Claims:WE CLAIM:
1. A restraint joint between ductile iron (DI) pipes comprising:
A first DI pipe (D1) with a weld bead (D5) on its spigot end;
A second DI pipe (D2) having a socket end for receiving the spigot end of the first DI pipe (D1), wherein a sealing gasket (D3) is locked between inner circumferential region of the second DI pipe (D2) and the weld bead of the first DI pipe (D1); and
Bearing type balls (D4) form a circumferential ring over the periphery of the spigot end of the first DI pipe (D1) in such a way that the balls (D4) come in contact with the weld bead (D5) on one end and with a circumferential runway (F2) of the second DI pipe (D2) on the another end.
2. The restraint joint as claimed in claim 1, wherein the weld bead (D5) on the spigot end of the first DI pipe (D1) runs circumferentially 360 degrees.
3. The restraint joint as claimed in claim 1, wherein the weld bead is positioned at a specific distance from the end of the DI pipe.
4. The restraint joint as claimed in claim 1, wherein the balls (D4) completely fill the circumferential runway (F2) to form the contact between the spigot weld bead (D5) and socket.
5. The restraint joint as claimed in claim 1, wherein the balls (D4) are inserted through a socket ball insert slot (F4).
6. The restraint joint as claimed in claim 5, wherein a ball insert slot cap (D6) is used to close the ball insert slots (F4) to ensure the assembly is robust after the complete pipe assembly.
7. The restraint joint as claimed in claim 6, wherein the ball insert cap (D6) and ball insert slot (F4) form a tight connection with the help of taper features on the ball insert cap itself.
8. The restraint joint as claimed in claim 7, wherein a circumferential slot is made towards the socket mouth facilitating the ball movement based on the DI pipe deflections.
, Description:FIELD OF INVENTION:
[001] The present subject matter described herein generally relates to a restrained pipe joint for ductile iron (DI) pipe with fluid seal gasket and, in particularly, to a flexible restrained pipe joint for ductile iron (DI) pipe with fluid seal gasket.
BACKGROUND AND PRIOR ART AND PROBLEM IN PRIOR ART:
[002] The Ductile Iron (DI) pipes are used for water transmission and distribution for very long distances. Normally, the DI pipes are connected with each other using flexible push-on joints, which are flexible to allow directional changes in the pipe line laying. In case of high-pressure water supply lines, push-on joints are not suitable as they experience large amount of axial thrust especially at bends, tees, reducers, dead ends etc. In such cases, restraint mechanism is employed to keep the DI pipes intact. Restraint joint is also necessary for laying DI pipes on slope, like in hilly terrains.
[003] To provide resistance to the thrust forces, generally thrust blocks are used, where the soil bearing capacity is good, though it is not practical in all situations. In hilly areas and/or in severe directional changing scenario, mechanical joint, flanged joint, restraint joints, ball and socket joints etc., are required for DI pipes to avoid the joint separation due to the unbalanced thrust forces.
[004] The DI pipes are subjected to type test according to ISO 2531. The tests include application of hydrostatic pressure, internal (positive and negative), external and cyclic internal hydrostatic pressure application under specific conditions. US 5197768 discloses a pipe joint and a locking member for use with the pipe joint are provided for a bell and spigot type joint, the locking member being a separate element disposed axially outwardly of a fluid seal gasket within the bell end of a first of the pipe elements, the locking member being made up of an elastomeric backing member and at least one locking segment, the elastomeric backing member being adapted to seat in a first annular recess in the bell end, and against a radially inwardly protruding shoulder, this seating position urging the outer surface of the locking segment into contact with the wall of the first annular recess, to effect a constant, positive wedging action against a spigot end of a second pipe element inserted into the bell end of the first pipe element. The locking member thus securely engages and retains the spigot end within the bell end against axial forces tending to separate the pipe elements, and the locking member serves as a dirt seal improving the prevention of dirt and other materials from entering the bell end of the joint which could adversely affect the integrity of the fluid seal or interfere with the ability to efficiently induce any desired joint deflection.
