Welding Inspection & Metallurgy API ICP Self Study Notes

Cellulosic type electrodes (e.g., E6010, E6011 or E7010) may be used for
root and hot passes. Although low-hydrogen electrodes are preferred,
some refining locations and the pipeline industry prefer to use cellulosic
electrodes frequently because they are easy to operate and provide
improved control over the welding arc. Root pass with low-hydrogen
electrodes reduces risk of HAC. It also reduces risk of burn through
because the amount of heat directed to the base metal is less than when
using cellulosic type electrodes. However, manipulation of low-hydrogen
electrode for root pass is not as easy but it can be done by training and
practice. It should be noted that cellulosic electrodes have the following
adverse effects on the integrity of the weldment:
a. Deep penetration, therefore higher risk of burn-through than low-hydrogen
electrodes; and
b. High diffusible hydrogen, therefore higher risk of hydrogen assisted
cracking.