HK1205549B - Fitting having receptacle of varying depth - Google Patents

Description

Fitting with varying depth receptacles

Cross Reference to Related Applications

This application is based on and claims priority rights to U.S. utility patent application No. 13/368,589 filed on day 2, 8, 2012 and incorporated herein by reference in its entirety.

Technical Field

The present invention relates to fittings such as elbow fittings and "tee" fittings for joining pipe elements together.

Background

Fittings, such as elbow fittings and tee fittings, used to join pipe elements together end-to-end include interconnectable housing portions that are positionable circumferentially about end portions of the pipe elements. The term "pipe element" is used herein to describe any tubular article or component having a tubular form. The pipe elements include pipe stock as well as fluid control components, such as valves, strainers, restrictors, pressure regulators, and the like.

An exploded view of an exemplary fitting is provided in fig. 1. Each housing portion of the fitting has a projection, also referred to as a "key," that extends radially inward and engages, for example, the outer surface of a plain end pipe element, a pipe element having a shoulder and a bead, or a circumferential groove extending around each pipe element to be joined. The engagement between the key and the pipe elements provides mechanical restraint to the joint and ensures that the pipe elements remain coupled even under high internal pressures and thrust loads and external forces. The housing portion defines an annular channel or pocket, e.g., receptacle, that receives a seal (e.g., an annular gasket), typically an elastomeric ring, that engages the ends of the various pipe elements and cooperates with the housing portion and the pipe elements to provide a fluid-tight seal. The tubing within the fitting extends between the annular gaskets to ensure that the entire fitting remains fluid tight. The housing portion has a connecting member, typically in the form of a lug projecting outwardly from the housing. The lugs are adapted to receive adjustable fasteners, such as nuts and bolts, which are adjustably tightened to draw the housing portions toward one another.

The projections on prior art couplings typically have arcuate surfaces with a radius of curvature that substantially matches the radius of curvature of the outer surfaces of the pipe elements that are intended to be engaged. For fittings used with grooved pipe elements, the radius of curvature of the arcuate surfaces is less than the radius of curvature of the outer surface of the pipe element outside of the grooves so that the projections fit within and engage the grooves.

The method of securing the pipe elements together comprises a sequential installation process when using a joint according to the prior art. Typically, a fitting received by a technician is threaded with the housing portions, wherein the annular gasket and the conduit, including the sealing element, are captured between the housing portions of the fitting. The technician first disassembles the joint by unscrewing it, removes the annular gaskets, lubricates them (if not pre-lubricated), and places them around the ends of the pipe elements to be joined. Installation of the annular gaskets typically requires that they be lubricated and deployed to accommodate the pipe elements. With the ring gasket in place on the pipe elements, the pipe engages with the ring gasket on each pipe element. The housing portions are then placed one at a time around the annular gasket and the pipe, straddling the ends of the pipe elements. During placement, the housing portions engage the annular gasket, the keys (when present) are aligned with the grooves in the pipe elements, the bolts are inserted via the lugs, the nuts are threaded onto the bolts and tightened, the housing portions are directed toward each other, and the annular gasket is compressed to effect a seal between the pipe elements, the pipeline, and the fitting. The key engages in a groove in the pipe element to provide mechanical restraint.

Fig. 2 shows a joint 11 with a first housing part 13 and a second housing part 15. The housing portions 13 and 15 are attached to each other by fasteners 17 and define a first receptacle 19 and a second receptacle (not shown). The first housing 19 defines an opening 21 for receiving a pipe element. The housing portions 13 and 15 are supported in spaced relation to one another on the outer surface of a seal 23 captured between the housing portions. This configuration is possible because the circumference of the outer surface of the undeformed seal 23 is greater than the total circumference of the surfaces on the housing portions that interface with the outer surface of the seal. When the housing parts are supported in this way, it is possible to insert the pipe elements into the openings 21 between the housing parts without disassembling the joint. However, this solution to the problem of installing mechanical joints has some drawbacks. Of particular note, the seal 23 is distorted into an oval shape by the geometry of the closely fitting housing portion resting on at least a portion of the seal before the seal is properly seated in the pocket of the housing portion. An oval shape can lead to pinching and failure of the seal if the degree of distortion of the seal is not controlled.

As is clear from the previous description, the installation of a joint according to the prior art requires the technician to handle typically up to thirteen separate parts and has to totally disassemble and reassemble the joint. Much time, labor and expense would be saved if the technician could install the joint without first disassembling it in its entirety and then reassembling it piece by piece. It is also clear that there is a need for a pipe joint with which twisting of the annular seal can be controlled so as to prevent damage to the annular seal with which it is used, but which will also allow pipe elements to be reliably inserted without disassembly of the joint.

Disclosure of Invention

The present invention relates to a joint for joining together at least two pipe elements. In one exemplary embodiment, the fitting includes first and second housing portions attached to one another and defining at least first and second receptacles. The first and second receptacles define first and second openings, respectively, for receiving pipe elements. The housing portion also defines a first passage extending between the first and second receptacles. At least one adjustable fastener attaches the first housing portion and the second housing portion to each other. The housing portions are supported in a spaced apart relationship sufficient to allow the pipe elements to be inserted into the receptacles when the housing portions are attached to one another. The fasteners are adjustably tightenable for drawing the housing portions toward one another and engaging the receptacles with the pipe elements for attaching the pipe elements together.

The first receptacle need not be coaxially aligned with the second receptacle. In this embodiment, the first receptacle surrounds a first axis oriented coaxially with the first opening and the second receptacle surrounds a second axis oriented coaxially with the second opening, the first and second axes being angularly oriented with respect to each other. The first axis and the second axis may have an orientation angle from about 90 ° to about 174 ° with respect to each other.

Each housing portion includes a first arcuate surface extending circumferentially about the first opening. At least a portion of each first arcuate surface is engageable with a respective one of the pipe elements. The first arcuate surface faces the first axis. The first arcuate surface has a first radius of curvature measured from a first center of curvature. The first back wall is positioned adjacent the first arcuate surface. The first rear wall has an arcuate surface facing the first axis. The arcuate surface of the first back wall has a second radius of curvature measured from the second center of curvature. The second center of curvature is not coincident with the first center of curvature (non-coincident) as measured in a plane perpendicular to the first axis.

In one embodiment, the first center of curvature is closer to the arcuate surface of the first back wall than the second center of curvature when measured to a point on the arcuate surface of the first back wall that is collinear with the first center of curvature and the second center of curvature. In another embodiment, the first and second centers of curvature and the point on the first back wall are collinear along a first line oriented perpendicular to a second line extending between the first end of the housing portion and the second end of the housing portion.

The second center of curvature may be offset from the first center of curvature by a distance of about 0.01 inches to about 0.1 inches, or by a distance of about 0.02 inches to about 0.04 inches, or by a distance of about 0.03 inches.

