1, fire safety function and tightness
Oil and gas storage and transportation systems in the media are inflammable and explosive materials. Fire is the oil and gas storage and transportation equipment in the design and selection of time to focus on the issue, and sealing devices require not only better, while the giant in the field under fire but also have a certain sealing performance. Double seal valve guide seal the form of both soft and hard seal combination, including the valve flap and cover, the chassis structure. Soft sealing ensures zero leakage under normal operation condition, when the fire scene, the soft seal may be damaged, when sealed, will play the hard role of the primary seal to prevent leakage of media a lot. In comparison, the gate with a hard seal, fire function better, but sealing performance is not easy to be guaranteed, long-term use is difficult to ensure zero leakage; valve soft sealing, its life is longer, but do not have fire safety features.
2, with line maintenance functions
When the valve flap on the soft seal for some reason, causing damage to internal leakage or manipulation devices (executing agency) fails, do not have to remove the valve from the pipeline will proceed with the replacement or repair, maintenance of the manipulator can also be Pipeline under the constant pressure condition. The sealed part of the damaged valve, or valve, the valve must be removed from the pipeline in order to carry out maintenance or replacement, or even directly to the valve scrapped.
3, with a pun-off and discharge function
Using two cut off valves (gate valve or ball valve) to cut off media, and in between these two cut off valves to install a discharge valve, internal leakage occurs when the cut off valve, the media will leak out through the discharge valve, so as not to can cause two kinds of media mixing. If the double-sealed rail valve, a valve can only achieve these functions, double-sealing valve at the bottom rail has a drainage medium
4, with the cavity pressure relief function
AP I6 D specification states that "for all pairs of sealed valves, when used in liquid medium, you must have a discharge pressure function" discharge of the pressure due to changes in ambient temperature generated. In the regular closed state, the double-sealed valve chamber pressure will result in the rapid increase in temperature, which if not promptly discharge pressure of the valve operation will have a serious impact. Manual operation of the dual-sealed rails usually have the following two pressure relief valve system.
(1) Manual pressure relief system for a manual pressure relief systems are usually installed on the end cap on the needle valve. When a small amount of media that can be excreted into the atmosphere when the liquid can be equipped with such a pressure relief system
(2) differential thermal pressure relief system, differential thermal pressure relief system is a piping system with a one-way valve. In this system, I often closed needle valve, needle-shaped valve always open. When the medium is not excreted into the atmosphere when the liquid is to be equipped with such a pressure relief system (typically upstream pipeline pressure relief). Differential thermal pressure relief system does not require artificial control only in the detection of internal leakage only when the need to manually open the needle.
5, with internal leakage test function
When the S & P valve is closed, its sealing effect of the test more difficult, but dual-sealed valve testing guide is very easy to open as long as the closed pressure relief system and the cover can be connected to needle valve, valve If valve internal leakage, the medium will flow through the needle valve. If the media not to discharge in the atmosphere, you can access in the needle valve on a pressure gauge, gauge pressure by observing the changes to determine whether the inner leakage
6, the unique function of the pipeline decompression
Pipeline manifold vacuum is the storage tank area need to focus on the design issues considered, that is, when the tank before the valve closed, the pipe network is still full of media: With the ambient temperature increased, the pipe network in the media will rapidly increase the pressure on large; when larger temperature changes, increasing the pressure would exceed pipeline capacity, will easily lead to pipeline leaks, therefore, pipes should be equipped with pressure relief device designed to pipe decompression. in the main shut-off valve on the connection between upstream and downstream pipe decompression system, which consists of two block valve (gate valve, ball valve or stop valve), and the two cut off valves, a valve between the composition of the high cost of the package system, but also take up space, convenient on-site management. Selection of pairs of the main shut-off valve pipe valve seal guide channel design principles, vacuum system, attached to the main shut-off valve on the design of simple structure, small footprint, and low cost.