G'day all

I'm doing a Lap-joint flange stress checking using Caesar II, (with 3.2mm spiral wound gasket). In the calculation result, I come up with negative tangential stresses as below:

CALCULATED STRESSES ( KPa )

OPERATING ALLOW SEATING ALLOW
--------- ----- ------- -----

Longitudinal Hub .. 161 206843 480 206843
Radial Flange ..... 49153 206843 146620 137895 *
Tangential Flange . -2899 206843 -8646 137895
Maximum Average ... 24657 137895 73550 137895
Bolting ........... 48170 258553 123469 172369

So how to interpret the negative stress values in the calculation. Or are there any input mistakes in my input? The FLG file and claculation report were zipped and attached as below.

Thanks very much.

Why did you consider hub length for this lap joint flange? Refer ASME Section VIII div-1, Appendix-2, section 2.7. you might get better understanding on the tangential stress with respect to radial stress .