Coupling for pipe elements

Abstract

A pipe coupling can integrate the clamping studs monolithically into the body of each coupling segment, eliminating separate bolts and their associated corrosion and mechanical failure risks. This design can avoid internal corners, remove material interfaces, and ensure better stress distribution and corrosion resistance. The coupling can also be easier to assemble and more reliable for use in corrosive and high-pressure environments.

Description

COUPLING FOR PIPE ELEMENTSBACKGROUND

[0001] Mechanical pipe couplings (hereinafter referred to more simply as “couplings”) are used to couple pipe elements such as pipe stock, pipe fittings (e.g., elbows, caps and tees) and / or fluid control components (e.g., reverse osmosis and ultrafiltration pressure vessels, valves, flow restrictors, pressure regulators) into pipe networks, as a means to provide suitable, leakless mechanical coupling between the pipe elements while also maintaining the fluid flow circulation ability across the coupling area. Many makes and models of couplings have been commercially available over the last decades, and the use of couplings remains preferred to welding in many applications. Many couplings have two or more arcuate segments designed to be assembled to one another around linearly-adjacent free ends of pipe elements at the worksite, with an elastomeric seal trapped firmly against the joint between the free ends by the assembled segments. While existing couplings were largely satisfactory, there always remains room for improvement, especially in high-pressure and corrosive environments.SUMMARY

[0002] It was found that in some embodiments, an improved coupling system that eliminates mechanical interfaces between bolts and coupling bodies could be provided by integrating the clamping studs monolithically into the segment structure. By casting or additively manufacturing the segments and studs as one continuous piece, several failure modes are reduced or eliminated: stress corrosion cracking under bolt heads, galvanic corrosion between dissimilar metals, and crevice corrosion in mechanical junctions. This design can thus increase mechanical reliability, simplify manufacturing, enable better material control, and / or improve assembly speed with only a nut required for fastening.

[0003] Additionally, eliminating bolt heads can avoid internal corners that weaken traditional couplings. A simplified geometry can allow improved stress distribution, particularly under high pressure. A monolithic design can also facilitate the use of the same alloy (e.g., 316L, 2205, or 2507) throughout the component, further enhancing resistance to corrosion.

[0004] Several factors are taken into consideration by pipe network designers in the choice of a coupling technology (reliability, structural resistance, cost, ease of assembly, and corrosionresistance). Reliability is a significant consideration, as it is typically sought that the coupling will remain reliably leakless for a predictably long period of time. Reliability is affected by different factors, namely the choice of materials, the structural resistance and ruggedness of the components, but also concerns related to the intended application. Structural resistance can include not only static effects, but also dynamic effects such as vibrations, and may evolve over time with more or less predictability due to environmental factors. For instance, some environments of use lead to exposure to corrosive fluids, and / or require high pressure resistance. Corrosion may affect couplings, namely by infiltrating and taking root in crevices located at mechanical interfaces between clamped components, or specifically affecting mechanical interfaces between components made of different materials. Cost also remains a significant factor in the choice of a coupling. Cost considerations may include initial component costs, but also assembly and maintenance costs, and to a certain extent, reliability may thus also be considered to affect costs. Size and accessibility considerations can also be relevant. Indeed, some couplings are used in areas where limited space may be available and larger couplings or couplings requiring the presence of large tools at assembly may be unsatisfactory for such uses. Moreover, larger couplings typically require more material which can also affect costs.

[0005] In contexts where the pipe elements operate under high fluid pressure conditions, a significant amount of mechanical force can be applied by the elastomeric seal, and / or the pipe elements themselves, to the coupling. The couplings can include two (or more) segments which are clamped to one another in a manner to trap the elastomeric seal around the joint between the free ends. The mechanical force can be exerted in a manner to cause internal stress within the segments and tension stress within the clamping. Both the design of the clamping elements, and the design of the segments themselves, may thus constitute design spaces which can receive significant attention from designers to provide resistance against expectable mechanical forces while also being affordable and relatively easy and quick to assemble. Corrosion can affect the structural integrity of the segments, and / or of the clamping elements over time, and the structural resistance couplings which are more susceptible to corrosion may evolve over time in a manner which may be difficult to predict. Mechanical failures are typically inconvenient and undesired.