The fitting may also include a first seal positioned within the first receptacle. The first seal surrounds the first opening. A second seal is positioned within the second receptacle and surrounds the second opening. The tube extends within the fitting between the first seal and the second seal. The tube may be integrally formed with the first and second seals, or the seals may sealingly engage the pipeline as they are compressed between the first and second housing portions. The seal supports the first housing portion and the second housing portion in a spaced apart relationship sufficient to insert the pipe element between the housing portions, and the seal may have a shape that is distorted to an oval shape, or it may be substantially undistorted and take on a circular shape. The degree of distortion of the seal is determined by the offset of the first and second centers of curvature. The first seal has an outer circumference having a length greater than the total length of the arcuate surface of the first back wall of the housing portion.

In another exemplary embodiment of a joint for joining pipe elements together according to the present disclosure, a distance between the arcuate surface of the first back wall and the first arcuate surface is a first value at a first point intermediate the ends of the housing portions and a second value at a second point proximate at least one end of the housing portions, as measured along a radially projecting line extending from the first axis. The first value is less than the second value.

The distance between the arcuate surface of the first back wall and the first arcuate surface may be at a minimum at a first point intermediate the ends of the housing portions and at a maximum at a second point. The second point may be located at least one end of the housing portion. The distance between the arcuate surface of the first back wall and the first arcuate surface may be a third value substantially equal to the second value at a third point positioned at the other end of the housing portion.

In certain exemplary embodiments, the arcuate surface of the first back wall includes a first portion having a curved surface, and a second portion having a curved surface. The second portion is positioned proximate to at least one end of the housing portion. Any point on the second portion is further from the first axis than any point on the first portion. The arcuate surface of the first back wall may also include a third portion having a curved surface. The third portion is positioned proximate to the other end of the housing portion. Any point on the third portion is further from the first axis than any point on the first portion.

The second portion of the arcuate surface of the first back wall may subtend an angle from about 5 ° to about 80 °, or an angle from about 5 ° to about 45 °. The third portion of the arcuate surface of the first back wall may subtend an angle from about 5 ° to about 80 °, or an angle from about 5 ° to about 45 °.

In another example of a fitting according to the present disclosure, the arcuate surface of the first back wall includes a first portion having a first radius of curvature and a second portion having an infinite radius of curvature. The second portion is positioned proximate to at least one end of the housing portion. Any point on the second portion is further from the first axis than any point on the first portion. The arcuate surface of the first back wall may also include a third portion having an infinite radius of curvature. Any point on the third portion is further from the first axis than any point on the first portion. The third portion is positioned proximate to the other end of the housing portion. The second portion of the arcuate surface of the first back wall may subtend an angle from about 5 ° to about 45 °, or an angle from about 5 ° to about 30 °. The third portion of the arcuate surface of the first back wall may subtend an angle from about 5 ° to about 45 °, or an angle from about 5 ° to about 30 °. In another exemplary embodiment, the arcuate surface of the first back wall may further include a plurality of second portions of the arcuate surface of the first back wall, each second portion having an infinite radius of curvature. Further, the arcuate surface of the first back wall may also include a plurality of third portions of the arcuate surface of the first back wall, each having an infinite radius of curvature. A third portion of the arcuate surface of the first back wall is positioned proximate the other end of the housing portion. The plurality of second portions of the arcuate surface of the first back wall may subtend an angle from about 5 ° to about 80 °, or an angle from about 5 ° to about 30 °. The plurality of third portions of the arcuate surface of the first back wall may subtend an angle from about 5 ° to about 80 °, or an angle from about 5 ° to about 30 °.

In another embodiment, the first housing portion and the second housing portion may further define a third receptacle. In this embodiment, the third receptacle defines a third opening for receiving one pipe element. The housing portion also defines a fluid passageway extending between the first, second, and third receptacles. In an exemplary embodiment of a fitting having a third receptacle, the first receptacle may surround a first axis oriented coaxially with the first opening, the second receptacle may surround a second axis oriented coaxially with the second opening, and the third receptacle may surround a third axis oriented coaxially with the third opening. The first and second axes may be coaxial with one another, and the third axis may be angularly oriented with respect to the first and second axes. The first axis and the third axis may have an orientation angle from about 30 ° to about 150 ° with respect to each other.

The example fitting embodiment may also include at least one lug extending from each of the first and second housing portions. Each lug defines an aperture for receiving one of the fasteners.

An example fitting embodiment has a first seal positioned within the first receptacle and surrounding the first opening. A second seal is positioned within the second receptacle and surrounds the second opening. A third seal is positioned within the third receptacle and surrounds the third opening. A conduit extends within the fitting between the first seal, the second seal, and the third seal. The conduit may be integrally formed with the first seal, the second seal, and the third seal.

In an alternative embodiment, the seal sealingly engages the pipeline when the seal is compressed between the first and second housing portions. The first housing portion and the second housing portion may be supported in spaced relation by contact with the first seal and the second seal. To this end, the first and second seals may have outer circumferences of the housing portions sized to be supported in a spaced apart relationship sufficient to allow insertion of the pipe element into the receptacle.

In another embodiment, the first housing portion and the second housing portion may be supported in spaced relation by contact with the first seal, the second seal, and the third seal. The first, second and third seals may have outer circumferences of the housing portions sized to be supported in a spaced apart relationship sufficient to allow insertion of the pipe element into the receptacle.

Drawings

FIG. 1 is an exploded isometric view of an exemplary elbow joint according to the present invention;

FIG. 2 is an elevational view of an exemplary mechanical pipe joint according to the present disclosure;

FIG. 3 is an elevational view of an exemplary mechanical pipe joint according to the present disclosure;

FIG. 4 is a cross-sectional view of a housing portion of an exemplary mechanical pipe joint according to the present invention;

FIG. 5 is a cross-sectional view of a housing portion of the exemplary mechanical pipe joint taken at line 5-5 of FIG. 4;

FIG. 6 is a cross-sectional view of a housing portion of an exemplary mechanical pipe joint according to the present invention;

FIG. 7 is a cross-sectional view of a housing portion of an exemplary mechanical pipe joint according to the present invention;

FIG. 8 shows a partial cross-sectional view of an exemplary housing portion on an enlarged scale;

FIG. 9 is an isometric view of the elbow joint shown in FIG. 1 pre-assembled into a ready-to-install configuration;

FIG. 10 is an isometric view of the elbow joint shown in FIG. 1 joining pipe elements together;

FIG. 11 is an isometric exploded view of an alternative embodiment of an elbow joint according to the present invention;

FIG. 12 is an isometric view of the elbow joint shown in FIG. 11 pre-assembled into a ready-to-install configuration;

FIG. 13 is an isometric view of the elbow joint shown in FIG. 11 joining pipe elements together;

FIG. 14 is an isometric view of an exemplary three-way fitting according to the present invention, and shown pre-assembled in a ready-to-install configuration;

FIG. 15 is a side view of a portion of the three-way fitting shown in FIG. 14 showing an interior surface of the fitting; and

figure 16 is an isometric view of the fitting shown in figure 14 joining pipe elements together.

Detailed Description

Fig. 3 illustrates an elevational view of an exemplary fitting 10 according to the present invention. Fig. 1 shows an exploded view of an exemplary fitting 10. The joint 10 includes a first housing portion 12 and a second housing portion 14. When attached to each other, as shown in fig. 9, the housing portions 12 and 14 define at least a first receptacle 16 and a second receptacle 18 at ends of the fitting opposite each other. Receptacles 16 and 18 define respective first and second openings 20 and 22 for receiving respective pipe elements 24 and 26, shown in phantom. Together, the housing portions 12 and 14 also define a fluid passageway extending between the first and second receptacles 16 and 18, which, for clarity, is depicted by the arrows 28 shown in fig. 1.

