NOVEL VENTED TWIN BARREL COUPLING FOR PIPE

FIELD OF THE INVENTION

[0001] This invention relates to a novel vented twin barrel coupling for pipe. The coupling comprises an outer barrel having a flange from which an inner barrel is supported. The outer barrel, flange and inner barrel form a cavity in which a terminal end of a pipe may be seated and abutted to the flange. At least one vent is provided in the outer barrel, inner barrel, flange or combination thereof, to allow air and dissipated adhesive to escape from the cavity, along with an amount of liquid adhesive sufficient to seal the vents upon curing. The novel coupling provides a protective seal for the terminal end of the pipe, as well as a more secure fit than prior art couplings.

BACKGROUND OF THE INVENTION

[0002] Piping in most countries is produced according to certain standards. These standards set, for example, the dimensions of the pipe and strict testing requirements the pipe must pass for the pipe to be employed in its intended application. For example, in the United States, there are ASTM standards that set strict standards for CPVC pipe. An example standard is ASTM D2846/D2846M, which sets standards for the pipe dimensions and temperature and pressure ratings the pipe must pass to be employed for use in hot and cold water distribution systems. Other examples exist, such as ASTM F438 and the like, which set standards for CPVC pipe fittings for various schedule pipe. Standards also exist for pipe of other material.

[0003] To produce couplings today, all one of ordinary skill need do is to find the appropriate standards in the jurisdiction in which the coupling will be employed, and produce the coupling to fit the standard. Still, even following the standards, the terminal ends of pipe could degrade. For example, delamination or bubbling can occur in composite pipe when the medium being transported through the pipe comes into contact with the terminal end of the pipe. Likewise, micro-droplets of the medium can enter and propogate micro-cracks at the terminal end of the pipe, or corrode a non-protected surface at the terminal end of the pipe.

[0004] U.S. Publication No. 2009/0139661 to Frimel, et al., published June 4, 2009, herein incorporated by reference, teaches a twin barrel coupling for use with composite pipe (pipe having a plastic outer layer, metal middle layer and plastic inner layer). It was found that the twin barrel type coupling could provide protection to the terminal end of the composite pipe, preventing delamination of the various layers. The protection was provided due to a seal created by adhesive as it dried between the twin barrels, which seal blocked the flow of the transport medium, for example, water, to the terminal end of the pipe and between the composite layers.

[0005] Unfortunately, it has been found in practice that the coupling can fail under increased pressure or temperature. Without wishing to be bound by theory it is believed that as the terminal end of a pipe coated with adhesive is inserted into the coupling, air and dissipated adhesive become trapped without escape. This trapped air and dissipated adhesive prevent the terminal end of the pipe from seating in the coupling properly and abutting the end of the coupling, thereby reducing the integrity of the joint. As pressure or temperature of the pipe system is increased, the coupling then can fail.

[0006] A new coupling is needed that can overcome these

shortcomings. SUMMARY OF THE INVENTION

[0007] As a solution to the above-mentioned problems, the inventors have created a new and improved coupling having vents. Surprisingly, incorporation of vents in a twin barrel coupling alleviate the shortcomings of prior art couplings. Further, it has been found that the novel twin barrel vented coupling described herein can be employed with many different materials and in any desired configuration.

[0008] The pipe coupling comprises at least one coupling unit. The at least one coupling unit comprises an outer barrel, a radially inwardly extending flange, a tapered inner barrel, and at least one vent. The outer barrel can have a fore end, an aft end, an inner surface, an outer surface, and a central axis. The inner barrel can share a common central axis with the outer barrel, and have a fore end, an aft end, an inner surface, and an outer surface. The radially inwardly extending flange can extend radially inward from the inner surface of the outer barrel, and support the aft end of the inner barrel coaxially with the outer barrel. A cavity can be defined between the inner surface of the outer barrel, the outer surface of the inner barrel, and the radially inwardly extending flange. The at least one vent can be located in the outer barrel, inner barrel, radially inwardly extending flange, or any combination thereof, at positions that provide vent flow of air and dissipated adhesive from the cavity, as well as an amount of liquid adhesive sufficient to seal the at least one vent upon curing.

