Don't Get Burned By A Boiler Retrofit Project
by John R. Puskar P.E.
January 9, 2009
When
it comes to that unexpected (and unwelcome) development, it’s
usually less a case of if than when. Avoiding confusion over the
specific technical scope of work up front, keeping an eye on codes
and insurance, and considering contingencies for discovered problems
along the way will smooth the path as much as possible.
It
seems simple enough doesn’t it? I need a new burner or controls for
my boiler, furnace, or oven, and you have these to sell. You give me
a price, do the work, and then we’re all happy, right?
Wrong! Unless we do some very careful
planning and communicate very carefully, we could be in for trouble.
All too often, our firm is hired by many of our clients in the role
of arbitrator, mediator, and neutral third-party expert on projects
that have gone wrong. The end result of these projects gone wrong can
range from damaged equipment that is out of service for months, to
long and ugly lawsuits. What’s even worse is the wasted money and
time on the part of the equipment owner.
Project Scoping and Responsibilities
We
encounter very few OEMs that make their own burners and control
systems. Therefore, calling them back in often brings no peace of
mind for a correct and functioning project. Retrofits are a different
animal. You are asking someone to try to fix, in some cases, years of
neglect and a history of changes made to a piece of equipment.
For example, in the case of a boiler that is
getting a new low NOx burner, there are several issues that can make
for disappointment. Sometimes, conditions inside the boiler itself
may have changed over the years, such as the spacing of tubes between
passes that can make for leaked CO rich flue gas to the flue. This is
not the fault of the burner, but it would most likely be discovered
in the burner commissioning process. Whose fault is this? How do you
as a customer feel when you are told the burner does not meet
performance expectations but it is not the burner vendor’s fault?
What about a furnace or oven where the
contractor starts to tear into that “snake pit” of a junction box
and finds out things are not as they seemed? What happens now? Is it
fair for the contractor to eat 25 years of sins and problems?
No retrofit project should commence without a
formal meeting to discuss all of the problems that could crop up and
all of the possible contingencies. Better that everyone knows that
even under the best of circumstances sometimes these projects do not
go well, rather than to try and deal with this later.
Safety Devices and Close-Outs
It
should be understood that changing anything regarding the piping of a
fuel train should trigger certain automatic events, regardless of
what anyone thought the scope was. For example, any time a fuel train
is opened up for any reason, the tightness of all automatic valves in
a system should be checked immediately prior to putting the device
back into service. They should again be checked within two weeks, and
then again after three months before the normal annual schedule is
continued. Opening up any fuel train creates the risk of passing
contamination down into valve sealing areas.
The
other issue that becomes very important is properly closing out a
retrofit. Every retrofit project should include a contractor
verifying the functionality of all safety devices in every possible
failure mode, and the verification of the correct setpoints and
calibration of all control and safety devices, whether they were part
of the project or not. Complete combustion fuel/air ration setting
and verification should follow. Of course, this kind of attention to
detail should be built into the original pricing and project scope.
It is also important to understand that
testing and calibration can mean the discovery of problems. You
cannot ask a contractor to be responsible for the cost of replacing
failed components, deriving switch setpoints that were never correct,
and/or the replacement of devices or the discovery of issues that may
have been a problem for years. Here is where you need to have
confidence in whoever you are using and make sure that you have a
source for a second opinion.
It also makes
sense to ensure that whoever you are using is able to provide you
with an analysis of how your current equipment and safety systems
match up with the current versions of the latest applicable safety
codes. This would be NFPA 85 for boilers and NFPA 86 for ovens and
furnaces (available at www.nfpa.org).
It may be illegal to do a partial retrofit in some states and not
make a piece of equipment totally compliant with the latest code
version.
Please remember that any time a
piece of equipment’s flame safety or control logic is modified, you
should involve your insurance provider. This is usually your property
and casualty (fire) insurance company for ovens and furnaces, and/or
fuel train or burner changes on boilers. In most cases, they will
want to review what you are doing, including approving drawings. You
need to build in approximately one month into your project schedule
for these reviews.
The Start Sets The Tone
Retrofitting
fuel trains, controls, and burners is not a simple or straightforward
process. When someone says they are upgrading controls, remember
there are two systems they could be referring to. Every piece of
fuel-fired equipment has two control systems, the CCS (sometimes
called the combustion control system) and the BMS (burner management
system or safety controls). These are usually two separate and
distinct systems. Make sure everyone’s talking about the same
thing.
It is important to make sure that
everyone enters into these projects with wide-open eyes. They need to
communicate often, budget properly, and have the proper insurance
folks involved for reviews, all before implementing a rigorous and
well-defined close-out process. It does not have to get ugly or be
difficult, but it can sure get that way in a hurry if you are not
prepared. ES
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