Electrodes with basic (low hydrogen) coatings (containing calcium carbonate) are prone to moisture
absorption from the atmosphere and therefore should be packaged in hermetically sealed containers.
Once the container is opened, the electrodes should be removed from their packaging and stored in a
holding oven at a temperature of about 120°C. Also, if the basic electrodes for welding carbon and low
alloy steel have been exposed at ambient temperature for 4 hours or more, or if their packaging has
been damaged, they should be rebaked at a temperature (370°C to 430°C) and for a time (1 to 2
hours) recommended by the electrode manufacturer. Cellulosic electrodes, however, should not be
placed in holding ovens or rebaked.
4) Selection of Electrode Diameter and Current
The classification and size of electrode, and the welding current for a given application are chosen in
light of the thickness of the material to be welded, groove geometry and welding position. Generally,
larger diameter electrodes are used for welding thick materials and in the flat position so that higher
deposition rates can be achieved. Smaller diameter electrodes are generally needed for welding the
root passes in V grooves and for out-of-position welds so that the welder can have better control of the
weld pool and the bead shape.
For prequalified joints, CSA Standard W 59 “Welded Steel Construction” limits the maximum electrode
size to 4 mm for welding in the vertical position (fillet and groove welds), and to 5 mm for groove welds
in horizontal and overhead positions, and fillet welds in the overhead positions. Larger diameter
electrodes are used for welding in the horizontal and flat positions only.
Table 4.1 shows typical current ranges for satisfactory electrode burn off and stable arc conditions
using steel electrodes of various diameters. However, the complete range of current may not be
suitable for all situations. When welding on thinner material, the lower end of the range might be
applicable. This would also apply when welding in the vertical or overhead positions. For example, 3.2
mm diameter E4310 electrode, according to Table 4.1 has a usable current range of 75 to 125 A. For
joining heavy material in the flat position, it would be logical to use the upper part of the range, 100 to
125 A. But if welding is to be done in the vertical up position, the range might be 90 to 110 A.