Published on 29 January 2013
The road crossings inspected in Alaska described in Case 6 below were sleeved. Work for Caltex, under sub-contract to International Refinery Services of Singapore, included tests on pipes buried directly in the ground. It was found that, whilst adherent earth and corrosion products attenuated the signals, ultrasound could be transmitted 10m or more. Attenuation made interpretation difficult. However, it was possible to isolate flaws at the reporting level, once the problem had been identified. An interesting aspect is that, in some cases, the pipe temperature exceeded 100°C. This had no adverse effect on the Teletest performance.
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