A plurality of lugs 30 extend from each housing portion 12 and 14. In the exemplary joint of fig. 1, each housing portion has three lugs. The lugs 30 define apertures 32. When the housing portions 12 and 14 are assembled in facing relationship as shown in fig. 9, the holes 32 in the lugs 30 are aligned to receive fasteners 34, the fasteners 34 attaching the housing portions to one another to form the joint 10. Fasteners 34 are adjustably tightenable to draw first and second housing portions 12 and 12 toward one another and engage first and second receptacles 16 and 18 with pipe elements 24 and 26 (respectively) to attach the pipe elements together as shown in fig. 10.

In the example fitting embodiment 10, the first receptacle 16 is not coaxially aligned with the second receptacle 18. As shown in fig. 3 and 10, the first receptacle 16 surrounds a first axis 36 oriented coaxially with the first opening 20, while the second receptacle 18 surrounds a second axis 38 oriented coaxially with the second opening 22. Axes 36 and 38 may be used to define the angular orientation of receptacles 16 and 18 with respect to each other, and thus the type of joint. In joint 10, the orientation angle 40 between axes 36 and 38 is about 90 °, marking the joint as a 90 ° elbow. For a practical elbow design, the orientation angle 40 may be in the range of about 90 to about 174 as shown in phantom.

As shown in fig. 5, each housing portion (housing portion 12 shown) has a first projection 42 extending circumferentially around the first opening 20. At least a portion of each first projection is engageable with a respective pipe element to provide a mechanical engagement and to hold the pipe elements together. The first projection 42 engages the outer surface of the pipe element, which may be, for example, a flat surface, a surface forming a circumferential groove, or a surface having a raised shoulder or a shoulder and a bead. The first projection 42 may have one or more notches 128 (see, e.g., fig. 1 and 9-10) to facilitate insertion of the pipe element into the first opening 20. As shown in fig. 4 and 5, each first projection 42 has an arcuate surface 44 facing the first axis 36. Each convex arcuate surface 44 has a radius of curvature 50 measured from a center of curvature 52 of the arcuate surface.

To establish and maintain the fluid-tightness of the connection between the pipe elements formed by the fitting 10, a sealing element 54 is positioned between the housing portions 12 and 14. As shown in fig. 1, the sealing element 54 includes a first seal 55 positioned within the first receptacle 16, a second seal 58 positioned within the second receptacle 18, and a conduit 60 extending along the fluid passageway 28 between the first seal 55 and the second seal 58 within the fitting 10. In this example, first seal 55 and second seal 58 are integrally formed as one piece with conduit 60. The sealing element 54 may be formed of an elastomeric material, such as EPDM (ethylene propylene diene monomer), as well as nitrile, silicone, neoprene, and fluoropolymer elastomers.

The receptacle 16 receives a first seal 55 (fig. 5 and 9) positioned between the housing portions 12 and 14 (see fig. 3) to ensure a fluid tight seal. In this exemplary joint, at least a portion of the seal 54 (e.g., the first seal 55) supports the housing portions 12 and 14 in spaced apart relation when assembled. The first rear wall 46 is positioned adjacent the first projection 42 and, as shown in fig. 4 and 5, has an arcuate surface 48 facing the first axis 36. The arcuate surface 48 of the first back wall has a radius of curvature 62 measured from a center of curvature 64 of the arcuate surface of the back wall. The center of curvature 52 of the arcuate surface 44 of the first projection 42 is not coincident with the center of curvature 64 of the arcuate surface 48 of the first back wall 46, as viewed or measured in a plane 66 oriented perpendicular to the first axis 36 of the joint 10. In the example shown in fig. 4, the center of curvature 52 is closer to the arcuate surface of the first back wall 46 than the center of curvature 64 of the arcuate surface of the first back wall 48, as indicated by line segment 70, when measured to a point 68 on the arcuate surface 48 of the back wall that is collinear with the centers of curvature 52 and 64. As further shown in FIG. 4, the centers of curvature 52 and 64 and the point 68 on the rear wall arcuate surface 48 are collinear along a line 70, which line 70 is oriented perpendicular to a second line 72 extending between ends 74 and 76 of the first housing portion 12.

The offset distance 78 between the center of curvature 52 and the center of curvature 64 results in an eccentrically shaped receptacle 16 of varying depth with the arcuate surface 48 of the first back wall extending further outward from the true circle as it progresses along the first back wall from the middle of the first projection 42 to the two ends 74 or 76 of the housing portion. If the depth 80 of the receiving portion 16, measured from the arcuate surface 44 of the first projection to the arcuate surface 48 of the rear wall, is a value of "h" at the middle of the first projection 42, the depth 80a at the ends 74,76 of the first housing portion 12 is approximately the offset distance 78 of "h" (80) +. The depth 80 may be defined as the distance between the arcuate surface 44 of the first projection 42 and the arcuate surface 48 of the first back wall 46, measured along a radially projected line extending from the first axis 36. In the exemplary embodiment, the distance (depth 80) varies from a value h at a point between ends 74 and 76 of first housing portion 12 and offset from a higher value h + at a point at each end of the housing portion. This increased depth at the end of the housing portion provides more radial space outward for the seal at the end of the housing portion, which, due to the geometry of the first seal 55 and the receptacle 16, will typically contact the first seal and, as shown in FIG. 2, distort it out of round. However, since the receptacle 16 is eccentric, with its eccentricity of the h + offset distance being greatest at the ends 74 and 76 of the housing portions 12 and 14 (and "h" being smallest at the end intermediate), contact between the arcuate surface 48 of the first rear wall 46 and the outer surface 56 of the first seal 55 can be controlled, and thereby the degree of out-of-round twisting of the first seal when the fitting 10 is factory assembled with the first and second housing portions 12 and 14 supported in spaced relation on the outer surface 56 of the first seal 55, so that pipe elements can be inserted into the first opening 20 without disassembling the fitting. It is possible to support the first housing portion 12 and the second housing portion 14 in spaced relation because the circumference of the outer surface 56 of the undeformed seal 55 is greater than the total circumference of the arcuate surfaces 48 on the housing portions 12 and 14 that interface with the seal outer surface 56. The degree of twist of seal 55 is in the range of substantially no twist, providing a circular shape as shown in fig. 3, to an oval shape as shown in seal 23 in fig. 2. As the offset distance 78 increases, the ovality of the seal decreases. While it is possible to eliminate substantially all deformation of the seal, it is sometimes advantageous to provide a controlled degree of distortion for practical designs. This is advantageously achieved when the degree of twisting is such that shrinkage of the seal is avoided while maintaining sufficient eccentricity that the seal grips one pipe end and holds it on the pipe element when it is inserted into the opening. This allows for an easy assembly of the pipe connection, as the technician does not need to hold the fitting and the first pipe element together when he manipulates the second pipe element to engage the fitting. An offset distance 78 of about 0.01 inch to about 0.1 inch has been found to be practical for a joint suitable for pipe elements having a nominal outer diameter of ten inches or less. The offset distance may further range from about 0.02 inches to about 0.04 inches, with an offset distance of about 0.03 inches being advantageous for some combinations of fittings and pipe elements.