[0006] One way to provide for the clamping of the segments with one another is to provide the segments with main bodies being arcuate in shape to adapt to a circular cross-sectional shape of the pipe element ends to be coupled, with protrusions extending radially outwardly at circumferentially opposite ends of the main body. The main body can protrude laterally on both sides and form protrusions having flat surfaces extending parallel to a joining plane of the segments and designed to receive bolt heads or nuts for the clamping. Fasteners such as bolts and nuts can be used to clamp the protrusions to one another, either by bringing them directly into contact with one another or in a manner to leave a spacing therebetween. While this approach to clamping coupling segments can be achieved at relatively low cost and a suitable degree of convenience, it was found that the associated shape of the protrusions could involve internal corners, namely where the flat surface and the main body meet, which can constitute zones of structural weakness where fissures may appear and propagate. Moreover, the mechanical interfaces between the bolt heads, the nuts, and the lugs, represent crevices and / or mechanical interfaces between different metals, where corrosion such as galvanic corrosion may more easily take root than in other areas of the coupling. Indeed, bolts are typically made by string-cutting an extruded metal rod and then stamping to form the heads and obtaining bolts at a suitable cost may necessitate the use of materials which are suitable to this manufacturing process, typically involving a certain degree of malleability. The segments themselves, on the other hand, may benefit from being cast, which may additionally limit the choice of material to materials which are suitable for the casting process. Such factors may prevent the feasibility of using a same material for the bolt or nut and for the segments, leading to mechanical interfaces between different metals in the final assembly.

[0007] Accordingly, there is a need for a coupling design that simplifies assembly, enhances mechanical strength, reduces corrosion risks and / or improves long-term reliability in demanding environments such as water treatment systems.

[0008] It was found that at least some embodiments, at least some of the afore-mentioned inconveniences could be addressed by designing the segments in a manner for a first one of the segments to integrate a bolt, or perhaps more specifically and as will be referred to herein, a stud having a threaded portion, which can be made integral to the material of the arcuate main body and protrusion, and which can be designed in a manner to protrude tangentially ina manner to engage a mating aperture formed in another one of the segments. Namely, the elimination of the bolt head and mechanical interfaces between dissimilar materials can eliminate failure zones and reduce the risk of failure due to stress corrosion cracking (SCC), localized crevice corrosion and / or galvanic corrosion. As used herein, the expression “made integral” involves that the stud, the protrusion and the main body are monolithic and made of a material which extends continuously and seamlessly from any one of these portions of the segment to the next, such as results when producing components via casting or additive manufacturing, and / or machining.

[0009] In accordance with one aspect, there is provided a coupling for mechanically sealing a joint between adjacent ends of two pipe elements aligned coaxially around an axis, the coupling comprising : an elastomeric seal having an annular shape; two or more segments, each one of the two or more segments having a main body defining a chamber extending arcuately around the axis, the chamber being open radially inwardly, and protrusions extending radially outwardly from the main body at circumferentially opposite ends of the main body, one or more studs extending tangentially from respective ones of the protrusions of the two or more segments, one or more apertures extending tangentially across respective ones of the protrusions of the two or more segments, the two or more segments being assembleable to one another around the adjacent ends via engaging the studs across the apertures, with the elastomeric seal extending circumferentially from one of the chambers to the next; and nuts threadingly engageable with threaded portions of the studs protruding from the apertures, to clamp corresponding pairs of the protrusions and thereby press the elastomeric seal radially against the adjacent ends of the two pipe elements.

[0010] In accordance with another aspect, there is provided a pipe network comprising : a first pipe element having a first end, and a second pipe element having a second end, the first pipe element and the second pipe element aligned coaxially relative an axis and defining a joint between the first end and the second end; a coupling mechanically sealing the joint, the coupling having two or more segments, wherein : each one of the two or more segments have a main body defining a chamber extending arcuately around the axis, the chamber being open radially inwardly, and protrusions extending radially outwardly from the main body at circumferentially opposite ends of the main body, one or more studs extend tangentially fromrespective ones of the protrusions of the two or more segments, one or more apertures extend tangentially across respective ones of the protrusions of the two or more segments, the two or more segments being assembleable to one another around the adjacent ends via engaging the studs across the apertures, with the elastomeric seal extending circumferentially from one of the chambers to the next, and clamping corresponding pairs of the protrusions to press the elastomeric seal radially against the adjacent ends of the two pipe elements.

