In 1984 a major gas supplier required a source of high quality small diameter thin wall pipe to be used for the transmission of high-pressure gas. The two main options available at that time were submerged arc welded pipe and seamless pipe. Seamless pipe was in short supply and the size range was at the bottom end of the supply range for submerged arc welded (SAW) pipe and thus made manufacture expensive.The alternative option was to use electric resistance welded (ERW)/high frequency induction (HFI) pipe. The range that HFI and SAW pipe overlap is 16”-20” diameter x 6-16 mm (0.25” – 0.625”) wall thickness. This manufacturing route had never been used by the gas supplier or any other major oil or gas supplier at that time for the production of high pressure pipe and they were wary of using this route because of the past performance of ERW pipe. A major upgrading of the inspection system was about to take place at the British Steel 20” ERW mill and after trials which proved that the weld line inspection system could detect defects to the required standard an order of ERW pipe for high pressure purpose was produced. Since then many innovations have occurred in the inspection of ERW/HFI pipe.This paper compares the changes that have been made in the production route and the inspection stages that have occurred since then.

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