GB1336122A - Apparatus for treating the internal surface of a pipeline - Google Patents

Abstract

1336122 Repairing pipes LA R ROSS 4 Nov 1970 [9 Aug 1969] 39943/69 Heading F2P [Also in Division B2] A self-propelled pipe-line pig has pressure coating means for sealing pipe-line leaks or for coating the internal surface of a pipe-line and includes first and second selectively outwardly expandable members adapted to grip the pipeline internal surface, and means for moving the members relative to one another to produce a step-by-step motion of the pig. The pig comprises a central tube 10 bounded by expandable seals 20, 22 which grip the pipe-line inside surface. Seal 20 is fixed to the pig but seal 22 is axially slidable with respect to the pig. The pig is moved along the pipe-line by the following sequence. Seal 20 is expanded by air to grip the pipe-line and seal 22, retracted, slides forwardly towards seal 20 by fluid pressure (sealant or other fluid), pneumatically, or electronically; seal 20 is retracted, seal 22 is expanded and seal 20 moves away from seal 22 by similar means to that for seal 22. The sealant is contained by the chamber 25 between seals 20, 22 or in a separate chamber between two similar seals, in front of, or behind, chamber 25. Alternatively the sealant is sprayed on to the pipe-line internal surface by a spraying head propelled by the pig. A two-reactant sealant may be applied to the pipe-line internal surface from two such chambers, or two spraying heads, or a chamber plus a spraying head. A television camera or flow detecting device may be propelled by the pig. A test chamber, similar to chamber 25, may be carried by the pig, to measure pressure drop in the chamber to detect flows or junction locations.