Pipe lining

Details Pipe lining Pipe lining

1997-03-28

1999-08-10

Hook, James F.

Pipes and tubular conduits

Repairing

Patches

138 97, 138119, 138DIG3, 138DIG11, F16L 55162

Patent

active

059343320

DESCRIPTION:

BRIEF SUMMARY
This invention relates to pipe lining for renovating or rehabilitating pipes or other conduits bearing, for example, water, gas, sewage or other fluids. The invention is particularly applicable to pipe liners for underground pipes.
When such underground pipes have deteriorated by, for example, corrosion, ageing or other damage, repair or renewal by methods which require the digging of a trench along the full length of the pipe are expensive, timeconsuming and cause disruption especially in urban areas.
Various methods exist to rehabilitate pipes by the in situ insertion of a pipe liner which fits closely within the pipe and which may be bonded to the inside of the pipe. Several processes exist whereby relatively rigid plastics lining pipes made from polyethylene or similar materials, are treated to reduce their original diameter sufficiently so that they can be pulled into the existing pipe and then further treated to regain their original diameter and form a close internal fit with the existing pipe.
A previously proposed collapsed pipe liner is illustrated in FIG. 1 of the drawings. Such liners have a smaller bend radius than a circular cross-section liner, require lower pull-in loads and may be used for lining pipes which are not truly circular in cross-section. However, such liners need to have relatively thin walls in order to be deformable into the described cross-sections and this limits their mechanical performance in terms of their ability to withstand internal or external pressure when unsupported. By way of clarification external pressure may be considered to be derived from loads transmitted through a saturated sub-soil from, for example, the vehicles on a roadway above. This external pressure can result in collapse of the liner if it is not sufficiently rigid.
A disadvantage with such systems is that the liners have a large bending radius due to their rigidity and circular cross-section. The diameter is only slightly less than the diameter of the pipe to be lined and, thus, long lengths of liner have very large coil diameters which is both inconvenient for delivery and use on site. Furthermore, insertion is difficult because of the small diameter difference between the pipe and the liner.
Underground pipe renovation using a relining technique requires first, the provision of suitable relining materials for the main pipeline. Secondly, tappings or branch attachments and a means of attaching them to pipes leading from the main relined pipeline to individual units such as houses, etc. and thirdly an integrated system for inserting such linings into the existing pipe and fixing such lateral attachments to the pipeline after it has been relined.
A further disadvantage of current systems is that the processes of insertion of the line and branch connections may allow the ingress of external soil and dirt requiring additional cleansing processes before the renovated pipeline system can be used for conveying water suitable for drinking and domestic and industrial use.
It is therefore an object of the present invention to provide pipe relining materials capable of easy insertion in long lengths. It is a further object of this invention to provide a hygienic inner surface without the need for further extensive cleaning and sterilisation after the pipe has been lined.
According to the present invention there is provided a method of lining a pipe comprising collapsing a tubular liner so that the liner comprises a pair of adjacent liner portions defining a middle region connected by longitudinally extending lobes, folding both lobes laterally onto the middle region so that the lobes lie in a laterally opposed relationship in the middle region, advancing the collapsed and folded liner along the pipe to be lined and unfolding and urging the liner against the internal surface of the said pipe.
A liner collapsed and folded in this way has a significantly reduced bending radius and can be inserted in a pipe to be lined at a more acute angle, saving on the space required at either end of the pipe.
Preferably, the

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