4 Conclusion At present, various specifications of double eccentric semi pneumatic ball valves have been applied to various projects in different industries, with good results and gradually expanding the scope of use.

The non-metallic compensator is better than the metal shrink joint
The structure of non-metallic contraction joint mainly includes skin, stainless steel wire mesh, insulation cotton, insulation filler layer, frame and baffle. Skin is a kind of high-strength sealing composite material, which is composed of a variety of silicone rubber and other materials with excellent performance, and has the function of waterproof and air leakage.
Stainless steel wire: It is an effect to prevent sundries from flowing out, and it is the lining of non-metallic contraction joint.
Insulation cotton: non-metallic contraction joint has sound absorption, vibration isolation and transmission functions, and has good extensibility and tensile strength.
Thermal insulation filler layer: an important guarantee for thermal insulation of non-metallic contraction joints, which is composed of a variety of high-temperature resistant materials.
Rack: It has sufficient strength and rigidity, and the material is consistent with the temperature of the medium.
The baffle plate is corrosion resistant, wear-resistant, and has the function of guiding and maintaining the thermal insulation layer.