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.

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

Applications Claiming Priority (1)

Publications (1)

Family

ID=3759956

Family Applications (1)

Country Status (3)

Families Citing this family (8)

Family Cites Families (4)

• 1981
  • 1981-09-22 AU AU75851/81A patent/AU7585181A/en not_active Abandoned
  • 1981-09-22 WO PCT/AU1981/000139 patent/WO1983001099A1/en not_active Ceased
  • 1981-09-22 EP EP19810902619 patent/EP0089334A1/de not_active Withdrawn

Non-Patent Citations (1)

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