Page 216 - Boiler_Operators_Handbook,_Second_Edition

Maintenance 201

of the program. It’s mounted on a stiff board and hung generator. Once you’re certain the flammable gas is out
near the equipment while it’s being maintained so it’s you follow up by purging the inert gas with air. Just us-
easily seen and used. As each valve is closed or opened ing air is only acceptable for very small lines (less than 3
and locked the number of the lock is marked on the dia- inches) because flammable mixtures could be produced
gram with a non-permanent marker. A quick look at the in the piping and ignited. Keep in mind that inert gas
diagram will tell you if all the valves and disconnects not only prevents combustion, it doesn’t contain any
are set and locked. All the keys for those locks are placed oxygen and you can’t breathe in it.
in one box which has a lid secured by means of a latch We were installing gas burners in a plant that had
that can accept multiple locks. a future gas line installed several years earlier. The gas
As each worker places their lock on that lock box line, a ten inch one, entered the plant through the west
his or her initials are added to the diagram so you can wall and was closed with a weld cap. I gave my foreman
see who is in there (or left their lock on) during the prog- specific instructions to prepare a steel plug in case it
ress of the maintenance job. When they leave they re- was necessary and be ready to insert it in a hole drilled
move their lock and their initials. When all work is done in the line. I also told him not to cut the line until I was
and all workers’ locks are removed you can remove the there with a gas tester. Luckily an apprentice overheard
keys from the lock box and remove the locks that ensure me and suggested to the foreman that he should call me
the equipment or system was isolated, erasing the lock before taking a cutting torch to the pipe. The foreman
numbers as you go. relented and called so I went to the plant with the tester.
In some cases the job could have several opera- He explained that he had talked to the gas company
tors removing locks and erasing the board as they are workmen, who had been there to check the meter loca-
removed. This method ensures they’re all off. Now the tion, and the piping was “dead.” He finally allowed as
board can be put away for use on the next turnaround. to how I was just being safe and had the apprentice drill
You’ll note it’s simple and effective while not producing a one-eighth inch hole in the top of the pipe. The gas
a lot of paper. The locks can have tags permanently at- detector went nuts and it took a lot of pressure by the
tached but I think the number on the lock serves as the apprentice’s thumb to stop the leak.
tag. The only time you may have to cut a lock is when No, the foreman hadn’t made up the plug either.
some worker leaves a lock on the lock box and goes We wandered around the plant looking for something
home. Of course, you have to make certain that’s what until I finally found a piece of wood and used my pocket
he or she did. knife (which I’m never without) to make a plug that we
It’s always important to include venting, draining used to seal the hole. The next day the gas company
and purging of systems as part of your procedures of managed to seal off the pipe and we vented it for ages
lock-out and tag out. That’s very important when the through that little hole.
system contains a hazardous substance, something cor- What do you think would have happened if the ap-
rosive or explosive. I’ve walked away from some loca- prentice had just started cutting with that torch? Safety
tions when I’ve observed contractors starting work on is an attitude, acquire it. Lock-out tag-out, purging and
pipes without making certain they’re vented, drained environmental testing are things you should take for
and purged. I walked away so I wouldn’t be injured if granted and insist upon happening before opening any
they opened a hot line. When dealing with certain sub- equipment for maintenance.
stances additional requirements should be followed. That was only one situation involving that super-
Don’t say it’s never happened. One of my crews intendent and I was never allowed to fire him. When I
cut open a hot line that was supposedly completely iso- think back to the many times he created hazards or sim-
lated. Caustic soda, if I recall correctly. The line penetrat- ply changed a job without approval, and got away with
ed several floors and the wrong valve got shut off at the it, I don’t wonder that I finally managed to get myself
lower level. I’ve also heard of several other incidents. fired. Looking back at what happened later, I feel satis-
Any time a gas line is opened it should be vented fied by the old adage “better safe than sorry.”
and purged. If the gas is considered hazardous to the
environment it should be purged through a flare or sor-
bent to prevent it escaping untreated. Flammable gases LUBRICATION
should be purged with inert gas. Usually that means a
few bottles of nitrogen or carbon dioxide but large and Lubrication is probably the second most important
long lines could be purged with inert gas from a special element of preventive maintenance. On larger pieces of