GB2119055A

GB2119055A - Repairing pipe joints

Info

Publication number: GB2119055A
Application number: GB08211105A
Authority: GB
Inventors: Michael Summerell
Original assignee: SIBEX
Current assignee: SIBEX
Priority date: 1982-04-16
Filing date: 1982-04-16
Publication date: 1983-11-09
Also published as: GB2119055B

Abstract

A flexible strap e.g. wire rope 15, 16 is tightened by a movable cross- head 21 around a leaking flanged pipe joint prior to injecting a sealant composition. <IMAGE>

Description

SPECIFICATION Improvements in and relating to clamps This invention relates to flanged pipe joints and in particular to a method and apparatus for sealing a leak at such a joint.

When a leak develops at a flanged pipe joint it is sometimes very expensive and/or inconvenient to shut down the pipeline to effect a repair. There are many well-known ways of dealing with leaking pipe joints. One of these, which has been in use for many years, is to fill the gap between the confronting pipe flanges with a malleable metal wire. This is done by wrapping the wire around the joint and then retaining it in place by peening over the edges of the flanges. Once the flange gap is filled, a settable composition or caulking material is injected into the flanges, radially inwardly of the wire, either down at least one of the flange bolt holes or through a hole drilled into one of the flanges especially for this purpose.

Whilst the foregoing method works and has been used for all manner of leaks, it has the major disadvantage that it causes damage to the flange edges, which have to be machined when the joint is eventually repaired properly. It also calls for great skill on the part of the operators, who have to not only wrap the wire but also to peen over the flange edges in unpleasant and/or dangerous conditions. It will be appreciated that the peening must be effective to retain the wire, even under the high pressures normally used for injecting the settable composition, not to mention any high pressure which may be present inside the pipeline itself.

According to one aspect of the present invention, a method of sealing a leak at a flanged pipe joint comprises the step of applying a flexible strap around the joint and tightening the strap into engagement with the margins of the gap between the confronting pipe flanges.

The strap may be applied to the joint after the gap has been filled with wire in a conventional wire wrapping step. Preferably the strap partly enters the gap as a result of the tightening operation.

According to a further aspect of the invention, apparatus for sealing a leak at a flanged pipe joint includes a flexible strap together with means for tightening the strap, when in position around the joint. The strap is preferably a length of wire rope or braid; it is preferred that its length be adjustable to substantially encircle the joint as a single turn, the ends of which are connectable to the means for tightening the strap.

It will be appreciated that the means for tightening the strap must be external to the flanged joint and that care must be taken to avoid leakage in the vicinity of the point where the ends of the strap meet, or nearly meet.

For practical purposes it is convenient to include disposable anchor block which locates against the flange and through which the ends of the strap pass, firstly in a path generally tangential to the flange and thereafter in a progressively radial direction until they emerge from the block radially of the flange. A common tensioning means co-operating with the block can then be used tighten the clamp, radially directed tension being converted into tangential tension at the points of entry of the ends of the single turn into the block. The flange-contacting face of the block is preferably shaped to seat against the flanges; it may be shaped to engage the gap between the flanges, so that it effectively seals the gap which would otherwise be formed at the point where the ends of the single turn meet.

Once the clamp has been tightened to a desired stress, the anchor block may be used to secure the ends of the strap so that the tensioning means can be removed. The free ends of the strap can then be cut away close to the anchor block leaving only the strap and the block in position. The tensioning means can then be used for a different leak.

In order that the method and apparatus of the invention be better understood a preferred embodiment of it will now be described with reference to the accompanying drawing in which: Figure 1 is a front elevation, partly in section Figure2 is a side elevation, partly in section and Figures 3A and 3B are side and front elevations, respectively, of parts shown in Figures 1 and/or 2.

In the Figures, an inverted U-shaped saddle 1 carries a pair of side pillars 2,3. The arms of the U have notches 4, 5 which serve to seat and locate a two-part disposable anchor block 6, 7. Bolts 8, 9 hold the parts of the block together as seen in Figure 2.

Block part 6 has a V shaped cut-away portion 10 between a pair of generally triangular lands 11,12.

Block part 7 (see Figure 3B) has a part circular land 13, and a serrated, gripping land 14. As shown only in Figure 2 the block parts co-operate to leave a gap between the land 14 and the facing portion of the part 6. This gap is the one which in use grips the free ends of a length of wire rope (shown only by dashed lines at 15,16).

The free ends of the side pillars 2,3 carry a fixed cross-head 17. This has a plain bore through which a rotatable actuating shaft 18 extends parallel to the pillars. The other end of the shaft seats in a plain bearing 19 in the saddle whilst the free end carries a nut 20. The shaft is screw threaded over most of its length and serves to displace a movable, correspondingly screw-threaded cross head 21 located between the cross-head and the saddle. The ends of the movable cross-head straddle the side pillars, which therefore serve to prevent it from rotating with the shaft 18.

