Title of Invention

AN IMPROVED MECHANICAL JOINT COUPLING OF TWO TUBULAR ELEMENTS

Abstract

An improved mechanical joint coupling of two tubular elements (1,2) one of said tubular elements (1) having a spigot end and the other being provided with a socket (2); said coupling comprises a set of withdrawable pins (5) capable of being fixed in the holes (6) provided on the rim of said socket, a gasket (4) made of a resilient material being housed within the space between said two tubular elements and a circular pressure plate (3); said pins capable of holding the pressure plate (3) and the said gasket (4) in predetermined position and thus preventing said circular pressure plate and said gasket to loosen out of the annular space between said socket and spigot.

Full Text

This invention relates to joints and more particularly to pipe joints, which are widely known, as stuffing box type joints. This joint is used in jointing sections of pipes of socket and spigot type or plain ended wherein a collar type coupling is used. This invention would be applicable to pipes made of metal, particularly ductile iron, ceramic materials, concrete, plastic or other compositions. It is well known in the art to which this invention relates that difficulties have been encountered in providing a simple economical flexible joint for spigot and socket or plain-ended pipe which is required to withstand high pressure and which would not impart rigidity to the pipeline in which it is employed. For the last forty years, pipe joints for moderate pressure, such as those found in city water mains, have been push-on rubber gasket joint. Where higher pressures are employed it has been customary to restore to bolted flanged joint or mechanical joint, which is the stuffing box type. The common disadvantages experienced in the slip-on or push-on joints are as follows: (1) For successful performance of push-on joint, the pipe dimensions need to be maintained at very rigid tolerance. If the dimensions vary even slightly more than the close tolerances, or oval pipe, which, particularly possesses large diameter, ductile iron pipes often become, the joint cannot be assembled as a result the joint leaks; (2) The main disadvantages of push-on joint pipe is, this needs special tools for its assembly; (3) In case the gasket gets displaced during assembly, there is no easy method of checking; (4) In case of any leakage at the joint, there is no means for repair of the joint. The only remedy is, to cut out the joint part and replace it with a barrel pipe and two mechanical joint collars; and (5) The whole repair operation of leaking joint is time consuming and costly. Therefore, an object of the present invention is to mitigate the known disadvantages of the prior push-on joints as described hereinabove. Another object of the present invention is to provide an improved mechanical joint. A further object of the present invention is to provide an improvement to what is commonly known as the mechanical joint or bolted gland joint. A still further object of the present invention is to avoid the inherent disadvantages associated with the known mechanical joints. In the course of the investigations leading to the present invention it is found that all the disadvantages of push-on joint can be eliminated by the use of mechanical joint or commonly known as bolted gland joint. But there are disadvantages of this mechanical joint, which are as follows: (a) Since mechanical joint pipe needs a socket having a peripheral flange cast with the pipe, it needs a special mould to manufacture pipes to suit this type of joint by spun cast process. (b) The joint also needs a follower gland, which needs to be cast separately. ( c ) Both of the peripheral flange and follower gland are required to be drilled similar to flange drilling which calls for additional procedure, equipment and cost. (d) A set of tee headed bolts and nuts are necessary to complete the jointing. (e) The joint can be dismantelled very easily with a spanner by removing the nut. (f) The joint is not tamperproof. The mechanical joint so made is flexible and very efficient, but due to many accessories and additional machining its operational cost becomes very high. The invention disclosed hereafter describes how all the advantages of mechanical joint are retained, eliminating the disadvantages in the present invention. Accordingly, a principal object of this invention is to provide a pipe joint, which is free from the noted disadvantages applicable to joints as heretofore constructed. Another object of the invention is to improve the design of pipe joints of this character to render them more economical to manufacture, and to facilitate the assembly of pipe sections without requiring skilled labour for this purpose. Other object, characteristics and advantages of the invention are sufficiently explained in the following detail description and the accompanying drawings, which show representative embodiments. After consideration of these examples skilled persons will understand that many variations may be made without departing from the principles disclosed. According to this invention, there is provided an improved mechanical joint coupling of two tubular elements, one of said tubular elements having a spigot end and the other being provided with a socket; said coupling comprising a set of withdrawable pins capable of being fixed in the holes