WO1995032376A1 - A method of fashioning an annular gasket with a frontal sealing action and the gasket thus obtained - Google Patents

A method of fashioning an annular gasket with a frontal sealing action and the gasket thus obtained Download PDF

Info

Publication number
WO1995032376A1
WO1995032376A1 PCT/IT1994/000191 IT9400191W WO9532376A1 WO 1995032376 A1 WO1995032376 A1 WO 1995032376A1 IT 9400191 W IT9400191 W IT 9400191W WO 9532376 A1 WO9532376 A1 WO 9532376A1
Authority
WO
WIPO (PCT)
Prior art keywords
strip
gasket
graphite
annular gasket
metal strip
Prior art date
Application number
PCT/IT1994/000191
Other languages
French (fr)
Inventor
Alberto Aliani
Luciano Rastelli
Antonio Cafaro
Giorgio Bartoccioni
Original Assignee
Keystone Vanessa S.R.L.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Keystone Vanessa S.R.L. filed Critical Keystone Vanessa S.R.L.
Priority to AU81154/94A priority Critical patent/AU8115494A/en
Publication of WO1995032376A1 publication Critical patent/WO1995032376A1/en

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J15/00—Sealings
    • F16J15/02—Sealings between relatively-stationary surfaces
    • F16J15/06—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces
    • F16J15/10—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing
    • F16J15/12—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing with metal reinforcement or covering
    • F16J15/121—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing with metal reinforcement or covering with metal reinforcement
    • F16J15/125—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing with metal reinforcement or covering with metal reinforcement generally perpendicular to the surfaces

Definitions

  • the present invention relates to a method by which, to fashion an annular gasket with a frontal sealing action, and to the gasket obtained by way of such a method.
  • the ring is compressed frontally between two mutually opposed sealing surfaces serving to isolate two environments one from another, one of which containing a fluid under pressure.
  • the steel strips exhibit a convex profile directed toward the pressurized environment .
  • a gasket of this type one example may be found in the butterfly shut-off valves installed conventionally on large diameter pipelines.
  • the gasket according to the invention is suitable for application to the moving element of such a valve: this consists in a disc rotatable through one quarter turn, to which the gasket is mounted in such a way as to impinge on a pack of movable rings fitted to the disc and interacting with the seat of the valve to create a lateral seal.
  • the gasket In a valve of this type, the gasket must be compressed in order to guarantee a sealing action, although not over-compressed to the point of disallowing the sliding movement of the movable rings, without which the valve will not be able to close properly.
  • Conventional gaskets of the type in question are fashioned currently by a method that consists in coiling a continuous strip of thin steel around a cylindrical former of predetermined diameter.
  • the initial coil is fixed in position by spot-welding, whereupon the metal strip is coiled together with a second continuous strip, in this instance graphite, in such a way as to build up a plurality of single coils.
  • the final coil is made with the metal strip only, and secured in place by welding.
  • the gasket appears as a plurality of alternating metal and graphite layers arranged one alongside another in the radial direction. Each such layer exhibits a convex profile directed toward the lateral surface of the gasket, on which the high pressure fluid impinges.
  • the gasket undergoes a deformation brought about by the very pressure of the fluid the valve is designed to shut off, which improves its frontal sealing action.
  • the selfsame pressure rise existing in one of the environments isolated by the valve helps to press the gasket against the surfaces with which it creates a seal.
  • gaskets of the conventional type in question betray certain drawbacks, a first among which is that they are not "bidirectional", i.e. the seal is effective only as long as the pressure rise takes place on one particular side of a valve isolating two environments; if not, or in effect, if the pressure rise takes place on the opposite side, then leaks will occur.
  • a butterfly valve fitted with this type of gasket is able to shut off a direct flow of fluid, without leaks, in one direction only.
  • gaskets of this conventional design require frequent replacement, principally by reason of the fact that the frontal sealing surfaces are subject to relatively rapid wear.
  • the object of the present invention is to overcome the aforementioned drawbacks inherent in the prior art, by providing an annular gasket with a frontal sealing action which is of simple design, durable, and bidirectional.
  • a further object of the present invention is to set forth a simple and inexpensive method of fashioning such a gasket.
  • the method comprises the step of forming a continuous strip of sheet steel in such a manner as to create at least one first longitudinal portion affording a convex profile presented by one side of the strip and at least one second longitudinal portion which affords a convex profile presented by the opposite side; viewed in a typical section on a radial plane, the annular gasket appears substantially as a plurality of alternating metal and graphite layers arranged one alongside another in the radial direction, and shaped in such a way that each will present convex profiles facing in a radial direction both toward the hollow centre and toward the periphery of the gasket.
  • - fig 1 illustrates a portion of the annular gasket according to the invention, viewed in perspective and in section on a radial plane;
  • FIG. 1 is a further perspective illustrating a length of strip obtained by the forming step of the method according to the invention.
  • a possible version of the method disclosed might comprise the following sequence of steps: a) preparing a strip or ribbon of sheet steel of predetermined width, typically 5.5 mm; b) forming the strip in such a way as to obtain a first longitudinal portion, aligned on the median axis of the strip, and two second longitudinal portions disposed on either side of and joined to the first, the two second longitudinal portions appearing as grooves with convex faces occupying one side of the strip, and the first longitudinal portion appearing likewise as a groove of which the convex face occupies the opposite side of the strip (fig 2 of the accompanying drawings shows a length of strip, denoted 2 in its entirety, produced by the forming step) ; c) looping one end of the formed strip 2 around a cylindrical support of diameter identical to the internal diameter of the gasket to be fashioned; this step consists in coiling the strip around the support initially through a limited number
  • 1 denotes an annular gasket with a frontal sealing action, fashioned by the method as described above, which comprises a plurality of annular layers 8 of thin strip metal, one overlaying another in the radial direction, alternated with layers 9 of graphite or other soft material.
  • the individual layers 8 and 9 are shaped in such a way as to exhibit a profile composed of a central first portion 3 and two lateral second portions 4, all appearing essentially as grooves of which the convex faces are directed respectively toward the periphery and toward the centre of the gasket 1.
  • the gasket 1 is faced frontally on either side by two respective layers 7 consisting of the graphite material, in this instance pressed and therefore of higher density than that occupying the core, each of which defines a flat frontal sealing surface 6.
  • the gasket further comprises a predetermined number of internal and external layers of the metal strip which are coiled without any interfacing layers of graphite. The first or innermost and the last or outermost coil are secured to the relative adjacent coil by spot-welds.
  • the two frontal surfaces 6 afford a sealing action intended to isolate two environments converging on the internal and external lateral surfaces of the gasket .
  • the second portions 4 will be stressed by the resulting force and the gasket 1 compressed against the frontal sealing surfaces.
  • the external lateral surface is that exposed to the higher pressure environment, then it will be the first portion 3 which deforms and causes the gasket to bear against the sealing surfaces in the same manner.
  • the gasket 1 is rendered especially resistant to wear.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Gasket Seals (AREA)

