1. With the increase of the axial tension of the nozzle, the maximum stress, film stress and primary stress + secondary stress in the connection area of the flat head double-opening nozzle continue to increase; as the axial thrust of the nozzle increases, the flat head double-opening nozzle The maximum stress, film stress, primary stress and secondary stress in the connection area are continuously reduced.

　　2. Under the combined action of the axial load of the nozzle and the internal pressure, the influence of the axial load of the nozzle on the elastic stress of the connection area of the double-opening nozzle of the flat head is partial. Appropriately increasing the axial thrust load of the nozzle can effectively reduce the double-opening of the flat head The elastic stress concentration effect caused by the structural discontinuity in the connection area of the hole nozzle. The influence of internal pressure on the elastic stress in the connection area of the double-opening nozzle of the flat head is global, but the influence on the connection area of the nozzle and the head is more significant.

　　3. The internal pressure and the axial load of the nozzle have significant effects on the ultimate load of the double-opening nozzle structure of the flat head. The axial thrust of the nozzle can effectively improve the ultimate pressure-bearing capacity of the nozzle area, and with the increase of the axial thrust, the ultimate internal pressure of the joint area of the flat head double-opening nozzle continues to increase. The axial tension of the nozzle will reduce the ultimate pressure bearing capacity of the connection area of the double-opening nozzle of the flat head, and with the increase of the axial tension of the nozzle, the limit internal pressure of the connection area of the double-opening nozzle of the flat head will continue to decrease.

　　4. The linear elastic finite element method can be used to draw the ultimate load relationship curve of the connection area of the flat head double-opening nozzle, which can guide the design and safe operation of the flat head double-opening nozzle structure pressure vessel.