WO2001079737A1

WO2001079737A1 - Bell and spigot pipe joint and method of sealing

Info

Publication number: WO2001079737A1
Application number: PCT/US2001/012419
Authority: WO
Inventors: Thomas P. Kearns
Original assignee: Bidco Plastic Extrusion, Inc.
Priority date: 2000-04-18
Filing date: 2001-04-17
Publication date: 2001-10-25
Also published as: CA2406406A1; AU2001253570A1

Abstract

A method for sealing a bell and spigot pipe joint comprises providing a gasket (26,126,226) having a bell-engageable portion (40,140,240), a spigot-engageable portion (42,142,242), and a stiffening portion (44,144,244). The stiffening portion has a first durometer hardness. The bell-engageable portion has a durometer hardness less than the first durometer hardness. The spigot-engageable portion has a durometer hardness less than the first durometer hardness. The bell-engageable portion, spigot-engageable portion, and stiffening portion are formed by co-extrusion. The gasket has an outer surface portion (46). The outer surface portion has a diameter D1 when the gasket is in a non-compressed condition. The method further comprises inserting the gasket into a bell (30) of a first pipe section (22), and inserting a spigot (34) of a second pipe section (24) through the gasket. Upon insertion of the spigot through the gasket, the spigot-engageable portion of the gasket is in engagement with a seat section (36) of the spigot and the bell-engageable portion of the gasket is in engagement with a seat section (32) of the bell. The seat section of the bell has a diameter D2 less than the diameter D1. The insertion of the spigot through the gasket occurs after insertion of the gasket into the bell.

Description

BELL AND SPIGOT PIPE JOINT AND METHOD OF SEALING

Background Of The Invention

This invention relates to bell-and-spigot pipe joints having flexible fluid- type seals.

Storm and sanitary sewer pipe sections are generally made of plastic, metal, concrete, or other suitable materials fabricated in configurations and sizes to meet particular requirements or specifications. Such pipe sections typically include a spigot (a male end) or a bell (a female end) adapted to receive a spigot. Resilient seals are typically provided by rubber or polymeric gasket elements. O-ring type gaskets are one type of resilient seal that is frequently employed. A gasket can be mounted on the spigot and then the spigot pushed into the bell.

The pipe sections are usually transported to a jobsite (e.g., a - construction site) in an unassembled condition and then joined together at the jobsite. Often the gaskets are placed on the spigots before transportation to the jobsite to minimize assembly time at the jobsite. A problem associated with transporting or storing pipe sections with gaskets already on the spigots is that the gaskets are occasionally damaged by careless handling or by prolonged exposure to the sun. Placing conventional gaskets in the bell of the pipe sections rather than on the spigots before transportation has not been a viable alternative because such conventional gaskets have not been sufficiently stiff to remain in the bells.

Summary Of The Invention

Among the several advantages and features of the present invention may be noted the provision of an improved method of sealing a bell-and- spigot joint; the provision of such a method which overcomes the disadvantages associated with prior art methods of sealing bell-and-spigot joints; the provision of such a method which resists damage to a gasket of the joint during transportation and storage; and the provision of an improved bell- and-spigot joint which overcomes the disadvantages of the prior art. Generally, a method of the present invention is for sealing a bell-and- spigot pipe joint. The method comprises providing a gasket having a bell- engageable portion, a spigot-engageable portion, and a stiffening portion. The stiffening portion has a first durometer hardness. The bell-engageable portion has a durometer hardness less than the first durometer hardness. The spigot-engageable portion has a durometer hardness less than the first durometer hardness. The bell-engageable portion, spigot-engageable portion, and stiffening portion are formed by co-extrusion. The gasket has an outer surface portion. The outer surface portion has a diameter D1 when the gasket is in a non-compressed condition. The method further comprises inserting the gasket into a bell of a first pipe section, and inserting a spigot of a second pipe section through the gasket. Upon insertion of the spigot through the gasket, the spigot-engageable portion of the gasket is in engagement with a seat region of the spigot and the bell-engageable portion of the gasket is in engagement with a seat region of the bell. The seat region of the bell has a diameter D2 less than the diameter D1. The insertion of the spigot through the gasket occurs after insertion of the gasket into the bell.

