Patent Publication Number: US-8528945-B2

Title: Split-ring gland pipe coupling with corrugated armor and annular gasket having pressure assist slot

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to pipe couplings and joints and, more particularly, to pipe couplings adapted to couple and seal adjacent ends of two pipe sections of the same or different diameters. 
     BACKGROUND OF THE INVENTION 
     Conventional pipe couplings for coupling and sealing adjacent ends of two pipe sections include a coupling sleeve or collar with each pipe end extending into a respective end of the coupling sleeve. A gasket is held adjacent each end of the sleeve overlying the pipe section. An annular flange or gland is associated with each gasket and end of the sleeve, and is tightened to draw down the gasket against the pipe end thus sealing the pipe coupling thereto. One pipe coupling is shown in my prior U.S. Pat. No. 6,168,210 and utilizes continuous flanges that are coupled together via bolts spanning the sleeve. The flanges, sleeve ends, and gaskets have particular relationships that affect the seal and allow the coupling to work over a range of pipe sizes to compress the gaskets against the pipe ends as the flanges are drawn towards each other. 
     While the continuous flange type of pipe coupling is considered to be particularly advantageous, another style of pipe coupling is proposed in which each flange is provided by a split-ring gland that presents spaced apart confronting ends which can be drawn together with a bolt to close down on the associated gasket. As a consequence, it is not necessary to have bolts that span the sleeve, nor cause the glands to move towards each other. Instead, each end of the sleeve can be independently coupled to the respective pipe end. 
     In order to work over a range of pipe diameters, the split-ring gland is sized such that it circumscribes most of the circumference of the sleeve end and gasket, but not that portion in the gap defined between the spaced apart confronting ends. However, it is important that the gasket not be exposed radially out of that gap as it will then be a source of leakage and/or failure during installation. To that end, the split-ring gland type of pipe coupling includes a bridge plate or “armor” spanning the gap over the gasket and extending into the gland at each end of the armor. The armor is shaped to conform to the arc of the gland and gasket so as to, in effect, define a continuation of the gasket-confronting surface of the gland. Thus, as the gland is closed down, the gasket will shift and seat throughout the combined circumference of the gland and the armor in order to facilitate installation and create the desired seal. 
     The gasket inserted into the split-ring gland is an annular gasket generally defining an outer circumferential surface facing the split-ring gland, an inner circumferential surface facing the pipe, and outer and inner side surfaces. One such gasket is provided with a generally annular pressure assist slot extending into the body of the gasket with an opening along the inner side surface of the gasket. Any pressurized fluid that may leak from the pipe along the inner side surface is collected into the pressure assist slot through the opening thereof at the inner side surface. The collected pressurized fluid within the pressure assist slot forces the gasket to expand outwardly to produce a better sealing contact with the pipe, the split-ring gland, and the armor. 
     As the gland is tightened, however, the opening of the pressure assist slot may be clamped down and closed off, thereby blocking flow of pressurized fluid into the pressure assist slot. It has been proposed to include separate vent holes along the inner side surface spaced radially outwardly from the opening of the pressure assist slot and tunneling through the gasket body into communication with an interior portion of the pressure assist slot beyond the opening. Inclusion of such vent holes can present drawbacks both in the use and in the manufacture of the gaskets. 
     SUMMARY OF THE INVENTION 
     The present invention in one aspect includes an improved annular gasket that provides the advantages of vent holes but without their drawbacks. To that end, and in accordance with certain principles of the present invention, the inner side surface of the gasket is provided with one or more cross grooves in the form of indentations adjacent to and extending into the opening of the pressure assist slot at the inner side surface. Each of the cross grooves defines a radially extending pathway from the slot opening along the inner side surface, but is recessed beyond the inner side surface so as to provide a fluid communication path into the interior portion of the pressure assist slot even if the opening of the pressure assist slot is clamped shut by compression of the gasket with a split-ring gland. The cross grooves can be formed when the gasket is molded by the same structure used to form the pressure assist slot, making the manufacturing process easier, more reliable, and less costly than inclusion of separate vent holes. Moreover, because the cross grooves extend immediately from the opening, there is less risk that they might become blocked by the rest of the structure of the pipe coupling as might occur with the vent holes. 
     The present invention in another aspect provides an improved armor for the split-ring gland type of pipe couplings. The conventional armor is cold formed of stainless steel and presents a generally flat, smooth surface to the outer periphery of the gasket. In accordance with the principles of the present invention, at least a portion of the gasket confronting surface is corrugated, i.e., it is provided a plurality of corrugations extending along the surface. The corrugations improves the performance of the armor and, unexpectedly, also enhances the assembly of the pipe coupling. In that regard, the corrugations are advantageously instilled by cold working and therefore provides both increased bending stiffness and tensile strength to the armor as compared to conventional armors. 
     Also, during installation with conventional armors, the gasket would tend to “bunch up” at the ends of the armor, making it difficult to properly install the pipe coupling. In fact, the gasket and possibly the armor might have to be heavily lubricated to facilitate the shifting of the gasket as the split-ring gland is compressed to help reduce the risk of bunching. But the lubrication further hampers installation as the components are more difficult to handle and can hold dirt and other debris to the parts which is undesirable. Moreover, bunching was not always avoided even with lubrication. Unexpectedly, the corrugations of the armor according to the present invention reduces or eliminates the tendency of the gasket to bunch up thereagainst and also allows the gasket to more readily shift as it is compressed by the gland. As a result, the need for lubrication may be reduced, if not eliminated, thus further facilitating installation of the split-ring gland type of coupling. 
     In accordance with another aspect of the present invention, the annular gasket may include ribs projecting outwardly from the outer circumferential surface and the inner and outer side surfaces. The ribs enhance the sealing performance of the annular gasket by providing a reliable sealing contact between the various surfaces of the annular gasket and the corresponding surfaces of the split-ring gland. Additionally, the ribs also reduce the frictional contact between the annular gasket and the split-ring gland, thereby reducing the tendency of the annular gasket to “bunch up” against the gland or an armor as described above when the annular gasket is compressed into sealing contact with a pipe end. To this end, the ribs reduce the need for lubrication between the annular gasket and the split-ring gland. Moreover, the combination of the corrugations of the armor, the ribs of the annular gasket, and the fluid in the pressure assist slot may collectively eliminate the likelihood that the gasket will bunch up on the armor during compression of the gasket. As a result, the need for added lubrication may be eliminated, thus further facilitating installation of the split-ring gland type of coupling. 
     With some split-ring type of pipe couplings, the gland may be formed as a unitary ring, but must be made of sufficiently flexible material that the spaced apart ends at the gap can be stretched or pulled apart to open up the gap in order to fit the gland onto the flange end of the sleeve. That design presents various drawbacks. Another proposal is to instead couple the abutting ends of two gland members by a fastener extending parallel to the longitudinal axis of the gland so that the gland members may “scissor” thereabout to increase the spacing of the gap from its nominal size for purposes of mounting the gland to the flange end of the sleeve. While the scissoring approach may facilitate assembly, for example, while using desirably more rigid materials, the ability of the gland members to scissor presents its own drawbacks. To that end, and in accordance with a second aspect of the present invention, the split-ring gland of the present invention utilizes two gland members, but securely couples them along one side with a fastener oriented tangential to the gland members. As a consequence, more rigid materials may be used, but without the disadvantage of scissoring. 
