Pressure Vessel

In skirt opening calcaulation skirt vent calculation

Skirt Opening Reinforcement Summary
Required
Thickness
tr
(mm)
AT
(cm2)
Ar
(cm2) Ratio Status
Operating Hot & Corroded
Wind Tensile 0 15.8675 0 N/A OK
Compressive 3.6 9.9175 1.8429 5.3816 OK
Seismic Tensile 0.89 19.6656 0.9295 21.1571 OK
Compressive 5.42 6.9247 2.7698 2.5001 OK
Operating Hot & New
Wind Tensile 0 20.0622 0 N/A OK
Compressive 3.27 14.2041 1.6723 8.4939 OK

Seismic Tensile 0.9 23.4971 0.94 24.9957 OK
Compressive 4.94 11.2191 2.5244 4.4443 OK
Empty Cold & Corroded
Wind Tensile 0.44 20.6311 0.462 44.654 OK
Compressive 2.01 12.5415 1.0302 12.1743 OK
Seismic Tensile 0.41 20.7127 0.4225 49.0229 OK
Compressive 1.94 12.6613 0.993 12.7503 OK
Empty Cold & New
Wind Tensile 0.43 24.5062 0.4515 54.2818 OK
Compressive 1.84 16.7643 0.9414 17.8074 OK
Seismic Tensile 0.42 24.5432 0.4335 56.6102 OK
Compressive 1.81 16.8175 0.9263 18.1563 OK
Field Test Corr Wind Tensile 0 15.8675 0 N/A OK
Compressive 3.12 10.7123 1.5967 6.7091 OK
Field Test New Wind Tensile 0 20.0622 0 N/A OK
Compressive 2.84 14.9791 1.451 10.3231 OK
External Pressure Hot & Corroded
Wind Tensile 0 15.8675 0 N/A OK
Compressive 3.6 9.9175 1.8429 5.3816 OK
Seismic Tensile 0.89 19.6656 0.9295 21.1571 OK
Compressive 5.42 6.9247 2.7698 2.5001 OK
Note: Skirt required thickness of zero on tensile side indicates load is compressive.

plz explain the under condtion which applicable on the field test new and field test corr. why tensile thickness is zero here.