GB2229245A

GB2229245A - A pipe repair or connection clamp

Info

Publication number: GB2229245A
Application number: GB8906204A
Authority: GB
Inventors: Francis Derbyshire
Original assignee: E Peart and Co Ltd
Current assignee: E Peart and Co Ltd
Priority date: 1989-03-17
Filing date: 1989-03-17
Publication date: 1990-09-19
Anticipated expiration: 2009-03-17
Also published as: GB8906204D0; GB2229245B

Abstract

A pipe repair or connection clamp comprising a non-continuous band (11) of stainless steel surrounding a resilient sealing gasket (17), with a bridge plate (18) bridging the gap between the ends of the band (11). The adjacent ends of the band are attached to respective lugs (13) which are drawn together by bolts (14). The invention provides either a support plate (20) in the form of a stainless steel strip bent in a zig-zag shape or a pair of relatively slidable wedges located between the bridge plate (18) and the bolt (14). As the lugs (13) close together during tightening of the clamp; the support plate (20) or wedges may expand axially but remain to support the bridge plate (18) and prevent it from being "extruded" into the gap. <IMAGE>

Description

A PIPE REPAIR OR CONNECTION CLAMP This invention concerns a clamp for repairing a pipe or for connecting a branch pipe thereto and consisting of a non-continuous band usually of high grade stainless steel with an internal resilient gasket sleeve. The clamp may be. in one or more parts and assembled as a circular member to be tightened around a pipe by fastening means such as bolts which draw the adjacent ends of the band or parts thereof together to reduce its effective circumference.

In order for the clamp to be capable of use on pipes of different diameters, the gap or gaps between the ends of the band or band parts is fairly substantial and may represent, in large diameter clamps, a distan#ce of some 20mm.

In order to prevent the resilient gasket seal from being "extruded" into the gap as the band is tightened, it is common to place a semi-rigid bridge plate across the gap which bears against the inside end regions of the band and lying radially outside the resilient gasket. However, the bridge plate is necessarily curved to conform with the outside shape of the pipe, and so during tightening of the clamp the resilient gasket applies a radial bursting force outwardly on the bridge plate tending to push it away from the pipe. Furthermore, the clamp parts are being tightened thus applying a crippling force to the bridge plate. This together with the radial bursting force can result in the bridge plate bending out of contact with the gasket thus allowing the completed clamp to leak.

An object of the present invention is to provide a simple expedient for preventing the bridge plate from being deformed outwardly during the tightening process so as to maintain, as nearly as possible, a uniform circular crosssection throughout the clamp.

According to the present invention there is provided a pipe repair or connection clamp comprising at least one non-continuous band of flexible material to be tightened around a pipe by fastening means outside the clamp and serving to draw the ends of the band together to reduce its effective circumference, and a bridge plate located between the ends of the band to bridge the reducing gap between the ends during tightening, characterised by a support member disposed between the bridge plate and the fastening means to prevent radial protrusion of the bridge plate but extendible in a direction parallel to the pipe axis thus permitting the ends of. the band to be drawn together.

Preferably, the bridge plate is attached to one; end region of the band and extends into circumferentially overlapping relationship with an adjacent other end of the band thus to be in sliding contact with the latter during tightening.

Further, a resilient gasket preferably extends around the inside of the clamp in abutting relationship with the inner surface of the band and of the bridge plate.

For many applications the band will preferably consist of two separate and generally semi-circular band parts with bolts for drawing the respective adjacent ends of the band parts together, there being a bridge plate across each gap in the region of the bolts and a support member disposed between each bridge plate and the respective bolts.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a partial end view of a pipe repair or connection clamp made in accordance with the invention in situ on a pipe; and Fig. 2 is a partial isometric view thereof.

Referring now to the drawings there is illustrated a pipe 10 around which has been tighened a pipe repair or connection clamp generally indicated at 11. The clamp 11 may comprise one or more non-continuous stainless steel band parts 12 of high grade stainless steel, the ends of which are anchored within lugs 13 which are arranged to be drawn together by bolts 14 to tighten the clamp around the pipe. Fingers 15 are provided to prevent the bolts from bending during tightening, and the roll formed ends of the band are held captive within lugs 13 by pins 16.

Within the band 11 is a continuous or noncontinuous and overlapping rubber gasket sleeve 17, and extending across the or each gap between the parts of the band is a steel bridge plate 18 which conventionally is welded to and within one end region of the band and extends across the gap into sliding engagement with the inner surface of the next adjacent end of the band.

Now, in accordance with the invention, to prevent radial and crippling forces applied during tightening of the bolts 14 from deforming and forcing the bridge plate 18 into the gap between the lugs 13, there is provided a support plate 20 in the form of a strip of stainless steel bent in a zig-zag shape and located between the bridge plate 18 and the fingers 15 attached to lugs 13. The ends of the strip 20 extend radially outwards and are hooked at 22 around fingers 15 thus loosely to retain the strip in place during assembly.

In use, as the bolts 14 are tightened the strip 20 prevents the bridge plates 18 from protruding radially, but their zig-zag shape enables them to be deformed in a direction parallel to the pipe axis thus permitting the ends of the clamp to be drawn together.

In an alternative embodiment, the support members 20 may be replaced by a pair of wedge-shaped members which slide relative to each other in an axial direction during tightening of the bolts but combine to remain within the gap thus preventing the bridge plate from buckling during tightening.

Claims

1. A pipe repair or connection clamp comprising at least one non-continuous band of flexible material to be tightened around a pipe by fastening means outside the clamp and serving to draw the ends of the band together to reduce its effective circumference, and a bridge plate located between the ends of the band to bridge the reducing gap between the ends during tightening, characterised by a support member disposed between the bridge plate and the fastening means to prevent radial protrusion of the bridge plate but extendible in a direction parallel to the pipe axis thus permitting the ends of the band to be drawn together.

2. A pipe repair or connection clamp according to Claim 1, wherein the bridge plate is attached to one end region of the band and extends into circumferentially overlapping relationship with an adjacent other end of the band thus to be in sliding contact with the latter during tightening.

3. A pipe repair or connection clamp according to Claim 1 or Claim 2, wherein a resilient gasket extends around the inside of the clamp in abutting relationship with the inner surface of the band and of the bridge plate.

4. A pipe repair or connection clamp according to any preceding claim, wherein said band consists of two separate and generally semi-circular band parts with bolts for drawing the respective adjacent ends of said parts together.

5. A pipe repair or connection clamp according to any preceding claim, wherein said support member is formed as a strip of stainless steel bent in a zig-zag shape and located between the bridge plate and the fastening means so as to be deformable in a direction parallel to the pipe axis thus permitting the ends of the band to be drawn together whilst maintaining radial support for said bridge plate.

6. A pipe repair of connection clamp according to Claim 5, wherein the ends of said strip extend radially outwards to be hooked around said fastening means thus loosely to retain the strip in place during assembly.

7. A pipe repair of connection clamp according to any one of Claims 1 to 4, wherein said support member comprises a pair of co-operating wedge-shaped members which may slide relative to each other in an axial direction during tightening of the clamp but combine to remain within a space between the bridge plate and the fastening means to provide radial support for said bridge plate.