Composite locking ring for pipe fittings

Abstract

Disclosed herein is a tube fitting having a composite locking ring. The tube fitting bell has a segment cavity into which a ring segment may be inserted through a slot on the face or outer surface of the bell end of the first tube. The locking ring has multiple ring segments, each segment having an arcuate outer surface. The outer surface may be a composite surface of multiple arcs.

Description

[Technical Field]

[0001] The present disclosure is in the field of pipe joints, particularly ductile cast iron pipe joints. [Background Art]

[0002] One common joint design for pipes used in building, infrastructure and pipeline projects, such as ductile cast iron pipes, is the spigot-bell pipe joint. Broadly, one pipe in the joint has a bell end that expands radially outward and is provided with a socket, and the second pipe has a spigot end inserted into the socket of the bell. To seal the pipes, a gasket is inserted between the bell and the spigot. A lock ring is also inserted into the joint to prevent the pipes from separating due to oblique or longitudinal forces acting on the pipes. [Summary of the Invention] [Problem to be Solved by the Invention]

[0003] While spigot-bell joints provide a strong joint for applications involving high internal pipe pressures, one limitation is that the joint does not provide large deflection capability when oblique or lateral forces that can induce bending moments around the joint act on the joint. A new joint design that allows the joint to deflect under oblique or lateral forces is desirable. [Means for Solving the Problem]

[0004] In one aspect, the present disclosure relates to a composite lock ring for insertion into a pipe joint defined by a spigot end of a first pipe and a bell of a second pipe, wherein the spigot end has a weld bead on the outer surface of the spigot, the bell has a narrow open end and an arcuate inner surface of the bell in the longitudinal direction, the composite lock ring has a plurality of ring segments, and each ring segment has a circumferentially arcuate inner surface, a notch defined to engage with the weld bead, and a longitudinally arcuate outer surface corresponding to the inner surface of the bell.

[0005] In further terms, the Disclosure relates to a set of lock ring segments for use in forming a lock ring inserted into a segment cavity defined by the outer surface of the spigot end of a first tube and the inner surface of the bell of a second tube, each lock ring segment having a circumferentially arcuate inner surface corresponding to the outer surface of the spigot, a longitudinally arcuate outer surface corresponding to the inner surface of the bell, a leading edge formed by the junction of the arcuate inner surface and the arcuate outer surface, a back surface, and a notch between the inner surface and the back surface.

[0006] In more detail, the pipe fitting system of the present disclosure includes: a first pipe having a bell end, having an outer bell surface and an inner bell surface having a lug opening, a segment cavity, a throat, a projection on the side of the throat facing the cavity, and an inner bell surface positioned above the segment cavity and defining a slot that allows access to the segment cavity; a second pipe having a spigot end having an outer spigot surface and a weld bead extending circumferentially around the outer spigot surface; and a plurality of ring segments, each insertable into a slot and having a circumferentially arc-shaped inner surface, a notch defined to engage with the weld bead, and a longitudinally arc-shaped outer surface corresponding to the inner bell surface of the segment cavity.

[0007] In more detail, the present disclosure method for forming a lock ring in a pipe fitting comprises the steps of: providing a first pipe having a bell end, having an outer bell surface, a segment cavity, and an inner bell surface positioned above the segment cavity and defining a slot that allows access to the segment cavity; providing a second pipe having a spigot end having an outer spigot surface, and a weld bead extending circumferentially around the outer spigot surface; inserting the spigot end of the second pipe into the bell end of the first pipe to a distance such that the slot extends longitudinally beyond the weld bead; inserting a number of ring segments into the slot, each ring segment having a circumferentially arcuate inner surface corresponding to the outer spigot surface and retainer bead, and a longitudinally arcuate outer surface corresponding to the segment cavity, such that the number of ring segments form a composite ring extending circumferentially around the spigot; and sealing the slot. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view of a joint according to one embodiment of the present invention. [Figure 2A] This is a perspective view of the fitting according to one embodiment of the present invention. [Figure 2B] This is a perspective view of the appearance of a joint according to another embodiment of the present invention. [Figure 3A] These are different diagrams of a single lock ring segment according to one embodiment of the present invention. [Figure 3B] These are different diagrams of a single lock ring segment according to one embodiment of the present invention. [Figure 3C] These are different diagrams of a single lock ring segment according to one embodiment of the present invention. [Figure 3D] These are different diagrams of a single lock ring segment according to one embodiment of the present invention. [Figure 4] This is a cross-sectional view of a joint showing a composite locking ring positioned within the joint. [Figure 5] This figure shows a conventional lock ring design. [Figure 6] This figure shows an integrally formed lock ring design having a compound arc-shaped outer surface. [Figure 7] This is an external view of the bell end of a pipe according to one embodiment of the present invention. [Figure 8] This is an exploded view of a composite ring and pipe end according to one embodiment of the present invention. [Modes for carrying out the invention]