[0009] In one embodiment, the inner barrel can have an inward taper in the range from greater than or equal to 0.4° to less than or equal to 4° towards the central axis, such that the diameter of the fore end of the inner barrel is smaller than the diameter of the aft end of the inner barrel.

[0010] In another embodiment, the coupling can comprise two or more coupling units. The flange can serve as a common flange for the two or more coupling units, or each coupling unit can comprise its own flange connected to the other flanges by an inner flow barrel in flow communication with the two or more coupling units.

[0011] In a further embodiment, the coupling can be joined to a pipe by coating adhesive on an outer surface, an inner surface and an annular surface of a terminal end of a pipe and inserting the pipe end into a fore end of the coupling, such that the adhesive is retained on the surfaces of the end of the pipe and the annular surface of the pipe is abutted to the flange.

[0012] In one embodiment, the coupling can be employed with a composite pipe.

BRIEF DESCRIPTION OF THE DRAWING

[0013] The foregoing invention will best be understood by reference to the following detailed description, and of particular fittings representative of those to be used to make a leak-proof connection between a fitting and a terminal end of a pipe, accompanied with schematic illustrations in which like reference numerals refer to like elements, and in which:

[0014] Figure 1A is a side elevation view of a cap coupling according to one embodiment of the invention;

[0015] Figure IB is a partial cross-section view of the same cap coupling shown in Figure 1A;

[0016] Figure 2A is a side elevation view of a coupling having oppositely directed coupling units according to one embodiment of the invention;

[0017] Figure 2B is a partial cross-section view of the same coupling shown in Figure 2A;

[0018] Figure 3A is a side elevation view of an example elbow coupling; [0019] Figure 3B is a partial cross-section view of an example elbow coupling;

[0020] Figure 4A is a side elevation view of an example coupling having three coupling units;

[0021] Figure 4B is a partial cross-section view of an example coupling having three coupling units;

[0022] Figure 5A is a side elevation view of an example U-joint coupling;

[0023] Figure 5B is a partial cross-section view of an example U-joint coupling.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0024] The invention is directed to a coupling that can couple terminal ends of pipe, such as, for example, piping in fire sprinkler systems or in potable water systems. In a preferred embodiment, the coupling is made of PVC or CPVC, however the coupling can be made of any material desired for a specific application, such as, for example, ABS, PEX, polypropylene (PP), polyethylene (PE) or other type of plastic, copper, steel or another type of metal, and even ceramic and clay. Likewise, the coupling may be employed with pipe systems of the same or different material. Pipe with which the coupling may be employed can be made of, for example, PVC, CPVC, ABS, PEX, PP, PE or other type of plastic, copper, steel or another type of metal, and even ceramic and clay pipes.

[0025] The pipe coupling comprises at least one coupling unit. The term coupling unit as used herein refers to a unit comprising an outer barrel, a flange, an inner barrel, and at least one vent.

[0026] The outer barrel can have a fore end, an aft end, an outer surface, an inner surface and a central axis. The fore end of the outer barrel comprises an opening for accepting a terminal end of a pipe. The aft end of the outer barrel terminates at the flange. The inner surface of the outer barrel may be tapered toward the outer surface from the aft end toward the fore end.

[0027] The outer barrel of the coupling unit can be of any shape, such as, for example, cylindrical, square, oblong or any other shape. In a preferred embodiment, the outer barrel is circular. In another embodiment, the outer barrel can be pentagonal, hexagonal, or octagonal. In one embodiment, the outer barrel can be square.