Fig. 6 and 7 illustrate respective housing portions 82 and 84, wherein a distance 80 between the arcuate surface 44 of the first projection 42 and the arcuate surface 48 of the first back wall 46, as measured along a radially projected line 86 extending from the first axis 36, is smaller at a point 88 intermediate the ends 74 and 76 of the housing portions than at a point 90 near one end of the housing portions.

For the housing portion 82 shown in fig. 6, the arcuate surface 48 of the first back wall 46 includes a first surface portion 92 having a first radius of curvature 94, and a second surface portion 96 positioned adjacent the end 74 of the housing portion 82 having a second radius of curvature 98. Any point on the second surface portion 96 is farther from the first axis 36 than any point on the first portion 92. Accordingly, the distance 80 between the arcuate surface 44 of the first projection 42 and the arcuate surface 48 of the first back wall 46 is less within the angle 100 encompassed by the first surface portion 92 than within the angle 102 encompassed by the second surface portion 96. The second surface portion 96 may enclose an angle 102 from about 5 to about 80. Wrap angles from about 5 to about 45 are also practical.

In this example, the arcuate surface 48 also includes a third surface portion 104 positioned at the opposite end 76 of the housing portion. The third surface portion 104 has a radius of curvature 106. (the respective radii of curvature 98 and 106 of the second and third surface portions 98 and 104 may be equal to one another.) any point on the third surface portion 104 is farther from the first axis 36 than any point on the first portion 92. Accordingly, the distance 80 between the arcuate surface 44 of the first projection 42 and the arcuate surface 48 of the first back wall 46 is smaller within the angle 100 enclosed by the first surface portion 92 than within the angle 107 enclosed by the third surface portion 104. The third surface portion 104 may enclose an angle 107 from about 5 ° to about 80 °. Wrap angles from about 5 to about 45 are also practical.

Note that the distance 80 and difference between the radii of curvature are exaggerated for clarity. While the geometric relationship between arcuate surfaces 44 and 48 is described with respect to one projection 42 on one housing portion, it should be understood that each housing portion of the fitting may have such a projection surrounding each opening of the fitting and such a rear wall positioned adjacent each respective projection. It will also be appreciated that the geometric relationship between the arcuate surface on each projection and the arcuate surface of each back wall may be the same. For example, it will be appreciated that each housing portion may also include a second projection extending circumferentially around the second opening 22 (see fig. 1 and 9-13) of the fitting. In this example, at least a portion of the second projection is engageable with one of the pipe elements (26, as shown in fig. 10 and 13), and the second projection has an arcuate surface facing the second axis 38 (see fig. 10). Each housing portion may also include a second back wall positioned adjacent to the second protrusion. The second rear wall has an arcuate surface facing the second axis 38. It will be appreciated that the geometric relationship between the arcuate surfaces on the second projection and the second back wall may be the same as the geometric relationship between the arcuate surfaces 44 and 48 of the first projection 42 and the first back wall 46.

For the housing portion 84 shown in FIG. 7, the arcuate surface 48 of the rear wall 46 includes a first surface portion 108 having a first radius of curvature 110, and a second surface portion 112 positioned adjacent the end 74 of the housing portion. The second surface portion 112 has an infinite radius of curvature, meaning that the second surface portion is a flat facet 114. The facets 114 are arranged such that the distance 80 between the arcuate surface 44 of the projection 42 and the arcuate surface 48 of the rear wall 46 is smaller within the corner 116 enclosed by the first surface portion 108 than within the corner 118 enclosed by the second surface portion 112 (which is the facet 114). The second surface portion 112 may enclose an angle 118 of from about 5 to about 45. Wrap angles from about 5 to about 30 are also practical.

In this example, the arcuate surface 48 also includes a third surface portion 120 positioned at the opposite end 76 of the housing portion. In this example, the third surface portion 120 also has an infinite radius of curvature, forming a facet 122. The facets 122 are arranged such that the distance 80 between the arcuate surface 44 of the projection 42 and the arcuate surface 48 of the rear wall 46 is smaller within the corner 116 enclosed by the first surface portion 108 than within the corner 124 enclosed by the third surface portion 120. The third surface portion 120 may enclose an angle 124 of from about 5 to about 45. Wrap angles from about 5 to about 30 are also practical. Although the second and third surface portions 112 and 120 of the housing portion 84 are shown as being formed from a single facet 114 and 122, respectively, it is advantageous to form multiple facets adjacent respective ends of the housing portion 84. An example of this multi-facet configuration is shown on an enlarged scale in fig. 8, wherein the surface 48 of the housing portion 84 includes a plurality of second surface portions 112a,112b,112c, each having an infinite radius of curvature and forming respective facets 114a,114b,114 c. The plurality of surface portions 112a,112b,112c may enclose an angle 125 of about 5 to about 80. Wrap angles from about 5 to about 30 are also practical.

Note that distance 80 may be exaggerated for clarity. While the geometric relationship between arcuate surfaces 44 and 48 is described with respect to one projection 42 on one housing portion, it should be understood that each housing portion of the fitting may have such a projection surrounding each opening of the fitting and such a rear wall positioned adjacent each respective projection. It will also be appreciated that the geometric relationship between the arcuate surface on each projection and the arcuate surface of each back wall may be the same. For example, it will be appreciated that each housing portion may also include a second projection extending circumferentially around the second opening 22 (see fig. 1 and 9-13) of the fitting. In this example, at least a portion of the second projection is engageable with one of the pipe elements (26, as shown in fig. 10 and 13), and the second projection has an arcuate surface facing the second axis 38 (see fig. 10). Each housing portion may also include a second back wall positioned adjacent to the second protrusion. The second rear wall has an arcuate surface facing the second axis 38. It will be appreciated that the geometric relationship between the arcuate surfaces on the second projection and the second back wall may be the same as the geometric relationship between the arcuate surfaces 44 and 48 of the first projection 42 and the first back wall 46.

Receptacles of varying depths that allow for a degree of distortion of the seal to be controlled provide several advantages over prior art housing portions having receptacles of constant depth. When the joint is factory assembled, the seal may have a controlled shape between oval and circle. Selecting a configuration for the seal (e.g., 55) with less twist means that as the pipe element is inserted into the opening, it will more consistently engage a pipe stop 57 (shown in fig. 5) within the seal, thereby promoting proper seating of the pipe element in the joint. Furthermore, for seals with less twist, there is less likelihood that the seal will be pinched between the ends of the housing portions. However, it is advantageous for the skilled person to induce some reasonable degree of distortion in the shape of the seal allowing it to grip and hold onto the pipe elements during assembly.