[0009] In all diagrams, for the purpose of illustrating orientation and direction, a longitudinal axis or direction refers to an axis or direction that runs parallel to the length of the tube. A radial axis or direction refers to an axis or direction that starts along the centerline of the tube and extends radially outward in a given direction. A circumferential direction refers to a direction that runs around the tube in a circumferential manner.

[0010] Figure 1 shows a cross-sectional view of a spigot bell pipe fitting. Such pipe fittings are commonly used with ductile cast iron pipe fittings, but may be used similarly with other pipe fittings. A spigot bell pipe fitting is broadly defined as one in which the bell end 12 of a first pipe 10 receives the spigot end 52 of a second pipe 50. The bell 12 has a receiving end shaped to receive the spigot end 52 of the second pipe 50. The formed internal portion of the bell 12 is the socket 14. The inclined leading edge 54 of the spigot end 52 is the spigot 54. When joined, the bell 12 overlaps the spigot end 12, and the spigot 54 seats on the base 16 of the socket 14. Each pipe has an outer surface and an inner surface. When joined as shown in Figure 1, the outer surface 56 of the spigot end 52 of the second pipe 50 fits into the inner surface 18 of the bell end 12 of the first pipe 10. The outer surface 56 of the spigot end 52 is typically smooth and has a uniform diameter, except for the addition of a weld bead 58 positioned at a certain distance from the spigot 14. The weld bead 58 extends circumferentially around the entire spigot end 52. The weld bead 58 is dimensioned to press against the throat 20 of the bell end 12 to prevent the spigot 54 from moving longitudinally beyond a desired distance into the socket 14 of the bell 12, as further movement could cause the spigot 54 to come into contact with the socket 14 and damage the bell 12.

[0011] The bell end 12 of the first tube 10 is larger in diameter than the body 22 of the first tube 10. A transition region 24 extends from the body 22 to the maximum diameter of the bell end 12. The transition region 24 may be tapered, as shown in Figure 1, or it may widen abruptly to the diameter of the bell end. The inner surface 18 of the bell end has numerous grooves and ridges extending circumferentially around the inner surface. At the outermost end of the bell end 12 is a longitudinally facing surface 26 that curves downward toward the locking lug 28. The minimum circumference of the locking lug 28 forms a lug opening 30 into which the spigot end 52 of the second tube 50 is inserted. The lug opening 30 has a relatively small diameter, not significantly larger than the diameter of the outer surface of the spigot. Immediately inside the lug opening 30, the inner surface 18 of the bell end extends into a segment cavity 32. The segment cavity 32 is sized to accommodate a lock ring segment 61, which will be described more fully below. The segment cavity 32 also passes over the weld bead 58 of the spigot end 52 when the spigot 54 and the bell 12 are fully joined. The inner surface 18 of the bell end 12 then narrows again, coming very close to the outer surface 56 of the spigot end 52. This narrowed portion is the throat 20. The weld bead 58 abuts the throat 20 when the pipe is fully joined. Figure 1 also shows a projection 34 on the inner bell surface extending into the segment cavity.

