Mechanical pipe joint, gasket, and method for restraining pipe spigots in mechanical pipe joint bell sockets

Abstract

A mechanical pipe joint, restraining gasket, and method for restraining pipe spigots within adjacent bell sockets. The restraining gasket is composed of two axially-separate components: a sealing portion and a restraining portion made of a plurality of arcuate locking members. The restraining gasket and a gland surround an outer surface of the pipe spigot. The mechanical pipe joint is formed as the pipe spigot is inserted into the bell socket and the gland is axially attached to the bell socket so that the restraining gasket is held between: the gland, an inner surface of the bell socket, and the outer surface of the pipe spigot, so as to provide a fluid seal in the joint and urge the locking members into contact with the outer surface of the pipe spigot, axially restraining the pipe spigot within the bell socket.

1 . A restraining gasket, for sealing and restraining a male piping member within an adjoining bell socket along an axis in a mechanical pipe joint, the restraining gasket being formed at least in part of an elastomeric material and comprising: 
 a sealing portion adapted to fit substantially within a sealing cavity defined between the male piping member and the bell socket;    a restraining portion adapted to surround the male piping member substantially outside the sealing cavity, the restraining portion comprising a plurality of circumferentially-spaced arcuate locking members formed from a rigid material and arranged for restraining engagement between a bearing surface of a gland and the male piping member, wherein the locking members are retained relative to each other by the elastomeric material before attachment of the gland to the bell socket; and    an interface between the sealing portion and the restraining portion, the interface being adapted to distribute an axial attachment force exerted by the bearing surface of the gland on the restraining portion to prevent a premature engagement of an outer surface of the male piping member by the plurality of circumferentially-spaced arcuate locking members.    
   
   
       2 . The restraining gasket according to  claim 1 , wherein the elastomeric material comprises the sealing portion and a plurality of spacers separate from and adhesively attached to the sealing portion, and wherein the plurality of circumferentially-spaced arcuate locking members are retained relative to each other by the plurality of spacers.  
   
   
       3 . The restraining gasket according to  claim 2 , wherein the plurality of spacers are composed of an elastomeric material having a different stiffness than the stiffness of the sealing portion.  
   
   
       4 . The restraining gasket according to  claim 2 , wherein each spacer is located circumferentially between two of the circumferentially-spaced arcuate locking members such that the plurality of circumferentially-spaced arcuate locking members are initially suspended out of contact with an outer surface of the male piping member at a distance of about 0.100 inches from the outer surface of the male piping member.  
   
   
       5 . The restraining gasket according to  claim 1 , wherein the plurality of circumferentially-spaced arcuate locking members are configured to restrain the outer surface of the male piping member with a means for gripping the outer surface of the male piping member, the gripping means selected from the group consisting of: 
 a plurality of teeth;    an abrasive grit;    a hard granular material; or    a plurality of radial ridges.    
   
   
       6 . The restraining gasket according to  claim 1 , wherein the interface further defines a slope, the slope being configured to convert the axial attachment force of the gland into a partially-axial force and a partially-radial force on the restraining gasket.  
   
   
       7 . The restraining gasket according to  claim 6 , wherein the slope is directed radially outward towards the bell socket at an angle of approximately 10 to 20 degrees, with respect to a plane that is perpendicular to the axis, such that the partially-axial force is exerted first on the sealing portion, and the partially-radial force is exerted second on the plurality of circumferentially-spaced arcuate locking members so that the axial attachment force of the gland seals the sealing cavity about the male piping member before urging the plurality of circumferentially-spaced arcuate locking members into engagement with the outer surface of the male piping member so as to axially secure the male piping member within the bell socket.  
   
   
       8 . The restraining gasket according to  claim 7 , wherein the slope is directed radially outward towards the bell socket at an angle of approximately 15 degrees, with respect to a plane that is perpendicular to the axis.  
   
   
       9 . The restraining gasket according to  claim 1 , wherein an arc length of each of the plurality of circumferentially-spaced arcuate locking members is at least 15 degrees, with respect to the axis.  
   
   
       10 . The restraining gasket according to  claim 1 , wherein an arc length of each of the plurality of circumferentially-spaced arcuate locking members is about 60 degrees, with respect to the axis.  
   
   
       11 . The restraining gasket according to  claim 1 , wherein the rigid material is selected from the group consisting of: 
 hardened metal;    mild steel;    ductile iron;    ceramic; or    plastic having a hardness greater than that of PVC.    
   
   
       12 . A restraining gasket for sealing and restraining a male piping member within an adjoining bell socket along an axis in a mechanical pipe joint, the restraining gasket being formed at least in part of an elastomeric material and comprising: 
 a sealing portion adapted to fit substantially within a sealing cavity defined between the male piping member and the bell socket;    a restraining portion adapted to surround the male piping member, the restraining portion comprising at least one arcuate locking member formed from a rigid material arranged for restraining engagement between a bearing surface of a gland and an outer surface of the male piping member; and    a raised portion disposed circumferentially on a radially-outward surface of the at least one arcuate locking member such that the raised portion provides a reduced surface area for reducing friction between the radially-outward surface of the at least one arcuate locking member and the bearing surface of the gland.    
   
   
       13 . The restraining gasket according to  claim 12  wherein the at least one arcuate locking member comprises a plurality of circumferentially-spaced arcuate locking members.  
   
   
       14 . The restraining gasket according to  claim 13 , wherein the elastomeric material comprises the sealing portion and a plurality of spacers separate from and adhesively attached to the sealing portion, and wherein the plurality of circumferentially-spaced arcuate locking members are retained relative to each other by the plurality of spacers.  
   
   
       15 . The restraining gasket according to  claim 14 , wherein the plurality of spacers are composed of an elastomeric material having a different stiffness than the stiffness of the sealing portion.  
   
   
       16 . The restraining gasket according to  claim 14 , wherein each spacer is located circumferentially between two of the circumferentially-spaced arcuate locking members such that the plurality of circumferentially-spaced arcuate locking members are initially suspended out of contact with an outer surface of the male piping member at a distance of about 0.100 inches from the outer surface of the male piping member.  
   
   
       17 . The restraining gasket according to  claim 12 , wherein the at least one arcuate locking member is configured to restrain the outer surface of the male piping member with a means for gripping the outer surface of the male piping member, the gripping means selected from the group consisting of: 
 a plurality of teeth;    an abrasive grit;    a hard granular material; or    a plurality of radial ridges.    
   
   
       18 . The restraining gasket according to  claim 13 , wherein an arc length of each of the plurality of circumferentially-spaced arcuate locking members is at least 15 degrees, with respect to the axis.  
   
   
       19 . The restraining gasket according to  claim 13 , wherein an arc length of each of the plurality of circumferentially-spaced arcuate locking members is about 60 degrees, with respect to the axis.  
   
   
       20 . The restraining gasket according to  claim 12 , wherein the rigid material is selected from the group consisting of: 
 hardened metal;    mild steel;    ductile iron;    ceramic; or    plastic having a hardness greater than that of PVC.