1. Double-sealed guideway valve has fireproof function and tightness

The medium in the oil and gas storage and transportation system is flammable and explosive. Fire prevention is a key concern in the design and selection of oil and gas storage and transportation devices. The device not only requires good sealing performance, but also has certain sealing performance in the event of a fire on site. The sealing form of the double-sealed guideway valve adopts a combination of soft and hard sealing, including the valve disc, end cover, chassis and other structures. The soft seal can ensure zero leakage under normal operating conditions. When a fire occurs on site, the soft seal may be damaged. At this time, the hard seal will play the role of the main seal, which can prevent a large amount of medium leakage. In comparison, the gate valve adopts a hard seal, which has better fire protection function, but the sealing performance is not easy to guarantee, and it is difficult to ensure zero leakage in long-term use; the ball valve adopts a soft seal, which has a long service life, but does not have the fire protection function.

2. Double-sealed guideway valve has online maintenance function

When the soft seal on the valve disc is damaged for some reason and causes internal leakage or the manipulator (actuator) fails, the valve can be replaced or repaired without removing the valve from the pipeline, and the manipulator can also be repaired in the pipeline. Do it without pressure. When the sealing part of the gate valve or ball valve is damaged, the valve must be removed from the pipeline for repair or replacement, or even the valve is directly scrapped.

3. Double-sealed guideway valve has double shut-off and discharge functions

Two isolation valves (gate valve or ball valve) are used to isolate the medium, and a drain valve is installed between the two isolation valves. When the isolation valve has internal leakage, the leaked medium will be discharged through the drain valve, so that there will be no A blend of two media. If a double-sealed guideway valve is used, only one valve can achieve the above functions.

4. The double-sealed guideway valve has the function of pressure relief in the middle cavity

The API6D specification stipulates that "all double-sealed valves must have a differential pressure relief function when used in liquid media", and the differential pressure relief is generated by changes in ambient temperature. In the normally closed state, the pressure in the middle cavity of the double-sealed valve will increase rapidly due to the increase in temperature. If the pressure difference is not released in time, it will have a serious impact on the operation of the valve. Manually operated double seal rail valves generally have the following two pressure relief systems.

(1) Manual pressure relief system The manual pressure relief system is usually a needle valve installed on the end cover. This pressure relief system can be equipped when the medium is a liquid that can be discharged to the atmosphere in small amounts.

(2) Differential thermal pressure relief system The differential thermal pressure relief system is a pipeline system with a one-way valve. In this system, the needle valve I is normally closed and the needle valve is normally open. When the medium is a liquid that cannot be discharged into the atmosphere, such a pressure relief system is required (generally, the pressure is released to the upstream pipeline). The differential thermal pressure relief system does not require manual control. Only when the internal leakage is detected, the needle needs to be opened manually.

5. Double-sealed guideway valve has the function of checking internal leakage

When the common valve is in the closed state, the detection of its sealing effect is more difficult, but the detection of the double-sealed guideway valve is very easy, as long as the needle valve connected with the pressure relief system and the end cover is opened in the closed state, if the valve disc is If there is internal leakage, the medium will flow out through the needle valve. If the medium is not to be discharged to the atmosphere, a pressure gauge can be connected to the needle valve, and the internal leakage can be judged by observing the change of the gauge pressure.

6. The double-sealed guideway valve has a unique pipeline decompression function

Pipeline decompression is a key issue that needs to be considered in the design of the tank manifold, that is, when the front valve of the tank is closed, the pipe network is still full of medium: as the ambient temperature increases, the pressure of the medium in the pipe network will increase rapidly. Large; when the temperature difference changes greatly, the increased pressure will exceed the bearing capacity of the pipeline, which is easy to cause pipeline leakage. Therefore, the pipeline should be equipped with pressure reducing equipment. Pipeline pressure reduction design. Connect the pipeline between the upstream and downstream of the main shut-off valve to reduce pressure The system consists of two shut-off valves (gate valve, ball valve or shut-off valve) and a pressure reducing valve between the two shut-off valves. The main shut-off valve adopts the pipeline design principle of the double-sealed guideway valve, and the decompression system is attached to the main shut-off valve. The design structure is simple, the space is small, and the cost is low.