Are there any special requirements for natural gas pipeline valves

With the development of the natural gas pipeline industry, the usage of natural gas pipeline valves has been increasing. These valves differ from ordinary valves in the following aspects:
1. Quick action, automatic shutdown
Due to the fact that management and control personnel are usually located within the station or central control room, it is required that in the event of a major accident such as pipeline rupture, the pipeline valves can automatically shut off. Pipeline valves require low operating force and can achieve accurate operation when affected by temperature and external force changes. Especially for emergency shut-off valves, they must be able to remain fully open for a long time and quickly lock the pipeline if necessary. At the same time, it is required that the opening and closing position and opening indicator of the valve be accurate and easy to understand, and meet the appropriate opening and closing speed.
2. Electric actuator  or pneumatic device, pneumatic hydraulic linkage or electro-hydraulic linkage device, high output torque, explosion-proof
Due to the high pressure, large diameter, and fast opening and closing time of pipeline transportation, pipeline valves require the use of high torque drive devices. Such as Electric Actuators or pneumatic devices, pneumatic hydraulic linkage or electro-hydraulic linkage devices. Electric Actuators or pneumatic devices must also have explosion-proof requirements, requiring EExdIIBT4 and a protection level of IP68.
3. Low leakage rate
Most natural gas pipelines are built on the outskirts of cities, and their operation and management are not like typical factories, where workers often operate, maintain, and inspect them. Generally, natural gas pipelines in cities are over hundreds of kilometers long and can only be patrolled and inspected regularly. Moreover, sometimes pipelines need to pass through areas with complex situations, and the leakage of media may cause serious fire accidents. Especially for pipelines closer to cities, preventing valve leakage is particularly important.
The leakage requirements for natural gas valves are very strict, and buried and important valves usually adopt a fully welded valve body structure. In order to ensure the sealing performance of pipeline valves, it is required that the sealing pair has excellent corrosion resistance, wear resistance, self lubrication, and elasticity. In recent years, the development of polymer materials has provided a broad selection space for pipeline valve sealing materials, such as polytetrafluoroethylene, nylon, nitrile rubber (NBR), special synthetic rubber (VITON), etc.
4. Corrosion resistant material
The natural gas transported by pipelines contains a large amount of hydrogen sulfide before desulfurization (this is a toxic and highly corrosive gas that reacts with iron to produce iron sulfide, which can peel off in flakes and corrode mechanical equipment). Even natural gas treated with desulfurization and other processes still has residual hydrogen sulfide. Therefore, the material selection for pipeline valves should be corrosion-resistant and sulfur resistant materials.
5. Long service life
   
Once the pipeline is put into operation, it is not allowed to stop running for several years. The longer the operation time, the better, unlike general chemical plants or refineries, which have major maintenance periods. The natural gas transported by pipelines faces a large number of users in the entire city, including residents, enterprises, factories, etc. Especially for enterprise users who use natural gas as raw material, there should be no momentary interruption. Once the pipeline valves connected in series fail, the consequences can be unimaginable. Therefore, the main sealing vulnerable parts of pipeline valves, such as valve seats, require long service life. The service life of valves in general trunk pipelines is required to be over 30 years.