The quick opening is called bandlock,including direct compression components(cylinder and blind sheeting) and the rapid belt tightening lock device and the pressure relief safety devices,the special form of ring and the transfer arm connecting cylinder with blind sheeting.

By the analysis of stress distortion of circular load symmetry flat plate, starting from the entire deriving course of thickness calculation formula, derives the simple formula of calculating blind flange thickness, which is fit for oral calculation of hydrostatic pressure testing of in-situ equipment and pipeline.

When he first arrived in Yan\'an,he was lost in blind happiness.