sulphate capsules inserted in the pipe where a joint was to be tested. A strip of this film was wrapped around the pipe at the weld, and the gamma rays emitted by the capsule exposed the film to give a picture of any flaws which might be a source of trouble.

This was but one of the several means taken to make as certain as humanly possible that this biggest diameter pipe line in history would stand up through the years. Not only were the welds tested by radioactivity but where the pipe is buried it was first coated with asphalt, fibre glass and still more asphalt. Where it is elevated it is held in ring girders, resting on concrete bases where the subsurface is solid, and being supported on steel bents where subkas or marshy spots are crossed. This system is called restrained above-ground construction, and was devised especially for the Tapline job. The line runs mainly straight ahead but there are some changes of direction and wherever there is such a change of more than one degree there are extra anchors.

After the pipe-pigs went through the line, trailed by the clicking Geiger counters, water flowed slowly along for the necessary sectional

Welders working inside 180,000-barrel bunker fuel tank