GB2298253A

GB2298253A - Flanged pipe joint

Info

Publication number: GB2298253A
Application number: GB9503457A
Authority: GB
Inventors: Barry Porter
Original assignee: DESTEC ENG Ltd
Current assignee: DESTEC ENG Ltd
Priority date: 1995-02-22
Filing date: 1995-02-22
Publication date: 1996-08-28
Anticipated expiration: 2015-02-22
Also published as: GB9503457D0; GB2298253B

Abstract

The joint has a metal sealing ring 4 positionable in rebates in the flange faces around the internal bore thereof, the sealing ring 4 having an external circumferential groove 4b therearound, one flange also comprising a radially inwardly-facing groove around the rebate therein and spring clip means 10b seating in the groove and extending into the circumferential groove 4b in the sealing ring 4 at two diametrically opposite locations by flat portions. The clip 10b is C-shaped.

Description

FLANGED JOINT Field of the Invention This invention relates to a flanged joint of the type having a metal-to-metal sealing ring, for use in pipe couplings in high pressure, high temperature and other demanding applications.

Background to the Invention Pipe flanged joints of the general type with which the present application is concerned are disclosed and claimed in UK Patent No 2 200 179. The two opposed flanges have a circumferential rebate around the internal bore into which is fitted a sealing ring which is compressed as the flanges are clamped together, thereby forming a fluid-tight seal. Such joints are especially suitable for use in such applications as sub-sea pipelines, where it is important that the seal made is as reliable as possible.

When assembling a joint of this type, it is necessary to position the scaling ring in the mating rebates and then bring together the two halves of the joint, finally bolting them together. Since the seal is compressed into position, and is required to float in order to ensure that it seats accurately between the flanges, it cannot be fitted securely into one of the two flanges prior to assembly; it is necessarily loose-fitting. To overcome the difficulty of assembling the joint with the seal in place in such difficult environments as are found in sub-sea oil fields and the like, various methods of retaining the sealing ring in one flange prior to assembly have been attempted. Typical of these are the small metal tabs which are screwed into recesses in the flange face to engage an edge of the sealing ring.Although these do prevent the seal from falling out of its rebate during assembly, they are difficult to install, and require that there should be space available around the rebate in which to form the reccsses.

In very demanding applications, especially sub-sea, it is becoming increasingly common to install a secondary seal between the flanges, for example a rubber O-ring, radially outwardly of the metal sealing ring, and to provide a passageway running from the space between the O-ring and the metal seal to a pressure tap- ping on the exterior of the flange body, so that the performance of the seal can be monitored by attaching a pressure gauge to the tapping and detecting any increase in the pressure measured. Since the secondary seal has to be located radially inward of the clamping bolts, there is relatively little room left in such installations for the provision of retaining tabs for the metal seal during assembly.

Summary of the Invention The present invention provides a flanged joint of the type having a metal sealing ring positionable in rebates in the flange faces around the internal bore thereof, the sealing ring having an external circumferential groove therearound, one flange also comprising a radially inwardly-facing groove around the rebate therein and spring clip means seating in the groove and extending into the circum fcrcntial groove in the scaling ring.

Preferably, the spring clip means comprises a wire spring portions of which seat in the inwardly-facing groove and at least two opposed portions of which extend into opposite sides of the sealing ring groove. The spring force is desirably sufficient to hold the sealing ring in the flange during all normal handling of the flange during assembly of the joint, but not so strong as to render fitting of the spring clip difficult.

The joint of the invention is simple and convenient to assemble, and the spring clip arrangement requires very little space, permitting its use with pressure tappings and secondary seals.

Brief Description of the Drawings In the drawings, which illustrate one example of the joint in accordance with the invention: Figure 1 is a cross-sectional elevation of one half of the joint; Figure 2 is a plan view of the half of the joint; Figure 3 is an enlarged view of part of Figure 1; and Figure 4 is a view corresponding to that of Figure 3, but showing the position at 900 around the flange.

Detailed Description of the Illustrated Embodiment The joint is formed from two flanges of the type shown in the Figures, each being welded to a pipe end. Each flange has a chamfered portion 1 furthest from the mating surface 2 which is welded to the pipe end, the chamfer being provided for filler metal in welding. An angled rebate 3 is formed around the bore through the pipe flange, in the mating surface, and a sealing ring 4 is seated in this, the ring having a circumference which is correspondingly angled at each side 4a, with a groove 4b in between, as may be seen from Figures 3 and 4.The flange is provided with a secondary O-ring seal 5 seated in a retaining recess 6 machined into the face of the mating surface 2 and spaced radially outwardly of the rebate, with a passageway 7 formed in the flange body, extending from the rebate 3 adjacent to where the groove 4b of the ring 4 is located in use, and opening to a pressure tapping 8 in the outer edge of the flange.

At the junction between the rebate 3 and the mating surface 2 a recess or groove 9 is machined into the mating surface in such a manner as to provide a slight retaining lip to prevent the spring wire 10 located therein from being dislodged too readily. The spring wire 10 is suitably in the general form of an incomplete circle having two opposed straight or inwardly curved portions l0a which, in use, extend into the groove 4b of the sealing ring 4 to prevent it from being dislodged out of the rebate 3 while the two flanges are being assembled together.

The spring clip 10 is readily installed by fitting its main curved part lOb into the groove 9 in one flange, and then bringing the free ends lOc of the spring into the groove, at the same time ensuring that the portions l0a enter into the groove 4b of the sealing ring resting in the rebate 3 to hold the sealing ring in place. The wire spring clip 10 is sufficient to hold the ring 4 in place during assembly of the joint, but is small enough not to interfere with the operation of the seal, in use, and permits the use of pressure tappings.

Claims

1. A flanged joint having a metal sealing ring positionable in rebates in the flange faces around the internal bore thereof, the sealing ring having an external circumferential groove therearound, one flange also comprising a radially inwardlyfacing groove around the rebate therein and spring clip means seating in the groove and extending into the circumferential groove in the sealing ring.

2. A flanged joint according to claim 1, wherein the spring clip means comprises a wire, spring portions of which seat in the inwardly-facing groove and at least two opposed portions of which extend into opposite sides of the sealing ring groove.

3. A flanged joint according to claim 1 or 2, wherein the spring force is sufficient to hold the sealing ring in the flange during all normal handling of the flange during assembly of the joint, but not so strong as to render fitting of the spring clip difficult.

4. A flanged joint as hereinbefore described with reference to, or as shown in, the accompanying drawings.