[0012] From the throat 20, the inner surface expands again to form a retainer seat 36 that receives the retainer 74 of the gasket heel 72. The inner surface 18 narrows to form a retainer veed 38, and then expands again to form a gasket seat 40. A gasket 70 is sandwiched between the outer surface 56 of one spigot end 52, the retainer seat 36, the retainer veed 38, and the gasket seat 40. The gasket 70 forms a seal between the inner surface 18 of the bell end 12 and the outer surface 56 of the spigot end 52. The gasket retainer 66 fits into the retainer seat 36, and the remainder of the gasket 70 fits around the retainer veed 38 and inside the gasket seat 40. Beyond the gasket seat, there may be a portion of the bell 12 that extends inward above the base 16 of the socket 14, called a land 42. At the base 16 of the socket 14, the inner surface 18 narrows to the uniform diameter of the inner surface 44 of the pipe body 22.

[0013] When the joint is formed, the inner bell surface 18 and the outer spigot surface 54 do not come into direct contact with each other. Instead, the composite lock ring 60 and gasket ring 70 come into contact with both the bell end 12 and the spigot end 52. The gasket ring 70 seals the pipe to prevent leakage at the joint. The gasket ring 70 used in connection with this disclosure may be formed from any conventional or composite material suitable for use in sealing joints. The composite lock ring 60 prevents the pipe from coming loose when longitudinal tension is applied to the pipe. The composite lock ring 60 may be formed from a metal or metal alloy that can withstand high compressive stress.

[0014] The composite lock ring 60 is located within the segment cavity 32. The composite lock ring 60 engages with the inner bell surface 14, the outer spigot surface 56, and the weld bead 58. Once installed within the joint, the composite lock ring 60 prevents the joined pipes from separating.

[0015] The composite lock ring 60 is composed of a number of ring segments 61. These ring segments 61 may be inserted into the segment cavity 32 after the spigot end 52 is fully inserted into the bell 12.

[0016] The slots 46 for inserting the ring segments 61 into the segment cavity 32 may be provided in a number of ways. For example, as shown in Figure 2A, the slots 46 may be provided on the surface 26 of the bell between the lug opening 30 and the outer surface 56 of the bell. Figure 7 also shows a separated bell 12 of a first tube 10 having slots 46 on the surface of the bell 12. In another embodiment shown in Figure 2B, the slots 46 may be located radially outward from the segment cavity 32 and can be directly connected to the outer surface 48 of the bell. The slots 46 extend circumferentially around the bell 12 for a predetermined distance. The slots 46 should be sized to be small enough that they do not substantially affect the integrity of the bell end 12 of the first tube 10. Otherwise, there is no particular limit on the potential size of the slots, but it may be preferable that the slots be as large as possible (as long as they are within the constraints required by the integrity of the tube) so that the number of lock ring segments 61 to be inserted into the segment cavity 32 can be minimized. Generally, a slot 46 with an arc dimension of approximately 20-25 degrees is found to be large enough to reduce the number of ring segments 61 for forming the composite lock ring 60 to approximately 15, without providing the integrity of the tube.

[0017] Figures 3A to 3D show a plurality of views of an individual lock ring segment 61. The lock ring segment 61 has an outer segment surface 62 substantially shaped to engage with a segment cavity 32 of an inner bell surface 18. The outer segment surface 62 is arcuate, and as will be further described below, allows the segment cavity surface 32 and the outer arcuate surface 62 to slide past each other when the pipe is deflected. The outer segment surface 62 terminates at a leading edge 63 closest to the lug opening 30 of the bell 12, and a trailing edge 64 which is an edge between the surface of the outer segment 62 and a back face 65. Both the leading edge 63 and the trailing edge 64 may be chamfered or rounded, as shown in Figures 3A to 3D. Alternatively, the leading edge 63 and the trailing edge 64 may be pointed or sharp edges. Chamfered or rounded edges are preferred because pointed or sharp edges can protrude outward into the sliding space between the ring segment 61 and the segment cavity 32, thereby limiting the amount of deflection allowed.

