diederichs

BTW: This topic was posted also on the newsgroup.
So far it received answers by Joe Buckley (jmb34@student.open.ac.uk)
Doug Breeze (isl@inspection.co.uk).
Click on 'Show posts' at http://www.ndt.net/newsweb/newsweb.htm



 
 Reply 
 

Product Spotlight

AMIGO2

TSC Amigo2 - ACFM technology has developed a solid reputation for accurately detecting and sizing
...
surface-breaking cracks through paint and coatings. As the industry demands increased performance in speed, signal quality, and portability, it’s time for an evolution. It’s time for Amigo2.
>

iProbe - USB Phased Array Probe

Turn your PC, Laptop or Tablet into a powerful 32:64 Phased Array system with our USB powered Phas
...
ed Array iProbe and inspection software package. Perform affordable weld inspection and corrosion mapping inspections with this powerful but small system. The probe has a 100V pulser, 8K PRF, dual axis encoder input and achieves outstanding signal quality.
>

Echomac® Small

Available with up to eight channels of electronics to detect and evaluate thickness, flaws and eccen
...
tricity, this UT tester is housed in a convenient, smaller cabinet. This instrument can be used in conjunction with bubbler or immersion tank systems, or with a test bench or in laboratory applications. The Echomac® Small is available in the FD4, FD6 or FD6A versions.
>

A1525 SOLO

A1525 Solo – the most compact and affordable TMF unit with two phased array transducers and 3D v
...
isualization and analysis software in standard delivery set. A compact, ergonomic and easy to handheld Phased Array unit based on Total Focusing Method for easy-going imaging of inspection objects with two-dimensional and three-dimensional visualization and evaluation of inspection results.
>

Share...
We use technical and analytics cookies to ensure that we will give you the best experience of our website - More Info
Accept
top
this is debug window