Code of Federal Regulations Title 49. Transportation § 49.179.400–8 Thickness of plates

(a) The minimum wall thickness, after forming, of the inner shell and any 2:1 ellipsoidal head for the inner tank must be that specified in § 179.401–1, or that calculated by the following formula, whichever is greater:

t=Pd/2SE

Where:

t=minimum thickness of plate, after forming, in inches;

P=minimum required bursting pressure in psig;

d=inside diameter, in inches;

S=minimum tensile strength of the plate material, as prescribed in AAR Specifications for Tank Cars, appendix M, table M1 (IBR, see § 171.7 of this subchapter), in psi;

E=0.9, a factor representing the efficiency of welded joints, except that for seamless heads, E=1.0.

(b) The minimum wall thickness, after forming, of any 3:1 ellipsoidal head for the inner tank must be that specified in § 179.401–1, or that calculated by the following formula, whichever is greater:

t=1.83 Pd/2SE

Where:

t=minimum thickness of plate, after forming, in inches;

P=minimum required bursting pressure in psig;

d=inside diameter, in inches;

S=minimum tensile strength of the plate material, as prescribed in AAR Specifications for Tank Cars, Appendix M, Table M1, in psi;

E=0.9, a factor representing the efficiency of welded joints, except that for seamless heads, E=1.0.

(c) The minimum wall thickness, after forming, of a flanged and dished head for the inner tank must be that specified in § 179.401–1, or that calculated by the following formula, whichever is greater:

t=[PL(3+ √ (L/r))]/(8SE)

Where:

t=minimum thickness of plate, after forming, in inches;

P=minimum required bursting pressure in psig;

L=main inside radius of dished head, in inches;

r=inside knuckle radius, in inches;

S=minimum tensile strength of plate material, as prescribed in AAR Specifications for Tank Cars, appendix M, table M1, in psi;

E=0.9, a factor representing the efficiency of welded joints, except that for seamless heads, E=1.0.