Calculate pressure stiffening using Navy 505
Pressure stiffening is not defined by default in the Code. You can include pressure stiffening on bends in the analysis by including the parameter Use Pressure Stiffening in the setup file.
Flanged end modifications using Navy 505
Modifications resulting from flanged ends are permitted in the code providing the bend is not a widely spaced miter.
Navy 505 girth butt welds default value
The default SIF value for a girth butt weld is 1.0. This is also Markl’s original basis for SIFs.
Calculate effective section modulus using Navy 505
Navy 505 has no provision for using an effective section modulus calculation at intersections.
Calculate stress intensification factors (SIF)s for intersections using Navy 505
In-plane and out-plane SIFs for intersections are the same.
Calculate liberal allowable using Navy 505
Navy 505 has no provision for a liberal allowable, that is, adding the difference between Sh and Sl to the allowed expansion stress range. This feature from the control parameter spreadsheet has no effect on 505 runs.
Calculate cold and the hot allowable using Navy 505
Navy 505 uses longitudinal weld joint efficiency (Eff) to compute the cold and the hot allowable stress. The use of this parameter is subject to some speculation however.
Calculate the Navy 505 allowable for occasional loads
Navy 505 has no specific allowable for occasional loads. An occasional load factor (k), similar to the B31.1 code is used, and the occasional allowable calculated from kSh.
Calculate the Navy 505 allowable stress limits
Use the equations below to calculate the stress allowables.
Expansion Allowable = [f(1.25Sc + 0.25Sh)]/Eff
Sustained Allowable = Sh/Eff
Occasional Allowable = k*Sh/Eff
Where:
f = Cyclic Reduction Factor
Eff = Joint Efficiency (Not explicitly in the Code)
Sc = Cold Allowable Stress
Sh = Hot Allowable Stress
k = Occasional Load Factor, Defaults to 1.15
Use the B31.3 SUS Case SIF Factor option to multiply the SIFs for sustained and occasional loads to be more in line with the current B31.1 practice.