The materials and the quality of gas valves are so important that their disqualification will lead to leakage in-or-outside the body of the valve. If the strength, rigidity and overall performance of the components of the valve body cannot meet the requirements or even break, it will result in the spillage of gas and explosion. Therefore, material and quality are the most critical part during the process of developing, designing, and studying gas valves.
How to choose materials for Gas Valves:
1. Mainly worked as fully open/close, there are gate valves,
butterfly valves and ball valves. Since the flexibleness of the gate and the existed hole for draining pressure, the amount of leakage from the export side of the valve will increase as the pressure rises (which is the destiny of gate valve of gas). However, gate valves and butterfly valves are generelly generally been used in the high pressure system (300LB) of gas. As more and more valves are used, consumers are familiar with the operation, which eliminates the insecurity at the early period of applying. Butterfly valves can only be applied to low-pressure pipeline (150LB). Ball valves are usually applied to pipelines of normal temperature system, which makes fully use of its advantages, since the short operating time and low resistance to medium.
2. Used for regulating flow, there are butterfly valves,
globe valves and needle valves. Generally, in valve industry, the butterfly valves and globe valves, which are easily operated and suitable for small-calibre small-dimension pipeline, are applied to gas pipeline with large calibre dimension and low pressure. But the pressure of the valve varies greatly before and after being used. Needle valves are used when regulating small flow.
3. Considering anti-reflux style,
Check valves are commonly used. Generally, when DN is less than 40mm, lift check valves will be used; when it is higher than 50mm, swing check valves will be applied; check valves with separated doors will be used when DN is even higher. Many times gas valves are permitted to adapt to the structure that will not lose its strength under the working temperature of medium. But the valves must be made from materials which can enable its strength under the working temperature.
