"(HE) on simple structures"
Question:
"My concern of (HE) is of a low tech but very common practice, that is of welding of bar joist toA572 grade 50 I-beams. I have been observing many welds being welded with E7024 electodes. AWS requires low hydrogen rod. Erector use these rod for economic reasons, ie;speed&rod ovens are not required. My concern is when these joist are loaded to the max with snow load or heavy rain. Most roof systems are redundant with at least two inches of 3/16" fillet each end, bridging and deck welds as a system. I have not seen any studies or case history, can you help me out."
Answer:
There is a large body of evidence pertaining to fasteners, which suggests that, in atmospheric service, a reasonable hardness break point between cracking due to hydrogen embrittlement (HE) and not cracking due to HE is approximately 35-38 HRC. If one can apply the same rationale to your structural steel example, which I believe that one can, then I would not expect hardnesses of that magnitude resulting from welding A 572 Gr. 50 steel using E-7024 welding electrodes.