Hi there
I am not familiar with eddy current thickness testing; only magnetic
particle testing for crack detection.
For the ultrasonic thickness testing, no reading can mean no sound signal
going into the pipe wall, or none coming back. Outside of the tubes should
be cleaned with emery paper, and many ultrasonic machines require an
acoustic couplant - sort of a jellylike liquid - to transfer the sound
signal into and out of the pipe wall. Are you using a couplant? Internal
deposits are not normally a problem and there should be a good wave
reflection.
Suggest you do some tests on the bench with a piece of clean tube of known
wall thickness.If you cannot get a good reading, then the problem lies with
the machine or the operator.
Cheers
Steve McKenzie
-----Original Message-----
From: e-Director [mailto:segip@tm.net.my]
Sent: Saturday, November 30, 2002 11:18 AM
To: PipingDesign@yahoogroups.com
Subject: [PipingDesign] UT and ECT method
Recently we have carry out an inspection of boiler tubing with Eddy Current and Ultrasonic method...
However some of the tubing do not have any reading....
What can cause this no reading of the tubing?? is it due to wrong eddy current/ultrasonic frequency or there is to much deposit/foulings on the surface of the tube wall that resulted in no reading??
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Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Received on Fri Nov 29 19:58:00 2002
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