[0018] The inner segment surface 66 is parallel to the outer spigot surface 56. A right side surface 67 and a left side surface 68 connect the outer arcuate surface to the inner segment ring surface. As shown, each side surface is substantially perpendicular to the circumferential direction, but when in contact with an adjacent lock ring segment 61, the side surfaces do not need to be perpendicular or coplanar with each other. As a non-limiting example, in the embodiment shown in Figures 3A to 3D, the lock ring segment 61 has a small notch 59 at the corner of each side surface. The inventors have found that the small notch 59 allows an operator to manipulate or reorient the lock ring segment 61 as needed. The small notch 59 also facilitates disassembly of the joint by allowing manipulation of the lock ring segment 61 to remove it, contrary to the assembly process. The back face 65 is substantially perpendicular to the longitudinal direction. Between the inner ring surface 66 and the back face 65, there is a large notch 69 shaped to engage with a weld bead 58 on the outer spigot surface. The body of the lock ring segment 61 is curved or arcuate in the circumferential direction such that the two side surfaces are perpendicular to the circumferential direction and parallel to the radial direction.

[0019] To install the composite lock ring 60, each ring segment 61 is inserted into the slot 46. The ring segments 61 are slid around the segment cavity 32 to allow additional ring segments 61 to be inserted. When all ring segments 61 are inserted, each ring segment 61 abuts against adjacent segments 61 to form the complete composite lock ring 60 within the segment cavity 32. This configuration is shown in Figure 4. The slot 46 can then be sealed to prevent the segments 61 from sliding out through the slot 46.

[0020] The arcuate outer segment surface 62 within the segment cavity 32 and the corresponding arcuate inner bell surface are formed so that when a force acting to break or separate the joint is applied, the outer ring surface 62 of the segment cavity 32 and the inner bell surface can slide past each other. For example, when an oblique force is applied to the pipes forming the joint, the force tends to buckle the pipes at the joint, causing deflection in the angle of the pipes. The composite lock ring 60 and the segment cavity 32 are curved to allow the pipes to deflect to a certain extent under the force without breaking the seal or rupturing the pipes. The geometry of the composite lock ring and the sliding manner of the ring segments along the cavity also change the amount of load converted from oblique load to longitudinal load as the deflection angle increases.

[0021] In some embodiments, the arc-shaped outer segment surface 62 may be a composite surface formed of a number of separate arc-shaped segments; that is, a number of arc-shaped segments may be present. In some of these embodiments, the junction line between two adjacent arc-shaped segments may be continuous, such that there is a continuously curved surface where the two adjacent arc-shaped segments intersect. In other embodiments, such as those shown in Figures 3A to 3D, the curves may be discontinuous, such that two adjacent arc-shaped segments 62A and 62B intersect at their edges. Having a composite surface for the arc-shaped outer segment surface 62 allows the lock ring segment 61 to have additional space for flexing within the segment cavity 32. As a non-limiting example, in the embodiments shown in Figures 3A to 3D, the arc-shaped outer segment surface 62 has a first arc-shaped surface 62A extending from the leading edge 63 to approximately the middle along the outer segment surface 62, and a second arc-shaped surface 62B extending from approximately the middle to the trailing edge 64 along the outer segment surface 62. The first arc-shaped surface 62A is an arc based on a radius of 2.37 inches. The second arc-shaped surface 62B is also an arc based on a radius of 2.37 inches, but it is taken from a radial center at a different position than the first arc-shaped surface. As a result, the second arc-shaped surface 62B is pushed slightly downward from where the first arc-shaped surface 62A would be located if the surfaces were continuous along the same arc.

[0022] Composite surfaces formed from a number of separate arc-shaped segments are described and illustrated herein for use in conjunction with composite rings 60 formed from a number of individual ring segments 61. However, composite surfaces may also be used on a single-piecely formed locking ring 80, i.e., a locking ring 80 formed from a single piece, rather than having a number of individual ring segments as described elsewhere herein. An example of a single-piecely formed locking ring is the “Centroidally Twistable Compression Ring for Pipe Joints” disclosed in U.S. Patent No. 7,137,653, which is incorporated herein by reference. The centrroidally twistable compression ring is a substantially ring-shaped body that is inserted into a predetermined position within a segment cavity and locked in place, as described in U.S. Patent No. 7,137,653. The ring-shaped body has a ring thrust surface that can engage with the segment cavity surface. However, while the ring thrust surface described in U.S. Patent No. 7,137,653 is set as a uniform surface at approximately 30 degrees radially, the ring thrust surface may instead have a composite surface formed from a number of distinct arc-shaped segments, as described above. An example of a prior art lock ring having a uniform surface at approximately 30 degrees radially is shown in Figure 5. An integrally formed lock ring having such a composite surface is shown in Figure 6.

