EP0089334A1 - Stem seals for ball valves - Google Patents

Stem seals for ball valves

Info

Publication number
EP0089334A1
EP0089334A1 EP19810902619 EP81902619A EP0089334A1 EP 0089334 A1 EP0089334 A1 EP 0089334A1 EP 19810902619 EP19810902619 EP 19810902619 EP 81902619 A EP81902619 A EP 81902619A EP 0089334 A1 EP0089334 A1 EP 0089334A1
Authority
EP
European Patent Office
Prior art keywords
stem
seal
valve
ball
valve body
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP19810902619
Other languages
German (de)
French (fr)
Inventor
Cecil Graham Richards
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BC Richards and Co Pty Ltd
Original Assignee
BC Richards and Co Pty Ltd
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 BC Richards and Co Pty Ltd filed Critical BC Richards and Co Pty Ltd
Publication of EP0089334A1 publication Critical patent/EP0089334A1/en
Withdrawn legal-status Critical Current

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
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K5/00—Plug valves; Taps or cocks comprising only cut-off apparatus having at least one of the sealing faces shaped as a more or less complete surface of a solid of revolution, the opening and closing movement being predominantly rotary
    • F16K5/06—Plug valves; Taps or cocks comprising only cut-off apparatus having at least one of the sealing faces shaped as a more or less complete surface of a solid of revolution, the opening and closing movement being predominantly rotary with plugs having spherical surfaces; Packings therefor
    • F16K5/0663—Packings
    • F16K5/0694—Spindle sealings
    • 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
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K41/00—Spindle sealings
    • 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
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K5/00—Plug valves; Taps or cocks comprising only cut-off apparatus having at least one of the sealing faces shaped as a more or less complete surface of a solid of revolution, the opening and closing movement being predominantly rotary
    • F16K5/02—Plug valves; Taps or cocks comprising only cut-off apparatus having at least one of the sealing faces shaped as a more or less complete surface of a solid of revolution, the opening and closing movement being predominantly rotary with plugs having conical surfaces; Packings therefor
    • F16K5/0257—Packings
    • F16K5/0285—Packings spindle sealing
    • 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
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K5/00—Plug valves; Taps or cocks comprising only cut-off apparatus having at least one of the sealing faces shaped as a more or less complete surface of a solid of revolution, the opening and closing movement being predominantly rotary
    • F16K5/04—Plug valves; Taps or cocks comprising only cut-off apparatus having at least one of the sealing faces shaped as a more or less complete surface of a solid of revolution, the opening and closing movement being predominantly rotary with plugs having cylindrical surfaces; Packings therefor
    • F16K5/0457—Packings
    • F16K5/0485—Spindle sealing

