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Maintenance
Maintenance of Heat Tracing
For many facilities, heat tracing is essential. Without
it, critical pipes and vessels would freeze during winter. This is why
smart maintenance managers ensure any heat tracing has been inspected,
tested, and repaired as necessary before winter. But stopping there and
hoping for no problems over the next few months is a dangerous game to
play.
Heat-tracing failures always seem to happen at night, during a
storm,
and just before a critical shipment must go out. The failures often
create economic losses for the company and possibly its customers.
Further complicating things, cold weather means discomfort for the
maintenance workers. If the repairs have to be done in slick
conditions,
you can add fall hazards to the list. Trying to do repairs by
flashlight
makes things especially dicey.
You can shift repair time from "worst conditions" to relatively
favorable ones if you follow these tips all winter:
- Conduct weekly visual inspections of heat tracing, during the warm
part of the day. Walk down the system and remove any snow or ice that
may present a falling hazard.
- Conduct an inspection during daylight, weather permitting,
following
any storm. If weather makes such an inspection unfeasible, conduct
testing from indoors where possible. For example, you could disconnect
a
resistive heat-tracing circuit, quickly ohm it out, and reconnect it
(assuming an indoor terminal board or control panel).
- During cold weather, ask the operators to monitor temperature
trends. Failure in the heat tracing won't show up as an immediate
change
in temperature, the way a pump failure would show up as an immediate
drop in pressure. Spotting a downward drift in vessel temperature may
allow you to restore operation before the lines freeze. Waiting for a
temperature alarm often means waiting too long.
The general idea is to anticipate heat-tracing system failures, rather
than being surprised by them. Walk down your system and develop a list
of vulnerable points. Then, monitor them closely so you aren't stuck
doing repairs in "worst-cast scenario" conditions.
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Repair
Electrical Troubleshooting
Quiz
A crew just finished repairing a heat-trace circuit
that
failed due to mechanical damage for unknown reasons. One of the lines
looked "chopped in two." Now that it's working, the plant manager is
happy -- especially with a 40° drop predicted for tonight. The
big dayshift maintenance crew will be leaving shortly. Is this job
completed? If not, what additional steps should be taken and why?
The answer to this question appears at the end of this
newsletter.
Repairs in Cold Weather
More protective clothing and less time are just two of
the factors that complicate troubleshooting and repair in cold weather.
We can take a page from the nuclear industry to improve the situation.
The key is to analyze the job, make a list of component tasks, and find
a way to complete as many of those tasks as possible "offline." In
nuclear plants, they want to do work where it's not "hot"
(radioactive).
You want to do work where it's not cold.
Breaking the job up this way may seem like it takes more time --
and maybe that is true in ordinary weather conditions. But when it's
very cold outside, this effort will reduce errors, improve safety, and
reduce time to completion. As a bonus, this forced look at every aspect
of the repair job will probably reveal ways to streamline the job for
all weather conditions.
For example, you might normally prepare individual wiring in the
field. That involves cutting, stripping, labeling, and other steps that
are more efficiently done in a shop environment. Changing out
connectors
for more rapid repair in cold weather will result in more rapid repair
in all weather. Think of prefab you can do for wiring harnesses,
control
cabinets, and other assemblies. Look closely at procedures for steps to
eliminate or simplify.
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Operation
NEC and Heat Tracing
Heat tracing has been in use for decades. It's very
reliable and has saved many companies a great deal of money. But
occasionally, existing systems need repair, replacement, or upgrading.
And facilities with existing heat-tracing systems may add heat tracing
to accommodate process changes or new equipment.
Some commonly overlooked points:
- You must install heat tracing in a way that protects it from
physical damage. Don't look just for what's present during summer
months. Ice can hang from a platform or other structure, and present a
physical hazard to the heat tracing below.
- If you install heat tracing across an expansion joint, you must
allow for expansion and contraction.
- Heat tracing installed on flexible lines must also be
flexible.
- Do not misconstrue the word "grounding" in 427.23 and 427.48. In
this context, the NEC means "bonding" and not "grounding." See the Art.
100 definitions of grounding and bonding.
- Your system must have a disconnecting means and not just a
temperature controller. However, a temperature controller with an "off"
position satisfies both requirements (if it is not
remote-controlled).
OSHA and Cold Weather Work
OSHA offers free tips for protecting
employees in cold weather. These range from recognizing danger
signs
to specific steps for preventing injury and illness. For free copies of
OSHA's Cold Stress Card in English or Spanish, go to
www.osha.gov or call
1-800-321-OSHA.
Quiz Answers
Answer to Electrical
Troubleshooting
Quiz
This is a classic case of the incomplete repair job.
Nobody identified the cause of the damage. Something appears to
have cut the cable. Was it falling ice? Did a rodent chew through it?
Did the pressure of a foot (human or otherwise) cause the cable to
break?
Leaving the precise cause undetermined may be unavoidable. But you
cannot leave the integrity of the remaining heat-tracing system
undetermined. With that severe temperature drop coming in just a few
hours, you can't rely on the fact a failure isn't yet obvious. If a
freeze would be catastrophic, you have no choice but to inspect the
entire system while there is still adequate light for finding and
repairing damage.
Heat tracing is not problem-prone equipment. If something causes a
failure, see if any other heat-tracing equipment has been affected --
before lines or vessels freeze.
Show & Events
It's Time to Hit the Beach
If it's your job to make sure all systems are "go," you
need to go to Electric West. This show and conference offers the right
information and product mix to meet all of your information needs. Do
you maintain and operate electrical systems in a facility? If so, you
have to make plans to attend the Electric West conference program next
year in Long Beach, Calif. Check
out this event's 40+ seminars in the areas of power quality,
safety,
Code changes, and industrial applications, and make plans to meet 200+
leading suppliers. Or register
now.
Enter The "You Be The Electrical Inspector" Contest at The
e-Tradeshow
Here's your chance to win a $100 American Express gift certificate and
show off your knowledge of the National Electrical Code by acting as an
electrical inspector and citing every Code violation appearing in five
actual electrical installations.
Submit your respective list of violations and, if you're selected as
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familiarity by having your picture posted in the EC&M booth on
the e-Tradeshow exhibit floor. And, of course, the $100 gift
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Click here for
information
on accessing the EC&M e-Tradeshow, a virtual online exhibition
and live conference center. Also available on the site is an archive of
various past presentations, such as Claim Litigation and
Harmonics: Causes, Symptoms, and Remedial Solutions.
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