Re-drying E7018

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Date

03-23-2008

Posted by Private on March 24, 2008, 1:08 am

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> "...or white powder deposits on the coating."
>
> Funny you should mention that. They DO have a white powdery residue on
> them. That's bad, I take it?

The exact chemistry of rod coatings is a bit beyond my knowledge but I have
noticed that rods that have been exposed to a lot of humidity often have a
white powdery residue that can often be wiped off with a glove. I suspect
it is from some coating substance that is leaching out due to moisture or
humidity. I have successfully used old rods that I have re-dried in a
kitchen range and while some did have a small amount of white residue, it
was not excessive and they were not used in critical applications.

I would suggest you dry some rods and do some test pieces to check for
weldability and porosity. Make a smallish weld on thick plate and break it
by bending with a long lever, this can often show porosity on the failure
line. For your fence job I would not be too concerned as long as the rods
burn OK and show no surface porosity. You can use good joint design and a
little more weld to add some allowance for reduced strength.

IMHE most failures of general fabwork are due to poor prep work, rusty
steel, poor joint design or just plain lack of operator skill. Most bad
rods make welds that look bad both as they are made and in post weld
appearance. Bad rods will exhibit coatings that bubble above the arc as
they are heated or do not burn off evenly and exhibit excessive
fingernailing or chunks of coating popping off as the rod is burned. It
sometimes acts like a bad case of arc blow. Bad rods are often very sticky
and the flux will fall off as the rod is bent to free the sticky end. they
can also cause excessive spatter. All these symptoms can have other causes
and most can also be found with new rods.

We all end up doing much of our general non-critical work with rods that
have not been stored to the standards required by critical work. I prefer
to buy rods in boxes that are sub packaged in 5 or10 lb sealed boxes and
open a new box when doing critical work. when I need to buy a big can of
rods I can often get my supplier to repackage the rods in smaller sealed
plastic bags with a blast of dry inert gas before sealing. It is always
easier to keep rods dry than to attempt to re-dry them.

Good luck, YMMV

Posted by Grant Erwin on March 24, 2008, 12:49 am

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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

Posted by Gunner on March 24, 2008, 4:28 am

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On Mon, 24 Mar 2008 04:49:42 GMT, Grant Erwin

>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

Posted by Richard Smith on March 24, 2008, 4:58 pm

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> On Mon, 24 Mar 2008 04:49:42 GMT, Grant Erwin
>

> >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

Posted by emmo on March 23, 2008, 5:31 pm

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Put them on a gas barbecue grill if you have one -- that will get a lot
hotter than your kitchen oven, and will eliminate the wife factor...

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