Definitions

  • This invention relates to stem seals for ball valves.
  • any ball valves used in such industries must comply with British Standard 5146.
  • B.S. 5146 specifies, inter alia, that "stem blow out” must not occur which would allow any flames of a pipeline fire to escape to the atmosphere from the ball valve.
  • the line pressure in the valve apply ⁇ ing a back-seating pressure on the seals to increase the effectiveness of the seals.
  • the present invention resides in a 5 ball valve of the type having: a valve body; a ball chamber in the valve body; an inlet to, and outlet from, the ball chamber; a -valve ball rotatably mounted in the ball 0- chamber; a stem housing in the valve body; a stem rotatably mounted in the stem housing and engaged in the valve ball to enable the valve ball to be rotated to open or close the valve; characterized in 5 that: the stem housing has a stepped bore;
  • ball valve shall be used to include other types of rotary or "quarter-term” valves, such as plug valves or butterfly valves.
  • the primary seal e.g. of PTFE or nylon, is completely enclosed and provides the normal 0 seal between the stem and the valve body.
  • the primary seal is damaged or destroy ⁇ ed in the event of fire to enable the stem to move and bring the secondary seal into effect.
  • line pressure on the collar applies a 5 back-seating pressure on the seals to increase their effectiveness.
  • the seals are maintained under a constant seating pressure by a spring under the stem lock nuts, which secure the stem in the stem housing, an 5 ' the valve body.
  • an external seal is interposed between the stem lock nuts and the valve body to prevent the entry of corrosive atmospheric material into the stem housing. 10 .
  • FIG. 1 is a sectional side view of a ball valve in 15 accordance with the present invention.
  • FIG. 2 is an enlarged view of portion A of FIG. 1.
  • the ball valve has a body 10 with end flanges 11 and 12.
  • An inlet passage 13 and an outlet passage 14 are respectively connected to a ball chamber 15 in the body 0 10.
  • a valve ball 16 is rotatably mounted in the ball chamber 15 and has a fluid passage 17. Seal assemblies 18, 19 seal the ball 16 to the walls of the ball chamber.
  • a socket 20 is formed in the upper side of the ball. 5
  • a stem housing 21 in the body 10 has a stepped bore 22. The lower portion 23 of the bore is connected to a reduced diameter intermediate portion 24 by a first annular abutment face 25, while the intermediate portion 24 is connected to the further reduced diameter upper 0 portion 26 by a second annular abutment face 27.
  • the stem 28 has a central stem body 29 rotatably mounted in the upper portion 26 of the stepped bore 22.
  • a stepped collar 30 is formed integrally with the stem at the lower end of the stem body and has first and 5 second annular abutment faces 31, 32 complementary to
  • a very small clearance is provided between the collar 30 and the lower and intermediate portions 23, 24 of the stepped bore 22. 5
  • a lower stem seal 33 e.g. of PTFE (sold under the name "Teflon", a Registered Trade Mark of Du Pont) or nylon is fitted between the first abutment face 25 in the . stepped bore 22 and the first abutment face 31 on the collar 30, while an upper stem seal 34, of high tempera-
  • ture fire resistant material e.g. of graphite or asbestos
  • Anti-static devices 36 provide electrical paths
  • An annular stop plate 37 is fitted to the stem 28, located by a stop pin 38 fixed in the stem housing 21, bears against the upper annular face 39 of the stem
  • a pair of stem lock nuts 40 are screwthreadably mounted on the upper body 41 of the stem 28 to prevent the stem from, being drawn into the ball chamber 15.
  • a wavy spring 42 is interposed between the stop plate 37
  • the wrench 43 is secured to the upper end of the stem 28 by a suitable retainer 44.
  • the wavy spring 42, and the line pressure in the ball chamber 15 applied against the underside face of the collar 30, will compress the low.er internal seal 33 between the first abutment faces 25, 31 in the stepped bore 22 and on the collar 30 respectively to form an effective seal between the stem 28 and body 10. Little, if any, sealing action is provided by the upper stem seal 34. However, in the event of a fire, the lower stem seal 33 becomes softened or destroyed. The stem 28 moves upwardly in the stem housing 21 until the upper stem seal 34 is compressed between the second abutment faces 27, 32 on the stepped bore 22 and on the collar 30 respectively. As this seal 34 is formed of high-temperature fire resistant material, it will not be affected by the fire and the flames cannot escape to the atmosphere.
  • the abutment faces 25, 31 may come into metal-to-raetal sealing contact to further enhance the "fire safe" sealing arrangement.
  • the small clearance between the collar 30 and the lower and inter ⁇ mediate portions 23, 24 of the stepped bore further limits any access of the fire to the upper stem seal 34.
  • the stem 28 cannot be forced out of the body 10 by the high pressures generat ⁇ ed in the valve during a fire.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Taps Or Cocks (AREA)

Abstract

L'agencement de joints de tige résistants au feu est destiné à des soupapes de retenue. La tige (28) est montée en rotation dans un alésage à gradin (22) dans l'enceinte (21) de la tige d'un corps de soupape (10), et elle est pourvue d'un collier (30) ayant des faces d'aboutement (31, 32) opposées aux faces d'aboutement correspondantes (25, 27) de l'alésage en gradin (22). Un joint inférieur de tige (33) en PTFE ou en nylon assure une étanchéité entre les faces d'aboutement (25, 31). En cas d'incendie, le joint inférieur de tige (33) est ramolli ou détruit et la tige (28) se déplace vers le haut dans l'enceinte (21) de la tige pour comprimer un joint supérieur de tige (34), en matériau résistant à des températures élevées et au feu, entre les faces d'aboutement (27, 32) pour empêcher les flammes de s'échapper à l'atmosphère. Un joint extérieur (46) assure l'étanchéité de la tige (28) dans l'enceinte (21) de cette dernière pour empêcher l'entrée de matériaux corrosifs dans le corps (10) de la soupape.The arrangement of fire resistant rod seals is intended for check valves. The stem (28) is rotatably mounted in a stepped bore (22) in the enclosure (21) of the stem of a valve body (10), and is provided with a collar (30) having abutment faces (31, 32) opposite the corresponding abutment faces (25, 27) of the stepped bore (22). A lower PTFE or nylon rod seal (33) seals between the abutment faces (25, 31). In the event of a fire, the lower rod seal (33) is softened or destroyed and the rod (28) moves upwards in the rod enclosure (21) to compress an upper rod seal (34), of material resistant to high temperatures and to fire, between the abutment faces (27, 32) to prevent the flames from escaping to the atmosphere. An external seal (46) seals the rod (28) in the enclosure (21) of the latter to prevent the entry of corrosive materials into the body (10) of the valve.

