GB2265432A - A plug - Google Patents

Abstract

A plug 1 for sealing a hole in a pipe, which may be threaded or plain, comprises a cup shaped outer plug body 2 having a closed bore 4 defined therein, and an inner plug body 3 adapted to be screw-threaded into the closed bore 4 so as to cause the outer plug body 2 to be expanded radially outwardly. The plug is preferably formed of plastics material. The plug is formed of only two parts which gives an advantage in manufacturing costs, ease of assembly on site and reliability of components. The inner body 3 may be self-tapping within the outer body, or vice versa, or they may have co-operating threads. <IMAGE>

Description

A PLUG The present invention relates to a plug, particularly but not exclusively for sealing a hole in a pipe.

When an appliance or a supply pipe is disconnected from a mains gas or water pipe, an internally threaded hole in the pipe will be left which needs to be sealed. One known plug for such a pipe is simply a tapered metal threaded plug which is screwed into the hole.

Another known plug comprises a cylindrical threaded body which is screwed into the pipe, sealing being provided by an external rubber sealing gasket.

It is often necessary to seal unthreaded holes in pipes in which case it is not possible to use the known simple metal plugs described above. A known type of plug suitable for both threaded and unthreaded holes is in the form of a metal body with an external conical surface bearing against a gasket with an internal conical surface. A bolt may be tightened to cause the conical surfaces to be drawn together and hence cause the gasket to expand to seal the hole.

Such plugs comprise a number of parts, which increases manufacturing costs and increase the risk of malfunction of the plug.

It is an object of the present invention to provide an improved plug for sealing either threaded or unthreaded holes in pipes.

According to the present invention there is provided a plug comprising a cup shaped outer plug body having a closed bore defined therein, and an inner plug body adapted to be screw-threaded into the closed bore so as to cause the outer plug body to be expanded radially outwardly.

The plug according to the present invention may thus be formed of only two parts. This gives an advantage in manufacturing costs, ease of assembly on site and reliability of components.

The plug is preferably formed of a plastics material. The outer plug body may be formed of polyethylene or a similar material. The inner plug body may be formed of acetal, nylon or a similar material.

Forming the plug of a plastics material means that it deforms readily and is suitable for use with a plastics pipe as well as a metal pipe.

Alternatively the inner plug body may be formed from metal.

Preferably the outer plug body is externally tapered to facilitate insertion of the plug into a hole. The exterior surface of the outer plug body may be plain or threaded so that the plug can be used in a threaded or unthreaded hole.

Preferably the inner plug body is provided with a recess in which a tool may be inserted to screw the inner plug body into the outer plug body. The inner plug body may be provided with a selftapping thread. Alternatively the inner plug body and the bore of the outer plug body may be provided with corresponding threads.

The present invention therefore provides a plug of relatively simple construction which can be used for a range of circumstances, for instance threaded or unthreaded holes in metal or plastics pipes.

A specific embodiment of the present invention will now be described by way of example, with reference to the accompanying drawings, in which: Figure 1 is an exploded perspective view of a plug according to the present invention; Figure 2 is an exploded sectional view of the illustrated plug; Figure 3 is an end view of the illustrated plug; Figure 4 is a part sectional view of the illustrated plug in position in a pipe, with a tool according to the present invention; Figure 5 is a part sectional view of the illustrated plug part screwed into a pipe; and Figure 6 is a part sectional view of the illustrated plug sealing a pipe.

Referring to the drawings, there is illustrated a plug 1 comprising an outer plug body 2 and an inner plug body 3.

The outer plug body 2 is formed of polyethylene or a similar material. The plug body is provided with a blind bore 4, which is slightly tapered inwardly along its length. The exterior of the plug body 2 is generally frusto-conical but has a varying angle of taper, forming a lead-in taper 5, a tapping area 6, and a sealing area 7, leading to an upper shoulder 8. Slots 9 are cut into the upper shoulder 8 directed radially outwardly from bore 4 at right angles to each other.

The inner plug body 3 is formed of a plastics material, such as acetal or nylon. Alternatively the inner plug 3 may be metal. Its exterior is slightly tapered and has an external self-tapping thread.

