GB2331334A

GB2331334A - A gasket seal

Info

Publication number: GB2331334A
Application number: GB9821601A
Authority: GB
Inventors: Shaun Henry
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-10-03
Filing date: 1998-10-05
Publication date: 1999-05-19
Anticipated expiration: 2018-10-05
Also published as: GB2331334B; GB9821601D0

Abstract

A gasket seal (1) is generally disc shaped and is machined from a tough material. The seal (1) has a slot (5) in its rim (4) which houses an elastomeric sealing material (6). There is also a mounting protrusion such as a lip (8). The mounting protrusion or lip (8) is to maintain the seal (1) in contact with other parts with which it may be assembled.

Description

2331334 qa Gasket Sealw Introductign The present invention relates to

gaskets and in particular to gaskets for sealing between facing surfaces of two contacting parts or ferrules for use in difficult environments such as In the pharmaceutical and food industries.

It has been known to provide solid gaskets of various fluoro-plastits materials such as tetrafluoroethylene (TFE) in which the gasket is of substantially disc-like in shape having a peripheral slot forming an inner core which is filled with an elastomeric material. Such a gasket, for example, is described and claimed in U.S. Patent Specification No. 3,775,832 (Werra). Such a.gasket is relatively efficient and performs its scaling function as it is possible to choose materials which are unaffected by most acids, bases or solvents and generally have useful physical properties.

However, there axe some difficulties with the gaskets such as described and claimed im this U. S. Patent Specif ication No. 3r775,832 in that if the gasket has to be loosened for any reason, the subsequent refitting of the gasket can be a time-consuming and difficult task and if errors are made, then the gasket is not correctly located causing the build-up of dirt and other contaminants within, for example, a pipe. It is of the utmost importance to ensure, particularly in the food and pharmaceutical industries, that gaskets interposed in pipes or pipe fittings provide in effect a smooth bore within the pipe so that there are no recesses within which contaminants way build-up.

It is particularly important that the seal be always retained in position during assembly and disassembly so that the gasket cannot fall, for example, from a ferrule onto possibly contminated surfaces.

A further problen with such gaskets or seals is the necessity to minimise the effect of stress cracking In the area of contact. This would further enhance the aseptic nature of the sealing system.

Also there is a need to provide a gasket which can be relatively easily fitted to one of the contacting par-ts of a joint and further that such a gasket will not be dislodged when the joint Is slackened or indeed the joint is completely disassembled.

Statements of Invention is According to the invention, there is provided a gasket for sealing between facing surfaces of two contacting partst the gasket being formed from a tough substantially nondeformable material and of general disc- ILke shape with contacting part faces and a peripheral circular rim having an outwardly directed slot forming an inner core housing an elastomeric sealing material characterised in that the disc incorporates a mounting protrusion on one of its faces for engagement with one of the parts. This ensures the adequate location of the gasket on one of the mounting parts so that there is an adequate location of the gasket, for example, relative to the bore of a part.

Further.. the invention provides a gasket in which the mounting protrusion is a force fit with the part. The advantage of this is that the gasket will not conLe adrift in assembly or disassembly.

ideally, the mounting protrusion is in the form of a lip for engagement across the pa-rt and its f acing surface and preferably is continuous forming on its outer surface an extension of the rim. This is a relatively simple way of making the gasket.

in one emb odiment of the invention, the thickness of the disc adjacent the bare is greater than adjacent the rim and preferably in this latter embodiment the thickness of the disc reduces gradually from the bore to the rim- This has been found to be a very suitable way of scaling and accommodates any irregularities that may occur between the parts.

In another embodiment of the invention, each of the contacting part faces includes a protruding ring for is engagement in a corresponding annular groove In a facing surface. This tends to -reduce the stress and prevent cracking- In this latter embodiment, it is preferable that the ring is force fit in the part so as to form the mounting protrusion. This provides a dual functionality of additional sealing and securem nt. in this latter diment, the thickness of the disc preferably reduces gradually from the bore to the protrudi-ng ring and is of substantially the same thickness from the ring to the rim.

It has been found that there is no need to taper the seal over the whole at Its length but the tapering in this manner is sufficient to provide the necessary sealing.

PRitai-led Description Qf the Invent,OL n The invention will be more clearly understood from the following description of an embodiment thereof given by way of example only with reference to the accompanying cross-sectional view Of portion of a gasket according to the invention.