Description

TITLE: "STEM SEALS FOR BALL VALVES" BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to stem seals for ball valves.
2. Description of the Prior Art
In many applications, e.g. in the plastics- and petroleum industries, any ball valves used in such industries must comply with British Standard 5146. B.S. 5146 specifies, inter alia, that "stem blow out" must not occur which would allow any flames of a pipeline fire to escape to the atmosphere from the ball valve.
Tests have shown that the ball valves presently available cannot fully comply with the specifications laid down in the British Standard, In some valves, the intense pressures generated in the valve during a. fire can cause the stem to be physically blown-out of the valve body. With other valves, the internal seal between the stem and the body fails and flames can escape between the stem and the body.
BRIEF SUMMARY OF THE PRESENT INVENTION It is an object of the present invention to provide an effective "fire safe" sealing arrangement between the stem and valve body in the event of a fire. it is a preferred object to provide two seals between the stem and the body, the seals comprising a primary seal and a secondary seal, the latter acting only as an emergency seal in the event of fire.
It is a further preferred object. to provide a collar on the stem, the line pressure in the valve apply¬ ing a back-seating pressure on the seals to increase the effectiveness of the seals.
It is a still further preferred object to provide an external seal between the stem and the valve body to prevent corrosive atmospheric materials from entering the
O PI
WIPO , valve body and damaging the primary and secondary seals. Other preferred objects of the present invention will become apparent from the following description.
In one aspect, the present invention resides in a 5 ball valve of the type having: a valve body; a ball chamber in the valve body; an inlet to, and outlet from, the ball chamber; a -valve ball rotatably mounted in the ball 0- chamber; a stem housing in the valve body; a stem rotatably mounted in the stem housing and engaged in the valve ball to enable the valve ball to be rotated to open or close the valve; characterized in 5 that: the stem housing has a stepped bore;
» a collar on the stem is rotatably mounted in the stepped bore; and primary and secondary seals are provided between 0= the collar and the stepped bore, the secondary seal comprising a high-temperature fire-resistant material providing an emergency seal between the stem and the valve body in the event of fire.
Throughout the description and claims, the term 5 "ball valve" shall be used to include other types of rotary or "quarter-term" valves, such as plug valves or butterfly valves.
Preferably the primary seal, e.g. of PTFE or nylon, is completely enclosed and provides the normal 0 seal between the stem and the valve body.
Preferably the primary seal is damaged or destroy¬ ed in the event of fire to enable the stem to move and bring the secondary seal into effect.
Preferably line pressure on the collar applies a 5 back-seating pressure on the seals to increase their effectiveness.
Preferably the seals are maintained under a constant seating pressure by a spring under the stem lock nuts, which secure the stem in the stem housing, an 5' the valve body.
Preferably an external seal is interposed between the stem lock nuts and the valve body to prevent the entry of corrosive atmospheric material into the stem housing. 10. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING To enable the invention to be fully understood, a preferred embodiment will now be described with reference to the accompanying drawings, in which:
FIG. 1 is a sectional side view of a ball valve in 15 accordance with the present invention; and
FIG. 2 is an enlarged view of portion A of FIG. 1. The ball valve has a body 10 with end flanges 11 and 12. An inlet passage 13 and an outlet passage 14 are respectively connected to a ball chamber 15 in the body 0 10.
