Hi Richard,

I need to understand how the diffrerence between priciple stress equals to Bending.

For example

Max. Shear = (x1-x2)/2 where (x1= Max. Priciple stress and x2= Min. Priciple stress)


There fore Max. Shear = Bending Stress/ 2


Pls hlp me

Hello There,

In a pipe wall, any face will have a normal and shear stress components. The sum of the orthogonal stress components is always equal. SL+SH+SR=S1+S2+S3. So any complex stress on an element can be represented by the principal stresses (S1, S2, S3) and/or the maximum shearing stress (τmax) in Mohr's circle.
Hoop stress is positive and below yield due to wall thickness calculation and requirement. Radial stress (S3) is zero in outer surface of pipe where bending stress is maximum. On the other hand, in Mohr's circle 2τmax = SL = (S1-S3) or τmax = SL/2. Also, SL = Fax/Am + PDo/4t + Mb/Z. Hoop is not typically in the code equations, but is earlier used in pipe sizing and ignoring internal force (Fax) then SL = S bending.