Pipes and tubular conduits – Repairing – Patches
Patent
1997-02-24
1998-11-24
Brinson, Patrick F.
Pipes and tubular conduits
Repairing
Patches
138 97, 156294, 156287, 264269, 264516, F16L 5516
Patent
active
058394753
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method of and apparatus for lining a pipe with a polymer liner.
The method is applicable, for example, to lining a buried gas, water or sewage pipe. Such pipes are made of cast iron or steel or particularly, in the case of water, of asbestos cement or concrete for example, and particularly cast iron pipes may be lined with bitumen or concrete.
In British Gas patent application GB-A-2186340 there is described a method applicable to buried gas, water or sewage pipes in which a length of synthetic resin liner is heated, pulled through a die and through the pipe to be lined and pressurised to cause it to expand into engagement with the internal wall of the pipe.
In U.S. Pat. No. 3,462,825 (Pope et al) there is described a method applicable to the lining of flexible or rigid pipes in the factory by pulling a liner through a die and through the pipe and then releasing the liner pipe, whereupon the liner pipe expands into tight engagement with the internal wall of the pipe. The pipe was of relatively small diameter, having an inside diameter of 2.06 inches (51.5 millimeters) and the liner pipe had an outside diameter of 2.3 inches (57.5 mm). The liner pipe was relatively thin, having a wall thickness of 0.07 inch (1.75 mm) giving a Standard Dimension Ratio (SDR) of 33. The liner pipe was of fluorocarbon. In general, the outside diameter of the liner pipe was 10 to 15% greater than the inside diameter of the pipe to be lined.
In British patent specification No. 807 413 (Tubovit Societa per Azioni) there is described a method applicable to the lining of metal pipes in the factory by pulling a heater line pipe through a die and through a pipe to be lined, releasing the liner pipe, and heating the liner pipe. The die diameter is the same as the pipe to be lined or very slightly less. The liner is of polyvinyl chloride very slightly larger than the pipe to be lined and is 3 mm thick or less. The liner is heated before or during the die reduction to a temperature at which it is relatively soft and the force used to pull it through the pipe is only relatively low.
In GB 2186340 such die swell as does occur after the main die is eliminated by the effect of the second die which makes the diameter of the throat, in each case, the diameter which does into the pipe. In U.S. Pat. No. 3,462,825 and GB 807 413, no die swell is shown and the diameter which goes into the pipe is the diameter of the throat. Die swell is the increase in diameter which the liner undergoes after passing through the die.
Our patent No. EP-B-0341941 describes a method of lining a buried pipe with a polymer liner, which comprises pulling a length of liner through a die to reduce its diameter and through the pipe and on removal of the pulling load allowing the liner to revert to at least the minimum internal diameter of the pipe, the liner having a maximum diameter before the die and a minimum diameter in the die, and the die having a central, longitudinal die axis and comprising an entry and a throat which are symmetrical about said axis, the entry decreasing in diameter towards said throat characterised in that the die also comprises an exit which increases in diameter away from said throat and the liner having an intermediate diameter after the die before the liner enters the pipe, the force of pulling being such as partially to restrain die swell of the liner after its emergence from the throat, and the liner bending inwards before first contacting the die at the entry, then leaving the entry before continuously bending through its minimum diameter as it passes the throat, and then undergoing die swell resulting in said intermediate diameter, which enters the pipe.
In that method, the liner bends as it passes through the die.
The present invention modifies the invention described in EP-B-0341941 in that the strain in the liner due to its bending is introduced into the liner more gradually compared with the method described in EP 0341941B. This is achieved using a die in which the entry is curved instead of straight.
Dies ha
REFERENCES:
patent: 2249510 (1941-07-01), Welker
patent: 3462825 (1969-08-01), Pope et al.
European Patent Applications #341,941 McGuire, Nov. 1989.
European Patent Application # 266,951 Whyman. May 1988.
Hicks Kenneth
Maine Leslie
Brinson Patrick F.
British Gas plc
Hinds William R.
Holt William H.
LandOfFree
Method and apparatus for lining a pipe with a polymer linear does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for lining a pipe with a polymer linear, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for lining a pipe with a polymer linear will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1694091