[005] The restraint joints are also subjected to type test as described in ISO 1080, where they undergo axial restraint, bending, shear and cyclic loads.
[006] Restraints joints offer flexibility and are available in wide variety of design as per the standards and manufacturer specifications. Many of the available design include socket and spigot joints along with the bolts, rubber seals and weld bead on the spigot end. These mechanisms are external joints, which have the restraint joint mechanism components outside the pipe assembly.
[007] Most of these restraint joint mechanisms are normally take significant amount of time during the assembly and comprise few extra components. The joint components are generally full circumferential and often create interference issues while assembly. Assembly procedure often requires careful handling of the pipe and joint components to achieve the required functionality of the DI pipe and restraint joint. They also need additional space arrangements outside the DI pipe to accommodate the restraint joint components. The design should be robust to deal with large axial separating forces during water transportation in both straight configuration and in bend configuration whenever there is a change in the direction of the pipe layout.
[008] On the other hand, anchor gaskets are also used as restraint joints, which are internal in nature. The restraint joint features in anchor gaskets are not visible from outside and also do not interfere with any other outside assembly features. However, anchor gaskets are not suitable for the above ground applications as they are subjected to cyclical movement, which results in poor performance of the gasket. The present design offers internal restraint joint design developed based on bearing concept does not have the disadvantages of an anchor gasket joints. The design is based on metal to metal contact unlike the metal inserts in the gaskets as in anchor gaskets.
[009] There are several design variations for the restraining purpose of DI Pipes. Michael & Randall developed a combined system for sealing and restraint for as-cast DI Pipes.
[0010] Kenneth et al in US20150176730A1 developed face to face positive restrained rotating pipe flange. It discloses an annular ductile iron flange of nominal size has a non-threaded inner longitudinal surface defining an inner diameter that exceeds the outer diameter of a corresponding length of hubless ductile iron pipe of nominal thickness. The flange also has a basal surface with both a plurality of evenly spaced bolt holes and an annular counterbore adjacent to the inner longitudinal surface. The counterbore has a longitudinal depth slightly larger than the nominal thickness and a radial depth slightly larger than twice the nominal thickness. The flange is coupled to, and configured to rotate longitudinally around, the length of pipe. The bell end of the pipe is machined to an annular stub configured to recess into the counterbore. A threaded annular ductile-iron flange may be screwed onto the spigot end of the pipe.
[0011] Billy et al in US20060279080A1 also developed a bell and plain end pipe joint, that has a series of locking segments. It further discloses a combination sealing and restraint system for an as-cast ductile iron fitting is shown for both sealing and preventing separation of an iron pipe fitting and a mating male pipe. The restraint system includes both a sealing ring and a combination gripping ring which are installed in a groove provided in a mouth region of the iron fitting. The gripping ring has teeth on an inner surface which are initially angled away from an outer surface of the male pipe. The teeth are forced into engagement with the exterior surface of the mating male pipe as the pipe joint at the fitting is assembled. The teeth are oriented to allow movement of the male pipe in a first direction relative to an end opening of the fitting during assembly, but to resist movement in a opposite direction after the fitting joint has been assembled. The sealing ring and gripping ring are installed in the annular groove of the as-cast iron fitting after the iron casting operation at the factory.
[0012] Randall in US5197768A developed locking member that works on a pipe joint of bellow and spigot type. It further discloses a pipe joint and a locking member for use with the pipe joint are provided for a bell and spigot type joint, the locking member being a separate element disposed axially outwardly of a fluid seal gasket within the bell end of a first of the pipe elements, the locking member being made up of an elastomeric backing member and at least one locking segment, the elastomeric backing member being adapted to seat in a first annular recess in the bell end, and against a radially inwardly protruding shoulder, this seating position urging the outer surface of the locking segment into contact with the wall of the first annular recess, to effect a constant, positive wedging action against a spigot end of a second pipe element inserted into the bell end of the first pipe element. The locking member thus securely engages and retains the spigot end within the bell end against axial forces tending to separate the pipe elements, and the locking member serves as a dirt seal improving the prevention of dirt and other materials from entering the bell end of the joint which could adversely affect the integrity of the fluid seal or interfere with the ability to efficiently induce any desired joint deflection.
