When should dual valves be used, and what are the relevant standards?

The standard is unknown; it is generally a medium with high pressure and high corrosivity

When using dual valves, it depends on the purpose: for example, in the case of media subject to severe erosion, with dual valves in use, the valve that serves as a barrier remains fully open, while the valve used for regulation takes care of control. Adjusting the valve plates of functional valves in this way can lead to easy wear, so they need to be replaced after some time of use. Such a dual-valve configuration also ensures the ability to isolate the pipeline. 2. In conditions of high pressure and high temperature, implementing a dual-valve isolation system enhances the isolation performance and improves safety. 3. For applications with special requirements, such as reducing pressure, a combination of an isolation valve and a pressure reducing valve can be used ； For example, restricting the direction can be achieved through a combination of a shut-off valve and a check valve ； For example, flow restriction can be achieved through a combination of isolation valves and flow control valves (orifice plates), etc. LZ’s concern is likely related to safety; Sinopec’s requirements for high-temperature pumps specify that quick-cut valves should be installed at the pump inlet, which to some extent implies the need to use dual valves

To determine whether double valves or single valves should be used at the connections of utility systems and process pipelines, refer to GB50160, which contains explicit regulations on this matter.