Technical Papers37th Annual Meeting
International Institute of Ammonia Refrigeration
March 22–25, 2015
2015 Industrial Refrigeration Conference & ExhibitionSan Diego, California
ACKNOWLEDGEMENT
The success of the 37th Annual Meeting of the International Institute of Ammonia
Refrigeration is due to the quality of the technical papers in this volume and the labor of its
authors. IIAR expresses its deep appreciation to the authors, reviewers and editors for their
contributions to the ammonia refrigeration industry.
ABOUT THIS VOLUME
IIAR Technical Papers are subjected to rigorous technical peer review.
The views expressed in the papers in this volume are those of the authors, not the
International Institute of Ammonia Refrigeration. They are not official positions of the
Institute and are not officially endorsed.
International Institute of Ammonia Refrigeration
1001 North Fairfax Street
Suite 503
Alexandria, VA 22314
+ 1-703-312-4200 (voice)
+ 1-703-312-0065 (fax)
www.iiar.org
2015 Industrial Refrigeration Conference & Exhibition
San Diego, California
© IIAR 2015 1
Technical Paper #1
Case Study – Economic Justification for Replacing Ice-laden Refrigerant Pipe
Thermal Insulation with New Insulation
Gordon H. Hart, P.E.Artek Engineering, LLC
Technical Paper #1 © IIAR 2015 3
Case Study – Economic Justification for Replacing Ice-laden Refrigerant Pipe Thermal Insulation with New Insulation
Introduction
In 2011, following a severe hail storm, the owner of a large food processing plant
discovered that the thermal insulation systems on his roof-top ammonia refrigeration
pipes had been badly damaged. A subsequent inspection conducted soon after
the storm by the building owner revealed that the pipe insulation was ice-laden
and/or soaked with water, following its fifteen years of continuous service. To
remedy the situation, the owner hired an insulation contractor to replace the ice-
laden and wet insulation over the course of several years, as his budget and schedule
would allow, using a different insulation system design. After the owner made this
decision to replace the old insulation system with new materials, an energy analysis
was conducted to determine the cost effectiveness of that replacement based on
the value of energy saved and the cost of replacement. The decision to replace the
original insulation system with a new one, of a different design, was made solely by
the facility owner. This author had no role in that decision or recommendation. It
should also be noted that the type of replacement insulation used, polyolefin, is no
longer commercially available for industrial refrigeration applications.
Description of the Refrigerant Pipes and Original Thermal Insulation
The damaged pipe insulation was located on the roofs of two food processing
buildings, located adjacent to one another in central South Carolina. The affected
ammonia pipes included suction lines with a design operating temperature as low
as -25°F, hot gas lines with a design operating temperature of 60°F, and others with
design operating temperatures that fell between these two extremes. Pipe sizes varied
from as small as ¾ inch NPS to as large as 12 inches NPS. In total, there were 4,756
lineal feet of pipe requiring insulation system replacement servicing of 39 roof top
evaporators on the two buildings.
4 © IIAR 2015 Technical Paper #1
2015 IIAR Industrial Refrigeration Conference & Exhibition, San Diego, CA
The original pipe insulation system consisted of extruded (XPS) polystyrene foam
covered with an All Service Jacket (ASJ) vapor retarder plus vapor retarder mastic in
the fittings. This type of ASJ is a laminate of white Kraft paper (on the outer surface),
glass fiber scrim reinforcement, and thin aluminum foil with a thickness of 0.00035
inches. The ASJ was sealed using ASJ tape, a tape made of the same materials as
ASJ and with a pressure sensitive adhesive inner surface. Note that the use of ASJ
on outdoor refrigeration pipes is not recommended by the current IIAR Ammonia
Refrigeration Piping Handbook, Chapter 7 (Ref. 1). The straight pipes were then
covered with 0.016 inch thick aluminum protective jacketing with fittings covered
with 0.020 inch thick polyvinyl chloride (PVC) molded fittings as the protective
jacketing. Note that the use of PVC jackets on outdoor applications is also not
recommended by the Piping Handbook (Ref. 1) and recommends the use of 0.030
inch, rather than 0.020 inch, thick PVC. Pipe supports, on the mostly horizontal
pipes, were insulated with the same type of insulation, ASJ vapor retarder, and
protective jacketing. Figure 1 shows an array of several of the affected insulated roof
top refrigeration pipes.
