NFPA 68

[sme75]

Lets say one has a bin with set dimensions and vent area. NFPA 68 can then be used to determine a value for Pred that allows the design conditions to work. Now what is the design pressure that should be used for the bin? Assume that deformation of the bin is not allowed. According to 6.3.1.2 Pred should be less than 2/3 of the yield strength of the enclosure. According to 6.3.2.2 Pred should be less than 2/3 of the enclosure strength, Pes.

Should the design pressure be set equal to Pred and the allowable stress values used in the bin design be limited to a miximum of 2/3*Fy?

Should the design pressure be set to 1.5*Pred and the bin designed using Fy for the allowable stresses?

Should the design pressure be set to 1.5*Pred and the bin designed using typical allowable stresses per whatever code is used?

Should the design pressure be something else? Any thoughts would be appreciated.

 

[psafety]

SME,
Pred should be less than 2/3 of the yield strength of the enclosure.

The design pressure could be much greater, the key is assuring during the vent the reduced pressure does not deform the vessel.