Another aspect of the present invention is a pipe joint comprising a first pipe section, a second pipe section, and a gasket. The first pipe section has a bell. The bell includes a bell seat region. The bell seat region has a diameter D2. The second pipe section has a spigot adapted for insertion into the bell of the first pipe section. The spigot includes a spigot seat region. The gasket has a bell-engageable portion, a spigot-engageable portion, and a stiffening portion. The stiffening portion has a first durometer hardness. The bell-engageable portion has a durometer hardness less than the first durometer hardness. The spigot-engageable portion has a durometer hardness less than the first durometer hardness. The bell-engageable portion, spigot-engageable portion, and stiffening portion are formed by co- extrusion. The gasket has an outer surface portion. The outer surface portion has a diameter D1 when the gasket is in a non-compressed condition. The diameter D1 is greater than the diameter D2. The spigot-engageable portion of the gasket is in engagement with and surrounds the seat region of the spigot. The bell-engageable portion of the gasket is in engagement with and surrounded by the seat region of the bell. The gasket, bell, and spigot are adapted such that the gasket is inserted into the bell before insertion of the spigot into the bell.

Other objects and features will be in part apparent and in part pointed out hereinafter.

Brief Description Of The Drawings

Fig. 1 is an exploded, fragmented, section view of a gasket and first pipe section of a pipe joint of the present invention;

Fig. 2 is an enlarged, fragmented, section view of the pipe joint of Fig. 1 , showing the gasket inserted in a bell of the first pipe section and showing a spigot of a second pipe section of the pipe joint being inserted into the bell of the first pipe section;

Fig. 3 is a section view similar to that of Fig. 2 but showing the pipe joint in a fully assembled position; Fig. 4 is an enlarged section view of the gasket of Fig. 1 ; Fig. 5 is an enlarged section view of another embodiment of a gasket of the present invention; and

Fig. 6 is an enlarged section view of another embodiment of a gasket of the present invention. Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Detailed Description Of The Preferred Embodiment

Referring now to the drawings, and first more particularly to Figs. 1-4, a pipe joint of the present invention is indicated generally be reference numeral 20. The pipe joint 20 comprises a first pipe section generally indicated at 22, a second pipe section generally indicated at 24, and a gasket generally indicated at 26. Preferably, the pipe sections 22, 24 are large diameter corrugated polymeric pipe sections of the type commonly used in sewer systems. The first pipe section 22 has a bell 30. The bell 30 includes a bell seat region 32. The bell seat region 32 constitutes the annular, inner surface portion of the bell 30 sealingly engaged by the gasket 26 upon complete assembly of the pipe joint 20.

The second pipe section 24 has a spigot 34 (Figs. 2 and 3). The spigot 34 is sized and shaped for insertion into the bell 30 of the first pipe section 22. The spigot 34 including a spigot seat region 36. The spigot seat region 36 constitutes the annular, outer surface portion of the spigot 34 sealingly engaged by the gasket 26 upon compete assembly of the pipe joint 20.

The gasket 26 has a bell-engageable portion 40, a spigot-engageable portion 42, and a stiffening portion 44. The stiffening portion 44 has a first durometer hardness. The bell-engageable portion 40 has a durometer hardness less than the first durometer hardness. The spigot-engageable portion 42 has a durometer hardness less than the first durometer hardness. The bell-engageable portion 40, the spigot-engageable portion 42, and the stiffening portion 44 are simultaneously formed by co-extrusion. The gasket 26 has an outer surface portion 46. Preferably, the bell-engageable portion 40 constitutes the outer surface portion 46. The outer surface portion 46 has a diameter D1 (Fig. 1) when the gasket is in a non-compressed condition. The bell seat region 32 has a diameter D2. The diameter D1 is greater than the diameter D2. The stiffening portion 44 of the gasket has an outer surface portion having a diameter D3 when the gasket is in the non-compressed condition. The diameter D3 is less than the diameter D2. Preferably, the stiffening portion 44 is sufficiently stiff or rigid to compress the outer surface portion 46 against the bell seat region 32 when the gasket 26 is in position in the bell 30. More particularly, the stiffening portion 44 is sufficiently stiff so that its compression of the outer surface portion 46 against the bell seat region 32 retains the gasket in the bell 30 even before insertion of the spigot 34 into the bell, and without substantial reduction in the diameter of the stiffening portion (e.g., without reducing the compressed outer surface portion to a diameter less than that of the spigot).