Technical Paper #1 © IIAR 2015 5
Case Study – Economic Justification for Replacing Ice-laden Refrigerant Pipe Thermal Insulation with New Insulation
Figure 1. Shows some of the affected insulated refrigerant pipes on the roof of this food processing facility. Pipes with dark, oxidized aluminum jacketing, on the right, have original insulation, those with shiny aluminum jacketing have new insulation, and those with either white vapor retarder film or green-grey insulation have new insulation as well but the insulation system installation is still in progress.
The condition of original refrigerant pipe insulation
The damaging hail storm occurred in the spring of 2011. Prior to that, the facility
owner had noticed that some of the PVC fitting covers had been damaged although
the storm further damaged them. Following the storm and upon inspection of
the pipe insulation, the facility owner noted that even though some of the metal
6 © IIAR 2015 Technical Paper #1
2015 IIAR Industrial Refrigeration Conference & Exhibition, San Diego, CA
jacketing had holes punched in it by the storm, and these holes had gone through
the ASJ vapor retarder jacketing. The ASJ had also been damaged, apparently by
moisture, in other locations that were not hail damaged. Observing the insulation
to be ice-laden or very wet in most locations inspected, the facility owner decided
that all the original pipe insulation materials needed to be replaced. The selection
of the new insulation system design, and the selection of the contractor were made
independently by the facility owner.
The insulation system replacement started in late 2012. About a year later, some
of the original pipe insulation system that was being removed and replaced with
a new insulation system was inspected. The observations were done during the
late fall of 2013, on a day when the absolute humidity was low and the bare pipes,
which were charged, would not experience much surface condensation while bare.
It was observed that the original pipe insulation was heavily ice-laden. Due to this
condition, the insulation contractor’s insulators were observed using hammers and
chisels to chip the insulation away from the pipe until it was bare and cleaned of
most ice and insulation. In this laborious process, the insulator team worked on
several lineal feet at a time so as not to leave a large length of the pipe exposed to the
ambient humidity for more than half an hour. See Figures 2–4.
Technical Paper #1 © IIAR 2015 7
Case Study – Economic Justification for Replacing Ice-laden Refrigerant Pipe Thermal Insulation with New Insulation
Figure 2. Shows an insulator preparing to use a hammer and chisel to remove ice-laden insulation from this charged ammonia refrigeration line. This particular pipe is 3 inch NPS and had 2.5 inches of insulation on it. The original aluminum jacketing and ASJ vapor retarder had already been removed prior to this photo being taken.
8 © IIAR 2015 Technical Paper #1
2015 IIAR Industrial Refrigeration Conference & Exhibition, San Diego, CA
Figure 3. Shows some of the ice-laden insulation in the middle of the removal process. The partially removed ASJ vapor retarder, which was also saturated, can be seen on the left.
Technical Paper #1 © IIAR 2015 9
Case Study – Economic Justification for Replacing Ice-laden Refrigerant Pipe Thermal Insulation with New Insulation
Figure 4. Shows the author holding a piece of ice-laden insulation that the insulators had just removed. The ice extended from the pipe surface to the outer surface of the insulation. This is what the author refers to as “ice-laden.”
It was concluded, based on this observation, that the original insulation was ice-
laden. The ice extended from the pipe surface to the insulation outer surface. The
ASJ that was seen, and held, was very wet but not frozen.
As mentioned earlier, some of the PVC jacketing on insulated fittings had been
damaged by the hail storm. This is illustrated by the photograph in Figure 5.
