I don't exactly know where it came from, I'm old but not that old, but I have come across it. I guess old technology did not provide for adequate welds at one time with this process. But things are changing, equipment, consumables and personnel are getting better, now there is just the culture to catch up with it. Attitudes will have to change and "old specifications" will have to be brought into the present. But remember not every process is the best for every situation.
Depending on who the engineer is and his attitude, would you be able to change their mind. It can happen, we've done it, but you have to have the evidence to show them. It will take "qualifying" the procedures, obtaining data from the equipment and material manufacturers and providig test records and affidavits. We went as far as extending our warrenty on the work to help the change.
i believe that was nr211, and it was never rated for what it was used for.
Hello hogan, I believe you are correct about the NR211, it is considered a single-pass only electrode. There was a fabricator in my area who welded about 60 tons or so of structural steel with it and then sent it to a job site in Portland; my understanding was that the pinging could be heard as they were loading it on the truck. They also received all of it back and half the city went dark as the air arcing progressed. I still don't understand why they were using self-shielded in a shop environment. Best regards, Allan
"...and half the city went dark as the air arcing progressed"
Coffee just shot out my nose!
but we have always used this wire. why is it not ok now?
I'm not sure about the multi pass question, but i believe that it has always been limited to 1/2" material
Hello Gerald, I just looked at the latest Lincoln information in their 2008 catalog, it doesn't say anything about multi-pass limitations, it does say something about thickness limitation, up to 1/2" maximum with any wire diameters above .045 dia., .045 dia. limited to 5/16" thickness. I believe I have an old catalog somewhere where it does comment on the limitation to single pass application only, I'll try to find that one just to satisfy my own curiosity. Best regards, Allan
I was working for a company back in the early 90's that used this wire on some parts and I am pretty sure I looked into it then. The 71T11 didn't have a restriction on multiple passes but I am not sure if I remember that from Lincoln literature or the AWS filler metal spec.
One thing I did know is that it was nearly impossible to weld over the Self Shielded FCAW deposit with GMAW or GTAW. Even SMAW had increased porosity .
I though of the 71T11 and a never ending 6010. It had a place but required caution. I think you get better impact from 6010.
Thanks Gerald, it is likely I had one of those brain-farts again and didn't remember correctly. Allan
They say when you're welding thicker than 1/2" you should move to NR212. I love my fluxcore wire for most anything and everything low carbon steel. I have been using NR211 for 12 years now almost exclusively. What a great way to go! Pipe - structural steel beams - anything. It rocks! If someone tells you you can not weld pipe with nr211 then they are lying to you. Good rule of thumb to stay below 1/2" though.
Also, if I remembering correctly, the thickness limitations were related to the wire diameter. The restriction is due to buildup of various elements in the weld metal from the flux.
Though I like welding some things with E71T-11, I have had issues welding over it with other processes. That can be a pain.
There seems to be a lot of confusion in regards to 211, by inspectors and fabricators. Like all filler metals it has it place. It is always best to follow the manufactures recommendations. It is allowed to be used, but it has more restriction that most CS wires.
Allen,
To save money on gas of course. :)
I believe that must have been it! Regards, Allan
Martin,
I would agree wholeheartedly that regardless of data or success there is no replacing welding engineering. But this is not an indictment of the process as a whole.
For example:
Yo don't use bismuth containing fluxes for FCAW of SS's in high temp service.
You don't use acidic fluxed FCAW for toughness or cryo regimes.
And the opposite you wouldn't want to use a basic fluxed wire for less than pristine plate.
As you indicated, you don't use single pass wires for multipass applications.
You would need to limit FCAW for overlays due to high arc density and high dilution.
The varieties of limitations are endless, but they are not an indictment of FCAW as a whole.
sorry all,
my memory failed to serve me like I was tryin' for -I miss referenced the electrode type and for credibility of the source you judge for yourself, here's the link
http://www.weldreality.com/north%20ridge%20earth%20quake%20story.htmTo js55 I wasn't bad mouthing FCAW self shielded or gas shielded or even metalcore, I was just trying to point to a possible suggestion for original posters' question.
Martin,
I didn't put it very well.
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