The following appears while using AutoPIPE:
* * * W A R N I N G - MODEL * * * W2164-78: D/t ratio for the following pipe ID(s) is less than 20. The hoop stress equation may not be applicable for these pipe IDs as per B31.4. Use Model Result Option Y factor to control hoop stress equation.
What piping code and year are listed on the General Model options dialog? Review the specific code to see if there is a D/t ratio restriction.
Piping code and year are ASME B31.4 - 2016, find in section 402.3 Stress from internal pressure:
As mentioned above, this is a Warning that the user should be aware of and to take any steps mentioned in the message to address it. At this time, the warning will not go away while the ratio of D/t is less than 20. Only options are to ignore the message or change the ratio by changing one or more of the values in the ratio calculation (ex. D (nominal outside diameter of pipe) or t (the nominal wall thickness)).
Warnings Messages displayed in AutoPIPE