Insulation System Failure Prevention on Below-Ambient Piping
An ounce of prevention is worth a pound of cure
when it comes to a properly designed, installed, and maintained pipe insulation
system. Mechanical insulation failures occur for a variety of reasons,
including improper design for the application conditions, faulty materials,
poor installation techniques, or damage to the insulation. Many of these
failures can be prevented through careful preparation and planning.
Appropriate design, quality
materials, and proper installation can drastically reduce the possibility of a
compromised insulation system. Damage should be minimal or nonexistent with the
proper selection of materials. A proper design anticipates the stresses and
abuse an insulation system will face and specifies an appropriate insulation
and jacket. There are a variety of insulation and jacketing choices, but often
the lowest cost product is selected rather than the one that best meets the job
criteria, which may result in system failure down the road.
All insulation systems require
a degree of maintenance, and some materials may require considerably more than
others. Insulation systems should always be properly maintained; but, if
resources for maintenance will be minimal, then that should be factored into
the material selection and insulation system design. Proper installation of the
insulation system, including planning for the other parts of the construction
process and the scheduling of other trades, will result in a system that is
less vulnerable to damage. Frequently, buildings are not enclosed before
insulation is installed, and the insulation may be exposed to the environment.
Similarly, other aspects of building construction may affect insulation. Thus,
engineers and general contractors should consider types of insulation or
jacketing that can withstand the environment stressors such as higher humidity.
Appropriate storage is another important consideration, as materials can become
wet or damaged if left exposed at the job site. Again, careful planning and the
anticipation of potential issues are key to reducing damage to the insulation.
The consequences of a damaged
insulation system vary greatly based on whether it is a hot or cold (below
ambient) system. Damage to a hot system will result in energy loss and possibly
pipe corrosion, depending on the conditions. Damage will likely be fairly
localized and manageable if repaired in a timely fashion. Damage to a cold
system can, and often does, result in a catastrophic failure of the whole
system, especially if it is not repaired immediately. Damage to a cold system
will usually result in moisture penetration, which can cause a number of
- Loss of thermal
- Mold growth
- Corrosion under
- Formation of
ice on or in the insulation system
- Complete system
If damage to the insulation system is not repaired immediately, the
failure will spread as moisture penetrates to other areas of the insulation.
Potential solutions for limiting the extent of an insulation failure on a cold
system include the following:
- Select low
permeability, closed cell insulation materials that resist moisture
- Choose insulation
and jacketing materials that are mold resistant. If a problem with mold growth
is anticipated, materials which meet certain performance requirements such as
ASTM C1338—08 Standard Test Method for Determining Fungi Resistance of
Insulation Materials and Facings or others can be helpful in this area.
- Select the best type of vapor retarder jacket for
the type of application—e.g., indoor, outdoor, or buried applications. ASTM
standards can be an excellent resource. For example, ASTM C 1423 addresses
criteria for choosing jacketing materials for application over thermal
insulation covering piping, ducts, and equipment. ASTM C 1136 lists several
jacket options for indoor applications. Furthermore, a specification for
outdoor applications is in the works at ASTM Subcommittee C16.40: Insulation
System under the Laminate Protective Jacket and Tape for Use on Thermal
Insulation task group. These examples are by no means all inclusive; vapor
retarder jacket selection based on the specifics of a given application will
yield the best results.
- Choose materials and accessories that meet the
performance criteria for the specific job, and make sure they are properly
installed—which includes ensuring that workers are trained in how to protect
the integrity of the system during installation. Foot traffic and other
physical abuse can damage many insulation systems and should be considered when
selecting materials. It is also important to consider whether the environment
is conditioned, as well as the humidity level of the space, as different
options will perform better under different conditions.
- Use moisture
vapor stops on cold systems to isolate insulation sections and limit the
failure caused by a damaged section.
- Be sure all
seams, joints, and termination points are secure and moisture tight on the
vapor retarder and/or the insulation. Do not leave any seams or termination
points unsecured or any insulation exposed when leaving a job location at the
end of the day. Only install in a day what can also be covered by vapor
retarder and jacketing that same day.
- Perform an inspection of each insulated area before
moving on to another section, specifically checking for any open seams,
discontinuities in the vapor retarder, or problems areas. Immediately repair
any areas that need attention.
- Install an
outer protective jacket (e.g. aluminum outdoors or PVC indoors) if needed to
protect the insulation system and the vapor retarder from physical abuse.
While the frequency of problems is probably equal for hot and cold
systems, the failures most often publicized are those on cold systems—e.g.
chilled water—due to their severity. For example, cold systems where the
ambient space is unconditioned can have a particular concern for the issue of
surface mold, which can result in major problems sometimes culminating in
lawsuits and replacement of entire insulation systems. Project types where this
could occur include condominiums, office buildings, dormitories, hotels, sports
arenas, or convention centers. Lawsuits occurring from system failures can
become very difficult situations where blame is exchanged between multiple
parties—the designer blames the installer, while the installer blames the
designer, manufacturer, or other trades that may have damaged the insulation
while they were on the job. Regardless of who is at fault, the failure may have
been prevented if proper materials were selected in the design stage, better
installation scheduling and techniques were used, and proper maintenance was
Unfortunately, when failures do occur, it is typical for those involved
to look for a guilty party rather than consider how the problem may have been
prevented. Proper preparation is often all it takes to prevent insulation
damage that can cause a system failure. It is time to approach hot and cold
systems differently by specifying materials that are designed for below ambient
conditions on cold systems. This is particularly critical when the insulated
pipe is located in an unconditioned space.
When looking at materials,
designers must examine the physical properties of the material—specifically,
the properties of the material as installed. The design should consider the
building envelope, building use, maintenance that will be available after the
job is completed, as well as the desired energy savings when the building is
actually operating. Insulation should be viewed as a way to lower operating
costs and save energy, rather than just a building expense.
All contractors should work
together, allowing each trade to do its job while keeping in mind how their
actions will affect the entire project. The insulation contractor should use
the best installation techniques available—those that not only save time, but
also ensure performance and reliability. If they do follow these protocols,
they should be able to produce cold insulation systems that operate effectively
and without errors.