The maximum allowable stress value is the maximum
unit stress permitted in a given material used in avessel constructed under these rules. The maximum allowable
tensile stress values permitted for different materials
are given in Subpart 1 of Section II, Part D. Section II,
Part D is published as two separate publications. One publication
contains values only in the U.S. Customary units
and the other contains values only in SI units. The selection
of the version to use is dependent on the set of units selected
for construction. A listing of these materials is given in
the following tables, which are included in Subsection C.
For material identified as meeting more than one material
specification and/or grade, the maximum allowable tensile
stress value for either material specification and/or grade
may be used provided all requirements and limitations
for the material specification and grade are met for the
maximum allowable tensile stress value chosen