Pipes and tubular conduits – Repairing – Patches
Patent
1998-04-30
2000-12-19
Hook, James
Pipes and tubular conduits
Repairing
Patches
138 97, 138148, F16L 551645
Patent
active
061615889
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the technology of the application of linings to the inner surfaces of pipes and pipelines and to the surfaces of passageways. The pipes, pipelines and passageways usually will, but need not be located underground. Also, but again not exclusively, the surfaces to be lined will be located underground.
Therefore, in order to simplify the description, reference will be made hereinafter only to underground passageways and the surfaces thereof which are to be lined, but it will be kept in mind that the invention has wider application.
There is now established throughout the world a lining process known as "soft lining" or "cured in place" lining in which a tubular liner is constructed to have a soft and flexible character so that the liner can be moved into the passageway and, by fluid pressure, urged against the surface to be lined. Because the liner is soft and flexible, it shapes to the surface contour, which is desirable. However, the liner is also constructed so as to include a curable synthetic resin which, after the liner is in position on the surface, can be cured (which means that it becomes hard) and the liner turns into a rigid pipe on the surface. The thickness of this pipe depends upon the thickness of the starting liner tube and this in turn depends upon application involved. The process may be designed so that the cured pipe is bonded to the surface, but in the majority of cases, bonding to the surface will not be necessary, and the pipe will be freestanding in the passageway. Many countries have benefited from this technology insofar as the technology has been used with great effect to rehabilitate the sewers of such countries and restore such sewers to full functioning at a fraction of the cost which would have been involved had full replacement been required. In many cases, the technology has been and continues to be a means which has supplied a long felt want.
The original processes of softlining are described in U.S. Pat. Nos. 4,009,463 and 4,064,211 and these patents describe not only methods of installation of the liner, but also the materials used for the liner. Thus, the first patent describes that the liner comprises a felt material which is impregnated with the synthetic resin and that the so impregnated liner is introduced into the passageway and then inflated onto the surface, following which the liner is heated to cure the resin. In the second patent the liner, composed of the same basic material, is everted into the passageway, this process having a number of advantages over the first method in that the fluid which is used for the eversion is also sued for the urging of the liner against the surface to be lined.
Essentially, these two processes have not changed since their introduction over twenty years ago, although many attempts have been made in this direction.
There is room for improving the basic methods, despite the fact that they have stood the test of time extremely well; and the present invention seeks to provide an improvement in the known softlining methods without sacrificing any of the considerable, existing benefits. In the preparation of the liner in the conventional method involving eversion of the liner, which is the most commonly practised method, a web of felt is made into a tube and if that tube is to form the outer layer of the liner, it also has on its outer surface a film or coating. Inner layers of the felt do not have such coating. After the liner has been thus manufactured, and it is to be used, it is impregnated with the resin by pumping the resin into the liner and by squeezing the liner whilst at the same time drawing a vacuum in the inside of the liner so as to exclude air (which is quite important). The fabrication and usually the impregnation take place under factory conditions, and then the impregnated liner is transported to site for installation as described in said U.S. Pat. No. 4,064,063.
All of this preparation adds to the expense of the installation, as indeed does the cost of the felt material. Also, the felt prevents
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patent: 5803665 (1998-09-01), Stephens
Bellamy Norman West
Bellamy Sheila
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