Pipe joints or couplings – With casing – lining or protector – Lined
Reexamination Certificate
1998-12-04
2001-05-29
Browne, Lynne H. (Department: 3629)
Pipe joints or couplings
With casing, lining or protector
Lined
C285S123100, C285S123150
Reexamination Certificate
active
06237963
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention related to a service riser, particularly for use in the gas supply industry.
Gas is increasingly supplied through plastics pipes, especially polyethylene pipes although not exclusively so. The main advantage of plastics pipes is their resistance to corrosion and their flexibility. However where a plastics pipe is buried underground and rises to the surface to supply a house or other establishment, it is desirable to shield it. Also, of course, it requires an adapter at its end for connection to a meter or other equipment in the house. Indeed there are various regulations in different jurisdictions that require this additional protection at the transition from under- to over-ground.
Numerous patents describe such systems. For example U.S. Pat. No. 4,482,170 (Jacobson et al) discloses gas riser apparatus in which a metal tube is swaged to produce an internal step. The plastics pipe is terminated with an internal strengthening sleeve (to give the pipe radial compression strength), a collar then being swaged down around the end of the pipe, teeth on the collar biting into the plastics material. The end of the pipe is then pulled back into the metal tube with the collar then squeezing between itself and the internal step an elastomeric seal ring which thus seals the tube against the pipe. The tube then becomes the gas carrier and usual connection means are provided on the end of the tube for connection to a meter etc. The tube is finally indented or pinched onto the collar to retain the collar in position.
The tube is generally of mild steel meeting specific requirements but, usually, it has quite a wide tolerance on its dimensions. Thus, for example, a thread typically formed on its end is frequently tapered, at least partly so as to accommodate these wide tolerance.
U.S. Pat. No. 4,801,159 (Seborn) discloses another suitable arrangement, not dissimilar to the above-described arrangement. Other arrangements are disclosed in U.S. Pat. No. 4,519,634, U.S. Pat. No. 5,590,914 and EP-A-0539728.
Because the metal tube is at least partly taken underground it is necessary that it be provided with effective environmental protection. This is normally afforded by coating with an epoxy resin or the like or by galvanising the tube. In such a case a minimum of reworking should be effected when connecting the tube to the end of the gas pipe to avoid disturbing the environmental protection. However, some methods involve fitting an adapter to the end of the pipe and then welding the adapter to the tube. This of course renders re-application of protection necessary.
It is therefore an object of the present invention to provide a riser which is simple to construct, meets all relevant standards and requirements and has minimum disruption of the environmental seal.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is therefore provided a riser comprising:
a plastics pipe sealed inside a protective tube intermediate the ends thereof;
a retainer sleeve and compression band on the end of the pipe between them compressing the wall of the pipe and retaining and sealing the sleeve on the pipe; and,
an elastomeric band on the sleeve and compressed against the sleeve by a swaging of the tube.
Preferably, the sleeve is partially inserted in the pipe and said band is on an exposed end of the sleeve.
Preferably, the sleeve has at least one circumferential step overlapped by the band so that the band is compressed to different degrees. In that event, it is preferably compressed to a first, small degree on one side of the step and to a second larger degree on the other side of the step, an ideal compression degree for optimum sealing by said elastomeric band lying between said first and second degrees for all size tolerances of said sleeve, band and tube.
Preferably two steps are provided defining a groove. Indeed, there may be several axially spaced grooves along the sleeve. Moreover, the grooves may be of different depths.
Preferably, the sleeve is flared on at least one side of the swaging to resist withdrawal of the pipe in the direction of said swaging. However, preferably, the sleeve is flared at its end remote from said pipe.
Preferably the sleeve in contact with the pipe has a serrated profile so that, on being clamped between the sleeve and compression band, the material of the pipe cold-flows into the serrations of the sleeve.
Preferably, at least one groove is formed between serrations to receive an O ring elastomeric seal to seal the sleeve with respect to the pipe.
In another aspect, the invention provides a service riser for a gas line comprising a plastics material pipe, wherein the service riser comprises a metal tube surrounding and protecting the pipe and transferring the flow of gas from the pipe to the tube, the tube having two ends, one end having a connector for gas equipment and the other end surrounding the pipe, the end of the pipe terminating intermediate the ends of the tube at a transition joint, the transition joint comprising a transition sleeve partially inserted in the end of the pipe and having a compression band around the end of the pipe so that the end of the pipe is squeezed between the transition sleeve and compression band to retain and seal the sleeve in the pipe, the exposed end of the transition sleeve having a flared end, and circumferential grooves spaced from the said flared end, an elastomeric band being disposed on the exposed end, the tube being swaged around the exposed end so as to prevent pull out of the pipe from the tube, at least in the direction of the end thereof surrounding the pipe, and to compress the elastomeric band to seal the retainer sleeve to the tube.
REFERENCES:
patent: 1088491 (1914-02-01), Waitz
patent: 2226039 (1940-12-01), Wiltse
patent: 3834012 (1974-09-01), Pogonowski
patent: 4085950 (1978-04-01), Alewitz
patent: 4426761 (1984-01-01), Sassak
patent: 4482170 (1984-11-01), Jacobson et al.
patent: 4519634 (1985-05-01), Hand
patent: 4801159 (1989-01-01), Sehorn
patent: 4922971 (1990-05-01), Grantham
patent: 5135267 (1992-08-01), Wilson
patent: 5285744 (1994-02-01), Grantham et al.
patent: 5590914 (1997-01-01), Platner et al.
patent: 195 43 103 A1 (1996-10-01), None
patent: 0 539 728 A1 (1993-05-01), None
patent: 2 280 939 (1993-08-01), None
Browne Lynne H.
Fish & Richardson P.C.
Malcolm Tomlyne A
Uponor Innovation AB
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