A656 Grade 60 and 70

[HakiNoir]

Hi folks,

We manufactured penstock pipes made of A656-12 Gr 60 Type 7. They have flaring (by mechanical deformation) at the ends for assembly and been delivered to the customer on spec but after a while the very tip (bell)part of the penstock was sinked back in and went out of tolerance (shrunk 1-3 mm in diameter). Usually we use A572 Gr 50/60/65 for penstock and never had this issue. I am wondering if anyone has a clue on this?

I checked the A656-13: apparently S, Mn and N content has been revised from A656-12. Not sure this might be a smoking gun!
Appreciate if you can share your ideas/experiences!

Thanks,

 

[metengr]

The "sinked in" description sounds to me local like plastic deformation. What caused this? Either excessive force or the wall thickness may have been to thin for the application. What you have stated regarding chemistry would not be applicable.

 

[HakiNoir]

@metengr: Thanks for your input. There is no local warp or distortion on the OD/ID; maybe I`d better called it shrinkage. I will check the wall thickness.