Relax -- I'm not advocating turning the taggers and their spray cans loose in your plant. I'm just recommending you do a little creative marking of your heat processing equipment.
After over 30 years of working with ovens, I can tell you that one of the great frustrations in checking and tuning this equipment is not being able to find accurate setup documentation when it's needed. There are lots of reasons -- somebody's misplaced the manual, setup data have been revised, or someone simply prefers faking it to searching for the instruction book.
Many years ago, we had another problem -- the Phantom Tinkerer. You know, the guy who skulks around, palming a screwdriver, changing settings when no one's looking. Here, the hassle dealt with undoing the Phantom's handiwork every week or two, and that involved checking and resetting a couple of dozen burners.Inspiration came in the form of a mail truck sitting next to me in traffic. Above each wheel well, the tire inflation pressure was marked in neat numbers. What a great idea! No need to guess the pressures or look them up - they were posted right where they were needed!
Soon afterward, we began marking the proper adjustments right on the valves and burners with a paint pen. It saved chasing down the manuals, lugging them up to the top of the oven and trying to find a spot where they wouldn't catch fire, blow away or just get covered with grime. We never did succeed in bringing the Phantom to justice, but we did make the resetting process a little less painful.
I've recommended this many times, but somehow, people seem reluctant to do it. Maybe they belong to that generation that was told never to write in books, and somehow, that taboo got transferred to process heating equipment, too.
Well, it's OK. It's far better to have some settings marked on the equipment than to have it running out of adjustment or, worse, adjusted incorrectly. If you really have a hangup about scribbling numbers and notes on the equipment, make up some nice metal tags and fasten them to the appropriate components.
In another plant, the local representative of Phantom Tinkerers Anonymous was fond of resetting drive motor linkages to the control valves. His dedication to the task was exceeded only by his inability to get it right. This was a problem we couldn't ignore because he really had the burners messed up. Now, anyone who has set up control valve linkages will tell you it can be a tedious, time-consuming exercise, so the Tinkerer had to be stopped. One of the maintenance techs came up with the solution. He shopped around until he found a spray can of a very oddly-colored paint. After he had set the linkage correctly, he'd give each of the connection points a little shot of that weird-colored paint. It put the Tinkerer on notice that his efforts were under scrutiny. The frequency of unauthorized adjustments dropped like a rock, and when he did sneak one in, the paint shadows made it easier to restore the correct settings. The only thing we had to watch out for was that he didn't locate our source of that strange paint.One thing that does seem to stop the Phantoms cold (well...OK, hot) is controls located on top of ovens or other hot, noisy and difficult-to-reach spots. That's fine, but unfortunately, it also discourages authorized checking and adjustments as well. If that problem plagues you, consider installing tees at the various pressure test points and running pressure lines to some more accessible location. In fact, why not route all these lines to some common location, attach them to a plate with bulkhead fittings and label all the test points, complete with desired settings? (See figure 1 for a clearer idea.) Now someone can check out key settings without clambering through all that heat and filth. And, because the plate was put there for the purpose of displaying settings, it's OK to write numbers on it. Honest.