By -
Date 07-18-2001 18:57
I can only agree with Gerald. I believe that the "Building Department" has some preference for the SMAW process. This may be due to some typical problems that have been experienced by using FCAW in the past. These problems being lack of impact strength and ductility.
These problems can be caused by using too high a heat input (very easy in the case of FCAW) or by using a "single pass" (Maintenance) wire when performing multi pass welds.
Often, people think that the lack of fusion problems typical of Dip-Transfer GMAW is also a problem with FCAW.
Your approach would not be to convince them of the strength of the wire, but rather that you have suitable procedures qualified, and that you have good quality control on the job when using FCAW.
Hope this helps
Regards
Niekie Jooste
Very often, drawings and specs will call out E70XX electrodes to be used for a project because the specifier really doesn't know what they want. They do know they want everything to hold together and that electrodes should be compatable with the base metal. And they know that E70XX has been specified on many jobs that worked out fine.
It sounds like, in your case, someone does know a bit about the subject and probably had a bad experience or two. E71T-X (FCAW) is a good process for speeding up production as you undoubtedly know. It is also easy to make a lot of bad welds fast. GMAW is another popular alternative to SMAW(E70XX) and, again, it is easy to run a lot of bad welds before you know it. Whoever wrote that spec just wants some assurances that whatever process and electrode is used will work as expected.
FCAW is prequalified per D1.1 so you might not have to run tests if you can comply with prequal requirements. (I am assuming D1.1 because you mentioned "building department" and that code is most often used for buildings.) Possibly, you may need to run some fillet tee tests or similar instead of PQR tests. Either way, if you have all your welder quals and other information in order you should not have a hard time gaining approval.
Hope it goes well,
CHGuilford
In my experience with architectural and engineering firms that design structural steel for buildings, the specifications often call for using only E70XX electrodes, whether they mean it or not. It seems that they use it as a generic way to specify 70ksi tensile strength weld metal. It becomes obvious when they call for E70XX electrodes and then specify some limitations for wire feed welding that they don't think D1.1 covers adequately. Obviously, you wouldn't be using E70XX rod while wire feed welding, but that is what they put. The designers usually have thier own generic specifications book that was written when SMAW was the only process used in construction, that only gets updates when neccessary, so some of the terminoligy sticks with it.
Possibly the building department for your area wrote this stipulation because some engineers really mean to use the E70XX electrodes, and some don't. Then all it would take is a RFI to the engineer to clear this up. In my experience though, it is usually pretty easy from the rest of the specifications to tell if they really meant it.
So it would seem from your original inquiry that the engineer of record, not the building department, is the one that you really need to convince, if he really means to use E70XX welding rod, that your wire procedures are up to the job.
It sounds like some one is trying to bring up a very old worn out discussion concerning 7018 Up Hand and 7018 Down Hand, Oh bother! 