Abstract

An annular gasket for disc valves is fashioned by a method that consists in forming a continuous strip of sheet steel initially, so as to create at least one first longitudinal portion presenting a convex profile on one face of the strip, and at least one second longitudinal portion presenting a convex profile on the other face, then coiling the strip together with a wider graphite strip to produce a centreless flat spiral, and finally, pressing the flat faces of the spiral; viewed in radial section, the annular gasket (1) appears as a succession of alternating metal and graphite layers (8) arranged one alongside another in the radial direction and sandwiched between two flat layers (7) of harder graphite, obtained by the pressing operation, which provide two frontal sealing surfaces (6).

Description

A METHOD OF FASHIONING AN ANNULAR GASKET WITH A FRONTAL SEALING ACTION AND THE GASKET THUS OBTAINED
Description
The present invention relates to a method by which, to fashion an annular gasket with a frontal sealing action, and to the gasket obtained by way of such a method. Reference is made in particular to flat gaskets consisting in a ring formed by pairing together spiral wound strips of dissimilar materials (for example, steel with asbestos, steel with graphite, or others) . In operation, the ring is compressed frontally between two mutually opposed sealing surfaces serving to isolate two environments one from another, one of which containing a fluid under pressure. The steel strips exhibit a convex profile directed toward the pressurized environment . Among the possible uses for a gasket of this type, one example may be found in the butterfly shut-off valves installed conventionally on large diameter pipelines. In particular, the gasket according to the invention is suitable for application to the moving element of such a valve: this consists in a disc rotatable through one quarter turn, to which the gasket is mounted in such a way as to impinge on a pack of movable rings fitted to the disc and interacting with the seat of the valve to create a lateral seal. In a valve of this type, the gasket must be compressed in order to guarantee a sealing action, although not over-compressed to the point of disallowing the sliding movement of the movable rings, without which the valve will not be able to close properly.
Conventional gaskets of the type in question are fashioned currently by a method that consists in coiling a continuous strip of thin steel around a cylindrical former of predetermined diameter. The initial coil is fixed in position by spot-welding, whereupon the metal strip is coiled together with a second continuous strip, in this instance graphite, in such a way as to build up a plurality of single coils. The final coil is made with the metal strip only, and secured in place by welding.
Viewed in a typical section on a radial plane, the gasket appears as a plurality of alternating metal and graphite layers arranged one alongside another in the radial direction. Each such layer exhibits a convex profile directed toward the lateral surface of the gasket, on which the high pressure fluid impinges.
By virtue of the particular shape of its component layers, the gasket undergoes a deformation brought about by the very pressure of the fluid the valve is designed to shut off, which improves its frontal sealing action. In short, the selfsame pressure rise existing in one of the environments isolated by the valve helps to press the gasket against the surfaces with which it creates a seal.
Nonetheless, gaskets of the conventional type in question betray certain drawbacks, a first among which is that they are not "bidirectional", i.e. the seal is effective only as long as the pressure rise takes place on one particular side of a valve isolating two environments; if not, or in effect, if the pressure rise takes place on the opposite side, then leaks will occur. In practice therefore, a butterfly valve fitted with this type of gasket is able to shut off a direct flow of fluid, without leaks, in one direction only.
In addition, gaskets of this conventional design require frequent replacement, principally by reason of the fact that the frontal sealing surfaces are subject to relatively rapid wear. The object of the present invention is to overcome the aforementioned drawbacks inherent in the prior art, by providing an annular gasket with a frontal sealing action which is of simple design, durable, and bidirectional.