     Further, some split ring type of pipe couplings utilize a gasket having a plurality of layers integrally connected to each other. The inner layer typically defines an opening adapted to receive small pipe ends therethrough. Where it is desired to couple to a larger pipe end than can fit through the inner layer opening, one or more of the layers may be torn off the gasket to increase the size of the opening through the gasket to accommodate that larger pipe. Situations arise where the smaller diameter opening provided by the inner layer(s) was desired. But the torn-off layer(s) cannot be reused necessitating that the gasket be discarded and replaced with an entirely new gasket. In accordance with a third aspect of the present invention, a gasket is provided that is comprised of two separate and reusably coupled layers. To that end, the gasket advantageously includes an outer gasket and an inner gasket including corresponding interdigitated surfaces adapted to reusably couple the outer gasket and the inner gasket. The inner gasket may be wider axially than the outer gasket such that the inner gasket includes lips that may be gripped for pulling the inner gasket interdigitations radially inwardly and away from the outer gasket interdigitations. The interdigitations may be symmetrical along an axial direction such that the inner gasket may be re-coupled with the outer gasket in a different orientation rotated 180 degrees from an original orientation of the inner gasket. 
     The foregoing and other advantages of the present invention will be apparent in light of the accompanying drawings and detailed description thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the general description of the invention given above and the detailed description of the embodiment given below, serve to explain the principles of the present invention. 
         FIG. 1  is a perspective view of a first embodiment of a pipe coupling utilizing armors in accordance with the principles of the present invention; 
         FIG. 2  is a perspective view of the pipe coupling of  FIG. 1  for purposes of describing the use of the pipe coupling to sealingly couple two pipes in fluid communication; 
         FIG. 3  is partially-exploded perspective view of the pipe coupling of  FIG. 1 ; 
         FIG. 4  is a perspective view of one of the armors of  FIG. 1 ; 
         FIG. 5  is an exploded perspective view of a gasket used with the pipe coupling of  FIG. 1 ; 
         FIG. 6  is a partial cross-sectional view of one end of the pipe coupling of  FIG. 1  taken along line  6 - 6  in  FIG. 1  with one of the pipes of  FIG. 2  inserted into the pipe coupling; 
         FIG. 7  is an enlarged partial cross-sectional view of one end of the pipe coupling and pipe of  FIG. 6 , showing details of the gasket and armor thereat; and 
         FIG. 8  is an enlarged partial cross-sectional view of one end of the pipe coupling and pipe of  FIG. 6 , including a different gasket configuration; 
         FIG. 9  is partially-exploded perspective view of a second embodiment of a pipe coupling in accordance with the principles of the present invention; 
         FIG. 10  is an exploded perspective view of a gasket used with the pipe coupling of  FIG. 9  in a reverse orientation from  FIG. 9 , illustrating the pressure assist slot and the plurality of cross grooves formed in the inner side surface of the gasket; 
         FIG. 11  is a partial cross-sectional view of one end of the pipe coupling of  FIG. 9  taken along line  11 - 11  in  FIG. 9  with one of the pipes of  FIG. 2  inserted into the pipe coupling; 
         FIG. 12  is an enlarged partial cross-sectional view of one end of the pipe coupling and pipe of  FIG. 11 , showing details of the gasket and armor thereat; 
         FIG. 13  is an enlarged partial cross-sectional view of one end of the pipe coupling and pipe of  FIG. 11  with the gasket clamped so as to close the opening of the pressure assist slot; 
         FIG. 14  is another enlarged partial cross-sectional view of one end of the pipe coupling and pipe of  FIG. 11 , showing details of the gasket thereat; and 
         FIG. 15  is an enlarged partial cross-sectional view of one end of the pipe coupling and pipe of  FIG. 14  with the gasket clamped so as to close the opening of the pressure assist slot. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIGS. 1 and 2 , a split-ring gland type of pipe coupling  10  according to one embodiment of the present invention is shown. The pipe coupling  10  includes a sleeve  12 , a pair of split-ring glands  14 , a bridge plate or armor  16  associated with each split-ring gland  14 , and an annular gasket  18  associated with each split-ring gland  14 . In the fully assembled state of the pipe coupling  10 , an end E 1  of a first pipe P 1  is inserted into the sleeve  12  through one of the split-ring glands  14  and the corresponding gasket  18 , and an end E 2  of a second pipe P 2  is inserted into the other split-ring gland  14  and associated gasket  18 . The split-ring glands  14  are configured to be tightened onto the corresponding gaskets  18  to compress the gaskets  18  into sealing connection with the respective pipe ends E 1 , E 2 . The split-ring gland  14  and the armor  16  collectively define a generally closed annular periphery  19  around the gasket  18 , which further ensures that fluid passing through the pipes P 1 , P 2  and the pipe coupling  10  does not leak past the gasket  18  out of the pipe coupling  10 . Thus, the pipe coupling  10  provides a sealed coupling of two adjacent pipe ends E 1 , E 2  in fluid communication. 
     Further details of the components of the pipe coupling  10  are shown in  FIG. 3 , in which one of the split-ring glands  14  is shown partially exploded to facilitate discussion. The sleeve  12  includes a generally cylindrical body portion  20  defining a longitudinal axis LA of the pipe coupling  10  and having opposing open ends  22 . At each of the opposing ends  22 , the sleeve  12  further includes a radially outwardly-directed flange  24  that is used to accurately locate the split-ring gland  14  and the annular gasket  18 , as described in further detail below. Although the sleeve  12  of the exemplary embodiment is shown as cylindrical, it will be understood that the body portion  20  of the sleeve may also be tapered slightly inwardly adjacent both open ends  22  to provide clearance for slight angles between the pipe ends E 1 , E 2  to be coupled in fluid communication by the pipe coupling  10 . 
     Each of the split-ring glands  14  includes a first partially-circular gland member  26   a  and a second partially-circular gland member  26   b . The gland members  26   a ,  26   b  each define a half-moon shape and are configured to be centered about the longitudinal axis LA of the pipe coupling  10 . The gland members  26   a ,  26   b  include respective abutting ends  28   a ,  28   b  and respective spaced ends  30   a ,  30   b . The abutting ends  28   a ,  28   b  are configured to be securely coupled together in generally gap-free relationship as shown in  FIG. 1 . With the abutting ends  28   a ,  28   b  securely coupled, the spaced ends  30   a ,  30   b  define a nominal gap  32  therebetween. To this end, the abutting end  28   a  of the first gland member  26   a  includes a first abutting bolt flange  34   a  projecting radially outwardly from the abutting end  28   a . Similarly, the abutting end  28   b  of the second gland member  26   b  includes a second abutting bolt flange  34   b  projecting radially outwardly from the abutting end  28   b.    
     The first and second abutting bolt flanges  34   a ,  34   b  include corresponding apertures  36   a ,  36   b  oriented tangential to the axis LA and configured to receive a fastener, for example, the bolt  38  and nut  40  shown in  FIG. 3 . The bolt  38  extends through the apertures  36   a ,  36   b  and is coupled to nut  40 , such that the bolt  38  and the nut  40  are also oriented generally tangential to the split-ring gland  14  in the illustrated embodiment of the pipe coupling  10 . Consequently, when the bolt  38  and nut  40  securely couple the abutting ends  28   a ,  28   b , the gland members  26   a,    26   b  are restrained from pivotally rotating relative to each other thereat such that the ends  30   a,    30   b  are restrained from scissoring apart beyond the nominal gap  32 . The nominal gap  32  described above is thus generally considered the maximum length of gap of the split-ring gland  14 . The first and second abutting bolt flanges  34   a ,  34   b  may be provided with opposing countersinks (only  42   a  shown in  FIG. 3 ) facing away from one another and configured to receive the head  38   a  of the bolt  38  and the nut  40  generally flush with the structure of the first and second bolt flanges  34   a ,  34   b . However, the first and second abutting bolt flanges  34   a ,  34   b  may be securely coupled by alternative fasteners or may include internal threading at the apertures  36   a ,  36   b  in other embodiments. Furthermore, the first and second abutting bolt flanges  34   a ,  34   b  may be modified to be plate-shaped or another appropriate flange shape as well understood in the art. 