[0013] Apart from self-restraint joints, there are mechanical joints as developed by William et al in US7207606B2. It discloses a mechanical pipe joint, restraining gasket, and method for restraining pipe spigots within adjacent bell sockets. The restraining gasket is composed of two axially-separate components: a sealing portion and a restraining portion made of a plurality of arcuate locking members. The restraining gasket and a gland surround an outer surface of the pipe spigot. The mechanical pipe joint is formed as the pipe spigot is inserted into the bell socket and the gland is axially attached to the bell socket so that the restraining gasket is held between: the gland, an inner surface of the bell socket, and the outer surface of the pipe spigot, so as to provide a fluid seal in the joint and urge the locking members into contact with the outer surface of the pipe spigot, axially restraining the pipe spigot within the bell socket.
[0014] While some of the prior joint designs for restrained joints may generally be satisfactory in performance in many instances, the present design overcomes some of the disadvantages by providing a robust axial restraint and also providing the flexibility of the joint as required.
[0015] Another important advantage of the present invention, when compared to other restraint joint mechanisms, is that the simplicity of the assembly as it requires only filling the balls in the slot created by the push on joint and closing the slot with a cap in the end.
[0016] The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
OBJECTS OF THE INVENTION:
[0017] The principal objective of the present invention is to provide a restrained joint for push on type joint having a fluid sealing member or gasket, which takes care of the water leakages etc. and provides basic restraint for axial separating forces.
[0018] It is an additional objective of the present invention to provide a locking member for a restrained joint which may be modified pipe sections having various sized diameters.
[0019] It is another principal object of the present invention to provide a restrained joint for a push on type joint having a separate fluid sealing gasket without altering the existing features to control the dirt and other materials from gaining access to interior joint regions such as the region where the fluid member is positioned.
[0020] It is another important objective of the present invention is to suggest suitable welding process, geometry and material for creating the successful weld bead, a critical feature of the present design.
[0021] Yet another object of the present subject matter is to provide the above-mentioned advantages in a push on type DI pipe restrained joint.
[0022] These and other objects and advantages of the present subject matter will be apparent to a person skilled in the art after consideration of the following detailed description taken into consideration with accompanying drawings in which preferred embodiments of the present subject matter are illustrated.
SUMMARY OF THE INVENTION:
[0023] The present subject matter relates to a flexible restrained pipe joint for ductile iron (DI) pipe with fluid seal gasket to overcome the drawbacks of the prior arts. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be a part of the claimed disclosure.
[0024] In addition to the spigot end, socket end and gasket, the design consists of bearing type balls, ball insert slot cap and weld bead. The major modification required is on the socket end of the DI pipe casting to generate the circumferential ball runway. The number of bearing type balls depends on the circumference of the pipe and size of the ball.
[0025] Error! Reference source not found. shows the assembly of the pipes with the joint and there are no apparent differences from outside. Error! Reference source not found. to Error! Reference source not found. shows the internal features of the design showing the details. The design also fulfils the important requirement of the DI pipes, which is the flexibility for the pipe to bend to accommodate the change in the direction during the pipe laying. Error! Reference source not found. shows the cross-sectional view of the assembly with all the balls.
[0026] The push on joint pipe joint should be modified at two regions of the existing design: one on the spigot end of the pipe, where the weld bead is created circumferentially at the specified distance from the end of the pipe and secondly the ball inserting slots, on the pipe towards spigot end, where it is engaged with the socket end of another pipe, through which the balls are inserted into the slot. Figure 2 highlights the weld bead position on the pipe (spigot end). Once the balls are inserted in the slots, they come in contact with the socket end on one side and with weld bead on the other end. In this configuration, they act as the load carrying members and as axial force restraint. Even when the pipe line changes direction during layout, since, the restraint joint is based on the ball bearings, the spigot pipe or socket pipe can accommodate the deviation similar to the deviations and deflections allowed in vehicle ball bearings and keep the load transfer and axial restraint intact.