The varying depth receptacles described above and claimed herein are suitable for both rigid and flexible joints. A rigid joint is advantageous for use with circumferentially grooved pipe elements. The housing portions of the rigid joint have abutting surfaces that have an angular orientation relative to each other. In an exemplary rigid joint, when the fasteners joining the housing portions together are tightened, the abutment surface on one housing portion contacts its mating surface on the mating housing portion and the housing portions are forced to rotate about the vertical axis in opposite directions relative to each other. This causes the projections to engage the sidewalls of the circumferential grooves in the pipe elements and lock them in place to provide greater resistance to external bending forces, inward and outward thrust and torque applied to the connection, thereby limiting the relative deflection of the pipe elements. Examples of rigid joints are shown here in fig. 11-16. Rigid joints are disclosed in co-pending U.S. patent application No. 13/364,412 entitled Fitting for joining Pipe Elements, "which is filed on 2/2012 and which is incorporated herein by reference in its entirety, patents disclosing rigid couplings include U.S. patent nos. 4,611,839 and 4,639,020, which are incorporated herein by reference in their entirety.

In a flexible joint, the interfacing surfaces between the housing portions are typically not configured to cause any relative rotation of the housing portions. Thus, the projections do not normally engage the sidewalls of the circumferential groove due to the twisting action of the housing portions, which results in a more flexible connection in which the relative deflection of the pipe elements in torsional and axial bending is greater than a rigid joint under the same applied load (described above). Fig. 1 and 9-10 illustrate an exemplary flexible joint.

The varying depth receptacles described above and claimed herein are also applicable to adapter fittings, such as, for example and without limitation, reducing fittings (reducers), which allow pipe elements of different nominal sizes to be coupled together. In an adapter fitting, each housing portion has a projection of different radii of curvature that mates with mating and engaging different sized pipe elements. Examples of adapter fittings for coupling grooved pipe elements are disclosed in U.S. patent nos. 3,680,894 and 4,896,902, which are incorporated herein by reference.

Fig. 9 shows the fitting 10 in a "ready-to-install" state, i.e., with the first and second housing portions 12 and 14 partially assembled, held in spaced apart relation sufficient to allow the pipe elements 24 and 26 to be conveniently inserted into the respective openings 20 and 22 without disassembly of the fitting 10. To achieve a fluid-tight connection, pipe elements 24 and 26 are inserted into openings 20 and 22, and they engage first seal 55 and second seal 58, respectively. The fasteners 34 are then tightened, bringing the housing portions 12 and 14 together (as shown in FIG. 10), and compressing the first and second seals between the housing portions and the pipe elements 24 and 26, while also engaging the receptacles 16 and 18 with their respective pipe elements 24 and 26 to mechanically retain and hold the pipe elements together. In this example, full mechanical engagement between the fitting 10 and the pipe elements 24 and 26 is achieved by the projections 42 located on the respective housing portions 12 and 14. The projections 42 may each have notches 128 at opposite ends to provide clearance and facilitate pipe element insertion. When the fitting 10 is assembled, the projections surround the openings 20 and 22 and engage the circumferential grooves 130 in the pipe elements 24 and 26 (see FIG. 9). Of course, the joint according to the invention is not limited to use with grooved pipe elements, but may also be adapted to plain end pipe elements, flared pipe elements, and shouldered pipe elements. Housing portions 12 and 14 may be conveniently supported in spaced relation by contact with first seal 55 and second seal 58.

Fig. 11-13 illustrate a fitting 138 according to another exemplary embodiment of the present invention. It will be appreciated that the features and geometric relationships described above with respect to the joints 10,82, and 84 (see fig. 4-8) may also be included in the joint 138. For example, similar to fitting 10, fitting 138 includes housing portions 12 and 14 that are attached to one another by adjustable fasteners 34 and define first and second receptacles 16 and 18. As shown in fig. 12, the receptacles define openings 20 and 22 for receiving pipe elements 24 and 26. Each housing portion 12 and 14 has a first projection 42 that extends circumferentially around the first opening 20. The first projection 42 may have an arcuate surface. The first projection 42 may have one or more notches 128 to facilitate insertion of the pipe element into the first opening 20. The tab 138 may include a rear wall having an arcuate surface. The geometric relationship between the projections of the tabs 138 and the arcuate surface of the rear wall may be the same as described above with respect to the projections and rear wall of the tabs 10,82, and 84 (see fig. 4-8).

As shown in fig. 11, the sealing element 54 of the fitting 138 is formed of three separate components and includes first and second seals 140, 142 and a conduit 144. Seals 140 and 142 are positioned within the first and second receptacles 16 and 18, respectively, defined by the housing portions, and a conduit 144 extends between the seals 140 and 142 within the fitting 138. In this embodiment, seals 140 and 142 are made of a flexible material, for example, elastomers such as EPDM, and nitrile, silicone, neoprene, and fluoropolymer elastomers, while tubing 144 is formed of a more rigid material such as PVC, metal, glass, ceramic material, or one or more engineering polymers, including thermoplastic and thermoset polymers. Exemplary rigid engineering thermoplastic polymers that may be used to form the conduits 144 include both polyphenylene (polyphenylene) and polystyrene. This selection of different materials allows seals 140 and 142 to sealingly engage tube 144 as they are compressed between housing portions 12 and 14. As shown in FIG. 13, the sealing interaction between seals 140 and 142, pipe elements 24 and 26, and conduit 144 allows for a fluid-tight connection to be formed when fitting 138 is used to join pipe elements 24 and 26 together.

Similar to the fitting 10, the fitting 138 has a plurality of lugs 146 extending from the first and second housing portions. The lugs 146 define apertures 148, the apertures 148 being aligned with one another and receiving the adjustable fasteners 34 for attaching the housing portions to one another when the joint 138 is assembled as shown in fig. 12 and 13.

Similar to fitting 10, fitting 138 is also ready to be installed, meaning that it does not have to be disassembled to make a pipe connection. Fig. 12 shows the fitting 138 in a ready-to-mount configuration, in which the housing portions 12 and 14 are in spaced apart relation. In this example, the housing portions are supported in spaced apart relation by contact with a first seal 140 and a second seal 142. As shown in fig. 11, each of the first and second seals has an outer circumference 143 sized to support the housing portions 12 and 14 in a spaced apart relationship sufficient to allow pipe elements 24 and 26 (see fig. 12) to be inserted into the openings 20 and 22 without disassembly of the coupling. The notches 128 in the ends of the projections 42 facilitate insertion of the pipe elements by providing clearance.

Figures 14-16 illustrate an exemplary three-way fitting 152 according to the present invention. As shown in fig. 14, the joint 152 includes a first housing portion 154 and a second housing portion 156. When attached to each other, the housing portions 154 and 156 define a first receptacle 158, a second receptacle 160, and a third receptacle 162. Receptacles 158,160 and 162 define respective first, second and third openings 164,166 and 168 for receiving respective pipe elements 200,202 and 204 shown in phantom. Together, the housing portions 154 and 156 also define a fluid passageway extending between the first, second and third receptacles 158,160, 162, the fluid passageway being depicted by the arrows 170 shown in fig. 15 for clarity.