[0023] The advantage of the design disclosed herein is that the outer and inner bell surfaces of the numerous ring segments within the segment cavity can be shaped to provide a longer sliding distance and allow for greater deflection than conventional lock designs. Conventional lock rings or mechanisms do not allow for significant tube deflection at the joint before fracture. For example, the prior art design shown in Figure 5 provides a maximum deflection of about 0.5 degrees. In some embodiments and sizes, the composite lock rings disclosed herein allow for a deflection of about 2 degrees.

[0024] While composite lock rings allow for additional deflection, it has been found that individual ring segments are more likely to shift or detach during the pipe deflection process than conventional one-piece lock rings, because any individual segment can detach without being hindered by adjacent independent ring segments. To address this issue, a projection may be added to the front end of the throat so as to effectively extend the front end of the throat into the segment cavity toward the ring segments and weld bead. As shown in Figure 1, the projection eliminates the space behind the weld bead on the opposite side of the lock ring, acting to prevent the lock ring segment from detaching on or passing through the weld bead.

[0025] The embodiments disclosed herein may be used with pipes of any size that use bell and spigot fittings. For example, the embodiments may be used with pipes having diameters between 4" and 64" or even larger. In particular, the embodiments are useful for locking fittings in high-pressure pipes to allow flexing without causing pressure or fluid to burst or leak.

[0026] The number of segments provided in this manner may be at least three. In other embodiments, 10 to 30 segments or more may be used. In some embodiments, all segments may be uniform and have equal arc measurements around the circumference of the spigot. As a non-limiting example, in an embodiment having a 25-degree slot and uniform segments formed to fit snugly through the slot, the embodiment utilizes 15 segments. In other embodiments, the size of the segments may vary from thin segments to thicker segments, limited only by the size of the slot. Figure 8 shows an exploded view of the bell end 12 of the first tube 10, the spigot end 52 of the second tube 50, and the multi-segment composite lock ring 60. As shown in this figure, the lock ring 60 has 10 segments 61 that substantially completely enclose the spigot. An eleventh section may also be inserted.

Claims

1. A composite locking ring for insertion into a pipe fitting defined by the spigot end of a first pipe and the bell of a second pipe, wherein the spigot end has a weld bead on the outer surface of the spigot, and the bell has a narrow opening end and a longitudinally arc-shaped inner surface of the bell, and the composite locking ring is It comprises numerous ring segments, each ring segment having a notch defined to engage with the weld bead and a longitudinally arc-shaped outer surface corresponding to the inner surface of the bell. A composite lock ring wherein the outer surface terminates at a leading edge near the lug opening and adjacent to the outer bell surface, and terminates at a trailing edge near a projection on the inner bell surface, and further, the outer surface is defined by a first arc segment and a second arc segment, each arc segment having a start and an end, the start of the first arc segment located at the leading edge, the end of the first arc segment coinciding with the start of the second arc segment, and the end of the second arc segment located at the trailing edge, and further, the first arc segment and the second arc segment each have different radius centers.

2. The composite lock ring according to claim 1, wherein the ring segment has an arc-shaped inner surface in the circumferential direction.

3. The composite lock ring according to claim 1, wherein the ring segment has a left side and a right side.

4. The composite lock ring according to claim 3, wherein the left and right sides of the ring segment are parallel in the radial direction, respectively.

5. The composite lock ring according to claim 1, wherein the outer surface of the ring segment, which is arc-shaped in the longitudinal direction, has a composite surface formed from at least two unique arc segments.

