Practicing Cellulosic root for comparison. Same pipe in the "2G" position.
Around but not-less-than 2mm root-face and set 2.5mm root gap - bullet tacks so keep 2.5mm root gap spacing set with stubs of 2.5mm electrodes. Compared to the prep. for a Basic root, this has a bigger/thicker root-face. Also, running Cellulosic on DCEP as able to keep control while having plentiful fusion.
No-one has ever showed me how to root with a cellulosic. Found with this set (Miller inverter) and rods (Bohler Foxcel) than not hard push into root - more like open-arc albeit close-up, seeing and hearing keyhole under short arc while puddling the weld-pool. Best result was with 2.5dia rods. Tried 3.2mm, but less consistent results and rougher top surface. Whereas with 2.5dia rods, reasonable root-run top-surface as-welded.
The 3 pictures show the penetration bead in bore and the outer surface root bead.
So this improvised cellulosic root seems to work, but wish for tuition. The penetration bead - reckon would be more consistent if had gone all the way with 2.5dia rods. And tried different Amps. There are many stop-starts (not particularly visible - "feathered" restart ends of runs. Both penetration bead and outer bead surface could be better. However, this is a first try doing a pipe root with Cellulosic whereas in comparison the 7016 root-runs have benefited from a lot of practice and tuition (have done 1G plate root with 6011 Cellulosic with oversight before). Feel cellulosic has a wide "sweet range" which enables you to keep a well-controlled bead going with quite varying prep. Also easy restart down quickly feathered bead termination if need to pick up again after amps change for big change in root gap.
(14May2010 18May2010, Richard Smith)