[0011] In accordance with another aspect, there is provided a coupling comprising two or more segments each having a main body defining a chamber extending arcuately around an axis, the chamber being open radially inwardly, and protrusions extending radially outwardly from the main body at circumferentially opposite ends of the main body, wherein one or more studs extend tangentially from respective ones of the protrusions of the two or more segments and one or more apertures extend tangentially across respective ones of the protrusions of the two or more segments, the two or more segments being assembleable to one another around the adjacent ends via engaging the studs across the apertures, with the elastomeric seal extending circumferentially from one of the chambers to the next, and clamping corresponding pairs of the protrusions to press the elastomeric seal radially against the adjacent ends of the two pipe elements.

[0012] Many further features and combinations thereof concerning the present improvements will appear to those skilled in the art following a reading of the instant disclosure.DESCRIPTION OF THE FIGURES

[0013] In the figures,

[0014] Fig. 1 is an oblique view of an example of a pipe network;

[0015] Fig. 1 A is an exploded view of an example of a coupling, shown without the elastomeric joint;

[0016] Fig. 2 is another exploded view of the coupling of Fig. 1A, shown with the elastomeric joint;

[0017] Fig. 3 is a cross-sectional view taken along lines 3-3 of Fig. 1; and

[0018] Fig. 4 is a cross-sectional view taken along lines 4-4 of Fig. 1.DETAILED DESCRIPTION

[0019] Fig. 1 shows an example of a pipe network 10 where a coupling 12, shown here in an assembled configuration, seals a joint between adjacent ends of two pipe elements 14, 16 which are coaxially aligned around an axis. Fig. 1A shows the coupling 12 exploded, without the elastomeric seal 18, and Fig. 2 shows the coupling 12 exploded, with the elastomeric seal 18, from an angle different than the one represented in Fig. 1A. Fig. 3 presents a cross-sectional view taken along lines 3-3 of Fig. 1, where the elastomeric seal 18 can be seen to be pressed against the adjacent ends by the coupling 12.

[0020] Referring back to Fig. 1A, in this example, the coupling 12 includes two segments 20, 22 which are assembled to one another around the adjacent ends of the pipe elements 14, 16 by engaging studs 24, 26 across apertures 28, 30 in a manner to trap the elastomeric seal 18 against free ends of the pipe elements 14, 16. In this embodiment, the two segments 20, 22 are clamped to one another by threadingly engaging nuts 32, 34 onto threaded sections of tips of the studs 24, 26, which protrude from the apertures 28, 30. As will be noted, and more clearly shown in Fig. 2, the studs 24, 26 can be integral to the arcuate main body 36 of one of the segments 20, and be monolithic thereto, such as may be achieved by manufacturing the stud together with the main body 36 by casting, additive machining and / or machining. Manufacturing processes which result in monolithic configurations where the material extends continuously and seamlessly from one portion to another include casting, additive manufacturing, and machining from a block, for instance. In the specific embodiment shown in Fig. 1A, the segments were produced by casting. In some embodiments, manufacturing processes can be combined, such as casting followed by machining to form the threads, for instance. The studs 24, 26 can thus be made of the same material than the main body 36 of the segment 20 due to the monolithic construction.

[0021] Referring to Figs. 1A and 2, the main body 36 of the coupling 12 can define a chamber 38 extending arcuately around the axis 42. The chambers 38, 40 of the segments 20, 22 can come into an annular alignment when the segments 20, 22 are assembled, in a manner that the elastomeric seal 18 can circumferentially extend, continuously, from one of thechambers 38 to the other 40. The chambers 38, 40 are open radially inwardly, exposing the elastomeric seal 18 to the external surface of the adjacent ends of the pipe elements 14, 16.