     The first and second gland members  26   a ,  26   b  also include spaced bolt flanges  44   a ,  44   b  at the respective spaced ends  30   a ,  30   b . The spaced bolt flanges  44   a ,  44   b  project radially outwardly from the spaced ends  30   a ,  30   b  of the first and second gland members  26   a ,  26   b . The spaced bolt flanges  44   a ,  44   b  include corresponding apertures (only  46   b  shown in  FIG. 3 ) configured to receive an adjustable fastener such as the elongate bolt  48  and nut  50  shown in  FIG. 3 . In this regard, the nut  50  may be tightened on the elongate bolt  48  to draw the spaced bolt flanges  44   a ,  44   b  and the spaced ends  30   a ,  30   b  closer together from the nominal position to a tightened position, to thereby compress the annular gasket  18  onto one of the pipe ends E 1 , E 2 . With the ends  28   a ,  28   b  secured together as described above, tightening of the nut  50  advantageously uniformly closes down the gland members  26   a ,  26   b  about the annular gasket  18 . The elongate bolt  48  and nut  50  are oriented generally tangential to the split-ring gland  14  in the illustrated embodiment of the pipe coupling  10 . It will be appreciated that the spaced bolt flanges  44   a ,  44   b  may be coupled by alternative known fasteners. 
     Each of the spaced bolt flanges  44   a ,  44   b  includes a convex arcuate surface  52   a ,  52   b  facing the gap  32  between the spaced ends  30   a ,  30   b  and a concave arcuate surface (only  54   a  shown in  FIG. 3 ) facing away from the gap  32 . The head  48   a  of the elongate bolt  48  includes an arcuate surface  48   b  configured to be received in the concave arcuate surface  54   a  of the first spaced bolt flange  44   a . A spacer  56  disposed adjacent the nut  50  also includes an arcuate surface  56   a  configured to be received in the concave arcuate surface of the second spaced bolt flange  44   b . Consequently, when the nut  50  is tightened on the elongate bolt  48 , the engagement of the head  48   a  of the elongate bolt  48  with the first spaced bolt flange  44   a  and the engagement of the spacer  56  with the second spaced bolt flange  44   b  hold the elongate bolt  48  in position with respect to the split-ring gland  14 . One or more plastic or metal washers  58  may also be provided between the spacer  56  and the nut  50 . 
     The first and second gland members  26   a ,  26   b  each include a partially-cylindrical annular wall  60  with an inner edge  62  and an outer edge  64 . The partially-cylindrical annular walls  60  are generally flat rather than concave in cross section. The first and second gland members  26   a ,  26   b  each further include an inwardly-directed U-shaped wall  66  at the inner edge  62  of the annular wall  60 . The U-shaped walls  66  are configured to receive the flange  24  at the end  22  of the sleeve  12 , thereby accurately locating the split-ring gland  14  on the sleeve  12 . The first and second gland members  26   a ,  26   b  each also include an outer wall  68  extending inwardly in a radial direction at the outer edge  64 . As described in further detail below, at least a portion of the annular gasket  18  is captured between the outer walls  68  and the flange  24  of the sleeve  12 . Thus, the annular walls  60 , the outer walls  68 , and the flange  24  of the sleeve  12  collectively define a gasket seat  69  for the split-ring gland  14 . In the exemplary embodiment shown, the split-ring gland  14  may be tightened between a minimum diameter of about 10.00 inches ±0.13 inches and a maximum diameter of about 10.81 inches±0.25 inches. The sleeve  12  and the split-ring gland  14  are each formed from carbon steel in one embodiment, but these components may alternatively be formed from stainless steel, plastic, or another structural material. 
     The armor  16  is more clearly shown in  FIGS. 3 and 4 . The armor  16  is generally S-shaped in cross section and has an arcuate shape along its length. The armor  16  includes a central wall  70  with an inner side edge  72  and an outer side edge  74 . The armor  16  also includes an inner side wall  76  extending generally perpendicular to, and radially inwardly of, the central wall  70  at the inner side edge  72 , and an outer side wall  78  extending generally perpendicular to, and radially outwardly of, the central wall  70  at the outer side edge  74 . The inner side wall  76  and the outer side wall  78  extend in differing directions from the central wall  70  to form the generally S-shaped cross section of the armor  16 . The central wall  70  further includes lateral side edges  80  extending from the inner side edge  72  to the outer side edge  74 . 
     When the armor  16  is positioned at the gap  32  between the spaced ends  30   a ,  30   b  of the gland members  26   a ,  26   b , the central wall  70  is positioned adjacent the annular walls  60  of the gland members  26   a ,  26   b  at the spaced ends  30   a ,  30   b . To this end, the central wall  70  of the armor  16  defines an arc length that is at least long enough to span the gap  32  such that the lateral side edges  80  of the central wall  70  are disposed underneath the annular walls  60  of the gland members  26   a ,  26   b  in the nominal position of the split-ring gland  14 . In this position, the inner side wall  76  projects into the U-shaped walls  66  of the gland members  26   a ,  26   b , and the outer side wall  78  is positioned adjacent the outer walls  68  of the gland members  26   a ,  26   b  at the spaced ends  30   a ,  30   b . Thus, the armor  16  and the split-ring gland  14  collectively define a closed ring or loop for receiving the annular gasket  18 . More specifically, the central wall  70  of the armor  16  cooperates with the annular walls  60  of the gland members  26   a ,  26   b  to collectively define the generally closed annular periphery  19  for the annular gasket  18 . In the exemplary embodiment, the armor  16  is configured to cover at least about 15% to about 30%, and advantageously, about 20% of the circumference of the gasket  18  when the gasket  18  is installed in the split-ring gland  14 . 
     Shown most clearly in  FIG. 4 , the central wall  70  includes a plurality of corrugations  82  extending between the lateral side edges  80  and generally parallel to the inner and outer side edges  72 ,  74 . Advantageously at least three or four such corrugations may be provided, although more or fewer may be provided depending on the width of the central wall  70  between the inner and outer side edges  72 ,  74 . Furthermore, corrugations  82  advantageously extend radially outwardly from central wall  70 , but could additionally or alternatively extend radially inwardly therefrom. In any event, the corrugations  82  may be seen as defining a corrugated portion  82 ′ of the armor  16 . The armor  16  may be formed by cold forming stainless steel, although the armor  16  may be formed in other ways. In that regard, at least corrugations  82  of the exemplary embodiment are advantageously instilled in the armor  16  by cold forming. The cold forming process provides increased structural strength for the armor  16 , including increased tensile strength and work hardening. Furthermore, the corrugations  82  provide increased bending stiffness and an improved mechanical performance in the assembly of the pipe coupling  10 . The corrugations  82  reduce the surface area of the central wall  70  that contacts the annular walls  60  of the split-ring gland  14  and the annular gasket  18 . As such, the armor  16  more freely moves or slides with less friction against the split-ring gland  14  and the annular gasket  18  when the split-ring gland  14  is tightened to compress the annular gasket  18 . In this regard, less lubrication or no lubrication is necessary between these components of the pipe coupling  10  in operation. 
