GB2062132A

GB2062132A - Flexible bellows

Info

Publication number: GB2062132A
Application number: GB8031987A
Authority: GB
Original assignee: Pegler Hattersley Ltd
Current assignee: Pegler Hattersley Ltd
Priority date: 1979-10-12
Filing date: 1980-10-03
Publication date: 1981-05-20

Abstract

A flexible bellows 10 in a bellows sealed valve or expansion joint comprises respective 'omega' shaped support rings 11 for the individual convolutions of the bellows which are also of omega shaped cross-section. The rings 11, which may be disposed internally or externally of the bellows, are turned, stamped or sintered and the bellows are conformed to them hydrostatically or mechanically. The width of the base part 11b of each ring is such that adjacent rings abut when the bellows are compressed. <IMAGE>

Description

SPECIFICATION Improvements in flexible bellows This invention concerns flexible bellows, for example, for use in association with valves, expansion joints and the like.

As is known flexible bellows are produced in corrugated form to allow for variation in length.

These bellows are used in valves, expansions joints and the like either to replace or to supplement conventional packing glands.

The development of flexible bellows and in particular bellows for the so-called bellows sealed valves has, however, to some extent been curtailed by the pressure sustaining capability of the bellows and in particular their tendency to distort from the optimum shape of the individual corrugations, namely an 'omega' shape, under high test pressures.

Attempts have been made to improve the performance of the bellows by incorporating torroidal rings within the bellows convolutions but due to difficulties in producing blemish free rings and to handling problems in manufacture such ring reinforced bellows have been very expensive and generally restricted to the production of relatively small bellows. In any event the lack of reinforcement at the roots of the convolutions has led to failure of the bellows due to fatigue cracking at these points.

An object of the present invention is to provide an improved flexible bellows. A further object of the invention is to produce an improved bellows sealed valve.

Thus according to one aspect of the present invention there is provided a flexible bellows of corrugated form comprising a plurality a convolutions and a reinforcement comprising support rings for the convolutions, each such ring being of an external contour complementary to the shape of a bellows convolution.

According to a further aspect of the present invention there is provided a bellows sealed valve including a flexible bellows of corrugated form comprising a plurality of convolutions and a reinforcement comprising support rings for the convolutions, each such ring being of an external contour complementary to the shape of a bellows convolution, the bases of the rings being in edgeto-edge abutment when the bellows is in its retracted form with the valve open.

The invention will be described further, by way of example only, with reference to one practical form thereof and the accompanying diagrammatic illustration showing part of a flexible bellows and part of a valve stem around which it is located when used in a bellows sealed valve. It will be appreciated, however, that the flexible bellows is not restricted to use solely with a valve, or in fact to the particular construction set out in detail below.

As can be seen the bellows 10 is formed with a plurality of 'omega' shaped convolutions. The bellows is produced in known manner and may be formed of austenitic stainless steel. Within each convolution of the bellows 10 is a support ring 1 1 (one only of which is shown in full) including a body part 1 a and an integral base part 1 1 b. The base part 1 b of each of the support rings 1 1 is of such a width that when the bellows is compressed (i.e. when the valve is open) the peripheral edges 1 C of the rings lie in abutment and thus the bases collectively form what, in effect, is a solid tube around the valve stem 12.

The support rings are conveniently produced by turning, stamping or sintering and are inserted into a plain tube of flexible metal which is thereafter convoluted hydrostatically or mechanically to conform to the external contour of the support rings.

The invention is not restricted to the details set out above. For example, the support rings may be located externally of the flexible bellows when the bellows is to be subjected to internal pressure.

Such a construction can be required not only in certain types of valve but also in expansion joints.

It is also to be borne in mind that a bellows with internal support rings can be used in, for example, expansion joints as well as in valves of the kind specifically referred to above. Other ductile metals, such as nickel alloy, or copper; or synthetic plastics material may be used for the convolutions.

The support rings may be made of metal or synthetic plastics material. Instead of having an 'omega' shape, other shapes of convolution cross section such as 'u' shape could equally well be used.

1. A flexible bellows of corrugated form comprising a plurality of convolutions and a reinforcement comprising support rings for the convolutions, each such ring being of an external contour complementary to the shape of a bellows convolution.

2. A flexible bellows as claimed in claim 1, in which the bellows are made of metal.

3. A flexible bellows as claimed in claim 2, in which metal of the bellows is austenitic stainless steel or nickel alloy or copper or other ductile metals.

4. A flexible bellows as claimed in claim 1, in which the bellows are made of synthetic plastics material.

5. A flexible bellows as claimed in claim 1, in which the base part of each support ring is of such a width that, when the bellows is compressed, the base part of adjacent rings abut to effectively form a continuous tube.

