Method of installing pipes

Details Method of installing pipes Method of installing pipes

1998-02-23

2001-01-09

Maki, Steven D. (Department: 1733)

Adhesive bonding and miscellaneous chemical manufacture

Methods

Surface bonding and/or assembly therefor

C015S104330, C029S234000, C029S468000, C138S097000, C156S294000, C156S423000, C254S13430R

Reexamination Certificate

active

06171435

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to installing pipes.
More particularly, the invention relates to installing a plastic service pipe in an existing metallic e.g. steel service pipe.
BACKGROUND OF THE INVENTION
Typically the service pipe is a gas service pipe connected by a tee or bend to a cast iron main. Where the main has been lined with a plastic liner, the service pipe is required to have a plastic pipe installed inside it. An aperture is cut through the wall of the liner at each tee or bend (where the tee or bend joins the main) so that each aperture is aligned with the tee or bend. The cutting of such apertures is achieved, for example, using a machine which travels along inside the plastic liner.
SUMMARY OF THE INVENTION
The invention is not limited to installing gas service pipes but is applicable to water, sewage or other service pipes, for example.
According to the invention there is provided, a method of installing a plastic service pipe in an existing service pipe which extends from an existing aperture in a main containing a plastic liner to an open end, the method comprising inserting a flexible assembly through the open end and along the existing service pipe, feeding a plastic service pipe fitted over said flexible assembly along said flexible assembly through the open end and through said existing service pipe to a position at an aperture in the plastic liner aligned with the existing aperture, and at which position at least a leading portion of the flexible assembly enters said liner through the aperture therein and a leading end of the plastic service pipe can be joined to the liner at the said aperture in the liner, said flexible assembly comprising a first, flexible, coiled wire member having at its leading end a second, flexible, coiled wire member, the stiffness of the second coiled wire member being less than the stiffness of the first coiled wire member, the second coiled wire member having at its leading end a ball-and-socket connection formed of a ball element and a socket element of which one leads the other and is connected to a weight, said leading portion comprising said second coiled wire member, the ball-and-socket connection and said weight, and the arrangement being such that when the flexible assembly, except for said leading portion, is supported in an horizontal position and the leading portion is unsupported except for its connection with the remainder of the flexible assembly, the leading portion is deflected downwardly by gravity.
A flexible assembly for use in performing the method according to the invention comprises a first, flexible, coiled wire member having at its leading end a second, flexible, coiled wire member, the stiffness of the second coiled wire member being less than the stiffness of the first coiled wire member, the second coiled wire member having at its leading end a ball-and-socket connection formed of a ball element and a socket element of which one leads the other and is connected to a weight, said leading portion comprising said second coiled wire member, the ball-and-socket connection and said weight, and the arrangement being such that when the flexible assembly, except for said leading portion, is supported in a horizontal position and the leading portion is unsupported except for its connection with the remainder of the flexible assembly, the leading portion is deflected downwardly by gravity.
The existing service pipe may be joined to the main in many different ways. For example, the service pipe may be straight, and may join the main by being directly joined to it at an aperture through the wall of the main. The service pipe may have a swept bend in it, particularly adjacent the main. For example, the existing service pipe may be connected to the main at the top of the main and then have a swept bend to enable the service pipe to continue its run along a horizontal path. Alternatively, a tee connection may be connected to the main, e.g. at the top of the main. The tee connection, in effect, provides an internal path which changes abruptly in direction from a first direction say vertical to a second direction at right angles to the first extending in the horizontal direction.
The service pipe may have swept bends in it in order to negotiate obstacles in its path and for convenience. Often, the change in direction of the path of the service pipe is made by the use of one or more right-angle elbows each of which connect two straight lengths of pipe together at right-angles, instead of bending the pipe.
The plastic service pipe used depends on the operating conditions of the gas system as well as the size of existing service pipe, its length and the number and kind of the bends, tee joints or elbows in it. For example, plain polyethylene pipe may be used but, depending on its diameter and the number and kind of bends, tee joints or elbows present in the existing service pipe, difficulty be may experienced in persuading the plastic pipe to negotiate the various changes in direction of the existing service pipe. A thinner or more flexible material may be used for the plastic service pipe and the diameter of the plastic service pipe may be reduced, particularly where higher gas pressures are to be used in the completed system.
Another possibility is to use a plastic service pipe which has, at least at its leading end, a corrugated wall which enables the pipe more readily to negotiate bends, elbows and tee connections. A further possibility is to use a plastic service pipe which has a corrugated wall throughout its length or which has a corrugated wall containing means providing a plain bore to the pipe such as a plain inner wall.
In cases where the existing service pipe presents difficulties to the plastic service pipe's advance through it, for example where elbows are present or where there is a tee joint, apparatus may be used comprising a flexible assembly or a coiled wire member. Either the flexible assembly is inserted through the existing service pipe first and then the plastic service pipe is inserted over the flexible assembly or the flexible assembly is inserted first of all in the plastic service pipe and then the two are inserted together through the existing service pipe.


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