Properly reinforced openings in cylindrical and
conical shells are not limited as to size except with the
following provisions for design. The rules in UG-36
through UG-43 apply to openings not exceeding the following:
for vessels 60 in. (1 500 mm) inside diameter and
less, one-half the vessel diameter, but not to exceed 20
in. (500 mm); for vessels over 60 in. (1 500 mm) inside
diameter, one-third the vessel diameter, but not to exceed
40 in. (1 000 mm). (For conical shells, the inside shell
diameter as used above is the cone diameter at the center
of the opening.) For openings exceeding these limits, supplemental
rules of 1-7 shall be satisfied in addition to the
rules of this paragraph. Alternatively, openings in cylindrical
or conical shells exceeding these limits may be designed
for internal pressure using the rules of 1-10. [See UG-
36(c)(2)(d).]