SPIGOT PROJECTION OF SEISMIC PIPE FITTING AND FORMING METHOD FOR PROJECTION

PROBLEM TO BE SOLVED: To provide a structure equipped satisfactorily with a restraining force required to prevent separation and establish a method for executing works, by forming simply a spigot projection on the peripheral surface of a spigot, in particular a spigot of a cut pipe in a site adjustment. SOLUTION: The arrangement is configured with a split spigot ring 21 where a spigot projection 2 to be engaged by a projection protruding from the inside circumferential surface of a socket for prevention of pipe separation is fitted in a ring-shaped groove 11 furnished circumferentially at the spigot and a spacer 23 which is mounted in tying together the splitting ends 22 of the spigot ring 21 and consists of a shape memory alloy to make energization in the shrink direction on the circumference. Because the spacer is fitted in the spigot ring 21 and energized so as to shrink in the circumferential direction by the shape memory effect, the spigot ring 21 is engaged certainly by the spigot within the groove 11 and is restrained firmly even if it receives an external force in the direction of drawing off the pipe fitting, and thus separation from the groove can be precluded.