How to determine the pretightening force of double cone ring sealing surface studs

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When manufacturing a device with a double cone ring sealing surface, it was found that the stud preload force used on the double cone ring sealing surface in the drawings provided by the design institute was much smaller than the stud preload force of other forms of sealing surfaces. It can be understood here because the double cone ring is a self-tightening seal after all and does not rely on the stud pre-tightening force for forced sealing. However, the stud pretightening force given in the drawing is not equal to the main bolt pretightening load Wa of the biconical ring calculated according to Appendix C in GB150.3, which is about 2.6 times the main bolt pretightening load Wa. Please enlighten me on how to consider the preload force of the biconical ring in the design and how to accurately give the value of the preload force.