Valves and valve actuation – With means to increase head and seat contact pressure – With positive reduction
Patent
1992-11-12
1994-06-21
Hepperle, Stephen M.
Valves and valve actuation
With means to increase head and seat contact pressure
With positive reduction
251161, F16K 1520
Patent
active
053222610
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an arrangement in shutoff or closing valves, particularly ball valves, comprising a preferably valve-ball-shaped, movable, preferably rotary valve body adapted to cooperate sealingly with at least one axially displaceable seat ring, possibly through the intermediary of a seal, wherein the seat ring or each seat ring, respectively, is urged toward the sealing position through spring force and/or fluid pressure and/or some other influence of force.
The valve body in such closing valves with which the invention is concerned, has at least one annular sealing surface against which said seat ring(s) is(are) intended to be urged into sealing engagement. The seat ring or each seat ring, respectively, carries usually a seal ring with which it cooperates with the valve body, but there are also so called metal-to-metal seals lacking a soft seal. The present invention is equally usable in both cases.
A valve ball of a shutoff valve of this general kind will, usually, have a design substantially corresponding to a ball wherein two diametrally opposite spherical segments are cut off, and wherein the valve ball is formed with a central through-going bore having a diameter substantially corresponding to that of the "cut-off" spherical segments.
However, the invention may also be used in connection with differently shaped valve bodies, for example conical, tapered, cylindrical, barrel-shaped, double conical, etc.
According to one aspect, the invention aims generally at improving the seal in closing valves of the kind in question and/or enable that possible leaks relatively rapidly may be brought to an end.
In accordance with another aspect, the invention aims at realizing activation/deactivation of the seal according to need. A possibility of activating/deactivating the (primary) seat may be desirable or necessary in shutoff valves unable to be opened under the influence of a sufficiently high differential pressure, due to the risk of damaging/destroying the seal (such a situation exists i.a. in valves using soft seals, e.g. of the so called PTFE type). Prior art technique aims at solving this problem through "bypass" around the valve in order to equalize the pressure prior to the opening of the valve. This known solution involves relatively high costs and, moreover, represents a safety risk.
Leaking closing valves may represent substantial problems. Often, leakage between seat and valve body requires damage repairs involving stoppage, in extreme cases causing accidents. Within the valve industry, one has tried to improve the sealing devices. The new sealing devices developed and tried out, are partly of complicated construction as well as being expensive to manufacture. Furthermore, they are complicated to operate and require a comprehensive maintenance. Many recently developed sealing devices for closing valves have not yet been tried out and operated in practice, and to these many unforeseen problems might be attached, with regard to operation, both at short and long term.
Taking as one's starting-point the above-mentioned objects, one has, in accordance with the present invention, aimed at providing a sealing arrangement in shutoff or closing valves of the introductorily defined kind, wherein the conditions are arranged for the purpose of maintaining optimal functional reliability while retaining improved sealing conditions as well as enabling stopping of possible leakage in situ, so that stoppage due to leak problems may be postponed and planned.
In accordance with the invention, one has likewise aimed at providing possibilities for the deactivation/activation of one or more seats included in the valve structure, the deactivation/activation possibilities preferably existing at each single seat, independent on the other seat/seats.
According to the invention, said objects are realized through the features comprised by the following claims.
The ordinary axially displaceable seat ring or each axially displaceable seat ring, respectively, is, in accordance with the invention, assigned at least one
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patent: 3960363 (1976-06-01), Domyan
patent: 4137936 (1979-02-01), Sekimoto et al.
patent: 4280522 (1981-07-01), Pechnyo et al.
patent: 4718444 (1988-01-01), Boelte
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