A flow arrangement for a pressure relief valve assembly can include a bypass flow path extending from a pressure source to a dome of a relief valve. The bypass flow path can include a valve that is configured to open and close the bypass flow path based on pressure at the pressure source or the dome, or a pressure difference between the pressure source and the dome.

A pressure relief valve is disclosed with a first stage valve that is in series with a second stage valve, with an enclosed cavity between the first stage valve and the second stage valve. The first stage valve relieves pressure from an enclosure into the enclosed cavity between the stages, when the pressure is above a cracking pressure of the first stage valve. The second stage relieves pressure from the enclosed cavity when the pressure is above the cracking pressure of the second stage valve.

A pressure relief valve is disclosed with a first stage valve that is in series with a second stage valve, with an enclosed cavity between the first stage valve and the second stage valve. The first stage valve relieves pressure from an enclosure into the enclosed cavity between the stages, when the pressure is above a cracking pressure of the first stage valve. The second stage relieves pressure from the enclosed cavity when the pressure is above the cracking pressure of the second stage valve.

A flow arrangement for a control valve can include a plurality of flow-control components that are movable relative to each other and that define at least part of a flow path from a pressure source to a dome of a pressure relief valve. The flow-control components can be movable relative to each other in response to system pressure to selectively increase or decrease the flow capacity of the flow path. In some cases, flow capacity can be increased or decreased during initial loading of the dome, at low pressures, or at higher pressures.

An inadvertent actuation block valve includes inlet and outlet orifices being in selective fluid communication via a chamber. A disc is disposed within the chamber and a bellows is configured to contract at a predetermined pressure differential between reactor fluid entering a reference pressure orifice and control fluid entering the inlet orifice. When the bellows contracts, the disc engages the outlet orifice and isolates fluid communication between the inlet and outlet orifices. The inadvertent actuation block valve prevents inadvertent opening of an emergency core cooling valve when a reactor is at operating pressure that is above the predetermined set pressure range. The inadvertent actuation block valve permits the emergency cooling valves to open and to remain open when reactor pressure is below the predetermined set pressure range. The inadvertent actuation block valve does not impede long term emergency cooling that occurs when the reactor is at low pressure.

An inadvertent actuation block valve includes inlet and outlet orifices being in selective fluid communication via a chamber. A disc is disposed within the chamber and a bellows is configured to contract at a predetermined pressure differential between reactor fluid entering a reference pressure orifice and control fluid entering the inlet orifice. When the bellows contracts, the disc engages the outlet orifice and isolates fluid communication between the inlet and outlet orifices. The inadvertent actuation block valve prevents inadvertent opening of an emergency core cooling valve when a reactor is at operating pressure that is above the predetermined set pressure range. The inadvertent actuation block valve permits the emergency cooling valves to open and to remain open when reactor pressure is below the predetermined set pressure range. The inadvertent actuation block valve does not impede long term emergency cooling that occurs when the reactor is at low pressure.

A check valve bleed assembly eliminates the requirement for a person to enter the red zone when bleeding the grease out of a gate or other valve. A gas or other fluid is provided to the check valve bleed assembly. The gas or other fluid acts upon the surface driving a pin into the associated check valve with sufficient force to overcome the resistance of the object sitting on a seat and moves the object off of the seat. The force is maintained as long as is necessary. Usually, the check valve is held open until the gate transitions into the gate's associated gate recess thereby displacing the grease within the gate recess through the check valve, into the check valve bleed assembly, and finally to a waste collection tube. In some embodiments a gate valve greasing access port is included in the check valve bleed assembly such that grease may be injected into the check valve bleed assembly.

A check valve bleed assembly eliminates the requirement for a person to enter the red zone when bleeding the grease out of a gate or other valve. A gas or other fluid is provided to the check valve bleed assembly. The gas or other fluid acts upon the surface driving a pin into the associated check valve with sufficient force to overcome the resistance of the object sitting on a seat and moves the object off of the seat. The force is maintained as long as is necessary. Usually, the check valve is held open until the gate transitions into the gate's associated gate recess thereby displacing the grease within the gate recess through the check valve, into the check valve bleed assembly, and finally to a waste collection tube. In some embodiments a gate valve greasing access port is included in the check valve bleed assembly such that grease may be injected into the check valve bleed assembly.

Systems, devices, and methods of modulating a pressure relief valve are provided. A modulating pilot valve assembly can receive an inlet pressure of an inlet of a pressure relief valve and can receive a dome area pressure of a dome area of the pressure relief valve. The modulating pilot valve assembly and the pressure relief valve can be configured to maintain a leak-tight seal until reaching a pilot valve pressure set point, at which the modulating pilot valve assembly instantly reduces the dome area pressure instantly, via a biasing mechanism of the modulating pilot valve assembly causing the pressure relief valve to initially open and thereafter to progressively reduce the dome area pressure in proportion to an increase in the inlet pressure and to cause the pressure relief valve to open in proportion to the increase in the inlet pressure.

Systems, devices, and methods of modulating a pressure relief valve are provided. A modulating pilot valve assembly can receive an inlet pressure of an inlet of a pressure relief valve and can receive a dome area pressure of a dome area of the pressure relief valve. The modulating pilot valve assembly and the pressure relief valve can be configured to maintain a leak-tight seal until reaching a pilot valve pressure set point, at which the modulating pilot valve assembly instantly reduces the dome area pressure instantly, via a biasing mechanism of the modulating pilot valve assembly causing the pressure relief valve to initially open and thereafter to progressively reduce the dome area pressure in proportion to an increase in the inlet pressure and to cause the pressure relief valve to open in proportion to the increase in the inlet pressure.