Regarding the sealing and leakage issues of the waste boiler
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What is the best type of sealing for the flanges and gaskets of waste boiler drums operating at 3.5 MPA? Is it feasible to use a gasket with a concave-convex surface along with a graphite inner ring? There are quite a few leaks in our trapezoidal steel pads.
A male and female face is used for the flange, while metal wound gaskets or graphite gaskets are used as shims.
:Handshake: Octagonal gaskets should be used for handshakes. The waste heat boiler I am responsible for is also 3.5 MPa, and octagonal gaskets are used there as well. These gaskets provide linear sealing, but when replacing them, it’s important to allow a slight leakage at low temperatures; this way, the leakage points will disappear as the temperature rises. On another note, tightening the flanges properly requires expertise – it’s necessary to maintain a balanced stress on the gaskets, and this needs to be done by a fitter with sufficient experience. Additionally, when the temperature reaches a certain level, thermal tightening is required, and regular inspections for leaks are also necessary. By following these steps, I believe leakage problems can be minimized. The above are my personal views; please correct any mistakes. :handshake
The drum temperature at 3.5 MPa is around 249 degrees, and no steel gasket is required. We have been using high-strength asbestos boards, and the results are good. High-strength graphite should work as well. The key is to clean the flange surface thoroughly to ensure it is smooth. The manholes on the steam drum are all accessed from the inside; logically, the higher the operating pressure, the greater the sealing force.
A male-female face is used for the flange, and a metal wound gasket is used for the gasket. For areas where leaks occur frequently, use disc springs; Ai Zhi is recommended
An operating pressure of 3.5 MPa – using gasketing is only just sufficient; copper gaskets are preferable as they have good ductility and allow for easy re-tightening in the event of a leak. The downside is their high cost. Graphite gaskets do provide excellent sealing properties, but they lack strength and are prone to damage; once a leak occurs, the gasket must be replaced as it cannot be reused. It’s better to choose flanges with male and female surfaces
Our unit is also a 3.5 MPa waste heat boiler, which uses octagonal gaskets.