GB2060982A - Arrangement for shutting off a safety valve equipped with a blowoff conduit - Google Patents

Abstract

In an arrangement for shutting off a safety valve (3), to avoid an undesirable loss of pressure or materials from a pressurised protected system (1) because the safety valve improperly remains open after the pressure has dropped, on isolation valve (8) is installed in a blow off line (7) leading from the valve (3). The isolation valve (8) is circumvented by a bypass line (9). If the isolation valve (8) unintentionally closes, blow off of the safety valve (3) is ensured by a rupture disc (10) in the bypass line (9). <IMAGE>

Description

SPECIFICATION Arrangement for shutting off a safety valve equipped with a blowoff conduit This invention relates to an arrangement for shutting off a safety valve equipped with a blowoff conduit.

For safety reasons, pressure-loaded system components, e.g. a nuclear power plant steam system, must be protected against overpressure. As a rule, this overpressure protection is provided by a safety valve. However, there is a certain probability that the safety valve will not close when necessary after the pressure has dropped, but will reman open in error.

This results in an uncontrolled and undesirable loss of pressure and materials from the protected components or from the system. No shutoff capability which impairs the operation of the safety valve is permissible.

According to the present invention there is provided an arrangement for shutting off a safety valve equipped with a blowoff conduit, the arrangement comprising an isolation valve installed in the blowoff conduit, a bypass conduit circumventing the isolation valve, and a rupture disc sealing the bypass conduit.

An arrangement embodying the invention and described hereinbelow provides a reliable shutoff of a blowoff conduit leading from the safety valve in case it does not close after the pressure has dropped. In case of defective closing of the isolation valve, the rupture disc responds and ensures pressure relief of the system component.

The invention will now be further described, by way of illustrative and non-limiting example, with reference to the accompanying drawing, the sole figure of which is a schematic drawing of an arrangement embodying the invention for turning off a safety valve equipped with a blowoff conduit.

Referring to the drawing, a pressure conduit 2 leading away from a pressure-loaded system component 1 has a safety valve 3, controlled by an internal medium, installed therein. A pulse conduit 4 leads from the pressure conduit 2 to a control valve 5 of a control conduit 6 which triggers the opening of the safety valve 3 in a known manner. Any overpressure of the system component 1 is lowered through an open isolation valve 8 by way of a blowoff conduit 7 leading from the safety valve 3. if the safety valve 3 should not return to its closed position after the pressure has dropped, the isolation valve 8 is closed by any suitable means to prevent an undesirable loss of pressure and materials from the protected system component 1.In case a malfunction causes the isolation valve 8 to close, a rupture disc 10 located in a bypass conduit 9 circumventing the isolation valve 8 ensures a pressure drop in the system component 1 by rupturing.

With the above-described arrangement, shutoff of the safety valve 3 is possible when it does not close normally, without the operation of the safety valve being hindered when needed by defective operation of the isolation valve 8.

1. An arrangement for shutting off a safety valve equipped with a blowoff conduit, the arrangement comprising an isolation valve installed in the blowoff conduit, a bypass conduit circumventing the isolation valve, and a rupture disc sealing the bypass conduit.

2. An arrangement for shutting off a safety valve equipped with a blowoff conduit, the arrangement being substantially as herein described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (2)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Arrangement for shutting off a safety valve equipped with a blowoff conduit This invention relates to an arrangement for shutting off a safety valve equipped with a blowoff conduit. For safety reasons, pressure-loaded system components, e.g. a nuclear power plant steam system, must be protected against overpressure. As a rule, this overpressure protection is provided by a safety valve. However, there is a certain probability that the safety valve will not close when necessary after the pressure has dropped, but will reman open in error. This results in an uncontrolled and undesirable loss of pressure and materials from the protected components or from the system. No shutoff capability which impairs the operation of the safety valve is permissible. According to the present invention there is provided an arrangement for shutting off a safety valve equipped with a blowoff conduit, the arrangement comprising an isolation valve installed in the blowoff conduit, a bypass conduit circumventing the isolation valve, and a rupture disc sealing the bypass conduit. An arrangement embodying the invention and described hereinbelow provides a reliable shutoff of a blowoff conduit leading from the safety valve in case it does not close after the pressure has dropped. In case of defective closing of the isolation valve, the rupture disc responds and ensures pressure relief of the system component. The invention will now be further described, by way of illustrative and non-limiting example, with reference to the accompanying drawing, the sole figure of which is a schematic drawing of an arrangement embodying the invention for turning off a safety valve equipped with a blowoff conduit. Referring to the drawing, a pressure conduit 2 leading away from a pressure-loaded system component 1 has a safety valve 3, controlled by an internal medium, installed therein. A pulse conduit 4 leads from the pressure conduit 2 to a control valve 5 of a control conduit 6 which triggers the opening of the safety valve 3 in a known manner. Any overpressure of the system component 1 is lowered through an open isolation valve 8 by way of a blowoff conduit 7 leading from the safety valve 3. if the safety valve 3 should not return to its closed position after the pressure has dropped, the isolation valve 8 is closed by any suitable means to prevent an undesirable loss of pressure and materials from the protected system component 1.In case a malfunction causes the isolation valve 8 to close, a rupture disc 10 located in a bypass conduit 9 circumventing the isolation valve 8 ensures a pressure drop in the system component 1 by rupturing. With the above-described arrangement, shutoff of the safety valve 3 is possible when it does not close normally, without the operation of the safety valve being hindered when needed by defective operation of the isolation valve 8. CLAIMS

1. An arrangement for shutting off a safety valve equipped with a blowoff conduit, the arrangement comprising an isolation valve installed in the blowoff conduit, a bypass conduit circumventing the isolation valve, and a rupture disc sealing the bypass conduit.

2. An arrangement for shutting off a safety valve equipped with a blowoff conduit, the arrangement being substantially as herein described with reference to the accompanying drawing.