Referring to the drawing, there is provided a gasket indicated generally by the reference numeral 1. The gasket 1 is formed from a tough substantially nondeformable material, in this eniment polyf luoroethylene (PM). The gasket 1 is of generally disc-like shape having contacting part faces 2 and 3 and a peripheral eirculax rim having an outwardly directed slat 5_ The slat 5 forms an inner core housing an elastomeric sealing material 6. A protruding ring 7 is formed in each f ace 2 and 3 for engagement in a corresponding annular groove in a facing surf ace. A mounting protrusion f armed by a continuous annular lip 8 forming an extension of the rim 4 is provided projecting from the face 2_ The gasket includes a hare 9_ It will be noted that the width of the disc indicated by the dimension W is slightly greater adjacent its bore 9 than its general thickness and tapers inwardly from the bore 9 towards the rings 7.

Further it is vital that the surface finish of contacting sealing surfaces is very high.

It will be appreciated that completely machining the seal will ensure that there is accurate mating of the parts, preventing joint failures, where the poor dimensional quality of moulded seals has in the past caused such problems.

The lip will ensure that the seal bore is concentric with, for example, a ferrule bore. The lip effectively forms a mounting protrusion which fits an the outside diameter, for example, of such a ferrule. This provides suppo" in assembly and also ensures that the seal is always retained In position. This is particularly important where hygiene is of paramount importance ensuring that the seal cannot fall from the ferrule during assembly, or, indeed on disassembly.

It is envisaged that additionally or alternatively to the provision of the mounting protrusion in the form of the lip 8 that one of the rings 7 illustrated above may form a force fit in a corresponding groove in a mating part.

Similarly. many other forms of mounting protrusions could be used. However, the use of a lip is particularly advantageous as it is immediately apparent to anybody using the seal that it is correctly fitted.

While in the embodiment described above, the disc has been constructed with a slight taper over its inner portion, it is possible to provide this taper over the whole of it's depth. Thus, the thickness of the disc would reduce gradually from the bore to the rim.

Obviously the choice of sealing material will depend on the material being processed -and the operating temperatures.

PTFE as mentioned above often sold under the Trade Mark TEFLON has almost unIversal chemical inertness. It's major dif ficulty is that it cold f lows so that care has to be taken not to over-tighten and thus in many instances other materials such as ethylene-propylene (BP) or silicone is used. A fluoroelastomer such as that sold under the Trade Mark VITON may be used for the elastomeric material. There are many other useful elastomers and the invention is not limited to the use of any particular elastomeric material or indeed to any non-deformable material.

The terms include, includes, includ-ingo and kcomprise.

comprises, comprisingO and any variations thereof are to be afforded the same and broadest possible meaning- The invention is not limited to the embodiment hereinbefore described which way be var-led in both construction and detail within the scope of the claims- - 7

Claims

CLAIMS is A gasket for sealing between facing surfaces of two contacting

parts, the gasket being formed from a tough substantially non-deformable material and of general disc-like shape with contacting part. faces and a peripheral circular rim having an outwardly directed slot forming an inner core housing an elastomeric sealing material characterised in that the disc incorporates a mounting protrusion on one of its faces for engagement with one of the parts.

2. A gasket as claimed in claim 1 in which the mounting protrusion is a force fit with the part.

3.

A gasket as claimed in claim 1 or 2 in which the mounting protrusion is in the form of a lip for engagement across the part and its facing surface.

A gasket as claimed in claim 3 in which the lip is continuous forming an its outer surface an extension of the rim.

A gasket as claimed in any preceding claim, in which the thickness of the disc adjacent the bore is greater than adjacent the rim.

A gasket as claimed in claim 5 in which the thickness of the disc reduces gradually from the bore to the rim- 7. A gasket as claimed in any preceding claim, in which each of the contacting part faces includes a protruding ring for engagement in a corresponding annular groove in a facing surface.

- a - 1 A gasket as claimed in claim 7 in which the ring is force f it in the part so as to form the mounting protrusion.

A gasket as claimed in claim 7 or 8, in which the thickness of the disc reduces gradually from the bore to the protruding ring and is of substantially the same thickness from the ring to the rim.

10. A gasket substantially as described herein with reference to and as illustrated in the drawing.