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Science Forum Index » Engineering - Joining (Welding) Forum » Re-drying E7018
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| Gunner |
 Posted: Mon Mar 24, 2008 3:28 am |
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On Mon, 24 Mar 2008 04:49:42 GMT, Grant Erwin
<grant@NOSPAMkirkland.net> wrote:
Quote: What Ernie says about old 7018 is simple. Pick a single rod at random. Bend it
until the coating falls off the bend. If the metal underneath is corroded, the
rod is too old to use for code work. If it isn't, it can be restored to code
quality by reheating.
I had lots of old non-code-ever-again 7018 which had coating falling off, white
powder everywhere, all the things people say make it useless. I welded it all
up, every bit. Lots of times the coating would sort of disintegrate and I'd get
a funky spot in a weld, so what? I'd sand it a little and paint it and it was
all a whole LOT cheaper than buying new rod.
Grant
Same here.
Gunner |
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| Richard Smith |
| Posted: Mon Mar 24, 2008 3:58 pm |
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Gunner <gunner@NOSPAM.lightspeed.net> writes:
Quote: On Mon, 24 Mar 2008 04:49:42 GMT, Grant Erwin
grant@NOSPAMkirkland.net> wrote:
What Ernie says about old 7018 is simple. Pick a single rod at random. Bend it
until the coating falls off the bend. If the metal underneath is corroded, the
rod is too old to use for code work. If it isn't, it can be restored to code
quality by reheating.
I had lots of old non-code-ever-again 7018 which had coating falling off, white
powder everywhere, all the things people say make it useless. I welded it all
up, every bit. Lots of times the coating would sort of disintegrate and I'd get
a funky spot in a weld, so what? I'd sand it a little and paint it and it was
all a whole LOT cheaper than buying new rod.
Grant
Same here.
Gunner
British perspective, where there's
- theoretical knowledge from welding engineers working with
petrochemical refineries, oil-rigs and the like
but
- in fab. shops and site welding people will use Rutiles (6013's)
however ridiculous, absurd, slow and uneconomic it is (no-one ever
ever ever uses cellulosic (6010, 6011) or Basic (7016, 7018) for
general welding)
Experience from the experienced is that indeed Basics (7018's) are
hygroscopic - they suck up moisture - and will max out at about the
moisture level of Rutiles (6013's) or maybe a little bit higher.
That is NOTHING if you are welding a fence from mild steel.
From my limited experience:
- properly from-day-one dried and rod-ovened 7018's burn with a clean
transparent arc and you see big clean blobs of metal transferring
across the arc to the workpiece (I've only seen this once).
- rods which are not kept like this have a dirtier misty arc and I am
told if I look again I will see they spark and spit more. But they
weld just fine and then there's the sledge-hammer test, which is the
big bad final arbiter - which says all is well.
I know that 7016 half-rods kept in my boiler-suit pocket for days
produce sound welds
In the US, humidity in summer East of the Mississippi River is very
high - know from experience you can keep a cigar in your shirt pocket
and it's just fine to smoke. Does this cause problems for 7018's?
I've never seen a 7018 with the white powder on the surface which some
mention.
Rich Smith |
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| Ernie Leimkuhler |
| Posted: Tue Mar 25, 2008 1:15 am |
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In article <_vmdnSpRbON4PnvanZ2dnUVZ_vqpnZ2d@centurytel.net>,
"Alan Andrews" <no-spam@foobox.com> wrote:
Quote: Some time ago I purchased a 50# box of E7018 Hobart electrodes. I'm not a
professional welder, nor do I have occasion to do that much welding, which
means that I had an open box of low hydrogen exposed to atmospheric humidity
for quite some time, like a year.
I'm in the midst of building a custom steel fence on the front of my
residence property and some of the welding will be done with low hydrogen.
At the local welding supply I mentioned in passing the story about the
opened rods and asked if low hydrogen rods actually "got old," like I'd
heard for ever. They indicated that they did indeed degrade, such so that
they couldn't even be reconditioned in an oven.
When I got home I called Hobart and spoke with a technician who said that
once low hydrogen was exposed to the atmosphere, it immediately started
*irreversibly* degrading, and that, yes, re-drying them in an oven didn't
help. I said that that would seem to indicate that a chemical reaction had
taken place (with what I thought was rather inert inorganic material
(rutile, for instance)) and he, sorta handwavingly (if that's a word) said,
yeah.
To confuse and confound the question, I found a document on the Web from
Lincoln Electric that indicated that Lincoln E7018 could indeed be reclaimed
by drying in an oven (http://www.jflf.org/pdfs/papers/fabguide.pdf, p. 7).
So...what IS the story on storing an open quanity of 7018 for protracted
periods, in out of the weather (my garage, for instance), but nonetheless
exposed to Southern-style humidity.
Thanks,
Alan
The rule I have worked by is that unless the rod was soaking in water,
(which will break down the binders in the flux), you can usually bring
the rod back to usefulness.
However,the first test to see if the rod can be salvaged is easy.
Take a sample rod, or a few, and bend it in a tight "U" shape until the
flux breaks off.
If thew wire inside is rusted, trash it.
If the wire is OK, then roast it.
Lincoln has the PDF about roasting in an oven for a long period. |
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