§ 154.447 — Allowable Stress

(a) An independent tank type B designed from bodies of revolution must have allowable stresses

3 determined by the following formulae:

3 See Appendix B for stress analyses definitions.

σm≤f

σL≤1.5 f

σb≤1.5 F

σL + σb≤1.5 F

σm + σb≤1.5 F

where:

σm = equivalent primary general membrane stress

4

4 See Appendix A for equivalent stress.

σL = equivalent primary local membrane stress

4

σb = equivalent primary bending stress

4

f = the lesser of (σB/A) or (σY/B)

F = the lesser of (σB/C) or (σY/D)

A, B, C, and D = stress factors in Table 2.

Table 2—Values for Stress Factors

(b) An independent tank type B designed from plane surfaces must have allowable stresses specially approved by the Commandant (CG-ENG).