10 © IIAR 2015 Technical Paper #1
2015 IIAR Industrial Refrigeration Conference & Exhibition, San Diego, CA
The XPS polystyrene insulation, with a water vapor permeance of 1.5 perm-inch
and a water absorption of 1.0% by volume (Ref. 2), cannot by itself prevent vapor
migration from the ambient to the pipe, and its subsequent absorption by the
insulation. This insulation requires a high performance, continuously sealed vapor
retarder. The ASJ vapor retarder on the straight pipes, combined with the vapor
retarder mastic on the fittings, clearly did not perform sufficiently, resulting in a total
pipe insulation system failure due to water vapor intrusion and absorption by the
insulation. Perhaps this explains why the IIAR Piping Handbook (Ref. 1) recommends
against the use of an ASJ vapor retarder on straight pipe and PVC fitting covers that
are exposed to the weather. What the facility owner acknowledged is that after 15
years the insulation system became saturated with ice, water, or both and it needed
to be replaced to perform effectively. Furthermore, the facility owner concluded
that replacement by the same insulation system design (i.e., including insulation,
ASJ vapor retarder, mastic, PVC fitting covers, and jacket) would likely result in a
recurrence of this moisture failure. Consequently, he selected a new insulation system
design, using different materials, and he decided to spend a considerable amount of
money to have this insulation system replacement performed.
Technical Paper #1 © IIAR 2015 11
Case Study – Economic Justification for Replacing Ice-laden Refrigerant Pipe Thermal Insulation with New Insulation
Figure 5. Shows a 90° insulated elbow covered with PVC jacketing that had been damaged by the hail storm.
Description of the Replacement Pipe Insulation and Replacement Process
Following the removal of the original pipe insulation, the insulators installed new
replacement insulation of the same thickness as the original. The replacement
material selected by the facility owner was polyolefin insulation, sometimes also
referred to as polyethylene insulation. The material installed meets or exceeds the
performance requirements of ASTM specification C1427 (Ref. 3). Per the ASTM
12 © IIAR 2015 Technical Paper #1
2015 IIAR Industrial Refrigeration Conference & Exhibition, San Diego, CA
specification, this insulation material has a water vapor permeability less than or
equal to 0.05 perm-inch and a water absorption by submersion performance less
than 0.2% by volume. The insulation manufacturer’s product data sheet gave even
lower values, of 0.048 perm-inch and 0.05% by volume respectively. It was noted
earlier that the insulation manufacturer no longer manufactures and sells this
product (i.e., it has no longer been commercially available since of October, 2014).
The vapor retarder installed is a 4 mil thick polyvinylidene chloride (PVDC) film that
meets or exceeds the requirements of ASTM specification C1136, Type XIII (Ref. 4).
It has a permeance less than or equal to 0.1 perm and, as a homogeneous material
free of paper (i.e., it is not a paper-containing laminate), can be sealed tightly with
matching PVDC tape that has a pressure sensitive adhesive. The new 0.016 inch thick
aluminum jacketing meets or exceeds the requirements of ASTM specification C1729
Type I Class A (Ref. 5).
During installation, the insulators secured the insulation on the pipe with strapping
tape. When installing the outer most layer of the two layer insulation system, the
insulators applied a sealant to the butt and lap joints to prevent moisture intrusion
beneath the outer layer, should water vapor bypass the vapor retarder film. While
the use of the sealant may not have been necessary, since the sealed PVDC film
vapor retarder should suffice in excluding water vapor intrusion, the sealant use was
a design decision made by the facility owner. In effect, this replacement insulation
system has a double vapor retarder, the first being the 4 mil PVDC film (with a
permeance less than or equal to 0.01 perm) and the second one being the outer
inch of polyolefin insulation (with a permeance less than or equal to 0.05 perm).
This constitutes a redundant vapor retarder system. While perhaps not necessary,
redundancy can be valuable under certain circumstances, such as following a future
damaging hail storm.
Technical Paper #1 © IIAR 2015 13
Case Study – Economic Justification for Replacing Ice-laden Refrigerant Pipe Thermal Insulation with New Insulation
Figure 6. Shows an insulator cutting a section of new insulation for installation as a replacement for old ice-laden insulation.
14 © IIAR 2015 Technical Paper #1
2015 IIAR Industrial Refrigeration Conference & Exhibition, San Diego, CA
Figure 7. Shows three pipes which have been insulated with new insulation. The top one has yet to receive the PVDC film vapor retarder, shown in the middle pipe, with the lower pipe having been covered with protective aluminum jacketing. The PVDC film is sealed using a matching tape that has a pressure sensitive adhesive.
Technical Paper #1 © IIAR 2015 15
Case Study – Economic Justification for Replacing Ice-laden Refrigerant Pipe Thermal Insulation with New Insulation
Cost of the pipe insulation replacement
The facility owner has received a price from the insulation contractor to remove the
original insulation system and replace it with the new insulation system described
above for about $550,000, including material and labor to remove and discard the
old insulation and material and labor to install for the new insulation, as well as
contractor overhead. As of the fall of 2013, when the insulation system replacement
was observed, much of this work had already been completed, with the remainder
scheduled to be completed by early 2015.
