Could the experts please take a look and see if the graphite gasket for my autoclave can provide a proper seal?
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I am currently conducting research at a university, where I designed an autoclave. Could you help me check if it can be sealed? . Temperature: About 280 degrees. Internal pressure: 40 MPa. A graphite gasket is to be custom-made in a conical shape with an inner diameter of 108 mm.
Is there nothing at the graphite gasket and the triangle area on the plug head?
Yes, nothing. Please advise on what improvements can be made.
For such high-temperature and high-pressure equipment, why is threaded fastening still used? It would be safer to use flange fastening along with metal gaskets for sealing, right?
Because this stainless steel kettle already exists. Only the titanium sleeve and sealing plug inside have been replaced
Is it a graphite molding ring? This structure is not recommended as the graphite gasket does not have sufficient strength ； Graphite rings are relatively brittle. With such high pressure, a rigid seal should be chosen.
If sealing is required, it can be done as long as there is sufficient sealing force; however, your design likely requires a lot of graphite
For high temperature and high pressure, metal gaskets should be used, right?
I always feel that there’s something wrong with this structure. If that seal area is also drawn according to the actual dimensions. The strength of the graphite gasket should be known (it is said online that even those with high strength have a strength of only 60 MPa, which is far lower than that of metal gaskets). You can do some calculations: with an internal pressure of 40 MPa and an external pressure of 0.1 MPa, using the thickness of the graphite gasket specified in your drawings, you can determine the stress experienced by the gasket, and thus calculate the safety factor. And you say that the graphite pad and the triangular area of the plug are empty; I think the graphite pad might break. At a pressure of 40 MPa/280°C, it is recommended to use metal gaskets. Vent holes should be considered at the threaded area.
Firstly, a conical graphite gasket will definitely be damaged if pressed down by bolts. Moreover, it is difficult for the flexible graphite and the titanium sleeve to withstand a pressure of 40 Mpa; as a result, the medium will leak upward along the outer edge of the gasket and the inner wall of the tank. Given that the operating pressure is medium, a male-female surface seal is suitable; for example, a groove can be created on the upper surface of the titanium sleeve, with a matching male flange cover placed on top (the pressure rating must be sufficient and the material must meet the required standards), and a graphite gasket can be used between the male and female surfaces. This should solve the problem.
Thank you all; the design has been further improved