1.Auxiliary parts -- Beginning with the lack of pressure -- Bolt load grievance -- Bolt thread damage -- Wrong bolts -- Not at the flange surface 2. Gasket materials -- Old gasket secondary use -- Incompatible with the media -- Unsuitable for mining conditions -- Do not match the use of the complex -- Size misconduct -- High leakage rate 3. Design factors -- Bolt load inadequate -- Excessive load -- Flange bolts and the wrong choice 4.Flange --Surface Damage --Face grievance