The inner plug body 3 is provided with a socket 10 formed of a square recess 11 with a depending internally threaded bore 12.

A tool 13 is provided for insertion of the plug into a hole 14 in a pipe 15 (see fig. 4). The tool 13 comprises three separately rotatable co-axial spindles. The innermost spindle is a retaining spindle 16, an end 17 of which is screw threaded to engage the thread of bore 12 of the inner plug body. Around the retaining spindle 16 is an inner plug drive spindle 18, an end of which terminates in a square projection 19 to cooperate with the square recess 11 of the inner plug body 3.

Around the inner plug drive spindle 18 is an outer plug drive spindle 20, which ends in four projections 21, to engage slots 9.

In order to seal a hole with the plug, the plug assembly (comprising outer plug body 2 with inner plug body 3 seated therein) is first locked onto the tool 13 by screwing the retaining spindle 16 into the internally threaded bore 12 of the inner plug body. When the plug is retained on the tool, the projections 21 locate in slots 9, and the square projection 19 locates in square recess 11. The plug is then offered to the hole 14 and seats in the hole by virtue of the lead-in taper 5. The illustrated hole 14, provided in pipe 15 which is of steel, has an internal thread. The outer plug drive spindle 18 (and hence projections 21) are then rotated to drive the plug 1 into the hole 14, the thread on the interior of the hole 14 forming a thread on the tapping area 6 of the exterior of the plug (see fig. 5).

The inner plug drive spindle 18 is then rotated to drive the inner plug body 3 into the outer plug body 2. The external screw thread of inner plug body 3 causes an internal thread to be formed in the bore 4 of the outer plug body. As the inner plug body is forced down into the outer plug body, the outer plug body is forced to expand because of the taper of the inner plug body, thus sealing the hole. The sealing area 7 ensuring a good seal of the hole (see fig. 6).

The retaining spindle 12 is then rotated in the opposite direction in order to release it from the bore 12 in the inner plug body, the square recess 11 and square projection 19 of the tool ensuring that the inner plug body is not unscrewed from the outer plug body. The tool is then removed from the plug, leaving the latter in place to seal the hole.

The above described tool 13 is adapted for fitting the plug to pressurised pipes. However, it will be appreciated that a different form of tool could be used in other circumstances. In particular, much simpler tooling would be required to fit the plug to a non-pressurised pipe.

It will be appreciated that different thread arrangements may be provided on the plug bodies and the hole to . perform the invention.

For example, the hole may be pre-threaded, the outer plug body also being provided with a mating external thread. The outer plug body and the hole may alternatively both be plain, in which case as the plug is screwed into the hole the edge of the hole may shear off some of the surface of the outer plug body. The interior of the blind bore in the outer plug body may be provided with a thread, in which case the inner plug body would have a corresponding thread. The interior of the blind bore may alternatively be provided with a self-tapping thread to cooperate with a plain surface on the inner plug body.

Claims (12)

1. A plug comprising a cup shaped outer plug body having a closed bore defined therein, and an inner plug body adapted to be screwthreaded into the closed bore so as to cause the outer plug body to be expanded radially outwardly.

2. A plug as claimed in claim 1, wherein the plug is formed of plastics material.

3. A plug as claimed in claim 2, wherein the outer plug body is formed of polyethylene.

4. A plug as claimed in claim 2, wherein the inner plug body is formed of acetal or nylon.

5. A plug as claimed in claim 1, wherein the inner plug is formed of metal.

6. A plug as claimed in any preceding claim, wherein the outer plug body is externally tapered to facilitate insertion of the plug into a hole.

7. A plug as claimed in any preceding claim, wherein the inner plug body is provided with a recess in which a tool may be inserted to screw the inner plug body into the outer plug body.

8. A plug as claimed in any preceding claim, wherein the inner plug body is threaded so as to be self tapping within the outer plug body.

9. A plug as claimed in any of claims 1 to 7, wherein the outer plug body is internally threaded.

10. A plug as claimed in claim 9, wherein the inner plug body is screwthreaded.

11. A plug as claimed in any preceding claim wherein the outer plug body is externally threaded.

12. A plug substantially as herein described, with reference to the accompanying drawings.