Q: I am in my fifth year of teaching, and have yet to get a straight answer to my question: I store my E7018 rods in a rod oven. They are the only rods I have in the oven. The oven stays at 150 degrees F. for electrodes, and they are stored in a hermetically sealed can. I have been told that E6011 stick electrodes in the oven will dry out too much, and the moisture will move into the E7018 rods. I also have been told that stainless steel rods need to be in the oven, but can't be in the same oven. What should and shouldn't be in an oven and what rods can be in the same oven or need to be separated?

A: You are correct that storing E6011 or for that matter, any cellulosic electrode, in a rod oven will remove the required hydrogen from the coating. Removing the hydrogen from the coating will change the arc force, softening it, and that will cause an undesirable change to the product performance.

Additionally, the removal of hydrogen from these electrodes will drive the carbon equivalency up by increasing the overall retained alloy in the weld deposit. That will result in dramatic increases in weld strength, and a potential for cracking in certain applications. Therefore you should not store the cellulosic class of electrodes in situations in which the temperatures exceed 100 degrees F. That will cause over drying of the coating.

As far as the storage of your E7018 electrodes, you should consider changing the storage temperature from 150 degrees F. to 250 degrees F. That will put you in line withmost common welding codes such as American WeldingSociety Structural Code - Steel D1.1 2006.

Storage temperature for stainless stick electrodes is the same temperature as listed for E7018 electrodes, 250 degrees F., and can be referenced in American Welding Society Structural Welding Code Stainless Steel D1.6.

Storing E7018 and stainless stick electrodes in separate rod ovens is not a mandated practice by any code that I am aware of, and there is no technical reason why they cannot be store together.

However, it is good practice to separate electrodes such as stainless steel and mild steel to prevent inadvertently choosing the wrong filler metal or mixing electrodes in compartments in the oven.

Lastly, a properly heated and vented rod oven will not cause the transference of hydrogen from one electrode to another. But be sure that your rod oven is properly configured and maintained pursuant with the manufacturer's guidelines.

Welding structures for elevated in-use temperatures
Q: Our welders need to weld a 1/2 in. thick, 10 ft. diameter; 304L stainless steel ring inside a 10 ft. diameter 304L stainless steel kiln shell. The shell is exposed to elevated temperatures in excess of 500 degrees F. The welds made with E308L stainless electrodes in the past have cracked in this application, and we would to know what electrode should we use?

A: For elevated temperatures, the appropriate rod should be E308H with ferrite less than 10 FN. You also need to be certain of full penetration weld, as any incomplete root fusion will initiate cracking.

This column is sponsored by Penton and the Lincoln Electric Co., Cleveland. Dave Barton is a senior welding engineer in the Application Engineering Group of The Lincoln Electric Co. He oversees welding procedure development for both new technology and existing products, performs failure analyses for customers, and serves as a consultant on welding application problems. Barton has been with Lincoln Electric for 21 years. Send your questions for Mr. Barton in care of WDF by e-mail to: askdav@penton.com.