3.1.1 The minimum thickness of a spherical shell is to be determined by the following formula:
where t, p, R i, c, σ and J are as defined in Pt 5, Ch 10, 1.2 Definition of symbols.
3.1.2 The formula in Pt 5, Ch 10, 3.1 Minimum thickness 3.1.1 is applicable only where the resulting thickness does not exceed half the internal radius.
3.1.3 Openings in spherical shells requiring compensation are to comply, in general, with Pt 5, Ch 10, 2.5 Reinforced openings, using the calculated and actual thicknesses of the spherical shell as applicable.