While the electrodes don't typically have a defined shelf life, they do degrade over the course of time. I am assuming the electrodes are stored in the holding oven at the minimum temperature specified the entire time. I say this because I've encountered several contractors that figured they only had to energize the holding oven and heat the electrodes when they were about to use them. They were wrong, or so wrong.

I would say that if the electrodes are more than a couple of years old, it might be worthwhile to order fresh electrodes. Again, they is no data that I am aware of that limits the shelf life of electrodes that are properly stored or that are in unopened containers. My experience has been that electrodes that are more than a couples of years old don't perform as consistently as fresh electrode.

Al

sunil,
You can find a general guide to re-bake info in AWS D1.1 2015 paragraph 5.3.2.4. Please be advised that whomever you are purchasing your filler metal from, i.e. Lincoln, ESAB, Bohler, will have there own recommendations.