Common causes of flange leakage:
1. The mistake is that the pipeline and the flange are in a vertical state, but the two flanges are not centralized so that the bolts around them can not enter the bolt hole freely. Some will use reaming or small bolts, but this will reduce the tension of the flange.
2. The offset is that the pipeline and flange are not vertical, and the flange surface is not parallel and not centrifugal. Leakage will occur if the internal medium pressure exceeds the load pressure of the gasket.
3. Corrosion, a long time corrosion of the corrosive medium on the gasket will cause chemical changes of the gasket, making the gasket soft and lose the compressive force.
4. The staggered hole, which is well understood by comparison, is concentric between the pipeline and the flange, but the distance between the bolt holes opposite to the two flanges is too large, the bolt will produce stress, and the bolt will be cut off in a long time, which will lead to seal failure.
In addition to the above reasons, such as thermal expansion and contraction, stress effect, opening and so on, will cause leakage in flange operation. Appearance heat treatment is the only metal heat treatment process to change the surface mechanical properties of heated workpiece. Appearance heat treatment changes the surface mechanical properties of steel workpiece by heating and cooling. Surface hardening is the main content of surface heat treatment. Its purpose is to obtain a high hardness surface and favorable internal stress distribution, so as to improve the wear resistance and fatigue resistance of the workpiece.
External heat treatment process has too much heat to heat the workpiece's surface and interior. It is necessary to have a workpiece with high energy density, larger heat per unit area, or instantaneous high temperature on the surface of components or layers that can be shortened locally. The main methods of surface heat disposal are flame quenching and induction heating disposal, common heat source oxygen acetylene and oxygen propane flame, induction current, laser and electron beam, etc.