portions between adjacent annular grooves of each pipe GASKETS USED IN JOINING CORRUGATED PIPE end.
While O-ring and flat gaskets are commonly used for FIELD OF THE INVENTION such pipe joints, they do not consistently provide the
The present invention relates to elastomeric gaskets, 5 seal integrity (i.e. tightness) desirable for such pipe and more specifically to gaskets for sealing a joint be- joints. Pipe joints formed with these gaskets are known tween two pipes, such as corrugated storm sewer pipe. to leak- Therefore, there is a need to provide a gasket
which more reliably seals such pipe joints or at least BACKGROUND OF THE INVENTION aiiows only ininimal leakage.
It is known to join two pipes together end-to-end by 10 SUMMARY OF THE INVENTION
forming a joint between a circumferentially adjustable
annular band and the ends of the two pipes. Typically, This invention is directed to an elastomeric gasket the annular band used in these joints has two end edges which will provide a better seal in a joint between an and two annular side edges. When the band is circum- J5 annular band and annularly grooved ends of two ferentially adjusted, the two end edges move relative to lengths of pipe positioned end-to-end. An elastomeric one another. Such joints have been sealed by trapping gasket of the present invention forms an adequate seal in an elastomeric gasket between an outside surface of the such a joint with the same compressive force being two pipe ends and an inside surface of the annular band. exerted by the annular band.
These joints have been used to join annularly 2Q According to this invention, a profile gasket is progrooved ends of corrugated pipe in storm sewer sys- vided for forming a seal in a joint between an annular tems. The annular band typically used with such corru- band and annularly grooved ends of two pipes posigated pipe has a generally flat inside surface between tioned end-to-end. The profile gasket comprises a sheet two annular ribs, one rib running alongside each side of elastomeric material having a bottom surface with at edge. These two annular ribs are spaced far enough 25 least two integrally molded and laterally spaced ridges apart to mate with one annular groove on each pipe end running along its length. The bottom surface is adapted to help prevent the resulting joint from being pulled to form a seal in the joint by being circumferentially apart. The joints in storm sewer systems are generally extended completely around both of the pipe ends, with expected to withstand water pressures up to a maximum one 0f the ridges disposed in an annular groove at each of about 15 psi with only minimal leakage allowed. Two 30 pipe end. The bottom surface of the sheet is then corntypes of gaskets have been used to seal the joints of such pressed against an outside surface of the two pipe ends systems, O-ring gaskets and flat gaskets. A typical O- ^ trapped between the annular band and pipes by ring gasket has a continuous O-shape, with a circular reducing the circumference of the adjustable annular cross-section. A typical flat gasket has a flat top and band With these ridges on &e bottom surface, the gasbottom surface that are generally parallel and two side 35 ket has more surface area to contact and seal against the edges, giving the gasket a generally rectangular cross pipe ends Because there is more surface area in contact, section. tjje sea| formed will be less affected by irregularities in
When O-ring gaskets are used to seal such storm tfae sha of the yes at ^ • end ^
sewer pipe joints, at least two gaskets are used, with &d(Mon> the closer the proflle of the ^Kom surface of each gasket being seated m one of the annular grooves 40 ^ sheet ^ fl]e of ^ ... surface of
on each pipe end. When the joint is formed, each O-ring ±e tWQ j end thfi less ^ ^ forCf5j b ^ gasket is positioned between its respective annular TM ig ^ tQ ad ^
groove and a portion of the flat mside surface of the one embodiment of the t the
band. One advantage of using O-nng gaskets is that they ,it. ^ 1 * * ^ ^ . 2
, . . ° , e . j , . ., . . . ket has at least two seating portions, with each seating
can be pre-positioned on the pipe end before the joint is 45 .. ^ ,. , . „ i c ■ . „
Li J • .t e u n J u 1 • *i. * portion extending laterally from one of the integrally
assembled in the field. However, one drawback is that u , ■, T i^ -^i. i. ^ • the O-ring gaskets, by themselves, do not provide a moWed ridges. A gasket with such seating portions is wmpletelealforthejomtReducrngthecircumference Preferably used with an annular band having annular of the annular band compresses each O-ring gasket nbs" *fch of these «ata« Porton,s * adaPted for djfP0; between only a trough portion of its respective annular 50 Slt\0n betwefn such a nb fonned m jhe aannlar band groove and a portion of the inside flat surface of the and an annular groove at the pipe ends annular band. Additional steps must be taken to sepa- In another embodiment the gasket sheet comprises rately seal the two end edges of the annular band when *TM> longitudinal pieces with each piece having integral O-ring gaskets are used. This can be accomplished by ndSes for seahnS &e Jomt Llke the O"TM^ gaskets, applying a sealant between the two end edges. 55 ^ such Pieces would re(luire separate steps to
Unlike the O-ring gaskets, the single piece flat gasket seal the end edSes of the annular band but would also is used, when the flat gasket is used, the flat gasket aUow each gasket piece to be pre-positioned on each forms a seal in the joint by being circumferentially ex- pipe end before the pipe joint is formed in the field, tended completely around both of the pipe ends, with However, such a two-piece gasket sheet with integralthe side edges of the gasket extending out beyond at 60 ly-formed ridges would also seal better than two stanleast a portion of the annular grooves on each pipe end dard O-ring gaskets or even a two piece flat gasket, which mate with the two annular ribs on the band. because there is still greater surface area making sealing Thus, no separate steps are required to seal the end contact between the band and the pipe ends than that edges of the annular band. A portion of the gasket along found with standard O-rings or flat gaskets each side edge is sandwiched between one of the annu- 65 The objectives features and other advantages of the lar band ribs and its mating annular pipe groove. The present invention will become apparent upon considerbalance of the bottom surface of the flat gasket between ation of the detailed description and appended drawthe two band ribs usually only contacts upper or crest ings.