Drying arc rods

[madkayaker]

Hi all
As a sparky that occasionally welds brackets etc I don't understand much of the science behind the Arc rod. I understand that rods have to be kept dry but how does heating it up help the weld? I was welding at the weekend joining a drilled through bolt to some galv bar and as I had my MAPP torch there I gave the rod a little heat and it Arched easier and looked like a better weld. Explanations please.

 

[Paul.]

The main reason for keeping electrodes dry is so that moisture is not introduced to the weld pool as hydrogen, electrode coatings are Hygroscopic, ie they readily absorb moisture from the atmosphere, the coating will also deteriorate and fall apart and the electrode itself will go rusty, as you've found they also strike a bit easier when warm and dry.

 

[madkayaker]

Thanks TIG Paul that answers my question.

 

[knoba]

One of the BOC Stainsheild gases for austenitic stainless steels contain hydrogen. ...and why doesn't the, lighter than air, flammable, hydrogen just burn off?

...please TIG Paul?

I never was any good at chemistry.

 

[snowcat]

with TIG hydrogen is added to stifen the welding pool, and to burn off any oxogen that may trap within the shield...so esentialy is burnt away

Hydrogen within an arc weld, affects the HAZ zone causing porosity, and over defects, especially X-ray identifiable cracking......

 

[Paul.]

With austinetic materials (stainless) hydrogen can exist in solution at ambient temperature and is therefore effectively locked into the material structure, with ferritic materials eg steel, hydrogen does not form a compound and exists as a gas, this will migrate from the weld at ambient temperature and can cause cracking in the HAZ, hydrogen cracking is a well known problem amongst experienced welders, and is one of the reasons for pre and post heating and the use of hydrogen controlled electrodes, this will help to diffuse some of the trapped hydrogen,

 

[madkayaker]

A quick question what is the HAZ Zone?

 

[Paul.]

Heat Affected Zone

 

[madkayaker]

Is there an opertermin temp to heat rods to or is it just keep them toasty? Thanks tig Paul

 

[Paul.]

for general purpose electrodes, just good dry storage practice is ok, for correct use of low hydrogen electrodes, a proper drying oven is used about at 110 deg C, and the use of heated quivers is recommended to keep them dry at the welding site

 

[snowcat]

redrying instructions are normaly on the box, but around 150C for an hour or so, best to work from a quiver tho if working with Hi-Los

Edit crossed posts again paul

 

[knoba]

Kudos!

 

[madkayaker]

Thanks for all the help. I'm going to try making a drying box out of a metal tool box and a 500W halogen lamp with a thermal trip. (its OK I'm a spark so know what I'm doing(electrically))

 

[Paul.]

we've been here before have a look at this

 

[madkayaker]

What can I say I'm board and trying to avoid spending time with the wife! (But she does want me to teach her to weld).

 

[Robotstar5]

Thanks for all the help. I'm going to try making a drying box out of a metal tool box and a 500W halogen lamp with a thermal trip. (its OK I'm a spark so know what I'm doing(electrically))

You only need a low wattage bulb to keep them dry + cost of running 500W 24/7!

 

[madkayaker]

I was planing to use the box to heat them up on-site as and when i needed them. I must be barking up the wrong tree!

 

[Paul.]

We might be getting a bit carried away here, if you're only welding the odd cable tray bracket etc, your not going to be needing hydrogen controlled electrodes. just buy some E6013 rutiles
For the storage of general purpose electrodes if the work shops a bit damp put them in a plastic tupperware type container with some silica gel sachets, or just store them near the heater, just to complicate things further some electrodes such as cellulosics do require a determined small amount of moisture to work their magic properly, these should be stored at no more than about 50 deg C. there are also limits on how many times an electrode can be dried before they become damaged.

 

[madkayaker]

Thanks for the help.