FR2468055A1 - DEVICE FOR CLOSING A SAFETY VALVE HAVING A PURGE CONDUIT - Google Patents

Abstract

Device for closing a safety valve. To avoid undesirable leaks of pressure or material from a protected pressurized network, due to a safety valve 3 remaining unduly open after dissipation of an overpressure, an isolation valve 8 is fitted. on the purge pipe 7. This valve 8 is bypassed by a branch pipe 9. If the valve 8 closes improperly, decompression is ensured by rupture of a frangible disc 10 interposed on the pipe 9. Application, for example , to the steam network of a nuclear power plant.

Description

The present invention relates to a device for

  closing a safety valve provided with a purge duct.

  For safety reasons, it is necessary to ensure that

  of a pressurized network, for example the steam network of a nuclear power plant, protection against overpressure. In general, this protection is provided by a safety valve. However, there is some risk that the safety valve will not close when necessary after the disappearance of the overpressure, but remains incorrectly in the open position. This results in an uncontrolled and undesirable loss of pressure and materials from the components

  protected or installation. There can be no provision for

  positive closure that may affect the operation of the

the safety valve.

  The object of the present invention is to provide a device

  sitive able to close the purge duct which leaves the valve

  without jeopardizing the functioning of that

the valve.

  This problem is solved according to the invention by providing

  an isolation valve placed on the purge duct and

  turned by a derivative conduit sealed by a frangible disk.

  This arrangement reliably ensures the closure of the

  from the safety valve in the event that the safety valve

  dies open after the overpressure has disappeared. In the event of an improper closing of the isolation valve, the frangible disc breaks to ensure the decompression of the component concerned.

network.

  As an example, we will describe the structure and func-

  of a device according to the prior embodiment

  of the invention with reference to the schematic drawing of FIG.

  nexé, the single figure of which represents a device according to the invention for closing a safety valve provided with a

purge duct.

  On the pressure line 2, starting from the component to pro-

  1 of the pressurized network, a safety valve is installed

  3 governed by an inner environment. A pulsation conduit

  4 connects the pressurized duct 2 to a control valve

  5 of a control conduit 6, which causes

  the opening of the safety valve 3. The overpressure of the

  component 1 of the network is dissipated, through the isolation valve

  8 lation, through the purge duct 7 which leaves the safety valve 3. If it does not resume its position

  when the overpressure disappears, the isolation valve

  section 8 is closed by any appropriate means to prevent

  unwanted leakage of pressure and materials from the

  Protected posing 1 of the network. In the event of a malfunction causing closure of the isolation valve 8, the frangible disk 10, mounted in the bypass duct 9 which bypasses the isolation valve 8, breaks to dissipate the overpressure

  appeared in component 1 of the network.

  The device according to the invention ensures the closure of

  a safety valve when it does not occur normally

  without the action of this valve being impeded, when it is necessary, because of faulty operation.

of the isolation valve.

  The preferred embodiment described and illustrated is chosen purely by way of example and, in general, the arrangements described are amenable to various modifications.

  without departing, for all that, from the scope of the invention.

Claims (1)

CLAIM   Device for closing a safety valve provided with a purge duct, characterized in that it comprises an isolation valve (8) placed on said purge duct, a derivative duct (9) bypassing this valve of insulation and   a frangible disk (10) sealing said derived conduit.