[0027] The modification in the socket part of the pipe needs a cut to accommodate the balls once inserted and forms a path for the balls to rotate in the circumferential groove. The collection of balls inside the socket circumference groove also prevents the dirt from reaching sealing gasket. From maintenance point of view also, the process of cleaning, whenever required, would be an easy process as the balls can be removed from the slot by giving it a rotation.
[0028] This assures that the joint members will be able to deflect and transfer loads properly and efficiently. One of the key differentiations of the present invention is that many internal restraint joints do not have the weld bead and it’s only the external joints are designed to have a weld bead. The present invention incorporates the weld bead within the design of the internal restraint joint thus making it more robust design from the restraining point of view eliminating their disadvantages.
[0029] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.
[0030] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods or structure in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0032] Figure 1. Complete assembly of the DI pipe with restraint joint bearing type
[0033] Figure 2. Details of restraint joint features in cross section of the assembly
[0034] Figure 3. Circumferential runway in the socket & ball contact area (Cross section view on Socket)
[0035] Figure 4. Ball movement zone allowing the pipe deflections
[0036] Figure 5. Cross sectional view of the DI pipe assembly with all balls (as per Specified number)
[0037] Figure 6. Ball insert slot cap in the socket
[0038] Figure 7. Socket slot for ball Insertion into the runway (number as specified)
[0039] Figure 8. Cross sectional view of the DI pipe assembly in bent configuration (as per specified angle). Gasket gets compressed allowing the bending deflections.
[0040] Figure 9. Design parameters of the bearing type restraint joint.
[0041] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0042] While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.
[0043] The terms “comprises”, “comprising”, or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a device, system, assembly that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such system, or assembly, or device. In other words, one or more elements in a system or device proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or device.
[0044] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0045] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0046] Referring to the Error! Reference source not found., the complete pipe assembly along with the joint is illustrated highlighting the spigot end of the DI pipe (D1) and socket end of the DI pipe (D2). A sealing gasket (D3), which is integral part of the push on joint, is shown in Error! Reference source not found.. It should be noted that, while the specification discusses a joint between two sections of the pipe, the invention is not intended to be limited and can be expanded to piping accessories such as values, fittings, hydrants and non-piping elements may be employed as on or both of the elements to be joined. The term “pipe” and “piping element” are used herein as a genetic term which are intended to refer to these elements as well.
[0047] The present invention is based on the bearing type balls (D4), and form the crucial part of the design. The cross-sectional view of the assembly is highlighted in Error! Reference source not found.. The balls (D4), are inserted through socket ball insert slot (F4), and form a circumferential ring, as illustrated in Error! Reference source not found.. The balls (D4), come in contact with the weld bead (D5) on one end and on another end with the circumferential runway (F1). The balls (D4) transfer the axial thrust load from spigot end (D1) of the pipe to socket end (D2) of the pipe via a weld bead (D5) as shown in Error! Reference source not found.. As the balls (D4) are in spherical shape, they roll and adjust with pipe deflections to maintain the mechanism and transfer the load uniformly along the circumference through several point contacts in any deflection configuration. The number of balls (D4) depend on the size of DI pipe and the size of the ball. The balls (D4), inside the circumferential runway, F1, do not come in contact with the sealing gasket, D3, and hence the existing water leakage is not affected. To avoid the balls (D4) near the socket ball insert slot (F4), come out through the slot, ball insert cap, D6, can be inserted. Once all the balls are inserted into the circumferential groove, through the socket ball insert slot (F4), there is a chance the balls can come out through the same slot if the slot is kept open. In order to avoid such balls (un-filling), it is designed to have a ball insert closing cap (D6). It will ensure the assembly is completed and firm while in use. The balls, D4, can be filled in the runway slot, F1, from either side of the slot (F4), based on the position of the slot (F4) region due to gravity.
[0048] One of the very key component of the present invention is the circumferential weld bead (D5), (shown in Error! Reference source not found.) on the spigot end (D1) of the DI pipe to arrest the axial movement of the balls (D4), which are in contact with socket end (D2) of the DI pipe, thereby providing the restraint mechanism. The weld bead (D5), is in semi-circular in cross sections and separates the balls and the sealing gasket. It ensures the movement of the balls (D4), within a ball movement zone (F3). The weld bead outer surface, which is semi-circular shape, allows the ball (D4), roll around the bead surface and take the deflections on the pipe laying.
