Calculation of Circumferential Bending Strength of Ductile Iron Pipe

For ductile iron pipes, the strength of the pipe material should meet the stress requirements of the pipe wall only under the action of external loads.
The hoop bending strength of ductile iron pipes shall meet the requirements of the following formula:
KrRf≤Rmax
In the formula
Kr — hoop bending strength coefficient of ductile iron pipe, 1.5;
Rf—— hoop bending strength of ductile iron pipe, MPa;
Rmax—-The maximum allowable hoop bending strength of ductile iron pipe, 500MPa.
The hoop bending strength of ductile iron pipes can be calculated according to the following formula:

In the formula
∑P——vertical load acting on the pipeline, MPa;
DE—–outer diameter of socket, mm;
emin —– minimum wall thickness, mm;
Kb —– bending moment coefficient;
Kx —– deformation coefficient;
E —– the elastic modulus of the pipe, MPa, E=170000MPa;
E’—–The reaction modulus of the backfill soil on the side of the pipe, MPa.