BOLTLESS PIPE CONNECTOR

Abstract: A connector for a plain end pipe comprising a housing (7) for location over the pipe, an annular recess (4) formed in an inner surface of the housing (7), a seal (1) located in the recess (4), a nipple (8) for the supply of grease under pressure, and segmental grippers of L-shaped cross section comprising a leg (6) and a foot (5) having a serrated inner surface for engagement with the pipe. Such connectors have wide tolerance within a certain range of nominal pipe outside diameter.

Description: Boltiess Pipe Connector DESCRIPTION Technical Field The invention relates to boltiess pipe connectors suitable for attachment on or adjacent the end of a plain end pipe to enable coupling of said pipe to a further pipe, pump, valve, end cap or the like. These connectors are universal, that is they have a wide tolerance within a certain size range: pipes of a given nominal diameter do not all have the same outside diameter. EP 727026 uses grease under pressure to grip and seal pipes as they are joined. This technology has been limited to small tolerances, typically 4 or 5 mm, in pipe diameter. The maximum movement of the grippers is approximately half thickness of the grippers or they would slip out of the container groove in the housing. THE INVENTION According to the invention, a seal located in an annular recess in an inner surface of the connector has segmental grippers of L-shaped cross-section comprising a leg between the seal and a wall of the recess, and a foot having a serrated inner surface for engagement with the pipe. This allows for a tolerance exceeding 1 0 or 1 5 mm thereby allowing the pipe connection to be used with all pipes of a given nominal diameter. A metal shim may be provided between the legs of the adjacent grippers. Grippers may be provided between one or each side of the seal and an adjacent wall of the recess. The housing is provided with an inlet for a sealing fluid which may be a nipple for the supply of grease or oil under pressure or components for the formation of an epoxy resin to make the seal permanent. The housing is generally provided with an air bleed offset from the sealing fluid inlet for use during assembly when the recess is filled with grease or oil as sealing fluid. DRAWINGS FIG. 1 is a half-section of the pipe connector according to the above EP 727026: FIG. 2 is a section through a pipe connector according to the present invention; and FIG. 3 shows the configuration of a gripper in FIG. 2. In the prior art connector of FIG. 1 , a mechanism using high pressure grease activates a plurality of grippers. The grippers are pushed downward onto the pipe by grease from a high pressure grease gun but contained within the connector housing to cause a dynamic seal to press the arcuate segment shaped grippers onto the pipe. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 2, the connector comprises a hollow metal housing 7 having an annular recess 4. In the recess 4, there is an annular polymeric seal 1 having a concave outer surface and lateral wings in sealing engagement with the inside of the recess 4. Segmental grippers of L-shaped cross-section each comprise a leg 6 contacting the seal 1 through metal shims 3 and a foot 5 having a serrated inner surface for engagement with a pipe wall. The metal shims 3 extend across the gaps between the legs 6 of adjacent grippers to allow relative movement therebetween on sealing. During assembly, grease is applied at pressure through a nipple 8 to fill the recess 4. Air is allowed to escape through a bleed (not shown). On installation, more grease is applied at high pressure from a gun through the nipple 8 and presses the seal 1 downward so that the grippers are brought into engagement with the pipe wall, the air bleed being closes at this stage. This allows a greater tolerance in each pipe connector because the leg 6 of the gripper prevents the polymer seal 1 from protruding into the gap between the housing 7 and the pipe wall. The grease presses downward on the seal 1 and on its wings to ensure firm contact with housing 7. As the grease pressure increases, it moves the polymer seal 1 down the housing 7 towards the pipe wall. The polymer seal 1 presses on the feet 5 of the grippers to move them onto the pipe wall. The pressure of the grease causes the feet 5 to cut into the pipe wall. The gap between the gripper feet 5 allows the polymer seal 1 to flow onto the surface of the pipe and form a seal which prevents any leaks along the outer surface of the pipe wall. The metal shims 3 prevent nipping of the seal 1 between the legs 6 of the grippers, and protruding between the edges of adjacent gripper legs 6.

Claims: CLAIMS 1 . A pipe connector for a plain end pipe comprising a housing (7) for location over the pipe, an annular recess (4) formed in an inner surface of the housing (7) to surround the pipe, a seal (1 ) located in the recess (4), and an inlet (8) for the supply of sealing fluid into the recess (4) between the housing (7) and the seal ( 1 ), characterized by segmental grippers of L-shaped cross-section comprising a leg (6) between the seal ( 1 ) and a wall of the recess (4), and a foot (5) having a serrated inner surface for engagement with the pipe. 2. A pipe connector according to claim 1 characterized by a metal shim (3) between the legs (6) of the adjacent grippers. 3. A pipe connector according to claim 1 or claim 2 characterized by grippers (6) between each side of the seal ( 1 ) and an adjacent wall of the recess (4). 4. A pipe connector according to any preceding claim characterized by the inlet (8) being a nipple for the supply of grease under pressure.

Inventors: BALL DANIEL GRAHAM, BALL, DANIEL, GRAHAM
Applicants: BALL DANIEL GRAHAM, BALL, DANIEL, GRAHAM
Application year: 1998
Main classification: F16L17
IPC codes: F16L17, F16L37