hi

momentarily, I am working on a 24in line connecting to a huge Tank, I am trying to check the loads of the nozzle of the tank using API650 appendix P nomograms. I have got my axial force + longitudinal moment within the boundaries but checking the Fr+Mc, I am not quiet sure what the bottom boundary is. is it the x axis? or any minus value still within the tilted lines is also acceptable?

regards