Fishingrodburne,
JT would be the best one to explain this but I will give it a shot.
Some people do minimal grinding of the bead and put in a very hot pass, some people do more grinding and put in a colder hot pass. This is all personal preference.
The hot pass is put in using a flicking motion, as you flick forward you are gouging out the wagon tracks, as you step back you are pushing weld metal into the depression and hopefully washing the sidewalls. If you have any undercut on the hotpass from incorrect technique or too much heat you are going to create problems.
With all due respect I disagree with your statement that "fill and cap would take care of the problem".
All the pipelines I have worked on had the fill & cap put in with 4 or 5 mm 7010's. Even though cellulose rods have excellent penetration qualities they are not going to always burn out undercut, especially with 4 or 5 mm electrodes in the vertical down progression. Vertical up would be more likely to be able to burn it out.
Maybe the fill & cap crew asked the inspector to have a word with you, if there was a repair called after radiography and the repair area was identified as being between the hot pass and the fill who do you think would have been given the repair sheet.
Pipeline welders reputations are built on a combination of productivty and repair rates,if you are getting repairs due to what an earlier welder has done then you are going to be slightly p...ed!
Hope this helps,
Regards,
Shane