Preferably the stiffening portion 44 comprises a substrate 50 of a first elastomer, and the bell-engageable portion 40 and the spigot-engageable portion 42 respectively comprise outer and inner beads 52, 54 of a second elastomer on opposite faces of the substrate. The substrate 50 may be of polypropylene, high density polyethylene (HDPE) or any other suitable stiff material. Preferably, the substrate 50 has a durometer hardness of at least about 40 Shore D, and more preferably has a durometer hardness of about 50 Shore D. The outer and inner beads 52, 54 are preferably of a suitable thermoplastic elastomer such as ethylene propylene diene monomer (EPDM) having a durometer hardness of about 40 to 70 Shore A and more preferably having a durometer hardness of about 55 Shore A. Although the gasket 26 shown in Figs. 1-3 is shown with the bell-engageable portion 40 and the spigot-engageable portion 42 as being portions of separate elements of the gasket 26, it is to be understood that the bell-engageable portion and the spigot-engageable portion may be different portions of a single unitary elastomeric element joined to the substrate. The gasket 26 is formed by co-extrusion. Formation of the gasket 26 as well as some additional materials for forming the gasket is described in greater detail in co-pending U.S. Patent Application Serial Number 09/105,500, filed July 2, 1999 and titled CO-EXTRUDED DUAL DUROMETER HARDNESS PIPE GASKET, incorporated by reference in its entirety as if specifically set forth herein. In the assembled pipe joint 20 as shown in Fig. 3, the spigot- engageable portion 42 of the gasket 26 is in engagement with and surrounds the spigot seat region 36, and the bell-engageable portion 40 of the gasket is in engagement with and surrounded by the bell seat region 32. The gasket 26, bell 30, and spigot 34 are adapted such that the gasket is inserted into the bell before insertion of the spigot into the bell. Upon insertion of the spigot 34 into the bell 30, the gasket 26 is compressed between the bell seat region 32 and the spigot seat region 34 when the bell-engageable portion 40 of the gasket is in engagement with bell seat portion and the spigot-engageable portion 42 is in engagement with the spigot seat portion. In practice, the gasket 26 is inserted into the bell 30 of the first pipe section 22. Preferably, this insertion step takes place at a first site such as a pipe manufacturing plant where the pipe sections are manufactured. The first pipe section 22 and the inserted gasket 26 are then transported to a work site, such as a construction site, where the pipe sections are connected to form a piping system. Because of the stiffness of the stiffening portion 44, the gasket 26 is retained in the first pipe section 22 even when the first pipe section is subject to abuse typical during transportation. Although the stiffness of the stiffening portion is sufficient to retain the gasket in the first pipe section 22, it may be desirable to weld the gasket to the inside of the bell 30 to further resist removal of the gasket from the first pipe section. Because of the materials selected for the gasket 26, the gasket is adapted to be welded to conventional polymeric corrugated pipe section. Preferably, the welding step would be performed at the first site. At the work site, the spigot 34 of the second pipe section 24 is inserted through the gasket 26 such that the spigot-engageable portion 42 of the gasket is in engagement with the spigot seat region 36 and the bell-engageable portion 40 is in engagement with the bell seat region 32. Because of the shapes and sizes of the gasket, bell and spigot, the gasket is compressed between the spigot seat region 36 and the bell seat region 32 to provide a fluid tight seal all around gasket to prevent fluid leakage between the first and second pipe sections 22, 24. A second gasket of the present invention is generally indicated at 126 in Fig. 5. The second gasket 126 has a bell-engageable portion 140, a spigot- engageable portion 142, and a stiffening portion 144. A third gasket of the present invention is generally indicated at 226 in Fig. 6. The third gasket 226 has a bell-engageable portion 240, a spigot-engageable portion 242, and a stiffening portion 244. Other than shape, the second and third gaskets 126, 226 are similar to the gasket 26 of Figs. 1-4 and function and operate in the same manner. Thus, the description and function described above with respect to the gasket 26 is equally applicable to the second and third gaskets 126, 226. Although gaskets of only three different shapes have been specifically shown and described herein, it is to be understood that gaskets of different shapes or materials may be employed without departing from the scope of this invention.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained. As various changes could be made in the above constructions and methods without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. The invention therefore shall be limited solely by the scope of the claims set forth below.