     Corrugations  82  each advantageously taper as at  84  into the central wall  70  so as to stop short of either or both of the lateral side edges  80  and are also generally inboard of the inner and outer side edges  72 ,  74  so as to define one or more non-corrugated portions  85 . The non-corrugated portions  85  extend inwardly from respective ones of the inner side edge  72 , the outer side edge  74 , and/or the lateral side edges  80  toward the corrugations  82 . Where non-corrugated portions  85  are provided between each of the edges  72 ,  74 , and  80 , they cooperate to, in effect, define a frame about the corrugations  82 . Advantageously, the corrugations  82  do not extend into one or both of the lateral side edges  80 , such that the lateral side edge(s)  80  provide a linear edge for the armor  16  to confront and slide between the annular walls  60  of the split-ring gland  14  and the annular gasket  18 . It will be appreciated, however, that working of the armor  16  to instill the corrugations  82  may cause some portions of the lateral side edge(s)  80  to distort. Moreover, the tapers  84  may extend into or against the lateral edge(s)  80  or the corrugations  82  may extend all the way to the lateral sides edge(s)  80 . Unexpectedly, the inclusion of the corrugations  82 , especially where they stop short of the lateral side edges  80 , reduces the tendency of the elastomeric material of the annular gasket  18  to bunch up at the lateral side edges  80 . Thus, the corrugations  82  significantly improve the performance of the armor  16  as compared to conventional, completely uncorrugated bridge plates or armors. 
     The annular gasket  18  of the exemplary embodiment is further illustrated in  FIGS. 5 through 7 . The annular gasket  18  includes an annular outer gasket  86  and a separate annular inner gasket  88  reusably coupled to (i.e., repeatedly insertable into and removable from) the outer gasket  86 . The annular gasket  18  defines a gasket opening  89   b  therethrough centered on the longitudinal axis LA when the pipe coupling  10  is assembled. Each of the outer gasket  86  and the inner gasket  88  are composed of an elastomeric material such as rubber. The outer gasket  86  is configured to engage the split-ring gland  14  and the armor  16  along an outer circumferential surface  90 , and has an inner circumferential surface  92  configured to engage either the inner gasket  88  or the respective pipe end E 1 , E 2  (when the inner gasket  88  is removed). The inner gasket  88  is configured to engage the pipe end E 1 , E 2  inserted into the pipe coupling  10  and the inner circumferential surface  92  of the outer gasket  86  as will be described in greater detail below. 
     As shown most clearly in  FIGS. 6 and 7 , the outer gasket  86  includes the outer circumferential surface  90  facing the gland members  24   a ,  24   b  and the inner circumferential surface  92  facing the inner gasket  88  (or the respective pipe end E 1 , E 2  when the inner gasket  88  is removed). The inner circumferential surface defines a first opening  89   a  ( FIG. 5 ) having a diameter D 1 . The outer gasket  86  also includes an inner side surface  94  extending between the outer and inner circumferential surfaces  90 ,  92  and facing the sleeve  12 , and an outer side surface  96  extending between the outer and inner circumferential surfaces  90 ,  92  and facing away from the sleeve  12 . The outer circumferential surface  90  may be beveled such that the inner side surface  94  is longer than the outer side surface  96  to form a wedge-shaped configuration for the outer gasket  86 . Similarly, the inner gasket  88  includes an outer circumferential surface  98  facing the outer gasket  86  and an inner circumferential surface  100  facing the pipe end E 1 , E 2  or in an inward radial direction. The inner circumferential surface defines an opening  89   b  ( FIG. 5 ) having a second, smaller diameter D 2 . 
     The inner gasket  88  may be selectively disengaged from the outer gasket  86  and removed from the pipe coupling  10  to modify an effective range of pipe outer diameters that may be sealed by and accommodated within the pipe coupling  10 . In other words, the removable inner gasket  88  enables modification of an effective diameter of the pipe coupling  10  at the split-ring gland  14 . For example, diameter D 2  may allow the pipe coupling  10  to receive a pipe end E 1  or E 2  having an outer diameter (OD) in the range of 6.56 inches to 7.05 inches due to the presence of the inner gasket  88 . However, removal of the inner gasket  88  leaves the opening  89   a  of diameter D 1  which may allow the pipe coupling  10  to thus receive a pipe end E 1  or E 2  having an OD in the range of 7.05 inches to 7.65 inches. As will be appreciated, however, the diametrical dimensions and ranges of the split-ring gland  14  and the gasket  18  may be modified in other embodiments for pipes of different size ranges. 
     To facilitate reusable coupling of the inner gasket  88  to the outer gasket  86 , the outer gasket  86  and the inner gasket  88  have corresponding interdigitated surfaces. More particularly, the inner circumferential surface  92  of the outer gasket  86  includes a plurality of first interdigitations  102  configured to engage a corresponding plurality of second interdigitations  104  formed on the outer circumferential surface  98  of the inner gasket  88 . The engagement of the interdigitations  102 ,  104  discourages relative axial movement between the inner and outer gaskets  88 ,  86 . The interdigitations  102 ,  104  are configured to be symmetrical such that the inner gasket  88  and the outer gasket  86  may be engaged without regard to orientation of the inner gasket  88 . More specifically, the inner gasket  88  may be inserted into the outer gasket  86  in a first orientation along the longitudinal axis LA or a second orientation along the longitudinal axis LA wherein the inner gasket is reversed from the first orientation. 
     Also, because the outer gasket  86  and the inner gasket  88  are held together merely by the interdigitations  102 ,  104 , the inner gasket  88  may be readily removed from and reinserted into the outer gasket  86  if the pipe end E 1 , E 2  to be engaged by the annular gasket  18  has an OD within the smaller range provided above. For example, if a user (not shown) concludes that diameter D 2  is too small for the intended pipe end E 1  to be sealed by the pipe coupling  10 , the inner gasket  88  may be removed by grabbing the inner gasket  88  along any side and pulling radially inwardly such that the interdigitations  102 ,  104  disengage along that side. The inner gasket  88  may then be pulled or torqued out of engagement with the remainder of the outer gasket  86  by pulling the partially-disengaged inner gasket  88  along the longitudinal axis LA out of the outer gasket  86 . If, upon further examination, it is determined that diameter D 1  is too large, and diameter D 2  would actually suffice, the inner gasket  88  may be recoupled to the outer gasket  86  by reversing the steps described above. 
     In the illustrated embodiment, the first interdigitations  102  include several triangular cross-section annular grooves: two triangular-shaped shallow grooves  102   a  adjacent outer edges of the ring, two deeper triangular-shaped grooves  102   b  inboard of the outer shallow grooves  102   a , and two additional triangular-shaped shallow grooves  102   c  inboard of the deeper grooves  102   b . It will be appreciated that first interdigitations  102  may alternatively be formed with different shapes (i.e., circular), different depths (i.e., all grooves having a uniform depth), and with different numbers of grooves as opposed to the embodiment shown. In another alternative embodiment, the first interdigitations  102  may include a single concave smooth surface at the inner circumferential surface  92  of the outer gasket  86 . Likewise, the second interdigitations  104  include several triangular cross-section annular projections  104   a ,  104   b ,  104   c  sized and positioned to mate with the shallow and deeper grooves forming the illustrated first interdigitations  102 . It will be further appreciated that other types of projections or a single smooth concave surface could be provided for second interdigitations  104  to match the various alternatives described above for the first interdigitations  102 . Alternatively, the first interdigitations  102  may be projections and the second interdigitations  104  may be grooves in other embodiments. 