[0028] The dimensions of the outer barrel, such as, for example, the thickness of the outer barrel wall, the diameter of the fore and aft ends and taper of the inner surface from fore to aft end, the length of the barrel from fore to aft end, etc., will depend on various requirements of the final application for the coupling. The dimensions for pipe and pipe couplings can be determined with reference to the appropriate standards for a particular application accepted in the jurisdiction where the coupling is to be installed. For example, in CPVC applications, those of ordinary skill in the art would be readily able to determine the appropriate dimensions for the outer barrel wall, for example, based on ASTM standards, such as, for example, ASTM F438, F439, D2846/D2846M, and the like.

[0029] The outer barrel wall can support a radially inwardly extending flange, to which a terminal end of a pipe can abut. The flange may be supported at the aft end of the outer barrel inner surface, or at an annular surface of the terminal end of the outer barrel.

[0030] Similar to the outer barrel, the dimensions of the flange, such as, for example, the coaxial thickness, radial length of the radially inwardly extending flange, etc., will depend on the final application for the coupling and will be readily available to one of ordinary skill in the art, for example, based on ASTM standards. Generally, the coaxial thickness of the flange can be of about the same thickness as the outer barrel wall. However, the flange may be thicker or thinner. The flange can terminate at the inner surface of the inner barrel or provide a continuous surface capping the end of the coupling unit.

[0031] The radially inward extending flange can coaxially support the aft end of an inner barrel. The inner barrel can have a fore end, an aft end, an inner surface and an outer surface. Preferably the inner barrel is circular. However, the inner barrel can be of any shape that the outer barrel can be. In a preferred embodiment, both the inner barrel and outer barrel are circular. In another embodiment, the inner barrel can be circular and the outer barrel can be of different shape from the inner barrel. In a preferred embodiment, the inner barrel shares a common central axis with the outer barrel.

[0032] As with the outer barrel and flange, the dimensions of the inner barrel can depend on the final application for the coupling. Those of ordinary skill in the art would be readily equipped to determine the appropriate dimensions for the inner barrel based on accepted standards. Generally, the inner barrel can be about the same thickness as the outer barrel and flange. In a preferred embodiment, the inner barrel is from about ½ the length of the outer barrel to about 7/8 the length of the outer barrel.

[0033] The inner barrel can be tapered so that the diameter of the bushing meets the dimensional requirements set forth below, as found in ASTM-F2855, for pipe diameters of 0.5" CTS, 0.75" CTS and 1" CTS. Dimensions for larger pipe are determined by analogous computation.

[0034] The foregoing dimensions dictate that the inward taper of the inner barrel can be in the range from greater than or equal to 0.4° to less than or equal to 4° towards the central axis, such that the diameter of the fore end of the inner barrel is smaller than the diameter of the aft end of the inner barrel.

[0035] The inner surface of the outer barrel, the outer surface of the inner barrel, and the fore facing surface of the flange define an annular cavity within the coupling unit. The shape of the inner surface of the outer barrel and outer surface of the inner barrel will form the cavity in a shape that can accept the shape of a terminal end of a pipe within the cavity and allow the terminal end of the pipe to sit in the cavity and remain abutted with the flange.

[0036] The annular cavity can be of sufficient height to allow the terminal end of the pipe of pre-determined wall thickness to be inserted into the cavity, with the annular surface of the terminal end of the pipe abutting the fore facing surface of the flange. In a preferred embodiment, the height of the cavity at its shortest point, measured from the inner surface of the outer barrel to the outer surface of the inner barrel at the flange can be in the range from about 0.025 mm-0.25 mm (0.001"-0.010") greater than the wall thickness of the pipe.

[0037] The pipe may be joined to the coupling unit by any type of adhesive known in the art. Examples of adhesive can be solvent cement and reactive adhesive. In a preferred embodiment, the pipe and coupling unit are comprised of CPVC and joined by solvent cement, which solvent cement complies with ASTM F493.