So, the question remains, was this insulation system replacement worth the money?
Estimating the thermal conductivities of saturated and of ice-laden insulation
It is assumed that ice-laden and saturated pipe insulation has a greater thermal
conductivity than the same insulation in a dry condition, with no ice or water
within it. A literature search supports this assumption. For example, Cammerer, at a
laboratory in Germany (Ref. 6), conducted tests in 1987 on three types of insulation:
wet phenolic foam, EPS polystyrene, and mineral wool insulations and reported his
data graphically. The results for the two cellular insulation materials, EPS polystyrene
and phenolic foam, are reproduced as Figures 9a and 9b. Note that the data points in
these two graphs show a pronounced increase in thermal conductivity as a function
of water content, expressed as percent by volume. Furthermore, the mathematical
relationship appears to be best described by a second order polynomial rather than a
straight line.
16 © IIAR 2015 Technical Paper #1
2015 IIAR Industrial Refrigeration Conference & Exhibition, San Diego, CA
Figures 8a, on left, and 8b, on right, show the measured thermal conductivity of EPS polystyrene insulation and phenolic foam, respectively, in SI units, as a function of percent by volume water, from Cammerer (Ref. 6). Note that these data points follow the shapes of curves best described by a polynomial.
More recently, here in the Unites States, an Oklahoma State University research team
led by Cremaschi, as reported in ASHRAE Research Project RP-1356 (Ref. 6), tested
the thermal conductivity values of phenolic foam pipe insulation at different values
of condensed water content. The results of this research also support the assumption
that thermal conductivity of insulation increases with water content. Phenolic foam
and XPS polystyrene insulation, while different insulation materials, are both closed
cell foam plastics. It was assumed that, even with different densities between the
two materials, the percent increase in thermal conductivity, based on percent water
content by volume, are about equal. RP-1356 showed that dry phenolic foam pipe
insulation on a 42°F pipe had a measured thermal conductivity of 0.20 Btu-in/hr-ft²-
°F, and with a 5% water content by volume, it had a measured thermal conductivity
Technical Paper #1 © IIAR 2015 17
Case Study – Economic Justification for Replacing Ice-laden Refrigerant Pipe Thermal Insulation with New Insulation
of 0.31 Btu-in/hr-ft²-°F. This thermal conductivity for the wet insulation, with 5%
water content by volume, represents an increase of 56% over that of the dry material
at the same mean temperature. Note that these tests were conducted in a hot, humid
environmental chamber on phenolic foam pipe insulation with no sheet or film vapor
retarder. Thus, the vapor condensation and subsequent increase in moisture content
of the insulation occurred in a matter of about 24 days. The RP-1356 tests were
accelerated and compared to what one would expect in a real application, which has
a sealed vapor retarder covering the insulation to slow water vapor migration from
the air to the cold pipe beneath the insulation system. It was decided to use the RP-
1356 data, based on phenolic foam, rather than use the Cammerer data, to estimate
thermal conductivity curves for wet and for ice-laden XPS polystyrene since it is more
recent and more conservative.
Since the phenolic foam insulation tested was assumed to have had a dry density
of 2.5 lbs/ft³ and XPS polystyrene pipe insulation, that meets ASTM C578, Type XIII
(Ref. 2), was assumed to have a density of 1.6 lbs/ft³, it was further assumed that
at a given water content by volume, each will have the same percent increase in
thermal conductivity compared to the dry insulation. Hence, with 5% water content,
it was also assumed that the XPS polystyrene insulation would also have a thermal
conductivity that is 56% greater than when dry, just like the phenolic foam. Since
dry XPS polystyrene insulation has a thermal conductivity of 0.259 Btu-in/hr-ft²-°F
(Ref. 2), it would have a predicted thermal conductivity, under the same temperature
conditions, of 0.40 Btu-in/hr-ft²-°F with a 5% water content by volume.
