A steel pipe of 12-in. outer diameter is fabricated from 14-in.-thick plate by welding along a helix that forms an angle of 258 with a plane perpendicular to the axis of the pipe. Knowing that the maximum allowable normal and shearing stresses in the directions respectively normal and tangential to the weld are s 5 12 ksi and t 5 7.2 ksi, determine the magnitude P of the largest axial force that can be applied to the pipe.