provided on the rim of said socket, a gasket made of a resilient material being housed within the space between said two tubular elements and a circular pressure plate; said pins being capable of holding the pressure plate and the said gasket in predetermined position and thus preventing said circular pressure plate and said gasket to loosen out of the annular space between said socket and spigot. In the approved mechanical joint coupling of the present invention the pressure plate is capable of rotation around its axis and is provided with multiple faces of different thicknesses. Further, for gasket of said Joint coupling is of wedge-shaped and made of rubber or like material and said withdrawal pins are preferably made of stainless steel. In the improving coupling of the present invention a skirt is adapted at the front end of said socket through which a stainless steel bolt passes, said bolt being capable of holding the pressure plate which is of uniform thickness and comprises of more than one part and said rubber gasket in the annular space between said socket and spigot in predetermined position. In the accompanying drawings: Figure 1 explains the old method of mechanical joint assembled tightened and compressed. In Fig. 1 there is illustrated a somewhat conventional metal pipe socket (1) having peripheral flange (2) with apertures (3,30 for securing bolts and a first inner shoulder (4) complementally engagable with inclined inner shoulder (5) of compressible gasket (6). The socket interior defines an opening wall of maximum radius relative to a center line of the joint, joining in a first conical shoulder (4) of declining radius said first conical shoulder terminating rearwardly in a second shoulder (5) of shortest radius, whereby to form within the socket a rearwardly extending recess for the plain pipe end. Gasket (6) has an opposed inclined outer shoulder (5). A ductile iron, or of similar material, gland (7) having peripheral apertures (8,8') aligned with socket apertures (3,3') is shown as having a conical, axial aperture which terminates short of its forward end to form in extension thereof an inclined peripheral abutment (10). As best illustrated in the Fig.1 assembly, gland (7) inner surface (10) complementally engages the outer rubber sealing gasket (6) as the bolts (11,12) are placed through apertures (3,3', 8,8') and are tightened by means of nuts (13,14). Standard tee headed bolts (11,12) are engaged through mating holes (3,30 and (8,8') in gland and pipe fitting. Now, as bolts (11,12) are tightened gland (7) is drawn inwardly toward socket (1). This assembly action continues. The complemental, substantial parallelism of opposed contacting and corresponding surfaces of gland gasket and socket facilitate meeting the advantages set forth below. Rubber gasket (6) is now tightly compressed into bell socket offering a flexible leak-proof joint. Fig.2 illustrates the basic invention. Fig.2 shows the components of the joint is assembled position. (1) This invention comprises an improved method of compressing the Rubber gasket in the socket and spigot combination to offer a flexible bottle tight leak proof joint. (2) The construction of the newly invented joint - eliminates the peripheral flange which is normally cast with the socket which had to be machined, faced and drilled. (3) In the new joint the follower gland is cast machined and thus drilling has been eliminated. (4) All the tee headed bolts and nuts are eliminated and instead a few stainless steel shear pins have been utilized. (5) The pressure plate made of stiff metal or nonmetal material, which presses the wedged shaped rubber gasket. The pressure plate can be made in parts out of plastic or plastic coated iron to eliminate deterioration due to corrosion. The pressure plate may be made of varying thickness so that, it can be rotated to increase the effective thickness of the plate and thereby make the joint tighter, suitable for higher pressure. For a particular maximum pressure rating the pressure plate thick- ness can be specified. If arrangement for variable pressure is necessary that can also done. (6) The overall cost of the joint is drastically reduced from the conven- tional mechanical joint. (7) Since tee headed bolts and nuts have been eliminated the tampering the joint by opening of the nut is not possible. But for a knowledge- able semiskilled technician the joint can be opened form outside by removing the shear pins with the help of a lever. The pressure rating can be changed by increasing the effective thickness of the pressure plate and even change the gasket as and when necessary. Several embodiments of the invention will be described below by way of example. Fig.2 relating to a coupling or joint between two pipes (1) and (2). The tubular spigot end of the pipe (1) is inserted in a socket (2) of the pipe, which contains an elastrometric-sealing element (4). In front of the elastrometric ring a pressure plate (3) is placed which when compressed from outside transfers the pressure to the wedged shape sealing ring (4) which is turn seals the annular gap between the socket and spigot and seals the joint. The socket (2) has a set of radial holes (6,7) near the edge of the socket opening through which a set of stainless steel pins (5) can pass and can be shrunk fitted in these holes (6,7) of the socket. The pins (5) prevent the sealing gasket (4) to push out the