Welding by 7018 Electrode Without Heating

Pre-heating a welding electrode to 230-300 C must have a purpose. So what is the purpose and where did you get this idea? Some electrodes have a layer of flux on them and this flux has a tendency to absorb moisture from the air. Such a "moist" electrode has an adverse effect on weld quality. It is therefore customary to keep the electrodes in a moderately heated chamber (box) to keep the electrodes dry. Most of the better suppliers of welding accessories have such drying boxes on sale. But the drying temperature is nowhere near to 230-300 C.

I know from my studies and experience that the 7018 electode ia need to heating , i think that u did not read the title , i am sorry that i did mension that i am talking about 7018 elctrode.

It is recommended that the 7018 low hydrogen welding electrode be stored in a heated drying box at around 240-250 dg FAHREHEIT. This is to keep it dry. This is around 120 dg Celsius and not 250-300 dg C.

The electrodes are baked at manufacturer's work in desiccating atmosphere and then packed in an hermatically sealed condition, so for all practical purposes they are dry.

After the pack is opened, the ambient will aid in moisture absorption of the highly hygroscopic flux. This obviously be related to the ambient (humidity) and time of exposure. If you are in a relatively low humidity area and can limit the exposure (reseal the pack/ tie the open end immediately after few electrodes are taken out) the rest of the electrodes will remain dry enough.

Another way is to keep these in a desiccant aided box or holding oven with temperature a bit higher than the ambient)

The baking at 315⁰C is resorted to only when the electrodes were not properly handled/stored and possibility of moisture absorption is high. The main disadvantage is thet there is a limit on the time and number of times these can be baked at this high temperature without adversely affecting the flux.

The electrode ahs to be baked is a mistaken notion. It has to be baked if the storing is improper.

And frankly, there are some of the standards that do allow 9 hrs (with the above conditions) for use without baking after the seal is opened.

The answer above is perfect. Can you please let me know the standards where this 9 hour time is given.

Further I would like to know whether there is any standard which provides the shelf life of such hermitically packed electrodes.

You only need to heat the rods to a point warmer than the ambient temperature in order to prevent them from absorbing moisture once you open the can. I've seen some welding shacks that simply had an old refrigerator with a 100 watt light bulb in it to store welding rods in. It works like a charm. Just remember that the compressor should be inoperable. With that said, I've welded on plenty of projects that didn't heat the rods at all. If you are going to use them up in a couple of days they won't absorb enough moisture to make a difference. If the flux is breaking off of the rods then they have too much moisture. When the arc is thousands of degrees a little bit of moisture isn't going to make a whole heck of a lot of difference. inoperable.

Greetings all,

I will throw my two cents worth in simply speaking from experience working in a very damp climate. ( southeast Alaska rainforest ) We normally will simply keep the rod in an o-ring sealed tube made just for rod storage. When you get back to the shop it is kept in an old refrigerator with a light bulb in it like the previous post mentioned. The only time we use the rod oven to bake it is when it has been sitting open too long or otherwise absorbed too much moisture. I might add that we will usually put our root pass in with 6010 or similar and then run with the 7018. There is an awful lot of pipe and structural welded here using this technique. We sometimes have to work with a helper holding a torch to dry or preheat the metal as we go but it always gets done.

Just a correction on the above.

AWS D1.1 is clear if even the low hydrogen electrodes are recieved in a hermetically sealed, undamaged container from the manufacturer, no baking/conditioning is necessary.

Only when the reciept is in damaged condition then the required baking (260^oC to 430^oC as per AWS D1.1) is required. However the temperature and the cycle will be as recommended by the electrode manufacturer.

Check this

containers. When supplied in undamaged containers, they may be used without any preconditioning, orMany manufacturers now provide electrodes in hermetically sealed vacuum packs with hydrogen levels guaranteed to be less than 5ml/100g weld metal. These are particularly useful in site applications where there is a need to maintain very low hydrogen levels and baking and storage facilities are not available. The electrodes are taken directly from the pack and can be used for up to 12 hours from opening before sufficient moisture has been absorbed to require baking baking, before use. When SMAW electrodes are received in damaged containers or in non-hermetically sealed containers, AWS D1.1 requires that the electrodes be baked prior to use, in the range of 260oC to 430oC (500 to 800°F), to remove any residual moisture picked up from exposure to the atmosphere. The electrode manufacturer's guidelines should be followed to ensure a baking procedure that eliminates retained moisture, and these recommendations may vary from AWS D1.1 provisions.

Lincoln Electric

Low hydrogen stick electrodes must be dry to perform properly. Unopened Lincoln hermetically sealed containers provide excellent protection in good storage conditions. Opened cans should be stored in a cabinet at 250 to 300?F (120 to 150?C).

