CA1296752C - Ring seals - Google Patents

Abstract

ABSTRACT

A heat safe ring seal comprises a metallic hollow ring of uniform material thickness and radially inwardly facing channel-shaped radial profile. The walls of the channel adjacent their free ends are curved towards each other so as to form axially outwardly facing grooves which each accommodate and shield a concentric ring of PTFE or elastomeric material.

Description

M~C FOLIO: 230P53979 ~ANGDOC: 0392L

"IMPROVEMENTS RELATING TO RING SEALS"

This invention relates to ring seals intended to be interposed between parallel opposite metal surfaces for sealing the joint therebetween.

A known form of dynamic ring seal foc this eurpose is intended to be located in a groove or recess foLmed in the metal body which provides one of the aforesaid metal surfaces and comprises a tubular ring or core of metallic material which is surrounded by an outer ring of substantially U-shaped radial cross-section made of elastomeric material. The open face of the outer ring faces radially inwards and the outside surfaces of the sides of the outer ring are compressed between the opposed metal surfaces which have to be sealed, whilst the outer ring is exposed to internal pressure.

A ring seal constructed as abo~e described, performs extremely well but unfortunately it does not withstand extremely high temperature conditions and is not therefore regarded as being fire-safe.
^
~k ... . ... ,, `.~ .... . ...

:LZ~75;~

The object of the present invention is to provide a fire-safe ring seal which can safely be used as an alternative to the above-described ring seal in appeopriate situations.

In accordance with the present invention there is proposed a ring seal comprising a metallic hollow ring of uniform material thickness and radially inwardly facing channel shaped cadial pcofile, the walls of such channel~adjacent theic free ends, being curved towa~ds each other so as to form outwardly ~acing grooves which each accommodate and shield a concentric ring of PTFE oc elastomeric material.
,~ :
In radial cross-section, the metallic sealing ring may for instance have a profile which is almost circular with divergent straight wall terminations resembling one which is disclosed in British Patent Specification 1,213,454. ~l~ernatively however, and prefecably, the profile may be of somewhat omega (~ ) shape, parabolic shape, or ellipsoidal shape with in each instance ei~her ; 20 straight terminations which are in parallel diametric planes or terminations which lie on a common imaginary cylindcical surface.

Three typical embodiments of the invention are hereinafter described by re~erence to the accompanying drawings in which Figs. 1, 2 and 3 are radial cross-~Z~67~

sec~cional Yiew6 with Figs. lA, 2A and 3A to a reduced scale ~howing related rinq assembly hou~ing detail~.

In each o Fig~. l, 2 and 3, the ring as6embly therein shown i6 comprised of a metallic sealing ring l 5 and two PTFE or elastome~ic matelial sealing rings 2 which are located in grooves la formed by convergent parts of the metallic ~ealing ri~

~, The metal ring l ~hown in Fig. l i~ o~ capital omega ~V`) radial pro~ile and ls e6~entially the same a~ that 10 di~closed in British Patent 2038961 eor fitting with suitable clearance in a rece6s as illustrated in Fig. lA
and it should be noted that in radial profile the radially inward end parts lb of the ring are ~traight ~: and parallel.

Typical relati-re dimensions marked in Figs. 1 and lA
are set forth in Table l below:-I Seal Ibt~rial _ r r ~ t~ls I
Section Ihickr~s l rm mn A B C F G H K M I S N P
4.75.381 5.48 6.86 4.95 2.54 1.78 2.06 0.764.11 O.B9 8.05 4.75 + .02 6.35.635 7.G0 9.30 6.30 4.01 2.03 2.62 1.272.53 1.78 11.25 6.10 + .02 :~ 9.53965 10.44 14.22 9 73 6.1? ~.10 3.94. 1.93 7.87 ~ 15.0 9.52 + .02 1.4Z 6.76 2.64 2.84 3.10 _ :~
l , ~

~ ' :

~:9~7~i~
., Th~ ~econd embodiment of th~ invention, which is illu~trated in Fig. 2 , differ~ f~o~ the firs~ one i~
that the metallic rin~ 1 iB 0~ modi~ied pa-abolic radial profile 8omewhat a~ disGlosed i~ co-}~e~ding Briei~h Patent Application 8 6 0 3 0 4 with tha t~o halY~s of the eadially outward part of the ring l e~a~h being of varying radius and its radially innel:~o~t ~art~ lb contained by a common ima~inary cylindrical surface.

Typical relative dimensions o~ these Fig. 2 ring ~eala, and recesses as shown in Fiq. 2A, are ~et ~orth in Table 2 below:-T~E2 S~ l~teri~ _ _ _ _ _ l _ G~ ~tals , : ~æti~ ~d~ess A B C D E F G H ~___ L ~ N P
4.75 .381 5.48 6.86 4.95 4.47 2.06 1.27 .78 2.46 0.761 4.95 .17 8.05 4.75_.02 6.35 .635 7.00 9.30 6.30 5.66 2.49 1.65 .03 3.15 l.n 6.30 .65 11.20 6.10+.02 9.53 %5 10.44 14.2~ 9.73 8.51. 3.84 2.51 3.1C 4.72 1.93 9.45 .54 15.~ 9.52+.02 1.422 ¦ l 3.61 2.74 ~.64 2.84 _ The third embodiment of the ring 6eal, ~hich i~
illustEated in Fig. 3 , 1R si~ilar to that which has been described with reference to Fig. 2 except that each half of the radially outward pa~t of the metallic ring l i8 of con~tant radius. A~ with the Fig. 2 embodiment the radially innermost parts lb of the metallic ring ar~
contained by a common imaginary cylindrical surface.

Typical relative dimensions of these Fig. 3 ring seals and their recesses as shown in Fig. 3A are set 5 forth in Table 3 below:-: ` ~

_ _ Grnove Details ~Sectia~Ibter~al ¦~ 1 8 L~ ~ E ~- ¦~ ~:L K 1~1 I P
4.75 rm0.3 5.48 5.91 4 95 4.47 2.06 1.27 1.78 2.84 0.76 7,1414,75 ~ n.o~
6.351 0.64 7.00 7.51 6.30 ¦5.66 2.49 l1.65 j2.03 ¦3.43 1.27 9.53¦6.10 ~ 0.0~ , 10 ~ ~ i~ _ _ L~ ~ _ _ 2 51 ~ _ 1 93 13.26l9.52 + 0 0~ i It is chacact~ristic of the invention that in all of the embodiments described a perfect gas-tight and fire safe seal is achieved by both axial faces of the ring seal engaging the opposed surfaces which are to be 15 sealed.

In operaCion the ring 2 made of PTFE or elastomer compresses sufficiently to form an absolutely gas-tight seal whilst being shielded by the parts la and lb of the metallic ring. At the same time the outwardly conve~c ';

96~52 surfaces of the metallic ring 1 come to rest very firmly against the mating faces, thereby guaranteeing a completely fire safe seal.

:~' ~`
:

Claims (5)

1. A ring seal comprising a metallic hollow ring of uniform material thickness and radially inwardly facing channel-shaped radial profile, the walls of such channel adjacent their free ends being curved towards each other so as to form axially outwardly facing grooves which each accommodate and shield a concentric ring of PTFE or elastomeric material.

2. A ring seal according to Claim 1 in which the channel is of capital omega (?) shaped radial profile

3. A ring seal according to Claim 1 in which the channel is of ellipsoidal or parabolic radial profile.

4. A ring seal according to Claim 2 in which the radially inward end parts of the metallic ring are straight and parallel.

5. A ring seal according to Claim 3 in which the radially innermost parts of the metallic ring are contained by a common imaginary cylindrical surface.