pressure plate and remains in compression sealing the joint. The pressure plate may also have a set of steps distributed over its perimeter at number of places of the same as the numbers of pins. The pressure plate can be rotated at its own position through 2 holes placed on the opposite side of the pressure plate ring. As the thickness increases with the help of the shear pin the sealing rings gets further compressed making the joint tighter and consequently suitable for higher hydraulic pressure in the pipeline. Fig.3 describes the joint in another embodiment where there is a cast skirt (7) near the opening of the socket (1). Bolts (4 and 4') pass through this skirt and by tightening the bolts (4 and 4') the pressure plate which will be in parts to facilitate entry (3) can be moved deeper inside the socket further to make the rubber gasket (5) seal tighter suitable for higher pressure. In this embodiment also the need for flanges and follower glands have been eliminated. The present invention provided the following techniques of improved mechanical joint assembly: 1) A process for assembling two tubular elements one of which elements has a spigot end and the other has a socket. The coupling comprising of a set of withdrawable stainless steel pins capable of being fixed in the holes provided on the rim of the socket which prevents the circular pressure plate and wedge shaped compressed rubber gasket to come out of the annular space between the socket and spigot in the mechanical joint which is used for jointing using stuffing box principle keeping flexible property of the joint. 2) In an alternative arrangement where there is a skirt attached to the end of the socket through which a set of stainless steel bolts pass, which presses the pressure plate which in turn compresses the wedge shaped rubber gasket in the annular space between the socket and spigot and seals the joint but retains the flexible property of the joint. The invention described hereinabove is by way of an example. It will be appreciated by a person skilled in the art that other modifications or alterations in the pipe joint are also possible without deviating from the scope of the intended present invention. I CLAIM: 1. An improved mechanical joint coupling of two tubular elements, one of said tubular elements having a spigot (1) end and the other being provided with a socket (2); said coupling comprising a set of withdrawable pins (5) capable of being fixed in the holes (6) provided on the rim of said socket, a gasket (4) made of a resilient material being housed within the space between said two tubular elements and a circular pressure plate (3); said pins being capable of holding the pressure plate (3) and the said gasket (4) in predetermined position and thus preventing said circular pressure plate and said gasket to loosen out of the annular space between said socket and spigot. 2. An improved mechanical joint coupling of two tubular elements as claimed in Claim 1 wherein said pressure plate is capable of rotation around its axis and is provided with multiple faces (8 and 9) of different thicknesses. 3. An improved mechanical joint coupling of two tubular elements as claimed in Claim 1 wherein said gasket is made of rubber or like material. 4. An improved mechanical joint coupling of two tubular elements as claimed in claim 1, wherein said withdrawable pins are preferably made of stainless steel. 5. An improved mechanical joint coupling of two tubular elements as claimed in claim 2, wherein said rubber gasket is wedge-shaped. 6. An improved mechanical joint coupling of two tubular elements as claimed in any of the preceding claims, wherein a skirt (7) is adapted at the front end of said socket through which a stainless steel bolt (4) passes, said bolt being capable of holding the pressure plate (3) which is of uniform thickness and comprises of more than one part and said rubber gasket in the annular space between said socket and spigot in predetermined position eliminating the withdrawable pin arrangement. 7. An improved mechanical joint coupling of two tubular elements substantially as herein described and as illustrated in the drawings accompanying the Complete Specification. An improved mechanical joint coupling of two tubular elements (1,2) one of said tubular elements (1) having a spigot end and the other being provided with a socket (2); said coupling comprises a set of withdrawable pins (5) capable of being fixed in the holes (6) provided on the rim of said socket, a gasket (4) made of a resilient material being housed within the space between said two tubular elements and a circular pressure plate (3); said pins capable of holding the pressure plate (3) and the said gasket (4) in predetermined position and thus preventing said circular pressure plate and said gasket to loosen out of the annular space between said socket and spigot.

Documents:

331-kol-2004-granted-abstract.pdf

331-kol-2004-granted-claims.pdf

331-kol-2004-granted-correspondence.pdf

331-kol-2004-granted-description (complete).pdf

331-kol-2004-granted-drawings.pdf

331-kol-2004-granted-examination report.pdf

331-kol-2004-granted-form 1.pdf

331-kol-2004-granted-form 18.pdf

331-kol-2004-granted-form 2.pdf

331-kol-2004-granted-form 26.pdf

331-kol-2004-granted-form 3.pdf

331-kol-2004-granted-form 5.pdf

331-kol-2004-granted-reply to examination report.pdf

331-kol-2004-granted-specification.pdf