Pipe joints or couplings – With casing – lining or protector – Lined
Patent
1997-08-08
1999-10-26
Nicholson, Erick K.
Pipe joints or couplings
With casing, lining or protector
Lined
285369, 285351, 285230, F16L 914
Patent
active
059714409
DESCRIPTION:
BRIEF SUMMARY
This application is a national stage application, according to Chapter II of the Patent Cooperation Treaty. This application claims the priority date of Dec. 5, 1994, for UK Patent Application No. 9424501.6.
This invention relates to a pipe assembly, and particularly a corrosion resistant pipe assembly adapted for use with liquids having high chemical concentrations or of a corrosive nature and in ground having a corrosive nature.
Pipes are either laid in the ground by cutting an open trench, or are laid at increased depths by micro-tunnelling where the pipes are jacked through the ground. The pipes in the latter case have to be strong enough to withstand the forces imposed by jacking, and in each case have also to be strong enough to withstand the inherent ground forces. In conditions where the pipe contents have a high chemical concentration or are of a corrosive nature, the pipes cannot be made of conventional materials, which are incapable of withstanding chemical attack by the contents such as raw sewage, and sea water.
Pipes which are corrosion resistant, such as glass reinforced plastics or rigid PVC pipes, are classed as flexible pipes and rely on the surrounding ground to provide their strength. As a result, after laying the pipes, back filling has to be carried out fairly carefully using special graded materials. In areas with a high water table, or if construction takes place at a later date near the pipes, the ground surrounding the pipes can be disturbed, so removing the support for the pipes.
To overcome this, thicker pipes could be used, but this becomes expensive. Alternatively, glass reinforced plastics pipes incorporating sand with a glass fibre reinforcement have been used, but these are not very corrosion resistant, and the sand incorporated causes the laminate to break down so that they are not suitable for use at pressure.
Also in some countries, the nature of the ground is such that the pipes have to withstand possible attack from corrosive elements in the surrounding soil and are subject to high relative movements between adjacent pipe sections. Often they can be subject to not being laid in accordance with manufacturer's recommendations.
According to the present invention there is provided a pipe having an inner section preformed of a corrosion resistant plastics material, and an outer section which is required to enable the pipe to withstand external forces applied thereto during installation or from the surrounding ground after installation and to increase the rigidity of the inner section, the outer section being formed of polymer concrete which is moulded to a desired configuration around the inner section, the moulding enabling the concrete to provide the required rigidity, the inner section being adapted to provide means for sealingly surrounding the joint between the pipe and an adjacent pipe laid end to end therewith, the surrounding means being formed of a corrosion resistant material.
Preferably the inner section is moulded from a glass reinforced plastics material, preferably a material formed of a corrosion resistant resin and corrosion resistant glass fibre. Preferably also, the surrounding means is formed as an increased diameter end part on one end of the inner section and a longitudinally extending part on the other end of the inner section, whereby, in use, the one end part of the pipe can overlie the other end part of the adjacent pipe. Alternatively, the surrounding means comprises a sleeve located between the inner and outer sections to sealingly overlie a free end of the inner section. The sleeve is preferably also moulded from a glass reinforced plastics material, for example a material formed of a corrosion resistant resin with corrosion resistant glass fibre.
Preferably also the polymer concrete is formed from synthetic resin and inorganic fillers. The polymer concrete may be formed with an abrasion resistant outer face, for example of glass reinforced plastics material such as a synthetic resin with glass fibre.
According to the present invention there is f
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Article: Microtunneling, Sewres and Manholes with Polymer Concrete; www.microtunneling .com; 7 pages.
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