[dsraven]

a young welder's mistake I have seen is when working in Ft Mcmurray in the cold of winter the welders would weld on an extra lump to the grouser bars on the track pads of the dozers. this is for traction on ice because a dozer pad is fairly flat so going ahead and back the tracks will rather spin out instead of grip plus they can be slid sideways fairly easily on ice, like skates, if it is a side hill so the extra lump in the middle of the track pads helps stop or slow down the process. anyway, the dozers are put up on stands and the welder welds on pieces a few inches long onto each track pad, staggered so they don't all line up in the same footprint as the track spins around. long story short the inexperienced welders sometimes are not told to place their ground on each pad as they weld, instead of on a single pad for the whole job. if they don't do it right then welding current will pass through the bearings in each chain link of the track and leave a mark so the track wears out in fairly short order after the grouser bars are welded up. same goes for welding on vehicles if welding on something place the ground close to the weld, on the same part preferably, to eliminate the current flowing through something else first before making it's way to the weld