The causes of the leakage of the flange are generally as follows: 1. Partial mouth, refers to the pipe and flange is not perpendicular, different hearts, flange surface is not parallel. When the internal media pressure exceeds the load pressure of the gasket, the flange leakage occurs mainly in the process of installation, construction or overhaul, which is easier to find.
This kind of accident can be avoided as long as the project is completed with true inspection. 2. Wrong mouth, refers to pipe and flange perpendicular, but two flange different heart. Flange is not concentric, causing the surrounding bolts can not be freely pierced into the bolt hole. In the absence of any other means, only the expansion of the hole or a small number of bolts through the bolt hole, and this method will reduce the tension of the two flanges.
Also, the sealing surface of the sealing surface has a deviation, so it is very easy to leak. 3. Open mouth, fingering flange clearance too large.
When the clearance of the flange is too large to cause the external load, such as axial or bending load, the gasket will be impacted or shaken, lose the pressure, and gradually lose the sealing kinetic energy and lead to failure. 4. Wrong hole, refers to the pipe and flange concentric, but two flange relative to the distance between the bolt hole larger.
The wrong hole will cause the bolt to produce the stress, this force does not eliminate, will cause the shearing force to the bolt, the time will cut off the bolt, causes the seal invalidation.
5. Stress effect, in the flange installation, the two flanges are compared to the standard, but in the system production, pipe into the medium, resulting in pipe temperature changes, so that the pipeline expansion or deformation, so that the flange by bending load or shearing force, easy to cause gasket failure. 6. Corrosion effect, due to corrosive medium on the gasket for a long time erosion, so that the gasket chemical changes.
The corrosive medium penetrates into the gasket, the gasket starts to soften, loses the compression force, causes the flange to leak. 7. Thermal expansion and contraction, due to the heat and heat expansion of the fluid medium, resulting in expansion or contraction of the bolt, so that the gasket will produce gaps in the media through pressure leakage.