GB2264760A

GB2264760A - Seal

Info

Publication number: GB2264760A
Application number: GB9203519A
Authority: GB
Inventors: James Brown Mason
Original assignee: SEABOARD LLOYD Ltd
Current assignee: SEABOARD LLOYD Ltd
Priority date: 1992-02-19
Filing date: 1992-02-19
Publication date: 1993-09-08
Anticipated expiration: 2012-02-19
Also published as: GB9203519D0; GB2264760B

Abstract

A seal especially for use in the connecting of pipes, or wellhead or pressure vessel sections comprises an annular sealing body (4) defining a primary sealing means, an annular rib (6) extending radially outwardly from the body (4), and secondary seal means in the form of spring-loaded sealing rings (5) located on opposed faces of the rib (6). In use, the sealing rings (5) are compressed against the rib (6), for example by positioning the rings (5) in suitable grooves (5A/B) of associated clamping members (6A, B), thereby providing a secondary sealing force. <IMAGE>

Description

Seal The present invention relates to a seal intended for use in connector systems, for example, for connecting pipe, wellhead or pressure vessel sections, and relates especially to a seal utilising clamping or connecting means to provide a gas tight seal between elements when made up.

Seals are known for use in connector systems serving to connect pipework, wellhead or pressure vessel sections and the like, these seals comprising an annular sealing body on which an appropriate sealing force is applied when associated connecting/clamping members are pulled together on the seal. The seal can be used to sealingly connect pipe, wellhead and pressure vessel sections and the like at a join, and provides definite advantages over a conventional flanged connection at the join. In particular, the seal can better accommodate external loads such as bending loads.

It is an object of the present invention to provide an improved seal of the above type giving even greater sealing performance.

According to the present invention a seal for use in connector systems comprises an annular sealing body defining primary sealing means, a radial rib on the body, and secondary seal means at the rib.

Preferably the clamping members associated with the seal include a recess to receive the secondary seal means. Preferably the secondary seal means comprise sealing rings and these sealing rings are preferably of spring loaded type, e.g. comprise spring loaded 'C' type seals. The sealing rings can be located in annular grooves in the associated clamping members, the groove depth being such as to permit the necessary secondary sealing force. The seal, both in respect of its primary and secondary sealing means, is preferably made of metal.By means of the present invention, substantial point contact loading can be created between the secondary seal means and both the rib and the associated seal clamping members when the clamping members are tightened on the seal, so that the seal of the present invention can maintain an effective seal even under extreme conditions such as severe fire conditions.

The present invention is also a connector system including the inventive seal.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings wherein: Fig. 1 - shows, in diametrical section, a detail of a seal in accordance with the present invention; Fig. 2 - shows a plan view of the seal as applied in a connector system connecting pipe sections, including clamping or connecting members tightened on the seal; Fig. 3 - is a partial end view of the seal in greater detail; and Fig. 4 - shows in greater detail the force seal loadings present when the connector members are tightened on the seal.

Referring to the drawings, a seal 1 for use in connector systems, for example, for connecting wellhead or pressure vessel sections (i.e. sections 2/3 of Fig.

2) or other pipe or tubular sections and the like comprises a metallic ring member 4 defining a primary sealing means, and a pair of metal spring-loaded 'C' ring seals 5 located on a radial rib 6 of the member 4, the seal 5 defining secondary seal means. The connector system includes clamping members 6A, 6B in the form of connector halves or hubs which are pulled together in an axial directions (A) by a clamping device 7 to grip the seal 1 so as to place the seal in a sealing condition in the assembly. Clamping is achieved via the tapering interface 7B between the members 6A, 6B and the device 7 when the device 7 is tightened by bolts 7A. In an alternative clamping arrangement, radial flanges could be provided on the clamping members which flanges are bolted together by axial bolts, and this may be preferred for certain types of pipe or tubular sections.

The outer periphery of the ring member 4 includes tapering portions 8 constituting sealing faces for the connecting members 6A, 6B which have complementary internal clamping surface (see Fig. 4), chamfers 9, 10 being provided additionally on the member 4 and on the rib 6 to facilitate fitting of the seal 1. The members 6A, 6B include annular grooves 5A to receive the rings 5.