[0038] When the outer, inner and annular surfaces of the terminal end of pipe are coated with adhesive and inserted into one end of the coupling, the adhesive can be retained on the surfaces of the end and pushed against the flange. In some embodiments, when a pipe is inserted into the coupling, air and, for example, dissipated adhesive, can become entrapped between the inner and outer barrel of the coupling. The entrapped air can cause a pressure build-up within the coupling cavity that eventually leads to failure of the coupling. Thus, in some embodiments, the coupling unit includes a vent to relieve pressure on the coupling. For example, the vent can relieve pressure by allowing air and dissipated adhesive to escape from the cavity. Preferably, the coupling unit comprises at least one vent, and in some embodiments the coupling can comprise three, four or more vents.

[0039] The at least one vent can be located in the outer barrel, inner barrel, radially inwardly extending flange, or any combination thereof. In one embodiment, each vent in the coupling unit can be defined by a tunnel connecting an opening in a cavity facing surface of the outer barrel, inner barrel or flange with an opening in an opposing surface in the outer barrel, inner barrel, or flange.

[0040] The at least one vent can be positioned anywhere in the coupling unit, so long as the vents provides hydraulic pressure relief to the cavity by allowing vent flow of air and dissipated adhesive from the cavity, as well as vent flow of a sufficient amount of liquid adhesive to harden and seal the vents after the coupling unit is joined with a terminal end of pipe. The vents cannot be positioned in any manner that causes the vents to clog during joining and not allow sufficient vent flow of air and dissipated adhesive. An insufficient vent flow can result in, for example, the terminal end of the pipe not abutting the flange, or failure of the adhesive to seal the vent, which could lead to a leak. An insufficient vent flow can also result in loss of integrity to the joint and catastrophic failure of the coupling.

[0041] In one embodiment the coupling unit comprises two vents axially positioned near an aft end of the outer barrel, over the cavity, and circumferentially positioned at diametrically opposed surfaces of the outer barrel from one another. In another embodiment, the coupling unit can comprise more than two vents at axial positions above the cavity, and circumferentially positioned in an equidistant or other strategic location from one another. One of ordinary skill can readily determine appropriate positioning by ordinary experimentation.

[0042] In an embodiment, the at least one vent is positioned at the aft end of the outer barrel at a distance of no more than one diameter of the vent from the flange. In another embodiment, the at least one vent is a distance of no more than 10% of the diameter of the vent away from the flange, and in some embodiments, no more than 5% of the diameter of the vent, and in further embodiments, no more than 2.5% of the diameter of the vent away from the flange.

[0043] In an embodiment, the diameter of the at least one vent is no more than 3 times the wall thickness of the outer barrel. The diameter may also be no more than 2 times the wall thickness of the outer barrel. Preferably, the diameter of the at least one vent is no more than 1 time the wall thickness of the outer barrel.

[0044] The diameter of the at least one vent can meet the dimensional requirements set forth below for pipe diameters of 0.5" CTS, 0.75" CTS and 1 " CTS. Dimensions for larger pipe are determined by analogous computation.

[0045] Thus, the position of the at least one vent can meet the dimensional requirements set forth below for pipe diameters of 0.5" CTS (wall thickness 0. 177 inches) . Dimensions for larger pipe are determined by analogous computation.

[0046] The vent openings can be of any shape, such as circular, square, triangular, oblong, or any other shape. The vents are sized taking into consideration the type of adhesive being employed and the required integrity of the pipe. For example, in some embodiments the viscosity of the adhesive employed may be thin enough to escape from a tiny vent, whereas in another embodiment the viscosity of the adhesive may be such that a very large hole is required to allow vent flow. However, a large vent could compromise the integrity of the pipe and coupling at elevated temperatures and pressures. Thus, the vent should be large enough to allow vent-flow of air, dissipated adhesive, and an amount of liquid adhesive sufficient to seal the vents upon curing, but not large enough to compromise the integrity of the pipe and coupling unit when in use for its intended purpose. An amount of liquid adhesive sufficient to seal the vents upon curing means an amount that completely fills the vent and slightly leaks out of the vent opening.

