Minimum Allowable Temperature considering flanges

[kevlar49]

If a vessel has flanges made to ASME B16.5, does that limit the Minimum Allowable Temperature (mat) to -20 F regardless of the temperature reduction credit provided by Figure UCS 66.1? For example, if a vessel has an MDMT at 32 F but operates below its design pressure such that a temperature reduction of 60 F is allowed (mat=32-60=-38F). Would the mat have to be limited to -20F instead?

 

[metengr]

As long as the flange material of construction is one of the materials listed in UCS-23, you can use Figure UCS-66.1 for impact test exemptions including the temperature reduction.

 

[TomBarsh]

I'm "away from my desk" at the moment, but I believe that the relevant paragraph is UCS-66(b)(1)(b) for the reduction ratio, then use Figure UCS-66.1 for the reduction temperature as metengr says.