To install the seal 1, the body member 4 is firstly placed in position in the sections 2/3 so as to bridge the sections, and the clamping members (hubs) 6A, 6B are then pulled together by the clamping device 7 when the bolts 7A are tightened. Axial forces FA (Fig. 5) are created at the tapering surfaces 8 of the seal member 4 by the clamping members 6A, 6B, as represented by the force diagram in Fig. 4, resulting in the presence of a radial sealing force FR. Therefore an initial contact sealing stress is formed between the metal seal surface 8 and the complementary surface on the clamping members 6A/6B. The above described seal produced by the connector is pressure energised, that is the greater the pressure present at the seal, the more effective is the seal due to the increasing seal contact surface stresses up to the working pressure.Consequently the primary metal-to-metal seal at face 8 provides a high performance seal.

Further, the pulling together of the clamping members 6A, 6B causes the 'C' seal rings 5 to pre-load as shown in Fig. 4 and so exert substantial point contact loading P1, P2 onto the seal ring rib 6 and onto the mating members 6A, 6B respectively, the loading P1 P2 creating a secondary seal effect. The above connector system including seal 1 is capable of accommodating external loads such as bending loads (as created by force FB in Fig. 2, without serious adverse affect on the primary seal, and the connection is not affected unduly by separation forces. The system can also accommodate axial loading especially compression loading, and torsional loading in the system embodying the connector can also be handled.

The additional provision of the secondary seal formed by seal forces P1, P2 enables the seal 1 to seal effectively even when the primary seal fails (leaks), and this enables the seal to function under severe fire conditions, for example, where the primary seal may fail due to differential rates of expansion and extreme separation loads between elements of the assembly.

The connector system including the seal 1 therefore can be used advantageously in severe service, high temperature and/or high pressure applications.

Claims

CLAIMS.

I. A seal for use in connector systems comprises an annular sealing body defining primary sealing means, a radial rib on the body, and secondary seal means at the rib.
2. A seal as claimed in claim 1, wherein the secondary seal means are adapted to be located in a recess of a clamping member.
3. A seal as claimed in claim 1 or 2, wherein the secondary seal means comprise sealing rings.
4. A seal as claimed in claim 3, wherein the sealing rings are of spring loaded type.
5. A seal as claimed in claim 4, wherein the sealing rings comprise spring loaded 'C' type seals.
6. A seal as claimed in any one of the preceding claims, wherein the primary and secondary sealing means are made of metal.
7. A seal as claimed in any one of caims 3 to 5, wherein sealing rings are present on opposite faces of the radial rib of the annular body.
8. A connector system including a seal substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

8. A seal for use in connector systems substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

9. A connector system for use in connecting pipework and the like including a seal as claimed in any one of the preceding claims, the secondary seal means being located in recess means of the connector system so adapted as to cause the generation of a secondary sealing force by the secondary seal means when the connecting system and seal are placed in an in-use condition.

10. A connector system including a seal substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

Amendments to the claims have been filed as follows 1. A seal for use in connector systems comprises an annular sealing body defining primary sealing means, a radial rib on the body, and secondary seal means at the rib, said secondary seal means comprising sealing rings of spring loaded type.

2. A seal as claimed in claim 1, wherein the secondary seal means are adapted to be located in a recess of a clamping member.

3. A seal as claimed in claim 1, wherein the sealing rings comprise spring loaded 'C' type seals.

4. A seal as claimed in any one of the preceding claims, wherein the primary and secondary sealing means are made of metal.

5. A seal as claimed in s~V one of the preceding claims, wherein said sealing rings are present on opposite faces of the radial rib of the annular body.

6. A seal for use in connector systems substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

7. A connector system for use in connecting pipework and the like including a seal as claimed in any one of the preceding claims, the secondary seal means being located in recess means of the connector system so adapted as to cause the generation of a secondary sealing force by the secondary seal means when the connecting system and seal are placed in an in-use condition.