GB894574A - Apparatus for coating the internal walls of pipes - Google Patents

Abstract

<PICT:0894574/III/1> <PICT:0894574/III/2> Pistons comprising an annulus or centrally orificed disc-like member of india-rubber or other suitable flexible resilient material, split or divided radially so as to be capable of contracting or expanding, are used in apparatus for coating the internal walls of pipes, of the kind in which pistons are mounted in spaced relation and with freedom of traversing movement towards one another, on a carrier member which is pulled through the pipe, the pistons and the pipe wall forming a reservoir for coating medium. Each piston may comprise two such annular members, 10, 11 and 12, 13, loosely mounted on a carrier rod 15, between eyes 16 attached to wire ropes 17 and 18 by which the assembly may be traversed along the pipe 20. The rod 15 is centralized by thimbles 15a. Coating material 21 is introduced into the space between the pistons through a hole 22 made in the pipe 20, this hole then being plugged and the assembly traversed first in one direction, then, if desired, in the other. In a modification, two pistons are fixed on the ends of the rod 15, and a third piston is loosely mounted between them. Coating material is introduced into the rearmost compartment thus formed, while loose foreign matter and moisture collects in the forward compartment. The annular members 10, 11, 12, 13 may each be provided with a simple radial gap 19 (Fig. 4), or in addition, a tongue may be provided on one side fitting into a groove in the other. A twin piston may be used, with a metal disc between the two halves.