A valve ball 16 is rotatably mounted in the ball chamber 15 and has a fluid passage 17. Seal assemblies 18, 19 seal the ball 16 to the walls of the ball chamber. A socket 20 is formed in the upper side of the ball. 5 A stem housing 21 in the body 10 has a stepped bore 22. The lower portion 23 of the bore is connected to a reduced diameter intermediate portion 24 by a first annular abutment face 25, while the intermediate portion 24 is connected to the further reduced diameter upper 0 portion 26 by a second annular abutment face 27.
The stem 28 has a central stem body 29 rotatably mounted in the upper portion 26 of the stepped bore 22.
A stepped collar 30 is formed integrally with the stem at the lower end of the stem body and has first and 5 second annular abutment faces 31, 32 complementary to
OMPI
/., v/ιeυ the first and second abutment faces 25, 27 respectively. A very small clearance is provided between the collar 30 and the lower and intermediate portions 23, 24 of the stepped bore 22. 5 A lower stem seal 33, e.g. of PTFE (sold under the name "Teflon", a Registered Trade Mark of Du Pont) or nylon is fitted between the first abutment face 25 in the . stepped bore 22 and the first abutment face 31 on the collar 30, while an upper stem seal 34, of high tempera-
10. ture fire resistant material, e.g. of graphite or asbestos, is fitted between the second abutment face 27 on the stepped bore 22 and the second abutment face 32 on the collar 30. As shown both seals 33, 34 are fully enclosed and protected from any corrosive line medium
15 passing through the valve.
A tongue 35 on the lower end of the stem 28 engages the socket 20 in the valve ball 16 to enable the latter to be rotated.
Anti-static devices 36 provide electrical paths
20 between the stem 28 and body 10, and the stem 28 and ball 16 to prevent flashing in the valve.
An annular stop plate 37 is fitted to the stem 28, located by a stop pin 38 fixed in the stem housing 21, bears against the upper annular face 39 of the stem
25 housing around the bore 22.
A pair of stem lock nuts 40 are screwthreadably mounted on the upper body 41 of the stem 28 to prevent the stem from, being drawn into the ball chamber 15. A wavy spring 42 is interposed between the stop plate 37
30 and the stem lock nuts 40 to compress the lower stem seal 33, to ensure an effective seal between the stem 28 and the body 10.
The wrench 43 is secured to the upper end of the stem 28 by a suitable retainer 44.
35 An annular groove 45 is provided around the upper
OλfPI end of the stepped bore 22 at its junction with the upper annular face 37. An external seal 46 is fitted in the groove 45 and compressed against the stem 28 to prevent the entry of corrosive material into the stem housing 21.
In normal operation, the wavy spring 42, and the line pressure in the ball chamber 15 applied against the underside face of the collar 30, will compress the low.er internal seal 33 between the first abutment faces 25, 31 in the stepped bore 22 and on the collar 30 respectively to form an effective seal between the stem 28 and body 10. Little, if any, sealing action is provided by the upper stem seal 34. However, in the event of a fire, the lower stem seal 33 becomes softened or destroyed. The stem 28 moves upwardly in the stem housing 21 until the upper stem seal 34 is compressed between the second abutment faces 27, 32 on the stepped bore 22 and on the collar 30 respectively. As this seal 34 is formed of high-temperature fire resistant material, it will not be affected by the fire and the flames cannot escape to the atmosphere.
In certain conditions, the abutment faces 25, 31 may come into metal-to-raetal sealing contact to further enhance the "fire safe" sealing arrangement. The small clearance between the collar 30 and the lower and inter¬ mediate portions 23, 24 of the stepped bore further limits any access of the fire to the upper stem seal 34.
As the collar 30 is of larger diameter than the upper portion 26 of the stepped bore 22' and is opposed by the abutment faces 25, 27, the stem 28 cannot be forced out of the body 10 by the high pressures generat¬ ed in the valve during a fire.
As will be readily apparent to the skilled addressee, the embodiment described provides a simple, yet effective "fire safe" sealing arrangement for ball
OMPI valves .
Various changes and modifications may be made to the embodiment described without departing from the scope of the present invention.
OMPI