A further object of the present invention is to set forth a simple and inexpensive method of fashioning such a gasket. The stated objects and others besides are realized in a method and an annular gasket as disclosed and as characterized by the appended claims: the method comprises the step of forming a continuous strip of sheet steel in such a manner as to create at least one first longitudinal portion affording a convex profile presented by one side of the strip and at least one second longitudinal portion which affords a convex profile presented by the opposite side; viewed in a typical section on a radial plane, the annular gasket appears substantially as a plurality of alternating metal and graphite layers arranged one alongside another in the radial direction, and shaped in such a way that each will present convex profiles facing in a radial direction both toward the hollow centre and toward the periphery of the gasket. A preferred embodiment of the invention will now be described in detail, by way purely of example, with the aid of the accompanying drawings, in which:
- fig 1 illustrates a portion of the annular gasket according to the invention, viewed in perspective and in section on a radial plane;
- fig 2 is a further perspective illustrating a length of strip obtained by the forming step of the method according to the invention. A possible version of the method disclosed might comprise the following sequence of steps: a) preparing a strip or ribbon of sheet steel of predetermined width, typically 5.5 mm; b) forming the strip in such a way as to obtain a first longitudinal portion, aligned on the median axis of the strip, and two second longitudinal portions disposed on either side of and joined to the first, the two second longitudinal portions appearing as grooves with convex faces occupying one side of the strip, and the first longitudinal portion appearing likewise as a groove of which the convex face occupies the opposite side of the strip (fig 2 of the accompanying drawings shows a length of strip, denoted 2 in its entirety, produced by the forming step) ; c) looping one end of the formed strip 2 around a cylindrical support of diameter identical to the internal diameter of the gasket to be fashioned; this step consists in coiling the strip around the support initially through a limited number of turns (typically 2.75), having secured the first complete single coil by spot-welding; d) coiling the strip further, together with a strip of graphite or other soft material of width greater than that of the metal βtrip prior to being formed, in such a way that the two edges of the graphite strip project laterally beyond the metal strip on either side, the effect of the coiling action being ultimately to impress the graphite strip likewise with portions of convex/concave profile matched to the corresponding portions of the metal strip; in short, the softer graphite strip is caused by the harder metal strip to undergo a plastic deformation during the coiling operation; e) coiling the metal strip still further through a predetermined number of turns (typically 3.25), without the graphite strip, and securing the final turn by spot-welding; f) pressing the projecting portions of the coiled graphite strip in such a way as to create two flat frontal surfaces, respectively on opposite sides, which are destined to perform a sealing action; as a result of the pressing operation, the graphite material acquires specific physical and mechanical properties, including greater density and therefore surface hardness.
Referring to the drawings, 1 denotes an annular gasket with a frontal sealing action, fashioned by the method as described above, which comprises a plurality of annular layers 8 of thin strip metal, one overlaying another in the radial direction, alternated with layers 9 of graphite or other soft material. The individual layers 8 and 9 are shaped in such a way as to exhibit a profile composed of a central first portion 3 and two lateral second portions 4, all appearing essentially as grooves of which the convex faces are directed respectively toward the periphery and toward the centre of the gasket 1. The gasket 1 is faced frontally on either side by two respective layers 7 consisting of the graphite material, in this instance pressed and therefore of higher density than that occupying the core, each of which defines a flat frontal sealing surface 6. The gasket further comprises a predetermined number of internal and external layers of the metal strip which are coiled without any interfacing layers of graphite. The first or innermost and the last or outermost coil are secured to the relative adjacent coil by spot-welds.
The two frontal surfaces 6 afford a sealing action intended to isolate two environments converging on the internal and external lateral surfaces of the gasket . In the event that a higher pressure in one environment should i pijige on the internal lateral surface of the gasket, the second portions 4 will be stressed by the resulting force and the gasket 1 compressed against the frontal sealing surfaces. If the external lateral surface is that exposed to the higher pressure environment, then it will be the first portion 3 which deforms and causes the gasket to bear against the sealing surfaces in the same manner. By incorporating the layers 7 of pressed graphite, the gasket 1 is rendered especially resistant to wear.