Electrodes in unopened Lincoln cans or cartons retain the proper moisture content indefinitely when stored in good condition.

Any low hydrogen electrode should be discarded if excessive re-drying causes the coating to become fragile and flake or break off while welding, or if there is a noticeable difference in handling or arc characteristics, such as insufficient arc force.

The AWS specifies in fact that "As recieved diffusible hydrogen content of the weld beads (made from the electrodes) should be less than the classification ratings.

Or here page 84 (11)

In my response I was referring to storage requirements. I don't have copies of the current codes, (or any welding codes at hand) just some handbooks and field guides. From memory I recall storage requirements for E7018 rod to be to 250°F to 300°F (120°C to 150°C). Storing for 24 hours after receipt, and prior to use is precautionary as those temperatures are not high enough for reconditioning. Reconditioning temperatures; as I recall, are in the 650°F to 750°F (340°C to 400°C) range. I don't remember the soak time. I have verified the preceding temps on the internet

This issue is critical to the performance of welds requiring this electrode, whether they are structural or pressure retaining. Better to have a conservative approach that eliminates the potential for the presence of moisture leading to failures than to have to perform the analysis and remedial actions that will be necessary.

You are right, I have seen too many times that though we specify the manufacturer and the type of electrode to be "R", the contractor rarely adhere to them (unless caught in the act )

The conservative approach is the only direction to take with materials that are susceptible to under-bead cracking. Usually whatever code that you are welding to will detail the process. API, AWS or whatever. It's the hydrogen trapped in the weld that makes the difference. Depending upon materials, the defect may not be detectable for several days.

Some codes limit the maximum amount of time that the rod can be out of the oven and do not allow re-bake. You can get by with cutting corners until the pipe line fails. Oops. Preheat of the pipe is a prerequisite unless your welding mild steel.

Randouli; Thank you for your vote for a conservative approach and for mentioning the different codes.

On the same project or job there may be welding activities under several different codes. AWS D1.1 for structural, ANSI/ASME B31.1 for power piping, or ASME for pressure vessels. The system of welding material control must meet the most stringent requirements of these or there is too high a risk for noncompliance.

The Contractor is right provided the electrodes were supplied in hermetically sealed containers. Preheating is required when electrodes have started producing porosity in weld puddle. This happens only when flux of the electrodes have absorbed moisture from atmosphere. Some time thinner electrodes (3/32" and 1/8" ) are not heated in dry weather for preheating of electrodes is done during welding itself. Slow weaving of welding technique generates resistance in electrodes and the electrodes are preheated before it melts. Preheating of electrodes size 5/32" and 3/16" are preheated the very first day of opening of sealed container. Requirement of preheating depends up on the weather condition.

In one way the contractor is right , when he says the electrodes could be used without baking/ re-drying within a prescribed period of hours. The electrodes are baked at manufacturer's end in desiccating atmosphere and then packed in an hermetically sealed condition, so for all practical purposes they are dry.

These electrodes are grouped under the category of AWS SFA 5.1 E 7018 H4R. They are moisture resistant, hydrogen controlled,vacuum packed, basic coated.

Due to vacuum packing they do not require expensive treatment like re-drying at 250 deg. C for 2 hours or at high temperatures.

The hydrogen content of weld deposit when measured in accordance with AWS/ANSI 4.3-86 specification will be 4 ml/100 gms weld deposit. The typical values are between 1.5 to 200 ml/100 gms of weld deposit only. Thus the Hydrogen level is much lower compared to normal level of <15 ml/100 gms. of weld deposit in general category.

The deposited weld metal will meet X-ray quality standards and good for 6G/6GR positions and has a UTS value of 520/580 N/mm2 due to its lower impurities level.

The limitations are, the electrodes should be consumed within a period of 6 hrs. or so when the seal of the container broken. The cost of the electrodes are higher compared to normal category of E 7018 type electrodes.

Sridhar.

Sorry . There is one correction.

"The typical values are between 1.5 to 200 ml/100 gms of weld deposit only".

It should be read as

"The typical values are between 1.5 to 2.00 ml/100 gms of weld deposit only".

Thank U all.

Sridhar.

Yes it is true, If it is vacuum pack, it shall be used with out heating for a period of max 12 hours or as per manufacturer's recomendations

It may also be noted that as per quite a few codes (including AWS) the electrodes must be re-baked only once- so if you unnecessarily bake, you may land up with a truck load of rejected electrodes.

UD15

Preheat the oven at 350 degrees F. Put the rods in an oven bag and seal tightly. Bake at 350 degrees for one hour and turn over. Finish baking until the oven bag is dry inside. Remove from the oven and rinse in cold water to cool the rods to the touch. Deposit the rods in the trash and use a MIG or dual shield. Pulse preferred.