[0022] Each one of the segments 20, 22 can have protrusions 44 which extend generally radially outwardly from the main body 36 at circumferentially opposite ends. The studs 24, 26 can extend tangentially from one or more of these protrusions 44, whereas the apertures 28, 30 can extend tangentially across the one or more other ones of these protrusions 44, in a manner for each stud 24, 26 to be engageable into and across a corresponding one of the apertures 28, 30. A protrusion 44 bearing a stud 24, 26 can be referred to as a male protrusion, whereas a protrusion 44 bearing an aperture 28, 30 can be referred to as a female protrusion. The female protrusions can have two parallel planar surfaces, each circumscribing a respective, opposite side, of the aperture 28, 30. A first one of these two parallel planar surfaces can be configured to abut against a corresponding planar surface surrounding a root end of the stud 24, 26 of a male protrusion, whereas the second one can be configured to receive the nut 32, 34 directly, or indirectly (e.g., via a washer). It will be noted that to form the second one of the parallel planar surfaces, an internal corner may be formed between the female protrusion and the main body 31. Such corners are typically undesired as they may constitute an area which is prone to fissure generation and may need to be reinforced to achieve a suitable degree of confidence that it will resist the internal stresses which can be expected during the lifespan of the coupling.

[0023] In an alternate embodiment using two segments having female protrusions, a similar parallel planar surface design, and its associated internal corner, may be used to support a head of a bolt instead of a nut. It will be noted that by integrating a stud to the male protrusion, making it monolithic thereto, instead of using a bolt and female protrusion, the internal corner can be avoided.

[0024] Moreover, in an alternate embodiment using two segments having female protrusions and bolts instead of integrated studs, additional mechanical interfaces occur between the head of the bolt and the planar surface, forming crevices where corrosion may take root. Finally, in such an alternate embodiment, while it may be desired to use bolts and segments made of a same material, this may be unfeasible in practice due to the different material considerations associated to the different fabrication processes of bolts and of segments (string-cutting andstamping vs. casting), when factoring in cost considerations. An interface of different materials between the bolt and the segment can lead to increased likelihood that galvanic corrosion will occur at the interface between the bolt and the segment.

[0025] Accordingly, integrating a stud 24, 26 as part of the segment 20 instead of using a separate bolt can have the first advantage of avoiding a mechanical interface between a bolt head and a planar surface of the segment, avoiding the associated crevice and associated likelihood of corrosion, and / or the second advantage of avoiding an internal corner between the planar surface of the segment 20 and the main body 36 of the segment 20, and the associated structural weakness.

[0026] Moreover, integrating a stud 24, 26 as part of the segment 20 instead of using a separate bolt can make it natural to use a stud 24, 26 made of a same material as the rest of the segment 20, which can further avoid a mechanical interface between different metals and an associated likelihood of corrosion. Such a material can be 316 stainless steel, 2205 duplex alloy, or 2507 super duplex alloy, to name some non-limiting examples. In some embodiments, it can be preferred to further use a nut made of the same material.

[0027] To further optimize the design, two optional features may independently be implemented or not.

[0028] A first one of these features is a tapering of a shank portion 46 of the studs, 24, 26 which extends between a root end 48 of the studs 24, 26 where the studs 24, 26 meet the planar surface of the protrusion, and the threaded portion 50 of the studs, leading to a free end 52 or tip. Indeed, as best seen in Fig. 2, the shank portion 46 can narrow (taper), in the direction extending from the root end 48 to the threaded portion 50. The presence of this narrowing shank portion 46 can help reduce the sharpness of any internal corners and thereby avoid or alleviate potential structural weaknesses. In some embodiments, it may be preferred for the shank portion 46 to be truncated conical in shape. In other embodiments, such as the one illustrated, a curved shape may be preferred, bridging the radially-oriented planar surface and the tangentially-oriented threaded section 50 of the stud 24. In some embodiments, the apertures 28, 30 can be provided with a correspondingly tapering shape, such as exemplified in Fig. 1A, which narrows between a first end (see in Fig. 2) receiving the shank, and a secondend (seen in Fig. 1 A) receiving the threaded portion 50. It will be noted that this is the case of the illustrated embodiment, where the end of the apertures shown in Fig. 1A are broader than the end of the apertures shown in Fig. 2 and which can narrow based on a shape like the shape of the shank portion 46.