Claims

Claims
1) A method of fashioning an annular gasket with frontal sealing action, comprising the steps of:
- preparing a thin metal strip of predetermined width;
- looping one end of the metal strip to form a first coil of predetermined diameter;
- securing the first coil by means of a weld;
- winding the metal strip together with a strip of graphite material, in such a manner as to form a plurality of coils;
- winding the metal strip further to form a final coil;
- securing the final coil by means of a weld, characterized in that it comprises the step of forming the metal strip in such a way as to create at least one first longitudinal portion (3) affording a convex profile presented by one side of the strip and at least one second longitudinal portion (4) affording a convex profile presented by the opposite side.
PCT/IT1994/000191 1994-05-23 1994-11-09 A method of fashioning an annular gasket with a frontal sealing action and the gasket thus obtained WO1995032376A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU81154/94A AU8115494A (en) 1994-05-23 1994-11-09 A method of fashioning an annular gasket with a frontal sealing action and the gasket thus obtained

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITPR94A000024 1994-05-23
ITPR940024A IT1272822B (en) 1994-05-23 1994-05-23 PROCEDURE FOR MAKING AN ANULAR SEAL WITH FRONT SEAL AND GASKET SO MADE

Publications (1)

Publication Number Publication Date
WO1995032376A1 true WO1995032376A1 (en) 1995-11-30

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ID=11395891

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PCT/IT1994/000191 WO1995032376A1 (en) 1994-05-23 1994-11-09 A method of fashioning an annular gasket with a frontal sealing action and the gasket thus obtained

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IT (1) IT1272822B (en)
WO (1) WO1995032376A1 (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0803666A2 (en) * 1996-04-23 1997-10-29 Flexitallic Sealing Materials Ltd Spiral wound gasket
WO1998030817A1 (en) * 1997-01-14 1998-07-16 Garlock Inc. Anti-buckling spiral wound gasket
US7604239B2 (en) 2002-09-30 2009-10-20 Garlock Scaling Technologies LLC Split bearing isolator and a method for assembling seal
US8820749B2 (en) 2009-11-11 2014-09-02 Garlock Sealing Technologies, Llc Flooded bearing isolator
US10704692B1 (en) 2017-04-26 2020-07-07 Garlock Sealing Technologies, Llc Flooded metallic bearing isolator
US10753478B2 (en) 2016-11-07 2020-08-25 Garlock Sealing Technologies, Llc Bearing isolator for extreme conditions

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1942703A (en) * 1931-08-14 1934-01-09 Garlock Packing Co Gasket
FR1566996A (en) * 1967-09-11 1969-05-09
EP0391069A2 (en) * 1989-04-07 1990-10-10 Agency of Industrial Science and Technology of Ministry of International Trade and Industry Spiral wound gasket and fabrication method thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1942703A (en) * 1931-08-14 1934-01-09 Garlock Packing Co Gasket
FR1566996A (en) * 1967-09-11 1969-05-09
EP0391069A2 (en) * 1989-04-07 1990-10-10 Agency of Industrial Science and Technology of Ministry of International Trade and Industry Spiral wound gasket and fabrication method thereof

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0803666A2 (en) * 1996-04-23 1997-10-29 Flexitallic Sealing Materials Ltd Spiral wound gasket
EP0803666A3 (en) * 1996-04-23 1998-01-07 Flexitallic Sealing Materials Ltd Spiral wound gasket
WO1998030817A1 (en) * 1997-01-14 1998-07-16 Garlock Inc. Anti-buckling spiral wound gasket
US5964468A (en) * 1997-01-14 1999-10-12 Garlock Inc Anti-buckling spiral wound gasket
US7604239B2 (en) 2002-09-30 2009-10-20 Garlock Scaling Technologies LLC Split bearing isolator and a method for assembling seal
US8820749B2 (en) 2009-11-11 2014-09-02 Garlock Sealing Technologies, Llc Flooded bearing isolator
US10753478B2 (en) 2016-11-07 2020-08-25 Garlock Sealing Technologies, Llc Bearing isolator for extreme conditions
US10704692B1 (en) 2017-04-26 2020-07-07 Garlock Sealing Technologies, Llc Flooded metallic bearing isolator
US11365810B1 (en) 2017-04-26 2022-06-21 Garlock Sealing Technologies, Llc Flooded metallic bearing isolator

Also Published As

Publication number Publication date
ITPR940024A0 (en) 1994-05-23
IT1272822B (en) 1997-06-30
ITPR940024A1 (en) 1995-11-23
AU8115494A (en) 1995-12-18

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