Referring again to fig. 14, a plurality of lugs 172 extend from each housing portion 154 and 156. In this exemplary three-way joint 152, each housing portion has four lugs. The lugs 172 define apertures 174 (see fig. 15). When the housing portions 154 and 156 are assembled in facing relation as shown in fig. 14, the holes 174 in the lugs 172 align to receive fasteners 176 that attach the housing portions to one another to form the tee fitting 152. The fasteners 176 are adjustably tightenable to draw the first and second housing portions 154 and 156 toward each other and engage the first, second and third receptacles 158,160 and 162 with the pipe elements 200,202 and 204 (respectively) to attach the pipe elements together as shown in fig. 16.

In the example three way fitting embodiment 152, as shown in fig. 16, the first receptacle 158 surrounds a first axis 178 oriented coaxially with the first opening 164. The second receptacle 160 surrounds a second axis 180 oriented coaxially with the second opening 166. The first receptacle 158 is collinear with the second receptacle 160. The third receptacle 162 surrounds a third axis 182 that is angularly oriented relative to the first and second axes 178, 180. Axes 178,180, and 182 may be used to describe the angular orientation of receptacles 158,160, and 162 relative to one another. In the exemplary three-way joint 152, the orientation angle 184 between the axis 182 and the axis 178 or 180 is about 90 °. For practical tee designs, the orientation angle 184 may be in the range of about 30 to about 150 as shown in phantom. It will also be appreciated that the housing portions 154 and 156 may take any practical shape between receptacles 158,160 and 162. Thus, for example, the particular segments extending between receptacles may be linear segments as shown, or may be curved, so long as the receptacles are oriented relative to one another as defined herein and as defined by the orientation angle between their respective axes shown in fig. 16.

To establish and maintain the fluid-tightness of the connection between the pipe elements formed by the tee fitting 152, a sealing element 186, shown in fig. 15, is positioned between the housing portions 154 and 156. The sealing element 186 includes a first seal 188 positioned within the first receptacle 158, a second seal 190 positioned within the second receptacle 160, and a third seal 192 positioned within the third receptacle 162. A conduit 194 extends within the tee fitting 152 between the first, second and third seals 188,190, 192 along a fluid path indicated by arrow 170. In this example, the first, second and third seals are separate from the conduit 194, but it should be understood that the sealing element 186, including the three seals and the conduit, may be formed from a one-piece integral joint, similar to the seal 54 shown in fig. 1. When formed of one piece, the sealing element 186 may be formed of an elastomeric material, such as EPDM, as well as nitrile, silicone, neoprene, and fluoropolymer elastomers. When sealing element 186 is formed as a separate piece as in fig. 14, seals 188,190 and 192 can be formed of flexible elastomeric materials, for example, elastomers such as EPDM, as well as nitrile, silicone, neoprene and fluoropolymer elastomers, while tubing is formed of relatively more rigid materials such as PVC, metal, glass, ceramic materials or one or more engineering polymers, including both thermoplastic and thermoset polymers. Exemplary rigid engineering thermoplastic polymers that may be used to form the conduits 144 include polyphenylene and polystyrene.

FIG. 14 shows the tee fitting 152 in a "ready-to-install" condition, i.e., a factory-assembled condition in an untightened configuration in which the first and second housing portions 154 and 156 are maintained in a spaced apart relationship sufficient to allow for convenient insertion of the pipe elements 200,202 and 204 into the respective openings 164,166 and 168 without disassembly of the tee fitting. To achieve a fluid tight connection, pipe elements 200,202, and 204 are inserted into openings 164,166, and 168, where they engage first seal 188, second seal 190, and third seal 192, respectively. The fasteners 176 are then tightened, bringing the housing portions 154 and 156 together (as shown in FIG. 16), and compressing the first, second, and third seals between the housing portions and the pipe elements 200,202, and 204, while also engaging the receptacles 158,160, and 162 with their respective pipe elements 202, and 204 to mechanically capture and hold the pipe elements together. In this example, full mechanical engagement between the tee fitting 152 and the pipe elements 200,202 and 204 is achieved by the projections 42 positioned on each housing portion 154 and 156. The projections 42 may each have a notch 128 at opposite ends to provide clearance and facilitate pipe element insertion. As shown in FIG. 15, when the tee fitting 152 is assembled, the projections 42a,42b and 42c surround the openings 164,166 and 168, respectively, and engage annular grooves 206 in the pipe elements 200,202 and 204. The three-way joint according to the invention is of course not limited to use with grooved pipe elements, but may also be adapted to plain end pipe elements, flared pipe elements, crimped pipe elements, and shoulder pipe elements.

As described herein, the projections 42a,42b, and 42c may have arcuate surfaces that face the axes 178,180, and 182, respectively. Housing portions 154 and 156 may also include first, second, and third rear walls positioned adjacent projections 42a,42b, and 42c, respectively. The first, second, and third rear walls may have arcuate surfaces that face the axes 178,180, and 182, respectively. The geometric relationship between the arcuate surfaces of the projections 42a,42b, and 42c and the arcuate surfaces of the first, second, and third back walls may be the same as that described above with respect to the first projections 42 and first back walls 46 of the fittings 10,82, and 84 (see fig. 4-8).

Housing portions 154 and 156 may be conveniently supported in spaced relation by contact with first, second and third seals 188,190 and 190. In the example tee fitting 152 shown in fig. 14-16, the housing portions 154 and 156 are supported in spaced relation by contact with a first seal 188, a second seal 190, and a third seal 192. As shown in FIG. 14, each seal has an outer circumference 193 sized to support the housing portions 154 and 156 in a spaced apart relationship sufficient to allow the pipe elements 200,202 and 204 to be inserted into the openings 164,166 and 168 without disassembly of the tee.

The tee fitting 152 may be designed to provide a relatively flexible connection or a relatively rigid connection.

Elbow and tee fittings according to the present invention provide greatly improved efficiency in the formation of pipe connections by eliminating the need to disassemble and reassemble the fitting to create the connection.

Claims (68)

1. A fitting for connecting at least two pipe elements together, the fitting comprising:

a first housing portion and a second housing portion attached to one another and defining at least first and second receptacles defining first and second openings, respectively, for receiving the pipe elements, the first and second receptacles surrounding first and second axes, respectively, the first axis being oriented coaxially with the first opening, the second axis being oriented coaxially with the second opening, the first axis being angularly oriented with respect to the second axis, the housing portions further defining a fluid passageway extending between the first and second receptacles,

characterized in that each of said housing portions comprises:

a first arcuate surface extending circumferentially around said first opening, at least a portion of said first arcuate surface being engageable with one of said pipe elements, said first arcuate surface facing said first axis; and

a first rear wall positioned adjacent to said first arcuate surface, said first rear wall having an arcuate surface facing said first axis, a distance between said arcuate surface of said rear wall and said first arcuate surface being a first value at a first point intermediate ends of said housing portions and a second value at a second point proximate at least one of said ends of said housing portions, said first value being less than said second value, as measured along a radially projecting line extending from said first axis; and

at least one adjustable fastener attaching said first and second housing portions to one another, said housing portions being supported in a spaced apart relationship sufficient to allow insertion of said pipe elements into said receptacles when said housing portions are attached to one another, each said fastener being adjustably tightenable for guiding said housing portions toward one another and engaging said first arcuate surfaces of said housing portions with said pipe elements for attaching said pipe elements together.

2. The fitting according to claim 1, further comprising a first protrusion extending circumferentially around said first opening, said first arcuate surface being positioned on said first protrusion.

