Hydraulic and earth engineering – Subterranean or submarine pipe or cable laying – retrieving,...
Reexamination Certificate
1997-05-13
2002-09-03
Tsay, Frank (Department: 3672)
Hydraulic and earth engineering
Subterranean or submarine pipe or cable laying, retrieving,...
C405S184000
Reexamination Certificate
active
06443657
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to replacement or rehabilitation of existing underground pipe.
BACKGROUND OF THE INVENTION
Underground pipes, such as gas, sewer or water mains periodically need replacement or rehabilitation due to leakage caused by cracks if increased service capacity is needed. Replacement or rehabilitation of underground pipes is traditionally cumbersome, in part, because often times the underground pipe must be unearthed for removal.
Methods and equipment have been developed which facilitate the replacement of underground pipe without the need to unearth the entire length of pipe. Such methods and apparatus are described in, for example, U.S. Pat. No. 4,789,268 to Yarnell and U.S. Pat. No. 4,738,565 to Streatfield. As best illustrated in
FIG. 1
, each of these methods involve digging trenches
14
and
15
on opposite sides of a section of pipe
16
which needs replacement. It is not uncommon for such trenches to be 10-30 feet deep in practice with lengths of 14 feet and widths of six feet or more. A frustro-conical section
10
, having a constant tension guide cable
12
attached at one end, is passed through the section of pipe
16
being replaced. Guide cable
12
is also attached to a winch. Pipe
16
is cracked and/or fragmented with the fragments or pieces pushed into the surrounding earth, and a new plastic or flexible pipe
11
pulled into place. This process is commercially known as pipe bursting.
The operation extends from trench
14
, to trench
15
and completely replaces the pipe therebetween. Each trench provides a location from which the pipe fracturing apparatus may be launched or inserted and then retrieved or removed. The methods and apparatuses of both U.S. Pat. No. 4,789,268 to Yarnell and U.S. Pat. No. 4,738,565 to Streatfield eliminate the need to completely dig up the old pipe in order to replace it. Because trenches
14
and
15
do not extend the length of pipe
16
this method is less expensive and less intrusive into the community served by the original pipe.
The “two trench” method illustrated in
FIG. 1
may also be used to line old pipe
16
with a slip liner pipe. The plastic liner operates to prevent leakage but has the drawback that the repaired main typically has a decreased capacity. Because lining the pipe generally decreases the capacity of pipe
16
, the above described method of replacement or pipe bursting is often preferred.
Despite the convenience of the prior art over digging the old pipe out, the prior art methods still involve a degree of intrusiveness to the community because of the two adjacent trenches. Therefore, a need has arisen to decrease the inconvenience of replacing or rehabilitating pipe.
SUMMARY OF THE INVENTION
The present invention relates to a method of replacing existing or relining underground pipe. The existing pipe is surrounded by soil and includes a lumen and an associated longitudinal axis. The method includes the steps of forming a diagonal pilot hole between the existing pipe and an upper ground surface, forcing a ramming and fracturing tool through the pilot hole and existing pipe, where the ramming and fracturing tool is operative in placing a new pipe having an associated longitudinal axis so that the associated longitudinal axis of the new pipe is substantially the same as the longitudinal axis of the existing pipe. The section of pipe to be replaced generally runs from manhole to manhole.
The method of the present invention may also include the step of passing a guide cable having a proximal end and a distal end through the existing pipe and pilot hole. The proximal end of the cable is attached to a winch, and the distal end of the cable is attached to the ramming tool, so that the guide cable guides the ramming tool through the existing pipe and maintains an assistive force to the tool to provide a constant pressure against the pipe to be broken. After the existing pipe has been replaced, the ramming tool and guide cable may be removed through a manhole.
REFERENCES:
patent: 2027063 (1936-01-01), Reifel
patent: 3894402 (1975-07-01), Cherrington
patent: 3996758 (1976-12-01), Cherrington
patent: 4043136 (1977-08-01), Cherrington
patent: 4221503 (1980-09-01), Cherrington
patent: 4287953 (1981-09-01), Mazza
patent: 4453603 (1984-06-01), Voss et al.
patent: 4493379 (1985-01-01), Reichman et al.
patent: 4505302 (1985-03-01), Streatfield et al.
patent: 4507019 (1985-03-01), Thompson
patent: 4637756 (1987-01-01), Boles
patent: 4720211 (1988-01-01), Streatfield et al.
patent: 4738565 (1988-04-01), Streatfield et al.
patent: 4789268 (1988-12-01), Yarnell
patent: 5282696 (1994-02-01), Solomon et al.
patent: 5302053 (1994-04-01), Moriarty
patent: 5328297 (1994-07-01), Handford
patent: 5375945 (1994-12-01), Cherrington
patent: 5403120 (1995-04-01), Stekette, Jr.
patent: 5427475 (1995-06-01), Coss
patent: 5439320 (1995-08-01), Abrams
patent: 5452967 (1995-09-01), Fuller
patent: RE35271 (1996-06-01), Fisk et al.
patent: WO 92/13226 (1992-08-01), None
Exhibit A: British Gas plc “Introducing Pipebursting” brochure (Jan. 1994).
Tsay Frank
TT Technologies, Inc.
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