Fabrication of HPS 50W & 70W steel bridges 1

[71corvette]

Hi All,

AASHTO's "Guide specification for highway bridge fabrication with HPS 70W Steel", 2nd edition, Section 4.02 states the following:

"Only fabricators meeting the requirements of hte AISC Quality Certification Program, Major Steel Bridges (Cbr) with Fracture Critical Endorsment (F), or Engineer-approved equal, may fabricate with HPS 70W steel."

Can someone shed some light the the need for the "Fracture Critical Endorsement" for fabrcation with HPS 70W? I can understand the Cbr requirement, but I'm not quite clear as to why all fabricators are required to hold a fracture critical endorsement.

Also, do these same requirements apply to fabrication with HPS 50W steel?

Thanks,
Tim

 

[bridgebuster]

This is a requirement of Section 12 of AWS D1.5, Bridge Welding Code

 

[HgTX]

[Disclaimer: I am NOT a member of the committee that wrote the HPS guide.]

My understanding is that the FC endorsement was required as a means of limiting HPS 70W handling to those who have formally demonstrated ability to comply with the FC consumable handling provisions, which are required by the HPS guide (Appendix A, section 3.03.A) for both FC and non-FC work. See section 1.1 of the main body of the guide.

My personal assessment is that there is no reason to apply this requirement to HPS 50W. HPS 50W doesn't require any more special handling than regular Gr. 50W, and doesn't have any special reduced preheat provisions like HPS 70W which would require special attention (beyond the usual bridge standards) to the electrode hydrogen level.

Hg

Eng-Tips policies: faq731-376