3. The fitting according to claim 1, wherein for each of said housing portions, said distance is smallest at said first point intermediate said ends of said housing portion.

4. A joint as claimed in claim 3, wherein for each said housing portion, said distance is greatest at said second point, said second point being located at said at least one end of said housing portion.

5. The fitting according to claim 4, wherein, for each of said housing portions, said distance between said arcuate surface of said back wall and said first arcuate surface is a third value equal to said second value at a third point located at the other of said ends of said housing portions.

6. The fitting according to claim 1, wherein for each of said housing portions, said arcuate surface of said back wall includes a first portion having a curved surface, and a second portion having a curved surface, said second portion being located proximate said at least one end of said housing portion, any point on said second portion being farther from said first axis than any point on said first portion.

7. The fitting according to claim 6, wherein for each of said housing portions, said arcuate surface of said back wall further comprises a third portion having a curved surface, said third portion being positioned proximate to the other of said ends of said housing portions, any point on said third portion being further from said first axis than any point on said first portion.

8. The fitting according to claim 6, wherein, for each of said housing portions, said second portion of said arcuate surface of said back wall subtends an angle from 5 ° to 80 °.

9. The fitting according to claim 6, wherein, for each of said housing portions, said second portion of said arcuate surface of said back wall subtends an angle from 5 ° to 45 °.

10. The fitting according to claim 7, wherein, for each of said housing portions, said third portion of said arcuate surface of said back wall subtends an angle from 5 ° to 80 °.

11. The fitting according to claim 7, wherein, for each of said housing portions, said third portion of said arcuate surface of said back wall subtends an angle from 5 ° to 45 °.

12. The fitting according to claim 1, wherein for each of said housing portions, said arcuate surface of said back wall includes a first portion having a first radius of curvature, and a second portion having an infinite radius of curvature, said second portion being located proximate said at least one end of said housing portion, any point on said second portion being farther from said first axis than any point on said first portion.

13. The fitting according to claim 12, wherein for each of said housing portions, said arcuate surface of said back wall further comprises a third portion having an infinite radius of curvature, said third portion being positioned proximate to the other of said ends of said housing portions.

14. The fitting according to claim 12, wherein, for each of said housing portions, said second portion of said arcuate surface of said back wall subtends an angle from 5 ° to 45 °.

15. The fitting according to claim 12, wherein, for each of said housing portions, said second portion of said arcuate surface of said back wall subtends an angle from 5 ° to 30 °.

16. The fitting according to claim 13, wherein, for each of said housing portions, said third portion of said arcuate surface of said back wall subtends an angle from 5 ° to 45 °.

17. The fitting according to claim 13, wherein, for each of said housing portions, said third portion of said arcuate surface of said back wall subtends an angle from 5 ° to 30 °.

18. The fitting according to claim 12, wherein each of said housing portions further comprises a plurality of said second portions of said arcuate surface of said back wall, each of said second portions having an infinite radius of curvature.

19. The fitting according to claim 18, wherein for each of said housing portions, said arcuate surface of said back wall further comprises a plurality of third portions each having an infinite radius of curvature, said third portions of said arcuate surface of said back wall being positioned proximate to the other of said ends of said housing portions.

20. The fitting according to claim 18, wherein, for each of said housing portions, said plurality of second portions of said arcuate surface of said back wall subtends an angle from 5 ° to 80 °.

21. The fitting according to claim 18, wherein, for each of said housing portions, said plurality of second portions of said arcuate surface of said back wall subtends an angle from 5 ° to 45 °.

22. The fitting according to claim 19, wherein, for each of said housing portions, said plurality of third portions of said arcuate surface of said back wall subtends an angle from 5 ° to 80 °.

23. The fitting according to claim 19, wherein, for each of said housing portions, said plurality of third portions of said arcuate surface of said back wall subtends an angle from 5 ° to 45 °.

24. The fitting according to claim 1, wherein for each of said housing portions:

the first arcuate surface has a first radius of curvature measured from a first center of curvature; and

the arcuate surface of the back wall has a second radius of curvature measured from a second center of curvature that is not coincident with the first center of curvature when measured in a plane perpendicular to the first axis.

25. The fitting according to claim 24, wherein for each of said housing portions, said first center of curvature is closer to said arcuate surface of said back wall than said second center of curvature when measured to a point on said arcuate surface of said back wall that is collinear with said first and second centers of curvature.

26. The fitting according to claim 25, wherein for each of said housing portions, said first and second centers of curvature and said point on said back wall are collinear along a first line oriented perpendicular to a second line extending between a first end of said housing portion and a second end of said housing portion.

27. The fitting according to claim 26, wherein for each of said housing portions, said second center of curvature is offset from said first center of curvature by a distance of 0.01 inches to 0.1 inches.

28. The fitting according to claim 26, wherein for each of said housing portions, said second center of curvature is offset from said first center of curvature by a distance of 0.02 inches to 0.04 inches.

29. The fitting according to claim 26, wherein for each of said housing portions, said second center of curvature is offset from said first center of curvature by a distance of 0.03 inches.

30. The fitting according to claim 2, wherein each of said housing portions further comprises:

a second projection extending circumferentially about said second opening, at least a portion of said second projection being engageable with one of said pipe elements, said second projection having an arcuate surface facing said second axis; and

a second back wall positioned proximate to said second projection, said second back wall having an arcuate surface facing said second axis, a distance between said arcuate surface of said second back wall and said arcuate surface of said second projection, as measured along a radially projected line extending from said second axis, being a first value at a first point intermediate ends of said housing portions and a second value at a second point proximate at least one of said ends of said housing portions, said first value being less than said second value.

31. The fitting according to claim 1, wherein said first and second housing portions further define a third receptacle defining a third opening for receiving one of said pipe elements, said housing portions further defining said fluid passageway to extend between said first, second and third receptacles.

32. The fitting according to claim 31, wherein said third receptacle surrounds a third axis oriented coaxially with said third opening, said first and second axes being collinear with each other, said third axis being angularly oriented with respect to said first and second axes.

33. The fitting according to claim 1, further comprising at least one lug extending from each of said first and second housing portions, each said lug defining a hole for receiving one said fastener.

34. The fitting according to claim 1, further comprising: .

A first seal positioned within the first receptacle and surrounding the first opening;

a second seal positioned within the second receptacle and surrounding the second opening; and

a conduit extending within the housing portion between the first seal and the second seal.

35. The fitting according to claim 31, further comprising:

a first seal positioned within the first receptacle and surrounding the first opening;

a second seal positioned within the second receptacle and surrounding the second opening;

a third seal positioned within the third receptacle and surrounding the third opening; and

a conduit extending within the housing portion between the first seal, the second seal, and the third seal.

36. The fitting according to claim 34, wherein said first housing portion and said second housing portion are supported in said spaced apart relationship by contact with said first seal and said second seal.

37. The fitting according to claim 35, wherein said first housing portion and said second housing portion are supported in said spaced apart relationship by contact with said first seal, said second seal, and said third seal.