[0029] A second one of these features is a tapering 52 of the male protrusions in the radially-outer direction, such as perhaps best seen in Fig. 1A. Indeed, instead of having an internal corner such as the female protrusions best seen in Fig. 2, the male protrusions can have a second planar surface which is inclined relative the first planar surface, forming a wedge shape. The second planar surface can be tangentially-oriented and smoothly connect with an arcuate portion of the main body 36, such as best seen in Fig. 1A.

[0030] It was found the coupling design can eliminate a bolt head and its interface, thereby allowing to avoid stress corrosion cracking (SCC), crevice, and galvanic corrosion risks in some embodiments. Moreover, the system can enable faster and simpler assembly, requiring only a nut for fixation.

[0031] As can be understood, the examples described above and illustrated are intended to be exemplary only and various modifications may be made to the examples presented herein to adapt them to various circumstances or based on the designer’s concerns.

[0032] For instance, the embodiment shown in Fig. 1A and Fig. 2 includes two segments which meet at a median plane. Accordingly, the segments have planar surfaces which are radially oriented at the median plane in the assembled configuration. In such embodiments, two studs may be integrated within a same one of the segments, and the other segments may have two apertures as shown. However, in an alternate embodiment, both segments may be identical, with each segment a male protrusion and a female protrusion, and thus one stud extending tangentially on one side, and one aperture extending tangentially on the other side, which would still lead to an embodiment where the two segments can be assembled in a similar manner.

[0033] In some other cases, more than two coupling segments may be used to fully circumscribe the pipe element ends. For instance, three coupling segments each extendingarcuately along a 120° span, or four coupling segments each extending arcuately along a 90° span may be used. In such embodiments, it may be more convenient to use segments which have a male protrusion at one circumferential end and a female protrusion at the other circumferential end, to facilitate assembly. Moreover, while in some embodiments it may be preferred for coupling segments to be identical and / or to all have the same arcuate span, in other embodiments, it may be preferred for the coupling segments to be different, and / or to have different arcuate spans.

[0034] Moreover, instead of having two circumferentially opposite protrusions each bearing a stud or an aperture, in some embodiments, it may be preferred to provide the segments with a pivot on one side, and a clamp element only on one of the sides. For instance, in an alternate embodiment, a coupling can include two segments which are permanently pivotally secured to one another at one circumferential end around a pivot axis which extends parallel to the axis of the pipe elements, and, at the other circumferential end, one of the segments having a male protrusion and the other having a female protrusion.

[0035] Finally, while a nut and male thread engagement are used as the clamp element in the embodiments illustrated, it will be understood that other clamp elements exist and may be substituted to the nut and male thread engagement in alternate embodiments.

[0036] Accordingly, the scope is indicated by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A coupling for mechanically sealing a joint between adjacent ends of two pipe elements aligned coaxially around an axis, the coupling comprising:an elastomeric seal having an annular shape;two or more arcuate segments,each one of the two or more arcuate segments having a main body defining a chamber extending arcuately around the axis, the chamber being open radially inwardly, and protrusions extending radially outwardly from the main body at circumferentially opposite ends of the main body,one or more studs extending tangentially from respective ones of the protrusions of the two or more segments,one or more apertures extending tangentially across respective ones of the protrusions of the two or more segments,the two or more arcuate segments being assembleable to one another around the adjacent ends by engaging the studs across the apertures, with the elastomeric seal extending circumferentially from one of the chambers to the next; andnuts threadingly engageable with threaded portions of the studs protruding from the apertures, to clamp corresponding pairs of the protrusions and thereby press the elastomeric seal radially against the adjacent ends of the two pipe elements.

2. The coupling of claim 1 wherein the studs have a root end monolithically connecting the corresponding protrusion, and a shank between the root end and the threaded portion, the shank narrowing in the direction extending from the root end to the threaded portion in a manner to reduce internal stress concentrations.

3. The coupling of claim 2 wherein the narrowing of the shank extends along a curved surface between a radially-oriented planar surface surrounding the root end and a tangentially-oriented cylindrical surface leading to the threaded portion.

4. The coupling of claim 2 or 3 wherein the apertures are shaped to receive the studs and have a correspondingly narrowing portion.

5. The coupling of claim 4 wherein the apertures have a female shape corresponding to and mapping a male shape of the studs including the shank.

