Now I'm working at a model under B31.4.
You know the stress of OPE,SUS,EXP have allowable stress at B31.4.
But why not check the OPE W+T1+P1 under the result options of "code compliance" ?
The program said as follows
**** NO CODE COMPLIANCE CHECK DONE

HIGHEST CODESTRESS RATIO IS 0.0 AT NODE 1

LOAD CASE: CASE 2 (OPE) W+T1+P1



CASE 2 (OPE) W+T1+P1 DATE:MAY 25,2005
**** NO CODE STRESS CHECK PROCESSED
PIPING CODE: B31.4 -2002, October 4, 2002

HIGHEST STRESSES: ( KPa )
OPE STRESS: 232894.5 @NODE 110
BENDING STRESS: 166658.3 @NODE 30
TORSIONAL STRESS: 1666.5 @NODE 2050
AXIAL STRESS: 132496.5 @NODE 10
HOOP STRESS: 268643.8 @NODE 20
3D MAX INTENSITY: 279794.4 @NODE 40


Thanks for your help!

And I updated the program use the latest software of Build 050407 at this website.
Is it a bug?

Nope, not a bug. B31.4 defines an allowable for the OPE case only if the pipe is in compression. If your pipe elements are not in compression there is no code compliance performed.