38. A fitting for connecting at least two pipe elements together, the fitting comprising:

a first housing portion and a second housing portion attached to one another and defining at least first and second receptacles defining first and second openings, respectively, for receiving the pipe elements, the first and second receptacles surrounding first and second axes, respectively, the first axis being oriented coaxially with the first opening, the second axis being oriented coaxially with the second opening, the first axis being angularly oriented with respect to the second axis, the housing portions further defining a fluid passageway extending between the first and second receptacles,

characterized in that each of said housing portions comprises:

a first arcuate surface extending circumferentially around said first opening, at least a portion of said first arcuate surface being engageable with one of said pipe elements, said first arcuate surface facing said first axis; and

a first back wall positioned adjacent to the first arcuate surface, the first back wall having an arcuate surface facing the first axis, a distance between the arcuate surface of the back wall and the first arcuate surface being a first value at a first point intermediate the ends of the housing portion and a second value at a second point proximate the first end of the housing portion and a third value at a third point proximate the second end of the housing portion, the first value being less than the second value and the third value, as measured along a radially projecting line extending from the first axis; and

at least one adjustable fastener attaching said first and second housing portions to one another, said housing portions supported in spaced apart relation sufficient to allow insertion of said pipe elements into said receptacles when said housing portions are attached to one another, each said fastener adjustably tightens for guiding said housing portions toward one another and engaging said first arcuate surfaces of said housing portions with said pipe elements for attaching said pipe elements together.

39. The fitting according to claim 38, further comprising a first protrusion extending circumferentially around said first opening, said first arcuate surface being positioned on said first protrusion.

40. A joint as claimed in claim 38, wherein for each of the housing portions, the distance is smallest at the first point intermediate the ends of the housing portion.

41. The fitting according to claim 40, wherein for each of said housing portions, said distance is greatest at said second point, said second point being located at a first end of said housing portion.

42. The fitting according to claim 41, wherein for each of said housing portions, said distance between said arcuate surface of said back wall and said first arcuate surface is a third value equal to said second value at a third point located at a second end of said housing portion.

43. The fitting according to claim 38, wherein for each of said housing portions, said arcuate surface of said back wall includes a first portion having a curved surface, and a second portion having a curved surface, said second portion being positioned proximate to a first end of said housing portion, any point on said second portion being farther from said first axis than any point on said first portion.

44. The fitting according to claim 43, wherein for each of said housing portions, said arcuate surface of said back wall further comprises a third portion having a curved surface, said third portion being positioned proximate to a second end of said housing portion, any point on said third portion being farther from said first axis than any point on said first portion.

45. The fitting according to claim 43, wherein for each of said housing portions, said second portion of said arcuate surface of said back wall subtends an angle from 5 ° to 80 °.

46. The fitting according to claim 43, wherein for each of said housing portions, said second portion of said arcuate surface of said back wall subtends an angle from 5 ° to 45 °.

47. The fitting according to claim 44, wherein, for each of said housing portions, said third portion of said arcuate surface of said back wall subtends an angle from 5 ° to 80 °.

48. The fitting according to claim 44, wherein, for each of said housing portions, said third portion of said arcuate surface of said back wall subtends an angle from 5 ° to 45 °.

49. The fitting according to claim 38, wherein for each of said housing portions, said arcuate surface of said back wall includes a first portion having a first radius of curvature, and a second portion having an infinite radius of curvature, said second portion being located proximate to a first end of said housing portion, any point on said second portion being farther from said first axis than any point on said first portion.

50. The fitting according to claim 49, wherein for each of said housing portions, said arcuate surface of said back wall further comprises a third portion having an infinite radius of curvature, said third portion being positioned proximate to a second end of said housing portion.

51. The fitting according to claim 49, wherein for each of said housing portions, said second portion of said arcuate surface of said back wall subtends an angle from 5 ° to 45 °.

52. The fitting according to claim 49, wherein for each of said housing portions, said second portion of said arcuate surface of said back wall subtends an angle from 5 ° to 30 °.

53. The fitting according to claim 50, wherein, for each of said housing portions, said third portion of said arcuate surface of said back wall subtends an angle from 5 ° to 45 °.

54. The fitting according to claim 50, wherein, for each of said housing portions, said third portion of said arcuate surface of said back wall subtends an angle from 5 ° to 30 °.

55. The fitting according to claim 49, wherein each of said housing portions further comprises a plurality of said second portions of said arcuate surface of said back wall, each of said second portions having an infinite radius of curvature.

56. The fitting according to claim 55, wherein for each of said housing portions, said arcuate surface of said back wall further comprises a plurality of third portions each having an infinite radius of curvature, said third portions of said arcuate surface of said back wall being positioned proximate a second end of said housing portion.

57. The fitting according to claim 55, wherein, for each of said housing portions, said plurality of second portions of said arcuate surface of said back wall subtends an angle from 5 ° to 80 °.

58. The fitting according to claim 55, wherein, for each of said housing portions, said plurality of second portions of said arcuate surface of said back wall subtends an angle from 5 ° to 30 °.

59. The fitting according to claim 56, wherein, for each of said housing portions, said plurality of third portions of said arcuate surface of said back wall subtends an angle from 5 ° to 80 °.

60. The fitting according to claim 56, wherein, for each of said housing portions, said plurality of third portions of said arcuate surface of said back wall subtends an angle from 5 ° to 30 °.

61. The fitting according to claim 39, wherein each of said housing portions further comprises:

a second projection extending circumferentially about said second opening, at least a portion of said second projection being engageable with one of said pipe elements, said second projection having an arcuate surface facing said second axis; and

a second back wall positioned adjacent to said second projection, said second back wall having an arcuate surface facing said second axis, a distance between said arcuate surface of said second back wall and said arcuate surface of said second projection, as measured along a radially projected line extending from said second axis, being a first value at a first point intermediate ends of said housing portions and a second value at a second point proximate at least one of said ends of said housing portions, said first value being less than said second value.

62. The fitting according to claim 38, wherein said first and second housing portions further define a third receptacle defining a third opening for receiving one of said pipe elements, said housing portions further defining said fluid passageway to extend between said first, second and third receptacles.

63. The fitting according to claim 62, wherein said third receptacle surrounds a third axis oriented coaxially with said third opening, said first and second axes being collinear with one another, said third axis being angularly oriented with respect to said first and second axes.

64. The fitting according to claim 38, further comprising at least one lug extending from each of said first and second housing portions, each said lug defining a hole for receiving one said fastener.

65. The fitting according to claim 38, further comprising:

a first seal positioned within the first receptacle and surrounding the first opening;

a second seal positioned within the second receptacle and surrounding the second opening; and

a conduit extending within the housing portion between the first seal and the second seal.

66. The fitting according to claim 62, further comprising:

a first seal positioned within the first receptacle and surrounding the first opening;

a second seal positioned within the second receptacle and surrounding the second opening;

a third seal positioned within the third receptacle and surrounding the third opening; and

a conduit extending within the housing portion between the first seal, the second seal, and the third seal.

67. The fitting according to claim 65, wherein said first housing portion and said second housing portion are supported in said spaced apart relationship by contact with said first seal and said second seal.

68. The fitting according to claim 66, wherein said first housing portion and said second housing portion are supported in said spaced apart relationship by contact with said first seal, second seal and said third seal.