This programme involved the inspection of eight lines of 4", 6", 8" and 12" diameter, where they passed through the 0.8-1.0m thick sea wall at the Shell Haven Refinery. Inspection was possible from both sides of the wall. Thus the required transmission range was small in comparison to other projects. A feature of this project is that the pipes had a bitumastic wrapping. Such wrappings can lead to rapid attenuation of the ultrasound. Despite these reservations, in this case the technique performed successfully, partly because the required test range was so limited and partly because the wrapping was old and no longer strongly adherent.
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