Extrapolating the RP-1356 data to completely saturated phenolic foam, and then
estimating the thermal conductivity of XPS polystyrene pipe insulation using the
reasoning given above, the following graph was generated, Figure 10, which shows
the calculated thermal conductivity as a function of water content for both insulation
materials. Although it was not used, the Cammerer thermal conductivity data on wet
EPS polystyrene was included for comparison.
18 © IIAR 2015 Technical Paper #1
2015 IIAR Industrial Refrigeration Conference & Exhibition, San Diego, CA
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Apparent Thermal Conduc>vity Values, Btu-‐in/hr-‐sf-‐F
% moisture by volume
Measured and predicted values for thermal conduc>vity of phenolic foam and XPS polystyrene insula>ons, at 65 deg F mean,
as a func>on of % moisture by volume
RP-‐1356 Test Data on wet phenolic foam
Extrapolated Data on wet phenolic foam
Extrapolated data on wet XPS polystyrene
Figure 9. A graph generated by the author showing ASHRAE RP-1356 data on wet phenolic foam insulation, his extrapolated data on the same, and his extrapolated data on wet XPS polystyrene.
Using this extrapolation, the thermal conductivity of the saturated XPS polystyrene
works out to 1.56 Btu-in/hr-ft²-°F at a mean temperature of 65°F, a value which
is over six times greater than the 0.25 Btu-in/hr-ft²-°F value for the dry material.
However, this thermal conductivity value is considerably less than that of pure water
at the same mean temperature, which has a thermal conductivity that is about 4.15
Btu-in/hr-ft²-°F (Ref. 8), and 2.67 times greater than predicted for the saturated
insulation.
Using the thermal conductivity values as a function of mean temperature, a graph,
Figure 11, was generated. The graph shows three curves for thermal conductivity as
Technical Paper #1 © IIAR 2015 19
Case Study – Economic Justification for Replacing Ice-laden Refrigerant Pipe Thermal Insulation with New Insulation
a function of mean temperature, namely those of dry XPS polystyrene insulation, of
pure water, and of wet XPS polystyrene insulation. These three curves are shown
because the curve for dry insulation clearly bounds the lowest possible thermal
conductivity values, the curve for water clearly bounds the highest possible thermal
conductivity values, and that the middle derived curve, shows thermal conductivity
curve for the wet insulation that lies between those upper and lower bounding curves.
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 50 100 150 200 250
Apparent Therm
al Con
duc2vity, Btu-‐in
/hr-‐sf-‐deg F
Mean Temperature, Degrees F
Thermal Conduc2vi2es of Water, Dry and Saturated XPS Polystyrene Insula2on
Water
Saturated XPS Polystyrene, Calculated
Dry XPS Polystyrene, ASTM C578, Type XIII
Figure 10. Shows apparent thermal conductivity as a function of mean temperature for dry XPS polystyrene pipe insulation; for saturated XPS polystyrene; and for pure water. Since the thermal conductivity curve for saturated XPS polystyrene insulation is much less than that of pure water, it is reasonable and not overly conservative to use it for predicting the thermal performance of saturated pipe insulation on a below ambient temperature pipe operating at temperatures above freezing.
20 © IIAR 2015 Technical Paper #1
2015 IIAR Industrial Refrigeration Conference & Exhibition, San Diego, CA
However, the XPS polystyrene pipe insulation that was inspected was saturated with
ice rather than water. It was installed on an ammonia refrigeration line rated for
-25°F, not for 42°F, as in the RP-1356 research project. A literature review reveals that
ice, at a given mean temperature, has a thermal conductivity that is almost four times
greater than that of water (Ref. 9). Following the same reasoning used to generate
the graph in Figure 10. Figure 11 was generated for three curves for the thermal
conductivity as a function of mean temperature, namely one for dry XPS polystyrene,
one for ice-laden XPS polystyrene, and one for pure ice. These three curves show
that because the curve for dry insulation clearly bounds the lowest possible thermal
conductivity values, the curve for ice clearly bounds the highest possible thermal
conductivity values, and that the middle derived curve, derived by this author, shows
thermal conductivity curve for the ice-laden insulation that lies between these upper
and lower bounding curves.
