Longitudinal stress criteria for dimentionning an offshore pipeline

[mimouscha]

Hello, I've been trying to handle a project in which I should determine the wall thickness of an offshore pipeline.
I've done this study according to ASME 31.4
In this norm after calculating the wall thickness we should verify three criterias: hoop stress criteron, longitidunal stress criteron and combined stress criteron.
My problem is with the longitidunal stress criterion. I didn't know how to determine the axial forces, in-plane bending moment and out-of-plane bending moment in the equations Page 12 in the ASME 31.4 Norm
Can anyone help me please?
Thnx

 

[BigInch]

When looking at a pipe laying on the ground and curved in one plane only, an in-plane bending moment's deformation will change the radius of the curve. The out-plane bending moment will add a new bend radius perpendicular to the in-plane curvature, ie. a curve in the vertical plane. The last moment causes torsion about the axis of the pipe in whatever plane it happens to be in at the time.

Independent events are seldomly independent.