Claims

CLAIMS:
1. A ball valve of the type having: a valve body (10) ; a ball chamber (15) in the valve body (10) ; an inlet (13) to, and outlet (14) from, the ball chamber (15) ; a valve ball (16) rotatably mounted in the ball chamber (15) ; a stem housing (21) in the valve body (10); a stem (28) rotatably in the stem housing (21) and engaged in the valve ball (16) to enable the valve ball (16) to be rotated to open or close the valve; characterized in that: the stem housing (21) has a stepped bore (22) ; a collar (30) on the stem (28) is rotatably mounted in the stepped bore (22) ; primary and secondary seals (33, 34) are provided between the collar (30) and the stepped bore (22) , the secondary seal (34) comprising a high-temperature fire resistant material providing an emergency seal between the stem (28) and the valve body (10) in the. event of a fire.
2. A ball valve as claimed in Claim 1 and further characterized in that: the primary seal (33) , of PTFE or nylon material, is completely enclosed and provides the normal seal between the stem (28) and the valve body (10) .
3. A ball valve as claimed in Claim 1 or Claim 2 and further characterized in that: in the event of a fire, the primary seal (33) is damaged or destroyed to enable the ste ' (28) to move in the stem housing (21) to be compressed, and provide the seal between the collar (30) and the stepped bore (22) .
4. A ball valve as claimed in Claim 1 or Claim 2 and further characterized in that:
OMP WIP the line pressure in the ball chamber (15) applies a force on the collar (30) to compress the primary seal (33) or secondary seal (34) .
5. A ball valve as claimed in Claim-4 and further characterized in that: stem lock nuts (40) are provided on the stem (28) to axially locate the stem (28) in the stem housing (21) ; and a spring (4-2) is interposed between the stem lock nuts (40) and the valve body (10) to apply a constant compression force on the primary seal (33) or secondary seal (34) to increase the effectiveness of the seal between the stem (28) and the valve body (10) .
6. A ball valve as claimed in Claim 1 or Claim 2 and further characterized in that: an external seal (46) is fitted in an annular groove (45) in the stepped bore (22) , the external seal (46) being in sealing engagement with the stem (28) to prevent the entry of corrosive atmospheric material into the valve body (10) .
OMPI WIP
EP19810902619 1981-09-22 1981-09-22 Stem seals for ball valves Withdrawn EP0089334A1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/AU1981/000139 WO1983001099A1 (en) 1981-09-22 1981-09-22 Stem seals for ball valves

Publications (1)

Publication Number Publication Date
EP0089334A1 true EP0089334A1 (en) 1983-09-28

Family

ID=3759956

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19810902619 Withdrawn EP0089334A1 (en) 1981-09-22 1981-09-22 Stem seals for ball valves

Country Status (3)

Country Link
EP (1) EP0089334A1 (en)
AU (1) AU7585181A (en)
WO (1) WO1983001099A1 (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3609364C2 (en) * 1986-03-20 1995-08-17 Manibs Spezialarmaturen stopcock
DE4419426A1 (en) * 1994-06-03 1995-12-07 Klein Schanzlin & Becker Ag Shaft sealing for fittings
US5577709A (en) * 1995-10-17 1996-11-26 Henry Valve Company Stem seal configuration for ball valves
US6202668B1 (en) * 1998-03-20 2001-03-20 North American Corporation Valve with fire-resistant seal
AT413330B (en) 2002-04-18 2006-02-15 W & H Dentalwerk Buermoos Gmbh TORQUE TRANSMISSION FOR A SURGICAL OR DENTAL, ROTATING TOOL
JP2015086929A (en) * 2013-10-30 2015-05-07 コベルコ建機株式会社 Valve and construction machine

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2014237A1 (en) * 1970-03-25 1971-10-14 Westark Armaturen Piggable ball valve in welded design
US3788600A (en) * 1972-08-24 1974-01-29 Cameron Iron Works Inc Gate valve
US4006881A (en) * 1974-12-09 1977-02-08 Gachot S.A. Fluid-tight packing for closure devices and devices fitted with said packing
US4245661A (en) * 1978-10-27 1981-01-20 Combustion Engineering, Inc. Heat responsive back seat arrangement for valve operator

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8301099A1 *

Also Published As

Publication number Publication date
WO1983001099A1 (en) 1983-03-31
AU7585181A (en) 1983-04-08

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Inventor name: RICHARDS, CECIL GRAHAM