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This post was last edited by ZhiGE on 2020-4-10 at 10:52. 1. When is a bellows-sealed valve cover needed: Bellows-sealed valve covers are often used when the process fluid is toxic, volatile, radioactive, or extremely expensive. This special valve cover design protects the valve stem and valve packing from coming into contact with the process fluid. The standard or environmentally friendly stuffing box design placed over the bellows seal element prevents catastrophic consequences in the event that the bellows rupture or fail. 2. Precautions for diaphragm-sealed valve covers: Just as other control valves are subject to limitations related to pressure, temperature, and the medium, the pressure rating of diaphragm seals also decreases as temperature rises ； Direct contact with the medium, the corrosiveness of the medium, etc. The selection of the bellows sealing type should be carefully considered, and special attention should be paid to proper inspection and maintenance after installation. 3. Bellows sealing structure: I. Mechanically formed bellows ； II. Welded bellows. 4. Preventive maintenance of diaphragm-sealed valve covers: The diaphragm material should be carefully selected to ensure the longest possible service life for cyclic operation. It is expected to reach its service life, and replacement will be carried out as part of preventive maintenance.

This post was last edited by Xianjian Qiyuan2015 on 2020-6-7 at 16:18. ·1