     By positioning the inner gasket  88  within the outer gasket  86  with the projections  104  aligned with the grooves  102 , the outer and inner gaskets  86 ,  88  are held together by their own resiliency, although the gaskets  86 ,  88  may be easily separated by pulling the inner gasket  88  inwardly in a radial direction and then away from the outer gasket  86 . To this end, the inner gasket  88  is generally wider in an axial direction than the corresponding axial width of the outer gasket  86 . The inner gasket  88  therefore includes lips  106  projecting beyond the inner and outer side surfaces  94 ,  96  of the outer gasket  86 , the lips  106  facilitating easy gripping and movement of the inner gasket  88  inwardly radially away from the outer gasket  86  when the inner gasket  88  is to be removed from the pipe coupling  10 . 
     The inner circumferential surface  100  of the inner gasket  88  is generally smooth or planar such that the inner gasket  88  provides a reliable seal on the pipe end E 1  or E 2  sized to work with diameter D 2  and composed of various materials. However, the inner circumferential surface  100  may be provided with ribs, projections, or grooves similar to the interdigitations  102 ,  104  to provide an improved sealing connection with the pipe end E 1  or E 2  formed from semi-porous material such as cement. Similarly, with inner gasket  88  removed for use with the pipe end E 1  or E 2  sized to work with diameter D 1 , the first interdigitations  102  on the inner circumferential surface  92  of the outer gasket  86  may also improve the sealing connection with the pipe end E 1  or E 2  formed from semi-porous material. With any of these alternatives, the split-ring gland  14  is configured to be tightened sufficiently such that the inner gasket  88  or the outer gasket  86  forms a reliable seal around the corresponding pipe end E 1 , E 2 . 
     As shown in  FIG. 7 , the outer gasket  86  is configured to seat securely within the gasket seat  69  formed by the split-ring gland  14 , the armor  16 , and the flange  24  of the sleeve  12 . In operation, the outer circumferential surface  90  of the outer gasket  86  seats against the annular walls  60  of the gland members  26   a ,  26   b  and the central wall  70  of the armor  16 . The inner side surface  94  of the outer gasket  86  is positioned adjacent to the flange  24  of the sleeve  12 , and the outer side surface  96  of the outer gasket  86  is positioned adjacent to the outer walls  68  of the gland members  26   a ,  26   b  and the outer side wall  78  of the armor  16 . When the split-ring gland  14  compresses the outer gasket  86  inwardly, the outer gasket  86  seals the pipe coupling  10  from leakage adjacent the flange  24  of the sleeve  12  and adjacent the split-ring gland  14 . 
     The outer gasket  86  may also include a nominally-open, nearly horizontal, annular slot  108  extending into the outer gasket  86  from the inner side surface  94  and towards the outer side surface  96 . The slot  108  is advantageously continuous and angled at a shallow angle (e.g., 8.5°) from a plane  109  defined by the inner circumferential surface  92 , and angled such that the slot  108  traverses radially inwardly as the slot  108  extends from the inner side surface  94  towards the outer side surface  96 . The slot  108  is advantageously continuous and uninterrupted about the gasket opening  89   b  at the inner side surface  94 . The slot  108  is positioned to aim towards the sleeve  12  and faces the corresponding flange  24  of the sleeve  12 . Consequently, if pressurized fluid in the pipes P 1 , P 2  begins to pass between the inner side surface  94  of the outer gasket  86  and the flange  24  on the sleeve  12 , the pressurized fluid will enter the slot  108  and press outwardly on the outer gasket  86  at the slot  108 . This additional force applied at the slot  108  further enhances the sealing connection of the outer gasket  86  to the split-ring gland  14 , the armor  16 , and the flange  24  of the sleeve  12 . The angle and orientation of the slot  108  may be modified in other embodiments. 
     In the exemplary embodiment of the outer gasket  86  shown in  FIG. 7 , the slot  108  may have a length of approximately 0.75 inches when the outer gasket  86  has an axial width of 1.25 inches. The first interdigitations  102  or grooves may be spaced at regular 0.2 inch intervals and may define internal angles of about 40° to 45°. Additionally, the radial thickness of the outer gasket  86  may be in the range of about 0.75 inches to 1.0 inch. The radial thickness of the inner gasket  88  may be about 0.25 inches to enable the differing pipe OD ranges described above. It will be understood that these exemplary dimensions may be modified for differing sizes of pipe ends E 1 , E 2  and pipe couplings  10 . 
     With reference to  FIG. 8 , another embodiment of an outer gasket  112  for use with the inner gasket  88  is shown. The outer gasket  112  of this embodiment again includes an outer circumferential surface  114 , an inner circumferential surface  116 , an inner side surface  118 , and an outer side surface  120 . Once again, the inner circumferential surface  116  includes the plurality of first interdigitations  102  to enable coupling with the inner gasket  88  as previously described. In contrast with the previous embodiment, the inner side surface  118  and the outer side surface  120  are of the same length such that the outer gasket  112  defines a generally rectangular shape. Additionally, the nearly horizontal slot  108  is omitted and an angled slot  122  is added. The angled slot  122  extends into the gasket  112  at the junction  123  between the outer circumferential surface  114  and the outer side surface  120  at about an angle of 45° from each of the outer circumferential surface  114  and the outer side surface  120 . As the split-ring gland  14  is tightened, the gland members  26   a ,  26   b  tend to rotate slightly in cross section such that the outer side edge  120  of the outer gasket  112  is slightly more compressed than the inner side edge  118  of the outer gasket  112 . The angled slot  122  utilizes this uneven compression to create a wedging action on the portion of the outer gasket  112  disposed inwardly from the angled slot  122 , which thereby improves the sealing connection of the annular gasket  18 . In all other regards, the outer gasket  112  of this embodiment operates similarly as the outer gasket  86  of the previous embodiment. 
     Although the angled slot  122  is angled at a relatively steep angle (e.g., 45°) from the outer circumferential surface  114 , the angle and orientation of the slot  122  may be modified in other embodiments. In the embodiment of the outer gasket  112  shown in  FIG. 8 , the angled slot  122  may have a length of approximately 0.875 inches when the outer gasket  112  has an axial width of 1.25 inches. The first interdigitations  102  or grooves may be spaced at regular 0.2 inch intervals and may define internal angles of about 40° to 45°. Additionally, the radial thickness of the outer gasket  112  may be in the range of about 0.75 inches to 1.0 inch. It will be understood that these exemplary dimensions may be modified for differing sizes of pipe ends E 1 , E 2  and pipe couplings  10 . Additionally, it will be understood that the angled slot  122  may be used in combination with the nearly horizontal slot  108  in other embodiments of the outer gasket. 
     To assemble the pipe coupling, two split-ring glands  14  are assembled with the armors  16  and the gaskets  18  on the opposing open ends  22  of the sleeve  12 . For each of the split-ring glands  14 , the two gland members  26   a ,  26   b  are brought together such that the U-shaped wall  66  of the split-ring gland  14  is engaged or seated onto the flange  24  at one open end  22  of the sleeve  12 . The abutting ends  28   a ,  28   b  of the gland members  26   a ,  26   b  are securely coupled in gap free relationship with the bolt  38  and nut  40 . Securely coupling the abutting ends  28   a ,  28   b  in this manner will provide a nominal gap  32  between the spaced ends  30   a ,  30   b . The bolt  38  and nut  40  are oriented tangential to the gland members  26   a ,  26   b  and therefore restrain the gland members  26   a ,  26   b  from scissoring outwardly at the spaced ends  30   a ,  30   b  and increasing the length of the gap  32  from the nominal. The armor  16  is inserted to span the gap  32  between the spaced ends  30   a ,  30   b  of the gland members  26   a ,  26   b  and to form a generally closed annular periphery  19  with the gland members  26   a ,  26   b . The annular gasket  18  is inserted into the closed annular periphery  19  of the armor  16  and the first and second gland members  26   a ,  26   b . Alternatively, the armor  16  may be sitting on the gasket  18  and the gland members  26   a ,  26   b  may be brought together over the flange  24 , the armor  16 , and the gasket  18  simultaneously. In this position, the gasket  18  engages the corrugated portion  82  of the armor  16 . The spaced ends  30   a ,  30   b  may be coupled by the elongate bolt  48  and nut  50 . The elongate bolt  48  and nut  50  may be loosely engaged to leave the nominal gap  32  or, alternatively, may be tightened to begin compressing the gasket  18 . The pipe coupling  10  may be packed and shipped in this assembled state in one embodiment. 
