huangyhg

low hydrogen welding rods vs. mild steel eletrodes
i have a job site where the welder was welding the steel (joist seat welds, joist bottom chord to columns) with e7024 mild steel electrodes. we specify e7018 low hydrogen electrodes. i don't have enough of a background in welding knowledge to tell if this is a problem or not. the e7018 are recommended by the manufacturer for structural applications while the e7024 are recommneded for use on construction equipment, ships, and railcars. does anyone have experience in what kind of problems this can have?
yes, the e7018 is a low-hydrogen, mild steel electrode, and can be used in all positions. the e7024 is commonly called a "jet rod" and is used for general purpose, high deposition welding in the flat or horizontal position. it is commonly used in the shop, but less so in the field.
if you insist on e7018 electrodes, make sure that the welder's certification is appropriate and that the rods are kept in a "rod oven" (or at least a closed container) so that moisture is not absorbed by the flux coating (negates the low hydrogen quality).
low hydrogen electrodes are specified so as to minimize the effects or potential of hydrogen embrittlement of the weld cause when hydrogen diffuses into the weld metal. it is less of a problem in typical mild steels subjected to static loading than say, a bridge application.
in any case, make sure the welder is qualified and certified to weld the materials and positions demanded by the project.
from a welders point of view, i find it difficult to understand why the contractor is using jet rod. not the proper application at all from a labor/cost effective point. i've welded a few joists with 7018 (in the earlier years with 6010) but never with 7024! that was many years ago, perhaps 7024 has gotten easier to handle today.....doubt it!
rod
not exactly your question, but does your contract say anything about having a cwi (certified welding inspector) to supervise welding? my biggest concern after reading your post is that you may out of position welding going on without the proper consumables.
the specifications require certified welders as well as certified welding inspectors.
whir...just because the specs require them doesn't mean you'll get them! ask for them and then check them against aws requirements (assuming you are in the states...otherwise check your local or regional welding code requirements)
rod...i agree. e7024 is not the right electrode for this application. jet rods are fine for shop long welds in the shop but are miserable for start/stop work like clip angles.
i wouldn't have any problems welding with a low hydrogen electrode. its a better stronger weld. maybe requires a bit of extra welding skill but its a great weld.

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