Mechanical pipe joint

An improved mechanical pipe joint for use in a bell and plain pipe end assembly. The joint includes a gland having a conical cavity for receiving a toothed split ring that coaxially compresses and grips the plain pipe end as the gland is tightened to the bell. The joint is sealed by a compressible gasket positioned between the split ring and the bell. The gland further includes an integrally formed, radially extending shelf for abutting against the split ring and mechanically stopping the gland from being pulled over the split ring during joint assembly.

TECHNICAL FIELD 
The present invention relates to mechanical pipe joints and, in particular, 
to mechanical pipe joints including a gripping ring and a compressible 
gasket positioned between the pipe bell and the gland. 
BACKGROUND OF THE INVENTION 
Mechanical joints for securing bell and plain pipe end assemblies are well 
known in the art. One standard mechanical joint includes a compressible 
gasket slipped around the plain pipe end and positioned between the pipe 
bell and the gland. Tightening of included joint securing bolts forces the 
gland towards the pipe bell compressing the gasket in a conical cavity 
formed in the bell and securing the joint. The standard mechanical joint, 
however, ineffectively secures the bell and plain pipe end in instances 
where the pipe is internally exposed to varying hydraulic pressures. Such 
pressures tend to cause axial movement along the joint which may result in 
leaking around the gasket and/or releasing of the joint. 
To address the deficiencies of the standard mechanical joint, the prior art 
further teaches the use of a toothed split ring slipped around the plain 
pipe end and positioned in a conical cavity formed in the gland. The 
tightening of securing bolts forces the gland towards the pipe bell 
compressing the gasket to seal the joint, with the conical cavity of the 
gland coaxially compressing the split ring such that the included teeth 
grip the plain pipe end to secure the joint. The gripping action of the 
toothed split ring secures the joint by resisting axial movement in the 
joint when the pipe is exposed to varying internal hydraulic pressures. 
However, over-tightening of the securing bolts and/or improper initial 
assembly alignment may cause the split ring to become overly-compressed 
during assembly resulting in a deformation of the plain pipe end and 
destruction of the joint. In fact, in some instances, the gland may be 
pulled completely over the split ring during incorrect or improper 
assembly. 
SUMMARY OF THE INVENTION 
The present invention is an improved mechanical pipe joint for use in a 
bell and plain pipe end assembly, comprising a gland encircling the plain 
pipe end having a conical cavity for receiving a toothed split ring, the 
ring having a complementary conically shaped outer surface. Tightening of 
the gland to the bell causes the split ring to coaxially compress within 
the conical cavity and grip the plain pipe end. The gland further includes 
an integrally formed, radially extending shelf positioned at a narrow end 
of the conical cavity for abutting against an end of the split ring. As 
the gland is tightened to the bell, the shelf acts as a mechanical stop to 
certain excessive movement of the gland with respect to the coaxially 
compressing split ring. The shelf thus minimizes the likelihood of an 
over-compression of the split ring resulting in possible deformation of 
the pipe and destruction of the joint. The joint is sealed during 
tightening by a compressible gasket positioned between the split ring and 
the bell and received in a conical cavity of the bell.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIG. 1, there is shown an exploded cross-sectional view of 
the improved mechanical pipe joint of the present invention for securing a 
conventional bell 102 to the end 104 of a conventional plain pipe 106. The 
bell 102 includes a peripheral flange 108 having a plurality of apertures 
110 for receiving standard securing bolts (not shown, see FIG. 2) in a 
manner to be described. The bell 102 further includes a conical cavity 112 
narrowing in diameter from the peripheral flange 108 to a recess portion 
114 connected to a bell pipe 120 having substantially the same diameter as 
the plain pipe 106. The conical cavity 112 of the bell 102 is shaped to 
complement the outer conically shaped surface 116 of a compressible gasket 
118. The diameter of the bell 102 at the recess portion 114 is selected to 
receive the plain pipe end 104 in a manner to be described. 
The mechanical joint further includes a gland 122 with a peripheral flange 
124 having an opening 125 for encircling the plain pipe 106 and a 
plurality of peripheral apertures 126 equal in number and capable of 
alignment with the apertures 110 of the bell 102. The gland 122 further 
includes a conical cavity 128 associated with the opening 125 narrowing in 
diameter from a forward end 130 to a rearward end 132 of the gland. The 
conical cavity 128 of the gland 122 is shaped to complement the outer 
conically shaped surface 134 of a split ring 136. The split ring 136 
includes a plurality of circumferential teeth 138 on an inner cylindrical 
surface thereof, and also includes a well known gap or split (not shown) 
for facilitating a coaxial compression of the split ring within the 
conical cavity 128 and gripping of the plain pipe end 104 with joint 
assembly. The gland 122 further includes a radially extending and 
integrally formed shelf 142 positioned adjacent the rearward end 132 for 
abutting against the narrow end of the split ring 136 when the split ring 
is seated in the conical cavity 128. 
With reference now to FIGS. 1 and 2, assembly of the joint of the present 
invention will be described. The gland 122 is first slipped onto the end 
104 of the plain pipe 106 with the forward end 130 of the gland facing the 
plain pipe end. The split ring 136 is then slipped onto the plain pipe end 
104 with its narrow end facing the gland 122 for subsequent insertion into 
the conical cavity 128. The compressible gasket 118 is then slipped onto 
the plain pipe 106 and positioned a predetermined distance away from the 
plain pipe end 104. The pipe 106 is then inserted into the recess portion 
114 of the bell 102 with the conical cavity 112 of the bell 102 receiving 
the positioned gasket 118. The split ring 136 is then pushed against the 
gasket 118 and the gland 122 is pushed against the split ring such that 
the ring is received in the conical cavity 128. Standard securing bolts 
140 are then inserted through the aligned apertures 110 and 126 of the 
bell 102 and gland 122, respectively, and tightened to draw the gland 
toward the bell. As the joint is tightened, the split ring 136 is 
coaxially compressed within the conical cavity 128 of the gland 122, with 
the circumferential teeth 138 engaging the outer surface of the plain pipe 
106 to resist subsequent axial pipe movement. In this connection, the 
radial shelf 142 abuts against the split ring 136 and functions as a 
mechanically stop to certain excessive movement of the gland 122 with 
respect to the split ring. In particular, the shelf 142 resists the 
excessive movement of the gland 122 over the split ring 136 which is 
likely to cause over-compression of the split ring. The shelf 142 thus 
functions to save the plain pipe end 104 from deformation and the joint 
from destruction resulting from ring 136 over-compression. Furthermore, 
the radial shelf 142 abuts against the narrow end of the split ring 136 
pushing the split ring against the gasket 118, and compressing the gasket 
into the conical cavity 112 of the bell 102 to seal the joint. At the same 
time, the forward end 130 of the gland 122 is placed in contact with and 
compresses the gasket 118 to further seal the joint. 
Although a preferred embodiment of the improved mechanical joint of the 
present invention has been illustrated in the accompanying Drawings and 
described in the foregoing Detailed Description, it will be understood 
that the invention is not limited to the embodiment disclosed, but may be 
modified without departing from the spirit of the invention as set forth 
and defined by the following claims.