Claims

What is claimed is:

1. A method of sealing a bell-and-spigot pipe joint, the method comprising: providing a gasket having a bell-engageable portion, a spigot- engageable portion, and a stiffening portion, the stiffening portion having a first durometer hardness, the bell-engageable portion having a durometer hardness less than the first durometer hardness, the spigot-engageable portion having a durometer hardness less than the first durometer hardness, the bell-engageable portion, spigot-engageable portion, and stiffening portion being formed by co-extrusion, the gasket having an outer surface portion, the outer surface portion having a diameter D1 when the gasket is in a non- compressed condition; inserting the gasket into a bell of a first pipe section; inserting a spigot of a second pipe section through the gasket such that upon insertion of the spigot through the gasket the spigot-engageable portion of the gasket is in engagement with a seat region of the spigot and the bell- engageable portion of the gasket is in engagement with a seat region of the bell, the seat region of the bell having a diameter D2 less than the diameter D1 , the insertion of the spigot through the gasket occurring after insertion of the gasket into the bell.

2. A method as set forth in claim 1 wherein the step of inserting the gasket into the bell comprises inserting the gasket into the bell when the gasket and first pipe section are at a first site, and wherein the step of inserting the spigot through the gasket comprises inserting the spigot through the gasket when the gasket and first and second pipe sections are at a work site, the work site being remote from the first location, the method further comprising the intermediate step of transporting the first pipe section and gasket from the first site to the work site.

3. A method as set forth in claim 1 wherein the stiffening portion of the gasket has an outer surface portion having a diameter D3 when the gasket is in the non-compressed condition, the diameter D3 being less than the diameter D2.

4. A method as set forth in claim 3 wherein the gasket is compressed between the seat portion of the bell and the seat portion of the spigot when the bell-engageable portion of the gasket is in engagement with the seat portion of the bell and the spigot-engageable portion is in engagement with the seat portion of the spigot.

5. A method as set forth in claim 1 wherein the step of inserting the gasket into the bell of the first pipe section comprises inserting the gasket into the bell of a first corrugated pipe section.

6. A method as set forth in claim 5 wherein the step of inserting the spigot of the second pipe section through the gasket comprises inserting the spigot of a second corrugated pipe section through the gasket.

7. A pipe joint comprising: a first pipe section having a bell, the bell including a bell seat region, the bell seat region having a diameter D2; a second pipe section having a spigot, the spigot being adapted for insertion into the bell of the first pipe section, the spigot including a spigot seat region; a gasket having a bell-engageable portion, a spigot-engageable portion, and a stiffening portion, the stiffening portion having a first durometer hardness, the bell-engageable portion having a durometer hardness less than the first durometer hardness, the spigot-engageable portion having a durometer hardness less than the first durometer hardness, the bell- engageable portion, spigot-engageable portion, and stiffening portion being formed by co-extrusion, the gasket having an outer surface portion, the outer surface portion having a diameter D1 when the gasket is in a non-compressed condition, the diameter D1 being greater than the diameter D2; the spigot-engageable portion of the gasket being in engagement with and surrounding the spigot seat region, the bell-engageable portion of the gasket being in engagement with and surrounded by the bell seat region, the gasket, bell, and spigot being adapted such that the gasket is inserted into the bell before insertion of the spigot into the bell.

8. A pipe joint as set forth in claim 7 wherein the stiffening portion of the gasket has an outer surface portion having a diameter D3 when the gasket is in the non-compressed condition, the diameter D3 being less than the diameter D2.

9. A pipe joint as set forth in claim 8 wherein the gasket is compressed between the seat portion of the bell and the seat portion of the spigot when the bell-engageable portion of the gasket is in engagement with the seat portion of the bell and the spigot-engageable portion is in engagement with the seat portion of the spigot.

10. A pipe joint as set forth in claim 7 wherein the bell-engageable portion and the spigot-engageable portion are both of a second durometer hardness.

11. A pipe joint as set forth in claim 7 wherein the stiffening portion comprises a first elastomer and wherein the bell-engageable portion and the spigot-engageable portion comprises a second elastomer, the second elastomer being a thermoplastic elastomer.

12. A pipe joint as set forth in claim 11 wherein the first elastomer has a durometer hardness of at least about 40 Shore D.

13. A pipe joint as set forth in claim 12 wherein the second elastomer has a durometer hardness of about 40 to 70 Shore A.

14. A pipe joint as set forth in claim 11 wherein the first elastomer comprises one of the set of polypropylene and high density polyethylene.

15. A pipe joint as set forth in claim 11 wherein the second elastomer comprises ethylene propylene diene monomer.