Pipes and tubular conduits – Repairing
Patent
1995-11-13
1999-08-17
Brinson, Patrick F.
Pipes and tubular conduits
Repairing
138 98, 156294, 264269, 264 361, F16L 5516
Patent
active
059379103
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates generally to tubular linings for pipelines or passageways which linings are of a type known as `softlinings` or `cured in place` linings which employ resin absorbent material which is impregnated with curable resin which has been conditioned in order that it may be cured to produce a pipe on the surface of the pipeline or passageway (typically an underground sewer) thereby in effect forming a pipe within a pipe.
The lining to which the invention relates is a resin absorbent tubular structure (herein the "lining tube or pipe") which is to be used for lining an underground pipeline or passageway such as a sewer. In such utilization, which is now practiced widely throughout the world, the impregnated lining tube is inflated (by gas such as air, steam and/or liquid such as water) against the pipeline or passway surface whilst the resin is uncured, and whilst the lining tube is so held in position, the resin is allowed or caused to cure whereby the cured resin with the absorbent tubular structure embedded therein forms a self supporting rigid pipe, which may or may not bond to the pipeline or passageway wall. The purpose of this operation is to rehabilitate and/or repair the passageway or pipeline. A particular advantage of the provision of a self supporting rigid pipe is that bonding to the existing pipeline is not necessary, as is the case with some lining systems but it is to be mentioned that this invention can be applied to pipelining systems where the impregnated tube does bond to the existing pipeline or passageway, such systems being those wherein the lining tube is of relatively small thickness e.g. 5 mm or less and the resin acts like a bonding medium rather than an impregnating medium.
Also the lining tube when the resin is in the uncured state may not strictly be a tube in that it may be a web folded into tubular form so that its edges overlap and such edges become fused or held relatively together only when curing in place has been effected. In fact, this arrangement provides the advantage that the overlapping edges can slip relatively as the tube is being inflated so that the tube will best fit to the passageway surface.
Examples of methods of lining of underground pipelines and passageways using impregnated lining tubes which are cured in place are contained in many patent specifications of which examples are U.K. Patent No. 1,340,068, which is the original patent for this technology, and U.K. Patent No. 1,449,445.
All or by far the majority of the methods which are practised throughout the world using cured in place lining tubes for lining underground pipelines and passageways simply use a heat curable resin (e.g. polyester and heat for the curing of the resin, the application of heat causing a catalyst and/or promoter (accelerator) in the resin to release free radicals and commence cross linking of the resin molecules and crystal formation; the curing reaction is exothermic and heat is internally generated and the curing process accelerates.
One disadvantage of this arrangement is that even if heat is not applied to the impregnated lining tube, under ambient conditions the resin will eventually cure in a matter of days and of course if curing takes place before the lining tube is in place on the passageway of pipeline surface, the lining tube is completely lost and must be scrapped. This can represent a considerable loss if not a complete loss of profit on a contract. Should the lining tube cure when it is part way inside the pipeline or passageway, then the consequences financially could be disastrous for the contractor. In order to avoid the problem of the resin curing too soon, i.e. before the lining tube is in place, contractors have resorted to extensive measures, in particular to keeping the impregnated tube refrigerated until it is to be used on site. This means that the tubes must be delivered to the site in refrigerated vehicles.
The effect of this procedure is that the contractor is limited in terms of when he can mix the resin and i
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patent: 3036983 (1962-05-01), O'Connor
patent: 3607830 (1971-09-01), Kearnan et al.
patent: 3618599 (1971-11-01), Beightol
patent: 3896969 (1975-07-01), Basile
patent: 4581247 (1986-04-01), Wood
patent: 4680066 (1987-07-01), Wood
patent: 5200666 (1993-04-01), Walter et al.
Brinson Patrick F.
Sound Pipe, Ltd.
Wolfson Michael I.
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