The only thing I find is the time-honored "10% of set pressure".  I know this is the typical value to prevent capacity/stability problems in conventional SV's, but I'm not convinced it is appropriate for ASME Section I.
Section 1 check valves have open bonnets.  ANy backpressure will vent through the spring and likely constitute a hazard, or at least a mess.
Section VIII valves frequently have closed bonnets. Constant backpressure (example 100 psi set with 20 psi backpressure)superimposes its value upon the set pressure, but can be accomodated by setting the valve for, in this example,  80 psi; the differential between set and backpressure. 
Safety-relief (SecVIII) valves expecting to see VARIABLE back-pressure would be specified with a bellows.  The bellows effective area is the same as the disc, and the bellows is vented to atmosphere.  Therefore, variation in back pressure does not superimpose on the set pressure. The valve sees the difference between the process pressure and atmosphere at all times.

MORE NEWS