The movable cross-head has two apertures 23, 24 extending axially of the shaft 18, each provided with a cable clamp bolt 22 (see Figure 3A) comprising a plain peg 25, a bore 26 (to match the bore 23 or 24) and a screw-threaded portion 27 and nut 28, which together serve to misalign the bores 23 (or 24) and 26 so as to trap the wire rope, 15 (or 16). The anchor block cut-away portions co-operate to define arcuate gaps terminating in a common gripping area, at the land 14.

In use, a flanged joint, represented by the single pipe flange 29 in the drawing is assumed to be leaking. The gap between the confronting flanges is first filled by wrapping a malleable metal wire such as brass around the joint. Then one end of the wire rope is released to enable the rope and the anchor block to be assembled around the joint. The free end of the wire rope is threaded through the anchor block and firmly clamped in the movable crosshead.

The latter is then moved to tension the wire rope, pulling it firmly into engagement with the flange margins between which the gap is defined. After tensioning the wire rope, the usual step of injecting a settable composition radially inwardly of the wire wrapping may take place.

Tensioning is accomplished by rotating the shaft 18, using a torque wrench to develop sufficient stress in the wire rope to resist the injection pressure. The anchor block parts may then be firmly clamped together (by bolts 8, 9) to secure the wire rope in its stressed state and as soon as that is done, the movable cross-head can be disabled by releasing the nuts 28, enabling the whole saddle to be lifted off as a unit. The loose ends of the wire can then be cut off flush with the anchor block, to leave a neat assembly in position around the flange.

Claims

CLAIMS 1. A method of sealing a leak at a flanged pipe joint the method comprising the step of applying a flexible strap around the joint and then tightening the strap into engagement with the margins of a gap defined between confronting pipe flanges. 2. A method according to claim 1 including a preliminary step of at least partly filling said gap with wire by a wrapping operation. 3. A method according to claim 1 or 2 including the further step of injecting a settable composition into the joint radially inwardly of the strap. 4. Apparatus for sealing a leak at a flanged pipe joint including a flexible strap and means for tighten- ing the strap, when in position around said joint. 5. Apparatus according to claim 4 wherein the strap is a length of wire rope. 6. Apparatus according to claim 4 or claim 5 wherein the length of the strap is adjustable to substantially encircle the joint as a single turn, whose ends are connectable to the means for tightening the strap. 7. Apparatus according to claim 6 wherein the means for tightening the strap includes an anchor block locatable against the flange and through which the ends of the strap pass, firstly in a path generally tangential to the flange and then n a progressively more radial direction until they emerge from the block radially of the flange. 8. Apparatus according to claim 7 wherein the anchor block incoporates arcuate passageways to effect the change of direction. New claims or amendments to claims filed on 15/4/83 Superseded claims 1-8 New or amended claims:

1. Apparatus for sealing a leakfrom a gap defined between confronting flanges of a flanged pipe joint, said apparatus comprising a flexible strap constituted by a length of wire rope whose crosssection is such that, in use, it engages the radiallyoutermost edges of said confronting pipe flanges with a wedging action relative to the gap defined between them together with means operable to tighten said strap about the flanged pipe joint, said means including an anchor block adapted to seat against said edges and having passageways defined therein through which the free ends of said strap pass firstly in a path generally tangential to the circumference of the flanges and thereafter in a progressively more radial direction until they emerge from the block generally radially with respect to said circumference, so that when tightened, the strap and the anchor block together constitute a substantially continuous single turn about the joint.

2. Apparatus according to claim 1 wherein the anchor block has arcuate passageways therethrough to effect the progressive change of direction of the free ends of the strap.

3. Apparatus according to claim 1 wherein said means for tightening the strap comprises clamping means engageable with said free ends and displaceable radially with respect to the flanged pipe joint.

4. Apparatus according to claim 1 wherein the anchor block incorporates clamping means operable to grip the free ends of the strap, whereby the tightening means can be removed after use.

5. Apparatus according to claim 4 wherein the clamping means is constituted by a portion of the anchor block which is displaceable relative to another portion of said block.

6. Apparatus according to claim 1 wherein the tightening means comprises a screw jack operable to displace said free ends in a radial direction relative to the pipe joint.

7. A method of sealing a leak at a flanged pipe joint, the method comprising the steps of installing the flexible strap of claim 1 about a pipe joint and thereafter tightening the flexible strap and anchor block around said joint to substantially seal a gap between the confronting pipe flanges of said joint.

8. The method of claim 5 including a preliminary step of at least partly filling said gap with plural turns of wire by a wrapping operation.

9. The method of claim 5 or claim 6 including the further step of injecting a settable composition into the joint radially inwardly of the strap.

10. The method of claim 5 including the further steps of clamping the strap in place about the joint and thereafter removing the tightening means.