how do you store your welding rods (7018)

[MinnesotaDaveChalmers]

There are two reasons I can think of that ovens are maintained at higher temps. One is to vaporize light oils, like WD40, kerosene and diesel, which usually boil at about 400-500F. The other is to heat up the large masses of welding rods that get put in there as quickly as possible. If the oven were at 250F, it might take 8 hours to get 50# of rods to 250F. If the oven is at 500F, it only takes a few hours to get the rods to 250F. If water were the only contaminant in the rods, and no one was in a hurry, the oven could be kept at the boiling point of water.

Storage ovens are only approximately 250-300 degrees. This temp will not re-dry (re-condition) 7018 according to rod manufacturers.

It's the re-drying that is at the significantly higher temperatures. Lincoln's chart is 650-750 degrees for that.

 

[Shield Arc]

Right back at you naturally :thumbsup:

But as you know, I'm a part-timer and there are so many people with more knowledge and experience than me. Bunch of the weldingweb crew come to mind.

Yes, there is some serious talent on WW!

 

[Eric Salop]

Measuring 7018 moisture content

The Lincoln website has this piece of information on 7018 moisture content.

The rods I have have no such "R" marking, so only way to find out how fast they absorb water is to do a few measurements for myself.

A week ago I put some recently opened 7018 in an oven to make sure they were completely dry. Afterwards, I took a few rods and marked, then weighed them. They then went back on the scales regularly to see how fast and how much water they took up from the air.



This is what happened to those that were kept open to the air inside the house (at this time of year the relative humidity in the house is 35-45 %)



Using the 0.4% max moisture content that Lincoln quote suggests that even after being exposed to the air for several days, these would still be fine for use for any application.


I also left some rods outside, but under cover from any rain. Weight gains (and losses !) on them tell a different story. I'll put some figures up later.

 

[muddstopper]

I have noticed some rods will sort of change color down in my shop. If I leave a rod laying on the table for a few days, it will turn grayish in color. It also will fluff off flux when I start welding with it. If I place that same rod on top of the wood stove, which gets very hot, and leave it for a while, it will weld just fine and wont fluff the flux.The color will also change back to a more white-ish color. Since most of my welding involves just using a rod or two at a time, I always have a box of rods that have been opened, sometimes for a few month. If i know I have a large welding project, I just dump the whole box on the stove a few days before using them. A hot rod always seems to weld better than a cold on. My problem now is that the weather has warmed up and I am not keeping a fire in the stove.

 

[Eric Salop]

This shows how much water the 7018 rods took up when I left them outside. They were open to the air under a roof, so neither sun nor rain could get directly to them.

For the first 12 hours, although the moisture increased gradually, it was well below 0.4 percent. After that the weather changed and the moisture absorbed went up much higher.

What is interesting is that the moisture content doesn't stay permanently high, it goes up and down. If you look at the 72 hour point, it has actually gone back down to the Lincoln recommended figure of 0.4 percent. As Beezfun has said, this suggests that you don't necessarily need the elevated temperature in an oven to dry out a "damp" rod, all it takes is a drier atmosphere.

Shield Arc, when you showed us that picture, pouring water out of a can of rods, could that be because the air had cooled below the dew point, so when rods loose some moisture back to the atmosphere, it then condenses out on the inside of the cold can ?

 

[bigdeano]

An interesting experiment, thanks for doing it. I wonder if the .4% figure is based on the weight of the whole rod or just the flux. It's unclear to me in their literature. Maybe I'm overthinking it.

 

[Gary Fowler]

Just as big a problem as the hydrogen that is released when welding is that of rust of the steel electrode. When any rod whether it be cellulose coated like the 6010 or iron powder like the 7018 is left exposed to moisture, the iron core will start to rust. How fast depends on the amount of moisture. Cellulose rods don't absorb moisture like the iron powder rods do but will eventually become unusable if left in a high moisture environment as evidenced by the white powder that will form on the outside of the flux. Can you still weld farm equipment with it? Likely you can although the flux will start to "fingernail" that is it will start to burn off faster on one side than the other and leave a long point (fingernail) on one side that makes the arc a bit unstable.
The iron powder rods (xx18) rods will start to have lots of porosity even if you stick the rod and let it heat up till the cloud of steam erupts from it. This is because of the coating of rust on the electrode that you cant see by looking at the outside. Again, you may get "fit for purpose" welds for farm machinery from it as long as you get the water vapor out. The rust will just cause a bit of porosity that while weakening the weld, does not weaken it to point of it failing to hold the part together in most cases.
Hydrogen embrittlement which happens when water is welded over on in case of wet rods is very dangerous as it can cause the weld to fail catastrophically ( as in break in half with no warning and without bending or yielding ). This is very dangerous in lifting mechanism that could be holding something overhead or in something like bridge spans.

I keep my rods in an oven because it basically cost me nothing to do so AND more importantly because I have done so for more than 40 years in the construction industry (25 of which was in Quality Control Management) so it is a habit I really don't want to break.
My shop is on a separate meter and has a minimum charge which I don't normally go over unless I do a lot of welding. So if I didn't use the electricity to heat my rods, I would just be giving it to the electric company anyway. At over $2 per pound (last time I checked pricing which was a few years ago) having 50 lbs. of rods go bad will pay for a lot of electric utility.

 

[Eric Salop]

An interesting experiment, thanks for doing it. I wonder if the .4% figure is based on the weight of the whole rod or just the flux. It's unclear to me in their literature. Maybe I'm overthinking it.

Yes, I think you could be well be right about subracting the weight of the steel core before calculating the 0.4% pass level.

Guess the only way I am going to do that is to strip off the coating and weigh the core. That means wasting the whole rod ! I am a real cheapskate and that is going against my better nature, but I suppose it's got to be done

 

[PJSprog]

Yes, I think you could be well be right about subracting the weight of the steel core before calculating the 0.4% pass level.

Guess the only way I am going to do that is to strip off the coating and weigh the core. That means wasting the whole rod ! I am a real cheapskate and that is going against my better nature, but I suppose it's got to be done

That might also eliminate the possibility of contaminating the rod ends as you handle them, which could easily skew such minute data points.

 

[MinnesotaDaveChalmers]

Also of note, .4% is the maximum for AWS and .2% is the maximum for Military.

Here's ESAB's data for their "moisture resistant" coating: