Fluid handling – Processes – Cleaning – repairing – or assembling
Patent
1982-12-28
1985-09-17
Walton, George L.
Fluid handling
Processes
Cleaning, repairing, or assembling
137318, 285197, 408 67, 408207, F16K 4300, F16K 5100
Patent
active
045414475
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
This invention relates to a method and apparatus for use in connecting pipes and of particular use for connecting a pipe to a gas main while the main is pressurized.
BACKGROUND OF THE INVENTION
In the past pipe connection to a pressurized gas main has been achieved by means of a hot tap saddle fitting. That fitting provides a chamber which is mounted to the main pipe by a collar, the mouth of the chamber seating against the external wall of the pipe and sealing therewith. A drill bit inside the sealed chamber is operable from outside the chamber to drill radially into the main pipe. A subsidiary pipe to be connected with the main is connected to the chamber usually by coupling means integral with the fitting and the drill bit is then operated so as to pierce the main thereby placing the subsidiary pipe in communication with the interior of the main.
SUMMARY OF THE INVENTION
According to preferred embodiments the present invention provides a hot tap saddle fitting suitable for use with a main pipe made of plastics and which is of a simpler construction than previously known fittings of the type under discussion.
According to one aspect the invention consists in a hot tap saddle fitting of the kind comprising a chamber having an opening, the mouth of the opening being shaped for sealing engagement with the exterior of a plastics main pipe to be saddled, and piercing means within the chamber operable from outside the chamber to pierce the main pipe saddled whereby to place the interior of the main pipe in communication with the chamber,
said saddle fitting being characterised in that the piercing means comprise a cutter acting to cut the main pipe saddled in a chordal direction.
It has been found that by slicing the main in a chordal direction, rather than by drilling into it in a radial direction, a swarf free opening is obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
By way of example only an embodiment of the invention will now be described with reference to the accompanying drawings wherein:
FIG. 1 shows a cross-section of a saddle fitting according to the invention, and
FIG. 2 shows a part cross-section on line 2--2 of FIG. 1.
FIG. 3A is a top, cross-sectional view of a saddle fitting according to the invention, wherein the tubular cutter is midway through the process of cutting through a plastics main pipe;
FIG. 3B is a cross-sectional view of the tubular cutter illustrated in FIG. 3A along line 3B--3B;
FIG. 4A is likewise a top, cross-sectional view of a saddle fitting according to the invention, wherein the tubular cutter has completed its cutting stroke, and
FIG. 4B is a cross-sectional view of this saddle fitting taken along the line 4B--4B.
DESCRIPTION OF PREFERRED EMBODIMENTS
The fitting comprises a cylindrical split collar 1 adapted to sleeve a gas main. Collar 1 has a groove 10 on its internal surface extending in a direction parallel the cylinder axial direction and which facilitates hinge opening of the collar for positioning of the fitting to saddle a main pipe. Collar 1 has radially outwardly extending projections 11 adjacent the split whereby the collar may be clamped tightly to a gas main. For preference projections 11 are wedge shaped to facilitate tight clamping to a main pipe by clamp means not shown in the drawings.
An elongate tubular body 3 extends in the direction chordal to the circumference of collar 1 and defines a chamber 4 having an opening the mouth of which is defined by rim 14 which in use seals with a pipe saddled. Tubular body 3 extends to a pipe connection means 5 adapted for connection with a subsidiary pipe. In the present example connection means 5 is a spigot adapted for connection by the joining method described in co-pending application PCT/AU80/00020 but other connection fittings could be used.
Tubular body 3 extends from chamber 4 in a direction away from connection means 5 to house a hollow tubular cutter 6. Tubular cutter 6 has a cutting edge 61 at the end of adjacent chamber 4 of a radius less than the internal radius o
REFERENCES:
patent: 3692044 (1972-09-01), Wise
patent: 3905718 (1975-09-01), Luckenbill et al.
patent: 3983897 (1976-10-01), Gebelius
patent: 4067353 (1978-01-01), DeHoff
patent: 4076038 (1978-02-01), Wynne
patent: 4258742 (1981-03-01), Louthan et al.
patent: 4294470 (1981-10-01), Tucker
patent: 4415000 (1983-11-01), dmann
Erling Earl
Soumar Karel
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