Number of Bolt in tension for Saddle base plate on ASME vessel

[scorpio2310]

Hi guys
For a ASME Pressure vessel, The design software PV Elite suggest to maintain number of bolt in tension = 0.5 x Total Bolts in base plate.
Is any theory behind why we have to give one out of two bolt in tension?

Thanks

 

[MJCronin]

What did the PVElite people tell you when you called them ?

MJCronin
Sr. Process Engineer