     Alternatively, each of the split-ring glands  14  may be assembled with the corresponding armor  16  and gasket  18  as described above without seating the U-shaped wall  66  of the split-ring gland  14  onto the flange  24  of the sleeve  12 . In this assembly, the split-ring glands  14  may be shipped separately from the sleeve  12  and may be assembled with the sleeve  12  at a jobsite. The split-ring glands  14  will need to be loosened and mounted on the corresponding flanges  24  of the sleeve  12  at the jobsite in these embodiments. Any of the above-described assembly steps may be undone and repeated as required during installation and/or removal of the pipe coupling  10 . 
     In use, the assembled pipe coupling  10  is operable to couple the pipe end E 1  into fluid communication with the pipe end E 2 . With reference to  FIG. 2 , the pipe end E 1  of the first pipe P 1  is inserted through the gasket opening  89  of a first split-ring gland  14  and through one open end  22  into the sleeve  12  (arrow  134 ). The pipe end E 2  of the second pipe P 2  is inserted through the gasket opening  89  of a second split-ring gland  14  and through the other open end  22  into the sleeve  12  (arrow  135 ). The elongate bolt  48  and nut  50  of the first split-ring gland  14  is tightened to shorten the gap  32  between the spaced ends  30   a ,  30   b  thereof (arrows  136 ) and thereby generally uniformly compress the corresponding annular gasket  18  into sealed engagement with the first pipe P 1 . The elongate bolt  48  and nut  50  of the second split-ring gland  14  is tightened to shorten the gap  32  between the spaced ends  30   a ,  30   b  thereof (arrows  137 ) and thereby generally uniformly compress the corresponding annular gasket  18  into sealed engagement with the second pipe P 2 . Each pipe P 1 , P 2  may be inserted into the sleeve  12  prior to tightening the split-ring glands  14 , or one pipe (e.g., P 1 ) may be inserted and tightened into position before the other pipe (e.g., P 2 ) is inserted and tightened into position. Advantageously, the corrugations  82  of the armors  16  reduce the frictional engagement of the armors  16  with the corresponding annular gaskets  18  as the gaskets  18  are compressed. Thus, the annular gaskets  18  do not tend to bunch up on the armors  16  even with minimal lubrication in the split-ring glands  14 . 
     In some applications, the first pipe P 1  may be of a smaller diameter than the second pipe P 2 . To accommodate the larger diameter pipe (e.g., P 2 ), the inner gasket  88  of the annular gasket  18  may need to be removed. The corresponding interdigitations  102 ,  104  of the inner gasket  88  and the outer gasket  86  are disengaged from each other so that the inner gasket  88  may be removed from the split-ring gland  14 . More particularly, the inner gasket  88  is pulled radially inwardly away from the outer gasket  86  along any side so that the corresponding interdigitations  102 ,  104  are disengaged thereat. The inner gasket  88  may then be pulled along the longitudinal axis LA to torque the remainder of the interdigitations  102 ,  104  out of engagement as the inner gasket  88  moves away from the outer gasket  86 . The larger pipe P 2  may be inserted through the gasket opening  89  defined by the outer gasket  86  and through the open end  22  of the sleeve  12 , and the corresponding split-ring gland  14  may tightened the outer gasket  86  into sealing engagement with the larger pipe P 2 . If a larger pipe is to be replaced with a smaller pipe, or if it is determined that the larger pipe is not so large as to seal into just the outer gasket  86 , the inner gasket  88  may be re-inserted back into the outer gasket  86  by reversing the disengagement steps described above to accommodate the smaller diameter. The inner gasket  88  may be inserted back into the outer gasket  86  in the original orientation or in a reversed orientation along the longitudinal axis LA of the pipe coupler  10  because the corresponding interdigitations  102 ,  104  are symmetrical. Each of these steps may be repeated to use the pipe coupling  10  on pipes P 1 , P 2  of different sizes. 
     With reference to  FIGS. 9 through 15 , these figures illustrate a second embodiment of a pipe coupling  150  according to the principles of the present invention. For example,  FIG. 9  illustrates the pipe coupling  150  with one of the split-ring glands  14  shown partially exploded to facilitate discussion. It will be understood that all components of the pipe coupling  150  are identical to those described above with reference to the first embodiment of the pipe coupling  10 , with the exception of the annular gasket  152 . Accordingly, the same reference numbers have been used on non-gasket elements where those identical elements appear in the drawings without further description herein. 
     The modified annular gasket  152  of this embodiment is shown in further detail in  FIGS. 9 and 10 , with  FIG. 10  showing the gasket  152  in a reversed orientation from the view shown in  FIG. 9 . The annular gasket  152  includes an annular outer gasket  154  and a separate annular inner gasket  156  reusably coupled to (i.e., repeatedly insertable into and removable from) the outer gasket  154 . It will be understood that the annular inner gasket  156  of this embodiment may be identical to the annular inner gasket  88  previously described. The annular gasket  152  defines a gasket opening  158  therethrough centered on the longitudinal axis LA when the pipe coupling  150  is assembled. Each of the outer gasket  154  and the inner gasket  156  are composed of an elastomeric material such as rubber. The outer gasket  154  is configured to engage the split-ring gland  14  and the armor  16  along an outer circumferential surface  160 , and has an inner circumferential surface  162  configured to engage either the inner gasket  156  or the respective pipe end E 1 , E 2  (when the inner gasket  156  is removed). The inner gasket  156  is configured to engage the pipe end E 1 , E 2  inserted into the pipe coupling  150  and the inner circumferential surface  162  of the outer gasket  154  as will be described in greater detail below. 
     The outer gasket  154  includes the outer circumferential surface  160  facing the gland members  24   a ,  24   b  and the inner circumferential surface  162  facing the inner gasket  156  (or the respective pipe end E 1 , E 2  when the inner gasket  156  is removed). The inner circumferential surface  162  defines a first opening  164  ( FIG. 10 ) having a diameter D 3 . The outer gasket  154  also includes an inner side surface  166  extending between the outer and inner circumferential surfaces  160 ,  162  and facing the sleeve  12 , and an outer side surface  168  extending between the outer and inner circumferential surfaces  160 ,  162  and facing away from the sleeve  12 . The inner and outer side surfaces  166 ,  168  may each be acutely angled from the inner circumferential surface  162  (e.g., intersect at an 85° angle) such that the inner circumferential surface  162  is longer than the outer circumferential surface  160  to form a generally trapezoidal-shaped configuration for the outer gasket  154 . Similarly, the inner gasket  156  includes an outer circumferential surface  170  facing the outer gasket  154  and an inner circumferential surface  172  facing the pipe end E 1 , E 2  or in an inward radial direction. The inner circumferential surface  172  defines an opening  174  ( FIG. 10 ) having a second, smaller diameter D 4 . The inner gasket  156  defines a generally rectangular-shaped configuration as shown. 