[0049] The weld bead (D5), is made on the spigot end (D1) of the pipe (DI) at a specified distance from the end of the pipe. The distance is calculated from the end of the pipe (towards the spigot end) based on the length of pipe inserted into the socket end. It will be approximately equal to 70% of the length of the socket. Of course it depends on the design and length of socket etc. This predetermined distance will be selected based on the configuration of the push on joint assembly. The weld bead (D5), height should be slightly smaller than the socket mouth (D7), so as to make the weld bead (D5) move inside the socket without any obstruction. Alternatively, the socket mouth (D7), dimensions, can be determined based on the satisfactory weld bead dimensions to serve the critical function of the restraint mechanism.
[0050] A Ball insert slot cap (D6), as shown in Error! Reference source not found. is a small cylindrical component, which is used to close socket ball insert slot (F4) after filling all the balls (D4). There should be tight fit between the cap (D6) into the slot to make the assembly rigid. The number of caps (D6) required is equal to the number of slots (F4) in the socket to insert the balls (D4). The ball insert cap (D6), can have a slight taper in order to fix it properly. And also to take it out as and when required, a suitable secure means should be made in the slot. Once the cap (D6), is inserted, for any operational purpose, to take the balls out it is required to open the cap (D6). Since, the cap (D6) is firmly fitted or tapped to fit, it can be designed with any feature to pull it out. Eg: A cylindrical through hole to insert any rod to pull it out
[0051] The number of such caps, are in equal number as the number of slots.
[0052] Various design features are highlighted in Error! Reference source not found., Error! Reference source not found., Error! Reference source not found. and Error! Reference source not found. along with the dimensional parameters in Error! Reference source not found..
I. Db is diameter of the balls, based on which the width of the circumferential runway (Ws) in the socket is determined. The balls’ diameter and material is crucial for obtaining the required strength and also to determine the overall diameter of the socket end.
II. The inside socket end of the DI pipe consists of a runway along the circumference for full 3600 (as shown in Error! Reference source not found.) with a specific cross-sectional profile (Error! Reference source not found.) to accommodate all the balls. It is termed as Socket Ball Runway, F1. The socket end design is modified to incorporate the runway during the centrifugal casting process. The specific cross-sectional profile accommodates the ball adjustments for various pipe deflections. The sockets are normally made by collapsible casting and the design of this specific profile can be incorporated within the socket. The surface finish of the runway profile is important in the present invention, as it allows the movement of the spherical balls, D4, during the assembly process and as well as during the pipe deflection. However, it should be considered that the movement of the balls is not continuous as once the assembly process is complete and the pipe joint is configured in one the deflected configuration, assembly will be in stationery position for prolonged periods of time.
For geometrical purpose, the feature F1 is generated by rotating the feature F2 along the pipe axis.
III. The cross-section profile of the socket ball runway (F2) is the most important feature of the design as it determines the ball movement zone (F3) for balls to adjust during the pipe deflection and socket ball runway, F1. The features are highlighted in the Error! Reference source not found. and Error! Reference source not found.. The profile of the cross-section of the feature, F2, is formed on the socket based on the balls outer profile at the deflected positions in extreme angles in both directions.
The profile, F2, confirms to the spigot pipe, D1, and weld bead, D5, inside of socket mouth, D7, and a flat region inside the socket. All possible ball positions are limited to this profile for various configurations of the pipe assembly.
IV. Ball movement zone, F3, is the resultant space between the spigot inside and spigot outside regions. It is formed after the assembly of the pipes where the restraint mechanism is established between the socket and the weld bead of spigot via balls contact. The inner side of the profile, F2, above the weld bead, D5, should be made in such a way that the balls are not allowed to cross the weld bead in all the configurations, thus completing the restraint mechanism. The opening created after the assembly inside the socket region should be less than the ball diameter to make sure the balls cross the weld bead, D5, and enter into the seal gasket region.
