A106 Pipe Fatigue Limit

[danastructural]

Does anyone have any information regarding the fatigue limit of A106 pipe material (grades B&C)? Is there any difference between A53 and A106 material in relation to cyclic loads?

 

[YLWEA]

This is only a partial answer, but the actual mechanical properties often do not resemble the minimum specified properties (in our experience)so it is difficult to predict what the fatigue performance will be based on grade alone. The specified minimum yield strength of grade B pipe (either A53 or A106) is 35 KSI, but we have seen many test reports for heats of grade B pipe with actual yield strength above 60 KSI. The other consideration is whether the seam properties in some A53 pipe will or could impact your fatigue performance, even if the base metal is comparable to the A106 product.

 

[metengr]

If you have a problem with obtaining actual S/N curves for this material, I would use the following for comparison;

the endurance limit at 1E6 cycles under reverse bending of carbon or low alloy steels is generally 50% of the ultimate tensile strength of the material. The estimated endurance limit will get you in the ball park for comparison between materials of similar composition.