This type of analysis was not performed for the new replacement insulation, because
the facility owner selected the 0.01 perm PVDC film vapor retarder, for both the
straight pipes and the fittings, both of which are water repellent and seals tightly
with a matching pressure sensitive tape. In addition, the replacement insulation
selected by the owner has a much lower (i.e., by a factor of 30) water vapor
permeance and a somewhat lower water absorption performance (i.e., by a factor of
5) than the original insulation. Furthermore, the outer inch of replacement insulation
was sealed with a sealant. In the future, it is expected the replacement insulation
to prevent water vapor transmission through the insulation system and subsequent
condensation on the pipe and in the insulation, as has occurred in the old,
original insulation.
Technical Paper #1 © IIAR 2015 21
Case Study – Economic Justification for Replacing Ice-laden Refrigerant Pipe Thermal Insulation with New Insulation
0
2
4
6
8
10
12
14
16
18
20
-‐60 -‐50 -‐40 -‐30 -‐20 -‐10 0 10 20 30 40 50
Appa
rent The
rmal Con
ducivity, B
tu-‐in
/hr-‐sf-‐deg
F
Mean Temperature, degrees F
Thermal Conduc>vi>es of Ice, Ice laden, and dry XPS Polystyrene Insula>on
Ice
Ice laden XPS Polystyrene, calculated
Figure 11. Shows the apparent thermal conductivity, as a function of mean temperature, for dry XPS polystyrene pipe insulation; for the same insulation laden with ice; and for pure ice.
Estimating the heat gain savings by reinsulating the refrigerant pipes
Using the publicly available computer program known as 3E Plus® (available
for no charge from the North American Insulation Manufacturers Association at
www.pipeinsulation.org (Ref. 10)). Heat gain calculated for the refrigerant pipes
both before and after insulation replacement. It was assumed an average ambient
temperature, over the course of the year, of 65°F (Note: this temperature is not
intended to represent a design ambient temperature but simply an average for the
year) and an average wind speed of 5 mph. For the new replacement insulation, the
22 © IIAR 2015 Technical Paper #1
2015 IIAR Industrial Refrigeration Conference & Exhibition, San Diego, CA
polyolefin manufacturer’s data was used which has values very close to those for
dry XPS polystyrene insulation at corresponding mean temperatures. Table 1 gives
thermal conductivity values as a function of mean temperature for the polyolefin
insulation used in this analysis:
Mean temperature, °F Thermal conductivity, Btu-in / hr–ft²–°F-120 0.193-50 0.2290 0.25850 0.307120 0.339
Table 1. Mean temperature – thermal conductivity values for the polyolefin insulation used for heat gain calculations (provided by the manufacturer)
Using the facility owner’s as-built engineering drawings for refrigerant pipe
temperatures, sizes, and lengths, and records for pipe insulation thicknesses (which
were not changed with the insulation replacement), heat gain savings was calculated,
on an annual basis, for each pipe line. These savings were reduced by several percent
to account for scheduled defrost cycles (provided by the facility owner), and the heat
gain savings were summed. Tabulated results, pipe by pipe, are shown on tables in
Appendix A, Tables 1 and 2 with the summary on Table 3. As Table 3 shows, the
cumulative results came out to a total annual heat gain savings of 3,149 million Btuh
for the 4,756 linear feet of insulated refrigerant pipe. These results are tabulated in
Table 2 (copied from Appendix A, Table 3).
Total load with old insulation 402,116 BtuhTotal load with new insulation 42,570 BtuhTotal load reduction 359,546 BtuhPercent load reduction 89.4%Total Pipe Length 4,759 feetTotal Δ energy use 3,150 MMBtu/yr
Table 2. Summary of Calculated Heat Gain with old insulation and new insulation, and total reduction in energy use
Technical Paper #1 © IIAR 2015 23
Case Study – Economic Justification for Replacing Ice-laden Refrigerant Pipe Thermal Insulation with New Insulation
A cost/benefit analysis would really require financial records of electricity costs spent
by the facility owner on his refrigeration systems both before and after insulation
replacement, which were not available. Further, records of the refrigeration systems’
combined, average Coefficient of Performance (COP) values, over the course of a
year of operation, were also not available to this author. Hence, a range of values
was assumed.
