The valve flange seal connection between the contact parts according to the design requirements placed gasket, relying on the bolt to produce pre-tightening force to achieve a sufficient pressure, to prevent media leakage to the outside. Gasket materials and structures are: rubber gasket, asbestos rubber gasket, graphite gasket, stainless steel and graphite wound gasket, corrugated pipe and metal gasket. Gasket seal is a mandatory seal. Common flange leaks are the following species: a. Interface leaks - leaks between the seal and the face of the flange. The main reason: the gasket preload is not enough ----- Treatment: Appropriate to increase the preload; Flange sealing surface does not match the requirements of roughness - Remedy: Flange surface is uneven or horizontal scratches - Remedy: Rework; cold and hot deformation and mechanical vibration, etc. --- Remedy: improve the environment or material selection; flange connection bolt deformation elongation ---- treatment: materials and can not exceed the allowable torque; seal Long-term use of gasket plastic deformation - Treatment: replacement; gasket aging, cracking and deterioration --- Treatment: replacement. b. Penetration Leakage - - The media creates a leak through the gasket material gap under pressure. The main reason: with the gasket material; media pressure; media temperature; gasket aging, cracking and deterioration. c. Leakage - Leakage due to over-compression of the gasket due to mounting quality or insufficient seal pressure. Main reasons: the installation of gasket bias, the local seal than the lack of pressure or preload is too large, loss of resilience; flange connection bolts elastic uneven; two flange concentricity (centerline offset) skew ; Gasket selection wrong or not according to working conditions, the correct selection of gasket material and type; interface leakage and damage leakage will significantly increase over time, the leakage of leakage and the relationship between the time is not obvious. (If reproduced, please indicate source)