[0047] In some embodiments, the vent can act as a view hole. In some embodiments, when a pipe is inserted in the coupling, the installer cannot see if the pipe end is fully abutted to the flange. In such a situation, a proper water tight seal may not be achieved, and failure can occur. Thus, in some embodiments, the holes may be in the shape of slits sufficient to allow viewing of the pipe insertion, while also acting as vents.

[0048] A coupling according to the invention comprises at least one coupling unit. In one embodiment, the coupling comprises two coupling units. In another embodiment, the coupling can comprise three coupling units, or more. In embodiments having multiple coupling units, each coupling may be of the same size or of different sizes. For example, the coupling may be an expansion joint having two coupling units, and each coupling unit may be of different sizes.

[0049] When the coupling comprises two coupling units or more, the flange can be a common flange shared between some or all of the coupling units. Also, some or all of the coupling units can comprise a flange separate from the other coupling units. Where the coupling comprises two or more coupling units and some of the coupling units comprise a flange separate from the other, the aft end of the inner barrel can extend past the flange to communicate with the aft end of the inner barrels supported by the other flanges, forming an inner flow barrel. The inner flow barrel allows for flow communication between the coupling units. The inner flow barrel can be of any shape and may be a different shape from the inner barrel and outer barrel. Preferably the inner barrel and inner flow barrel are of the same shape.

[0050] The coupling may be in any form, such as a cap, a cylinder, an elbow, a U-joint, a T-joint, an expansion joint, or any common coupling typically used for joining pipes. Couplings according to the invention can be made in any manner known in the art. For example, a coupling of plastic, such as PVC or CPVC, can be made by extrusion and machining, injection molding, or a combination thereof. In one embodiment, bar stock is extruded and machined to specification, and in another embodiment a coupling is injection molded. [0051] The invention will be more thoroughly described with reference to various example embodiments in the figures. Fig. 1 displays perhaps a simplest embodiment of the invention, that being a cap 100. The cap coupling 100 is essentially one coupling unit. The coupling 100 has an outer barrel 1 having fore and aft ends 2 and 3 supporting a radially inwardly extending flange 4, which flange 4 in turn coaxially supports a tapered inner barrel 5, wherein the taper is exaggerated for the figure. Two Vents 6 are included at about diametrically opposed surfaces of the outer barrel 1 in the figure. Alternatively, three or more vents may be placed in any configuration. The vents 6 provide a tunnel from the cavity 8 to the atmosphere at the outer surface of the outer barrel 1.

[0052] In one embodiment, flange 4 can be a continuous flange running the entire diameter of the coupling unit. In such an embodiment, the flange 4 may be of sufficient thickness to act as a barrier end of the coupling 100. In another embodiment, an endcap 101 can be employed to provide a barrier end. The endcap 101 may be fitted to the coupling 100 in any manner known in the art, such as, for example, by adhesive, welding, or screw type fittings, or the cap may be extruded and machined or injection molded with an endcap 101.

[0053] Referring to Fig. 2, there is shown a cylindrical coupling according to one embodiment of the invention. The coupling 200 comprises two coupling units 20 and 30. Each coupling unit 20 and 30 has its own outer barrel 1 having fore and aft ends 2 and 3. In the embodiment of Fig. 2, the outer barrel 1 comprises one radially inwardly extending common flange 204, which is supported by the outer barrel 1 of both coupling units. Common flange 204 coaxially supports an aft ends of a common tapered inner barrel 5, wherein the taper is exaggerated for the figure. A cavity 8 is defined between the inner surface 81 of the outer barrel 1 , an outer surface 82 of the inner barrel 5, and the radially inwardly extending flange 204. The outer barrel 1 could also include three vents or more around the circumference of the outer barrel, and through the outer barrel 1 to the cavity 8 (not shown).