6. A flexible bellows as claimed in any preceding claim, in which the support rings are produced by turning, stamping, sintering or moulding.

7. A flexible bellows as claimed in any preceding claim, in which the convolutions are formed by conforming one or more plain tubes to the support rings.

8. A flexible bellows as claimed in claim 7, in which the conforming is carried out hydrostatically.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in flexible bellows This invention concerns flexible bellows, for example, for use in association with valves, expansion joints and the like. As is known flexible bellows are produced in corrugated form to allow for variation in length. These bellows are used in valves, expansions joints and the like either to replace or to supplement conventional packing glands. The development of flexible bellows and in particular bellows for the so-called bellows sealed valves has, however, to some extent been curtailed by the pressure sustaining capability of the bellows and in particular their tendency to distort from the optimum shape of the individual corrugations, namely an 'omega' shape, under high test pressures. Attempts have been made to improve the performance of the bellows by incorporating torroidal rings within the bellows convolutions but due to difficulties in producing blemish free rings and to handling problems in manufacture such ring reinforced bellows have been very expensive and generally restricted to the production of relatively small bellows. In any event the lack of reinforcement at the roots of the convolutions has led to failure of the bellows due to fatigue cracking at these points. An object of the present invention is to provide an improved flexible bellows. A further object of the invention is to produce an improved bellows sealed valve. Thus according to one aspect of the present invention there is provided a flexible bellows of corrugated form comprising a plurality a convolutions and a reinforcement comprising support rings for the convolutions, each such ring being of an external contour complementary to the shape of a bellows convolution. According to a further aspect of the present invention there is provided a bellows sealed valve including a flexible bellows of corrugated form comprising a plurality of convolutions and a reinforcement comprising support rings for the convolutions, each such ring being of an external contour complementary to the shape of a bellows convolution, the bases of the rings being in edgeto-edge abutment when the bellows is in its retracted form with the valve open. The invention will be described further, by way of example only, with reference to one practical form thereof and the accompanying diagrammatic illustration showing part of a flexible bellows and part of a valve stem around which it is located when used in a bellows sealed valve. It will be appreciated, however, that the flexible bellows is not restricted to use solely with a valve, or in fact to the particular construction set out in detail below. As can be seen the bellows 10 is formed with a plurality of 'omega' shaped convolutions. The bellows is produced in known manner and may be formed of austenitic stainless steel. Within each convolution of the bellows 10 is a support ring 1 1 (one only of which is shown in full) including a body part 1 a and an integral base part 1 1 b. The base part 1 b of each of the support rings 1 1 is of such a width that when the bellows is compressed (i.e. when the valve is open) the peripheral edges 1 C of the rings lie in abutment and thus the bases collectively form what, in effect, is a solid tube around the valve stem 12. The support rings are conveniently produced by turning, stamping or sintering and are inserted into a plain tube of flexible metal which is thereafter convoluted hydrostatically or mechanically to conform to the external contour of the support rings. The invention is not restricted to the details set out above. For example, the support rings may be located externally of the flexible bellows when the bellows is to be subjected to internal pressure. Such a construction can be required not only in certain types of valve but also in expansion joints. It is also to be borne in mind that a bellows with internal support rings can be used in, for example, expansion joints as well as in valves of the kind specifically referred to above. Other ductile metals, such as nickel alloy, or copper; or synthetic plastics material may be used for the convolutions. The support rings may be made of metal or synthetic plastics material. Instead of having an 'omega' shape, other shapes of convolution cross section such as 'u' shape could equally well be used. CLAIMS

9. A flexible bellows as claimed in claim 7, in which the conforming is carried out mechanically.

10. A flexible bellows as claimed in any preceding claim, in which the support rings are located internally of the convolutions.

1 1. A flexible bellows as claimed in any of claims 1 to 7, in which the support rings are located externally of the convolutions.

12. A flexible beliows as claimed in any preceding claim, in which the support rings are made of metal.

13. A flexible bellows as claimed in any of claims 1 to 11, in which the support rings are made of synthetic plastics material.

14. A flexible bellows substantially as hereinbefore described with reference to the accompanying drawings.

15. A bellows sealed valve including a flexible bellows as claimed in any preceding claim.

16. An expansion joint including a flexible bellows as claimed in any preceding claim.

17. A bellows sealed valve including a flexible bellows of corrugated form comprising a plurality of convolutions and a reinforcement comprising support rings-for the convolutions, each such ring being of an external contour complementary to the shape of a bellows convolution, the bases of the rings being in edge-to-edge abutment when the bellows is in its retracted form with the valve open.