6. A pipe fitting system, A first tube having a bell end, the bell end having an outer bell surface and an inner bell surface, the inner bell surface defining a lug opening, a segment cavity, a throat, a projection on the side of the throat facing the cavity, and a slot that allows access to the segment cavity, the first tube, A second pipe having a spigot end with an outer spigot surface, and a weld bead extending circumferentially around the outer spigot surface, A plurality of ring segments that can be inserted into a slot, each ring segment having a notch defined to engage with a weld bead and a longitudinally arc-shaped outer surface corresponding to the inner bell surface of the segment cavity, Equipped with, A pipe fitting system wherein the outer surface terminates at a leading edge near the lug opening and adjacent to the outer bell surface, and terminates at a trailing edge near a projection on the inner bell surface, and further, the outer surface is defined by a first arc segment and a second arc segment, each arc segment having a start and a end, the start of the first arc segment being located at the leading edge, the end of the first arc segment coinciding with the start of the second arc segment, and the end of the second arc segment being located at the trailing edge, and further, the first arc segment and the second arc segment each having different radius centers.

7. The system according to claim 6, wherein the slots are arranged on the bell surface.

8. The system according to claim 6, wherein the slots are located on the outer surface of the bell.

9. The system according to claim 6, wherein the ring segment has an arc-shaped inner surface in the circumferential direction.

10. The system according to claim 6, wherein the multiple ring segments comprise 3 to 30 ring segments.

11. The system according to claim 10, wherein the multiple ring segments comprise 15 ring segments.

12. The system according to claim 6, wherein the outer surface of the ring segment, which is arc-shaped in the longitudinal direction, has a composite surface formed from at least two unique arc segments.

13. A method for forming a lock ring in a pipe fitting, To provide a first tube having a bell end, wherein the bell end has an inner bell surface defining a segment cavity, a throat, and a slot that allows access to the segment cavity, To provide a second pipe having a spigot end with an outer spigot surface and a weld bead extending circumferentially around the outer spigot surface, Insert the spigot end of the second tube into the bell end of the first tube until the weld bead engages with the throat, Inserting a number of ring segments into a slot, wherein each ring segment has a notch for engaging with the weld bead and a longitudinally arc-shaped outer surface corresponding to the segment cavity, and as a result, when inserted, the number of ring segments form a composite ring extending circumferentially around the spigot end. To seal the slot, Includes A method for forming a lock ring in a pipe fitting, wherein the outer surface terminates at a leading edge near the lug opening and adjacent to the outer bell surface, and terminates at a trailing edge near a projection on the inner bell surface, and further, the outer surface is defined by a first arc segment and a second arc segment, each arc segment having a start and a end, the start of the first arc segment located at the leading edge, the end of the first arc segment coinciding with the start of the second arc segment, and the end of the second arc segment located at the trailing edge, and further, the first arc segment and the second arc segment each have different radius centers.

14. A pipe fitting system, A first tube having a bell end, the bell end having an outer bell surface and an inner bell surface defining a lug opening, a segment cavity, and a throat, A second tube having an outer spigot surface, a spigot end inserted into the bell end of a first tube, and a weld bead extending circumferentially around the outer spigot surface, A locking ring that is insertable through a throat and expandable within a segment cavity, wherein the locking ring twists in accordance with the angular displacement between the longitudinal axis of a first tube and the longitudinal axis of a second tube, and further, the locking ring has a longitudinally arc-shaped outer surface, the outer surface being a composite surface corresponding to a segment and formed from at least two inherent arc-shaped segments, and Equipped with, A pipe fitting system wherein the outer surface terminates at a leading edge near the lug opening and adjacent to the outer bell surface, and terminates at a trailing edge near a projection on the inner bell surface, and further, the outer surface is defined by a first arc segment and a second arc segment, each arc segment having a start and a end, the start of the first arc segment being located at the leading edge, the end of the first arc segment coinciding with the start of the second arc segment, and the end of the second arc segment being located at the trailing edge, and further, the first arc segment and the second arc segment each having different radius centers.

Images