     Similar to the previous embodiment, the inner gasket  156  may be selectively disengaged from the outer gasket  154  and removed from the pipe coupling  150  to modify an effective range of pipe outer diameters that may be sealed by and accommodated within the pipe coupling  150 . In other words, the removable inner gasket  156  enables modification of an effective diameter of the pipe coupling  150  at the split-ring gland  14 . To facilitate reusable coupling of the inner gasket  156  to the outer gasket  154 , the outer gasket  154  and the inner gasket  156  have corresponding interdigitated surfaces. More particularly, the inner circumferential surface  162  of the outer gasket  154  includes a plurality of first interdigitations  176  configured to engage a corresponding plurality of second interdigitations  178  formed on the outer circumferential surface  170  of the inner gasket  156 . The engagement of the interdigitations  176 ,  178  discourages relative axial movement between the outer and inner gaskets  154 ,  156 . The interdigitations  176 ,  178  are configured to be symmetrical such that the inner gasket  156  and the outer gasket  154  may be engaged without regard to orientation of the inner gasket  156 . More importantly, this engagement and removal of the inner gasket  156  may be repeated anytime the necessary pipe diameter to be held by the pipe coupling  150  changes. 
     By positioning the inner gasket  156  within the outer gasket  154  with the interdigitations  176 ,  178  aligned, the outer and inner gaskets  154 ,  156  are held together by their own resiliency, although the gaskets  154 ,  156  may be easily separated by pulling the inner gasket  156  inwardly in a radial direction and then away from the outer gasket  154 . To this end, the inner gasket  156  is generally wider in an axial direction than the corresponding axial width of the outer gasket  154 . The inner gasket  156  therefore includes lips  180  projecting beyond the inner and outer side surfaces  166 ,  168  of the outer gasket  154 , the lips  180  facilitating easy gripping and movement of the inner gasket  156  inwardly radially away from the outer gasket  154  when the inner gasket  156  is to be removed from the pipe coupling  150 . 
     In the illustrated embodiment and as most clearly shown in  FIG. 12 , the first interdigitations  176  include several triangular cross-section annular grooves: two triangular-shaped shallow grooves  176   a  adjacent outer edges of the ring, two deeper triangular-shaped grooves  176   b  inboard of the outer shallow grooves  176   a , and two additional triangular-shaped shallow grooves  176   c  inboard of the deeper grooves  176   b . It will be appreciated that first interdigitations  176  may alternatively be formed with different shapes (i.e., circular), different depths (i.e., all grooves having a uniform depth), and with different numbers of grooves as opposed to the embodiment shown. Likewise, the second interdigitations  178  include several triangular cross-section annular projections  178   a ,  178   b ,  178   c  sized and positioned to mate with the shallow and deeper grooves forming the illustrated first interdigitations  176 . It will be further appreciated that other types of projections could be provided for second interdigitations  178  to match the various alternatives described above for the first interdigitations  176 . Alternatively, the first interdigitations  176  may be projections and the second interdigitations  178  may be grooves in other embodiments. 
     As shown most clearly in  FIGS. 10 through 12 , the outer gasket  154  also includes a nominally-open, nearly horizontal, annular pressure assist slot  182  extending into the outer gasket  154  from the inner side surface  166  and towards the outer side surface  168 . The pressure assist slot  182  is advantageously angled at a shallow angle (e.g., 5°) from a plane  184  defined by the inner circumferential surface  162  such that the pressure assist slot  182  traverses radially outwardly as the pressure assist slot  182  extends from the inner side surface  166  towards the outer side surface  168 . In this regard, the pressure assist slot  182  is angled slightly towards the gasket opening  158  and is aimed at the corresponding flange  24  of the sleeve  12 . The pressure assist slot  182  includes a slot opening  185  at the inner side surface  166  that is advantageously continuous and uninterrupted about the gasket opening  158  at the inner side surface  166 . Consequently, if pressurized fluid in the pipes P 1 , P 2  begins to pass between the inner side surface  166  of the outer gasket  154  and the flange  24  on the sleeve  12 , the pressurized fluid will enter the pressure assist slot  182  through the slot opening  185  and press outwardly on the outer gasket  154  at the pressure assist slot  182 . This additional force applied at the pressure assist slot  182  further enhances the sealing connection of the outer gasket  154  to the split-ring gland  14 , the armor  16 , and the flange  24  of the sleeve  12 . The angle and orientation of the pressure assist slot  182  may be modified in other embodiments. 
     Although the slot opening  185  is shown in these figures as being directly adjacent to the flange  24  of the sleeve  12 , it will be understood that the particular positioning of the slot opening  185  with respect to the sleeve  12  may be modified in other embodiments depending on various factors, including the size of the pipe and whether the inner gasket  156  is used. For example, the slot opening  185  may be positioned adjacent the junction of the flange  24  and the cylindrical body portion  20  of the sleeve  12  in other embodiments to thereby more readily communicate with fluid from the pipe(s). This arrangement is particularly advantageous when the pipe coupling  150  is used with smaller pipes because the additional enhancement of the sealing connection caused by fluid pressure applied at the pressure assist slot  182  is even more relevant in these circumstances to forming a reliable seal with the pipe. 
     In accordance with one aspect of the present invention, the outer gasket  154  includes a plurality of cross grooves  186  in the form of indentations located coextensive with the slot opening  185  of the pressure assist slot  182  at the inner side surface  166 . To this end, the cross grooves  186  are provided adjacent to and extending into the slot opening  185  at the inner side surface  166 . More particularly, each cross groove  186  intersects with the slot opening  185  at the inner side surface  166  and also extends radially outward and/or radially inward from the slot opening  185  at the inner side surface  166 . In this regard, each of the cross grooves  186  defines a radially extending pathway from the slot opening  185  along the inner side surface  166 , but are recessed beyond the inner side surface  166  to provide an alternative fluid communication path into the pressure assist slot  182 . Thus, the cross grooves  186  enable continued flow of pressurized fluid into the pressure assist slot  182  after compression of the annular gasket  152  with the split-ring gland  14 , as explained in further detail below. 
     In one example, each of the cross grooves  186  is molded at the same time as the pressure assist slot  182  rather than separately drilled, and the coextensive or adjacent placement of the cross grooves  186  with the pressure assist slot  182  enables a single mold part to be used to form these features of the annular gasket  152 . This reliable and easy molding process is contrasted with the multiple mold parts or the separate drilling steps which may be required to form the previously-described vent holes in known gaskets. Each of the cross grooves  186  may be oriented generally perpendicular to the pressure assist slot  182  at the inner side surface  166 . As a result, when the slot opening  185  of the pressure assist slot  182  is clamped shut at the inner side surface  166  because of compression of the outer gasket  154 , the cross grooves  186  extend radially outward and/or radially inward from the annular pressure assist slot  182  to maintain flow into the pressure assist slot  182  from the inner side surface  166 . Although seven cross grooves  186  are illustrated in  FIG. 10 , it will be understood that more or fewer cross grooves  186  may be provided in other embodiments consistent with the current invention. Moreover, it will be understood that the annular pressure assist groove  182  and cross grooves  186  may be used on other gaskets such as single-piece gaskets that do not the inner gasket  156  described above in accordance with other embodiments of the present invention. 
     A portion of the outer gasket  154  not including a cross groove  186  is shown in an uncompressed state in  FIG. 12  and in a compressed state in  FIG. 13 . In this regard, the pressure assist groove  182  defines a pair of opposing corners  188  adjacent the intersection with the inner side surface  166  and defining the slot opening  185 . When the outer gasket  154  is not compressed or only slightly compressed as shown in  FIG. 12 , these opposing corners  188  remain spaced from one another such that flow of pressurized fluid passing between the flange  24  of the sleeve  12  and the inner side surface  166  will enter the pressure assist slot  182  through the slot opening  185 . However, when the outer gasket  154  is compressed by the split-ring gland  14  as shown in  FIG. 13 , the opposing corners  188  may bend or buckle inwardly into sealing contact with each other, thereby closing the slot opening  185 . As a result, any pressurized fluid passing between the flange  24  of the sleeve  12  and the inner side surface  166  at this location is prevented from entering the pressure assist slot  182 . 