6. The coupling of any one of claims 1 to 5 wherein the nuts are made of a same alloy than the segments in a manner preventing galvanic corrosion at an interface between the nuts and the protrusions.

7. The coupling of any one of claims 1 to 6 wherein the protrusions bearing the studs have a first planar surface circumscribing a root end of the corresponding studs and a second surface tangentially opposite the first planar surface, the second surface inclined relative the first surface in a manner to define a radially-outwardly tapering wedge.

8. The coupling of claim 7 wherein the second surface of the protrusions bearing the studs is planar and tangentially-oriented relative a curved outer surface of the main body.

9. The coupling of any one of claims 1 to 8 wherein the protrusions bearing the apertures have two tangentially opposite, parallel, planar surfaces circumscribing the corresponding aperture.

10. A pipe network comprising:a first pipe element having a first end, and a second pipe element having a second end, the first pipe element and the second pipe element aligned coaxially relative an axis and defining a joint between the first end and the second end;a coupling mechanically sealing the joint, the coupling having two or more segments, wherein:each one of the two or more segments have a main body defining a chamber extending arcuately around the axis, the chamber being open radially inwardly, and protrusions extending radially outwardly from the main body at circumferentially opposite ends of the main body,one or more studs extend tangentially from respective ones of the protrusions of the two or more segments,one or more apertures extend tangentially across respective ones of the protrusions of the two or more segments,the two or more segments being assembleable to one another around the adjacent ends via engaging the studs across the apertures, with the elastomeric seal extending circumferentially from one of the chambers to the next and clamping corresponding pairs of the protrusions to press the elastomeric seal radially against the adjacent ends of the two pipe elements.

11. The pipe network of claim 10 wherein the studs have a root end monolithically connecting the corresponding protrusion, and a shank between the root end and the threaded portion, the shank narrowing in the direction extending from the root end to the threaded portion in a manner to reduce internal stress concentrations.

12. The pipe network of claim 11 wherein the narrowing of the shank extends along a curved surface between a radially-oriented planar surface surrounding the root end and a tangentially-oriented cylindrical surface leading to the threaded portion.

13. The pipe network of claim 10 or 11 wherein the apertures are shaped to receive the studs and have a correspondingly narrowing portion.

14. The pipe network of claim 13 wherein the apertures have a female shape corresponding to and mapping a male shape of the studs including the shank.

15. The pipe network of any one of claims 10 to 14 wherein the nuts are made of a same alloy than the segments in a manner preventing galvanic corrosion at an interface between the nuts and the protrusions.

16. The pipe network of any one of claims 10 to 15 wherein the protrusions bearing the studs have a first planar surface circumscribing a root end of the corresponding studs and a second surface tangentially opposite the first planar surface, the second surface inclined relative the first surface in a manner to define a radially-outwardly tapering wedge.

17. The pipe network of claim 16 wherein the second surface of the protrusions bearing the studs is planar and tangentially-oriented relative a curved outer surface of the main body.

18. The pipe network of any one of claims 10 to 17 wherein the protrusions bearing the apertures have two tangentially opposite, parallel, planar surfaces circumscribing the corresponding aperture.

19. A coupling for mechanically sealing a joint between adjacent ends of two pipe elements aligned coaxially around an axis, the coupling comprising:an elastomeric seal having an annular shape;two segments each having a complementary semi-circular configuration, each one of the two or more segments having a main body defining a chamber extending arcuately around the axis, the chamber being open radially inwardly, and protrusions extending radially outwardly from the main body at circumferentially opposite ends of the main body,one or more studs extending tangentially from respective ones of the protrusions of the two segments, the one or more studs being integrated monolithically with the main body such that the main body and one or more studs are formed of a single continuous piece of material,one or more apertures extending tangentially across respective ones of the protrusions of the two segments, andthe two segments being assembleable to one another around the adjacent ends via engaging the studs across the apertures, with the elastomeric seal extending circumferentially from one of the chambers to the next; and nuts threadingly engageable with threaded portions of the studs protruding from the apertures, to clamp corresponding pairs of the protrusions and thereby press the elastomeric seal radially against the adjacent ends of the two pipe elements.

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