V. Socket Ball Insert Slot (F4), as shown in Error! Reference source not found., provides the means to insert the balls one by one to fill the socket ball runway after the normal pipe assembly procedure is completed. Along the circumference of the pipe one slot should be sufficient to insert all the balls as the balls move along the circumferential runway, however the number of slots can range from 1 to 4 depending on the complexity of the assembly and prevailing circumstances. The diameter of the slot is just higher than the size of the balls to insert the ball easily. As mentioned earlier, the ball insert slot cap (D6), will be inserted into the slot, F4, to avoid the balls running out the assembly. In case, the ball insert cap (D6), is designed to have taper along its length, the ball insert slot (F4), should also have the respective design to accommodate this cap and to make the assembly a robust design.
[0053] The present invention consists of a weld bead (D5) as part of the restraint joint and is created before the assembly process begins. The weld bead (D5) is created on the spigot end (D1) of the DI pipe with the specified dimensions and distance from the end of the pipe. It is recommended that the weld bead (D5) be made at the pipe manufacturing facility. It is also suggested to process the pipe with weld bead similar to the standard practice of the preparation of the push on joint pipes to achieve the similar corrosion properties, leak restraint properties. Following the weld bead generation, standard post welding processes including the grinding to remove the blurs etc to be performed.
[0054] As mentioned earlier, the socket end of the DI pipe is a modified version of the normal DI pipe including the circumferential runway (F3) and ball insert slots (F4), for inserting the balls (D4). The features of the DI pipes are made during the DI pipe manufacturing process itself by incorporating the suitable changes in the centrifugal casting process itself.
i. The standard procedure of assembly for DI pipe involves inserting the spigot end into the socket end of the DI pipe, where gasket is pushed radially and completes the basic pipe assembly process. With this the standard leakage restraint will be achieved as per the push on joint standards.
ii. The orientation of the DI pipe assembly then can be kept in a suitable position to insert the balls, D4. Ideally, one slot, F4, should be sufficient to insert all the balls, however, to ensure all the circumferential runway, F3, is filled with the balls, up to 4 ball inserting slots, F4, are recommended. This avoids the reorientation of the pipe assembly after the push on joint standard assembly. It is recommended to keep the single slot assembly in the vertical position to make sure the balls are filled from either side and forms the complete circumferential ring. Now, the balls, D4, are inserted from socket ball insert slot, F4, to fill the socket ball runway.
iii. Once the balls are filled, ball insert slot caps, D6, are inserted into the socket ball insert slots, thus completing the entire restraint joint assembly.
[0055] The design takes care of any deviations generated out of manufacturing tolerances as the balls move within ball moving space between the socket and spigot end of the pipe.
[0056] Normally, DI pipes without restraint joint offer approximately 5 deg bending. However, as per the requirements of the restraint joint, the maximum bending angle offered, can be half of the maximum bending angle without the restraint joint (typically it is around 2.5 degrees). The present design is developed to accommodate the bending as shown in Error! Reference source not found. so that there is no interference between restraint joint and DI pipes at both the extreme ends. Figure shows the deflection at top end and bottom end, where the ball movement is in opposite directions and as it can be noticed there is no interference with any other components. On top side the ball gets moves towards the socket mouth side of runway profile, F2, whereas the bottom side, the ball moves towards the gasket side of the runway profile, F2. The gasket gets compressed and accommodates the movement of the weld bead.
Relative Dimensions of the Design:
D – Diameter of the DI Pipe
Db – Diameter of the ball, Close to D/20 and higher
Dsb – Diameter of socket ball insertion slot, Equal to 1.05Db
Tsb – Angle of the socket ball insertion slot with vertical axis, Between +/-40 deg
Ws – Width of ball movement zone inside the socket, Close to 2D and higher
H1 – The socket opening height towards outside: Less than 0.5Db
H2 – The socket opening height towards inside: Less than 0.9Db
Hw – Weld bead height, Close to 8 mm
Rb – Radius of the ends of the socket slot for balls, Equal to Db

[0057] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.
[0058] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.