The crack detector

FINDING a defect is one of the key parts of the mobile equipment maintenance process. But what if that defect is beneath a centimetre of coating? Vetti Kakulas reports on a solution to this sort of problem.
The crack detector The crack detector The crack detector The crack detector The crack detector

Published in the January 2012 Australia's Mining Monthly

Non-destructive testing has been around for some time. One thing is for sure though, the systems to conduct it are getting easier to use.

Russell Fraser Sales, based in Kirrawee, New South Wales, has noticed an escalation in the number of non-destructive testing companies ordering its alternating current field measurement (ACFM) equipment.

RFS distributes Technical Software Consultants' technology systems offering results in the detection and sizing of surface breaking cracks.

ACFM is a specialised electromagnetic inspection technique said to provide accurate data on a defect's location and length.

The significance of a defect, in regards to structural integrity, depends on its depth.

ACFM uses mathematical models to provide the depth of the defect and provides an immediate evaluation of the crack.

Founder and director Russell Fraser said the ACFM instruments saved time and money compared to the conventional magnetic particle inspection, which involved stripping the paint before inspecting.

"I was talking to a guy out in Gladstone [Queensland] just recently and [he] said it cost $15,000 to remove the paint from the weld lines on the tank," Fraser said. "Then when they finished they had to clean it down and repaint it. You can never restore the true integrity of the paint coating because normally you have two [layers] of your primer and then another couple of layers [of paint]."

RFS' most popular system is the AMIGO crack microgauge. When using it, there is no need to clean the inspection area to bare metal - it is capable of inspecting through thin metallic and non-conducting coatings that are several millimetres thick.

"It is a very rapid inspection compared to magnetic particle inspection because you don't need to do any real preparation on the job before you start," Fraser said.

"There is no coating removal and no coating restoration afterwards. So you can come in, test the areas and get out quite quickly with minimum disturbance."

Fraser said the system would find defects even beneath a half-inch thick coating.

The ACFM system can record the results from each crack detection procedure to give the operator a record for future reference.

"All your test results are recorded, so they can be audited by a third party at any distance away," Fraser said.

"It is very easily useable by rope access. You can have the operator up to 50m away with the probe away from the guy with the computer viewing the results as he runs."

The AMIGO offers rapid scanning using a hand-held probe for crack detection and sizing.

"It is being used extensively in the coal seam gas field up in Roma [Queensland]. All their pipe work and everything is painted and the last thing they want to be doing is ripping the paint off so they can do crack testing on it," Fraser said.

The AMIGO has a dual-frequency growth option - five kilohertz for ferritic steel and 50 kHz for improved sensitivity on non-ferrous metals.

AMIGO can operate for more than five hours on a fully charged battery.

Full data storage of scans facilitates back-up, off-line view, audit purposes and reports.

Fraser said the company sold ACFM equipment systems throughout Australia.

"Some of our big users are in the mining industry," he said.

"They are the people checking the pins and boxes on the drill rods, because [the system] can very quickly and very easily check the threads on the pin and the box."

RFS offers a five-day training course for level one and level two operators, to become qualified ACFM equipment operators.

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