Design for external pressure 1

[skasliwal]

Can somebody suggest the procedure to carry out external pressure design for temperatures outside the range of External presssure chart.
I have design temperature of 1130° F and the yeild stress values are not listed at such high temperatures in 2-D. I believe that is what is causing the problem in calculating B-factor. Can I use the minimum yeild stree value listed in 2-D to carry my calculations.

Any suggestions will be greatly appreciated.

 

[TomBarsh]

ASME UG-23(c) specifies that "design temperatures for vessels under external pressure shall not exceed the maximum temperatures given on the external pressure charts."

FWIW, the "Guidebook for the design of ASME Section VIII Pressure Vessels" gives a method for determining allowable longitudinal compressive stress (as for weight, etc) when the temperature exceeds that on the external pressure charts (the "B" factors are also used to determine allowable longitudinal compressive stress). See equation 2.25 in Section 2.3.

 

[TGS4]

Simply put - NO. If you can make a solid engineering case (such as the one TomBarsh mentioned) for the extension of the external pressure chart, then go ahead and request a Code Case. That's really the only way.

 

[TomBarsh]

CORRECTION: It is ASME UG-20(c) that temperature external pressure to the max temperatures on the external pressure charts, ***not*** UG-23(c).