     By contrast, another portion of the outer gasket  154  that includes one of the cross grooves  186  is shown in an uncompressed state in  FIG. 14  and in a compressed state in  FIG. 15 . As shown in  FIG. 14 , the cross groove  186  extends radially beyond each of the opposing corners  188  in the illustrated embodiment. More particularly, the cross groove  186  includes first and second opposing sides  190 ,  192  that collectively define a generally conical indentation shape that tapers inwardly from the inner side surface  166  towards the outer side surface  168 . For example, while the corresponding first and second sides  194 ,  196  of the pressure assist slot  182  may be generally parallel to one another in the uncompressed state, the first and second opposing sides  190 ,  192  of the cross groove  186  are slightly angled (e.g., by 14°) from one another. It will be appreciated that the positioning, shape, and tapering angle of the cross grooves  186  may be modified in other embodiments consistent with the scope of this invention. For example, the first and second opposing sides  190 ,  192  may be obliquely molded so as to be parallel to one another yet still located radially beyond the first and second sides  194 ,  196  of the pressure assist slot  182  in another embodiment consistent with the principles of the present invention. Advantageously, when the outer gasket  154  is compressed by the split-ring gland  14  as shown in  FIG. 15 , the first and second opposing sides  190 ,  192  of the cross groove  186  remain spaced from one another despite the corners  188  of the pressure assist slot  182  coming together. Consequently, pressurized fluid passing between the flange  24  of the sleeve  12  and the inner side surface  166  continues to flow through the cross groove  186  to be captured within the pressure assist slot  182  despite the slot opening  185  being clamped shut. Moreover, the pressure assist slot  182  remains pressurized even if the outer gasket  154  is compressed to the extent shown in  FIGS. 13 and 15 . 
     Also shown in  FIGS. 10 through 15 , the outer gasket  154  of this embodiment also includes a plurality of ribs  200  projecting outwardly from the outer circumferential surface  160 , the inner side surface  166 , and the outer side surface  168 . The ribs  200  are configured to engage the corresponding outer side wall  78  of the armor  16 , the central wall  70  of the armor  16 , and the flange  24  of the sleeve  12 . The ribs  200  define a semicircular cross-section in the illustrated embodiment, although other shapes such as triangular are also possible in other embodiments. It will also be understood that more or fewer ribs may be provided on each of these surfaces  160 ,  166 ,  168  in alternative embodiments of the pipe coupling  150 . Similar to the corrugations  82  on the armor  16 , the ribs  200  enhance the sealing contact of the outer gasket  154  against each of the split-ring gland  14 , the armor  16 , and the flange  24  of the sleeve  12 . The ribs  200  also advantageously reduce frictional sliding contact between the outer gasket  154  and the other components during compression of the annular gasket  152  with the split-ring gland  14 . When the ribs  200  are provided on the outer gasket  154 , the need for lubrication added between the annular gasket  152  and the split-ring gland  14  may be reduced or even eliminated, thus further facilitating installation of the split-ring gland type of coupling  150 . Thus, the previously discussed disadvantages of applying a slippery grease or lubricant onto the components of the pipe coupling  150  are overcome with the currently described embodiment. 
     Advantageously, when the outer gasket  154  of this embodiment includes the plurality of ribs  200  and is combined with a corrugated armor  16  within the split-ring gland  14 , the need for lubrication between the annular gasket  152  and the split-ring gland  14  has been found to be eliminated. To this end, the combination of these features prevents the bunching up of the annular gasket  152  on the split-ring gland  14  or on the armor  16  as the annular gasket  152  is compressed. It will be understood that the plurality of ribs  200  may be provided on other annular gaskets without one or both of the inner gasket  156  (i.e., a single layer gasket) and the pressure assist slot  182  in other embodiments consistent with the scope of the present invention. 
     As shown most clearly in  FIG. 11 , the outer gasket  154  is configured to seat securely within the gasket seat  69  formed by the split-ring gland  14 , the armor  16 , and the flange  24  of the sleeve  12 . In operation, the outer circumferential surface  160  of the outer gasket  154  seats against the annular walls  60  of the gland members  26   a ,  26   b  and the central wall  70  of the armor  16 . The inner side surface  166  of the outer gasket  154  is positioned adjacent to the flange  24  of the sleeve  12 , and the outer side surface  168  of the outer gasket  154  is positioned adjacent to the outer walls  68  of the gland members  26   a ,  26   b  and the outer side wall  78  of the armor  16 . When the split-ring gland  14  compresses the outer gasket  154  inwardly, the outer gasket  154  seals the pipe coupling  150  from leakage adjacent the flange  24  of the sleeve  12  and adjacent the split-ring gland  14 . Furthermore, as described above, the combination of the outwardly-projecting ribs  200  on the outer gasket  154  and the corrugations  82  on the armor  16  collectively enables the split-ring gland  14  to compress the annular gasket  152  without lubrication added between the split-ring gland  14  and the annular gasket  152 . Accordingly, the annular gasket  152  of this embodiment advantageously improves the operation and reliability of the pipe coupling  150 . 
     By virtue of the foregoing, there are thus provided an improved armor, an improved gland, and/or an improved annular gasket for the split-ring gland type of pipe couplings in accordance with various aspects of the present invention. While the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. For example, an improved armor in accordance with the principles of the first aspect of the present invention may be used with the improved gland and/or improved annular gasket, but could also be used with other glands or gaskets. Moreover, each of the improved gland and the improved annular gasket in accordance with other aspects of the present invention may be used independently of each other. By way of further example, the armor and/or the corrugations  82  may be formed by hot working instead of cold working as will be appreciated by those skilled in the art. In regard to the gaskets, a generally solid outer gasket with no angled slots may be provided in other embodiments of the pipe coupling. Alternatively, an outer gasket with any combination of the nearly horizontal slot  108  of  FIG. 7 , the angled slot  122  of  FIG. 8 , and the pressure assist slot  182  of  FIG. 12  may be used in accordance with other embodiments of the invention. Although the cross grooves  186  are shown in combination with the pressure assist slot  182  in the illustrated embodiments, these cross grooves  186  may also be used with other slots in the outer gasket, including the nearly horizontal slot  108  and the angled slot  122 . Further, only a single gasket rather than a gasket  18  comprised of inner and outer gaskets, may be used. Additionally, the abutting ends  28   a ,  28   b  of the gland members  26   a ,  26   b  may be attached in other ways, including with a longitudinal bolt or the like, although scissoring of the gland members  26   a ,  26   b  may result. Further, while shown as being used to couple two pipe ends via the sleeve  12 , only one end thereof might be provided with the split-ring glands  14 , armor  16 , and/or gasket  18 . The cross grooves  186  of the gasket  182  may be used in combination with spaced vent holes in the gasket as well, and these cross grooves  186  and vent holes may be coupled together at the inner side surface  166  in some embodiments. Moreover, the various features of the present invention, including but not limited to the corrugated armor  16 , the ribs  200  on the gasket  152 , the pressure assist slot  182  and cross grooves  186  of the gasket  152 , and the removable inner gasket  156 , may be used individually or in any combination to improve the performance of the pipe coupling  10 ,  150 . The invention in its broader aspects is, therefore, not limited to the specific details, representative apparatus and method, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the general inventive concept.