A sealing element for a fitting part includes a top section. The top section includes a first surface configured to bear against an outer face of an annular groove of the fitting part and a second surface intersecting the first surface at a first angle. The second surface is configured to bear against a bottom face of the annular groove of the fitting part. The sealing element also includes a bottom section. The bottom section includes a third surface intersecting the second surface at a second angle. The third surface is configured to bear against the bottom face of the annular groove. The bottom section also includes a fourth surface intersecting the third surface. Furthermore, the sealing element includes an indentation formed at an intersection between the second surface and the third surface. The indentation provides a transition between a first width of the top section and a second width of the bottom section. Moreover, the second width is greater than the first width. Additionally, the sealing element extends as a continuous structure along a circumferential axis such that a conical plane of the sealing element is oriented at a third angle to a longitudinal axis of the fitting part.