Got a question about the safety of a welding rig having the ground mounted to frame?

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Just want to first say welding is not my line of work or specialty.  I do it as a hobbyist and for building small projects mainly around the house.  I'm by no means a professional but am around it fairly often.While at work today, I caught the ***-end of a conversation that was previously discussed by an MSHA inspector recently.  We received a citation on one of our welding trucks for a lug on a welder that was exposed because the cap had slid down a little.  While the inspector was focused in this area, he also pointed out the fact that we have the ground from the welder mounted to the truck bed as well so when doing projects off the back of the truck.. the ground doesn't have to be pulled out and hooked up.  From the way I understood it, the inspector said that if the welder was setup on DC- that it would energize the truck bed and shock someone.  Now personally I don't know either way but it did spark my curiosity on if this is safe.Was hoping some of you could post some insight into this and help me out?  I guess the issue was agree to disagree between the site supervisor and the inspector but if this is a safety hazard, I would like to know and get it fixed.
Reply:OSHA says that the terminals must be covered, so that in the event something bridges the lugs do not arc out. The body of the truck being grounded is only half of your circuit, the other half being the stinger, gun, TIG torch, should by rights be insulated.Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:Throughout the refineries, powerhouses and computer chip factories.... It's always been the practice to ground as close to the weld as "feasible". I've witnesses several instances of metal cans (propane cylinders, acetone, etc) becoming grounded either on the truck bed or welding table when the ground is not connected directly to the work. Yes, they did explode or catch fire... You bring up a good point.Thanks,HoboLincoln SA200's... at least 15 - 20. They come and go. Growing partial to the "Short Hoods" in my old age. Last count on Short Hoods was 13 in possession.