[0054] As depicted in Fig. 2, coupling units 20 and 30 are not distinguishable. However, it is contemplated that coupling units 20 and 30 can be of different shape or size. For example, coupling 200 can be an expansion joint in which one of coupling unit 20 or 30 is small than the other.

[0055] While the embodiment of Fig. 2 shows two coupling units positioned along the same axis running through the coupling, it is contemplated that the coupling units may be offset. For example, as shown in Fig. 3, an axis 21 running through the center of coupling unit 20 can be offset from an axis 31 running through the center of coupling unit 30 at a first angle Θ ¹ of up to about 180° in any direction. In Fig. 3, first angle Θ ¹ is about 90°. In another embodiment, depicted in Fig. 5, first angle Θ ¹ can be up to 180°.

[0056] Also depicted in Figs. 3 and 5 is inner flow barrel 40. The inner flow barrel 40 is formed to allow flow communication between coupling units 20 and 30. Coupling units 20 and 30 may also be offset by a second angle Θ ² , or any number of additional angles up to about 180° in any direction (not shown) . Second angle Θ ² , and any offset angle thereafter, can be measured from an axis running through the position of the coupling unit prior to the coupling unit being offset by the new offset angle.

[0057] Three or more coupling units 20, 30 and 60 may be included in a coupling as exemplified in coupling 400 of Fig. 4. The three or more coupling units may all be in flow communication through inner flow barrel 40 with each other coupling unit as depicted, or one or more of the barrels may comprise a barrier that closes one or more coupling units from one or more other coupling units (not depicted). In Fig. 4, coupling units 20 and 30 are positioned along a common central axis 21 , and the axis 61 through coupling unit 60 is offset at a first angle Θ ¹ of about 90°.

[0058] Various embodiments of the invention will be presented by way of example. The examples are not intended to limit the scope of the invention, but merely provide a better understanding of its various features and benefits.

EXAMPLES

Example 1

[0059] Adhesive is applied to 6 vented couplings according to the invention and 6 non-vented couplings. The couplings are applied to pipes and allowed to cure for 96 hours. After curing, the adhered couplings and pipes are cut in half along the pipe and coupling central axis, and the distance of the terminal ends of the pipes from the coupling flanges are measured. Given the small measurements, the average of the measurements are provided in Table 1.

Example 2

[0060] Adhesive is applied to non-vented couplings and vented couplings according to the invention. The couplings are applied to pipes and allowed to cure for 96 hours. After curing, the pipe and coupling systems are filled with water and brought to a pressure of 551 psi at a temperature of 180 °F for 6 minutes, and then lowered to 403 psi. A coupling is considered to pass if it can pass the 551 psi stage and then remain under 403 psi pressure for 4 hours. Table 2 shows time to failure (ttf) of the non- vented couplings.

[0061] As can be seen in Table 2, only one of the non-vented couplings, non-vented coupling 6, passed 551 psi but then immediately failed during the 403 psi test. Only one of the vented couplings, vented coupling 5, did not pass the 403 psi test, which coupling was tested with an insufficient amount of adhesive to completely fill the coupling cavity. The remaining vented couplings were left on pressure overnight and removed after 17.3 hours having not yet failed.

[0062] Each of the documents referred to above is incorporated herein by reference. The mention of any document is not an admission that such document qualifies as prior art or constitutes the general knowledge of the skilled person in any jurisdiction. Except in the Examples, or where otherwise explicitly indicated, all numerical quantities in this description specifying amounts of materials, reaction conditions, molecular weights, number of carbon atoms, and the like, are to be understood as modified by the word "about." It is to be understood that the upper and lower amount, range, and ratio limits set forth herein may be independently combined. Similarly, the ranges and amounts for each element of the invention can be used together with ranges or amounts for any of the other elements.