Spigot and socket joint for large fluid pipeline - has axial prestressing to offset joint movements in service, using external straps

摘要

The pre-stressing process is applied to the joints of a large dia. pipe line (15) conveying fluid under pressure. It compensates for joint movements due to axial service tensions in the pipe. Thrust blocks to bends in buried pipe lines are obviated, without joint slippage and leaks. A joint is made by placing a spigot end (14) in the socket ends (12) of a pre-installed pipe (13) and putting longitudinal external joint straps (18) in tension. The applied axial force equates to that arising when the pipe is in service, putting the spigot end (14) in compression, and joints are successively tensioned in the commissioning of a partic. pipeline length. Stress may be applied by external screw-jacks (24) or by wedges between pipe end shoulders (12a, 14a). Lashed (25) segmental barrel straps (18) and a screw jack (24), with the socket end (12, 21) and a spigot barrel rib (16) providing the reactions.