To determine how cost effective the replacement insulation is based on energy
savings, a Life Cycle Cost Analysis (LCCA) was performed. Assuming a 2% interest
rate over an assumed 20 year life of the replacement insulation system, Life Cycle
Costs in present US dollars were calculated for both the original insulation system, if
left in place, and the new replacement insulation. Equation 1 was used to calculate
Present Value (PV) for Energy and for Operations & Maintenance costs for several
different values of CO) for the refrigeration system:
Equation 1. PV / AV = ((1 + i)n -1) / (i (1 + i)n) (Ref. 11)
where
i = assumed interest rate (i.e., 2% annually)
n = assumed life of the new replacement insulation system, in years
(i.e., 20 years)
PV = present value
AV = annual value
24 © IIAR 2015 Technical Paper #1
2015 IIAR Industrial Refrigeration Conference & Exhibition, San Diego, CA
Equation 2 was used for calculation of Life Cycle Cost (LCC):
Equation 2. LCC = I + Repl — Res + E + W + OM&R + O (Ref. 12)
where
LCC = Total LCC in present-value (PV) dollars of a given alternative
I = Present Value (PV) investment costs (assumed to be zero)
Repl = PV capital replacement costs (i.e., $550,000)
Res = PV residual value (resale value, salvage value) less disposal costs
(i.e., already included in the $550,000 replacement cost)
E = PV of energy costs (i.e., calculated annual heat gain, in kWh, x $0.10/
kWh / COP x P/A from Equation 1)
W = PV of water costs (i.e., assumed to be zero)
OM&R = PV of non-fuel operating, maintenance and repair costs (i.e., assumed
to be $10,000 per year x P/A from Equation 1)
O = PV of other costs (e.g., contract costs for ESPCs or UESCs)
(i.e., assumed to be zero)
The tabulated results of the calculations are summarized in Appendix B, Table 1.
The results of this analysis are shown graphically on Figure 12.
Technical Paper #1 © IIAR 2015 25
Case Study – Economic Justification for Replacing Ice-laden Refrigerant Pipe Thermal Insulation with New Insulation
$-‐
$200,000
$400,000
$600,000
$800,000
$1,000,000
$1,200,000
$1,400,000
$1,600,000
$1,800,000
$2,000,000
1 1.5 2 2.5 3 3.5 4
Life
Cyc
le C
ost,
$
Coefficient of Performance, Assumed
Calculated Life Cycle Costs of Original InsulaEon and New Replacement InsulaEon
Old, original InsulaEon
New replacement insulaEon
Figure 12. Shows the results of a Life Cycle Cost Analysis, for the refrigeration pipe insulation, over a range of assumed values of Coefficient of Performance for the ammonia refrigeration system. As with all LCCAs, a number of assumptions were made on electricity escalation rate and life of the replacement insulation system.
Since the two curves cross at an assumed COP of about 2.75, that value represents
the break-even point for this $550,000 investment in new replacement insulation
based on future energy savings at $0.10 per kWh with an annual interest rate of 2%.
Therefore, for a COP value < 2.75, this new, replacement insulation system would
have an estimated lower LCC over 20 years than the original, ice-laden insulation
system. At higher COP values, leaving the original, ice-laden insulation system in
place would have a lower LCC than the replacement insulation.
26 © IIAR 2015 Technical Paper #1
2015 IIAR Industrial Refrigeration Conference & Exhibition, San Diego, CA
Conclusions and Recommendations
Following a damaging hail storm in 2011, the owner of a food processing facility
discovered his original ammonia refrigeration pipe insulation system’s protective
jacketing had become heavily damaged. Upon further inspection after the hail storm,
the owner discovered that the pipe insulation material had become ice-laden and wet
over the course of its 15 year life. This original insulation was covered with an ASJ
vapor retarder and aluminum jacketing, on the straight pipe sections, and with a 20
mil thick vapor retarder mastic and PVC jacketing on the fittings. As a result of his
inspection, the facility owner made the decision to replace all his roof-top ammonia
pipe insulation as his schedule and budget would allow. Replacement has been, and
continues to be, conducted during winter months with the ammonia pipes charged
and in operation. As of September 2014, much of the pipe insulation had already
been replaced and most of the remainder is scheduled to be replaced in late 2014 and
early 2015. There are a total of 4,756 linear feet of refrigeration pipe that is affected,
with sizes ranging from 3/4 inch to 12 inch NPS and design operating temperatures
from a low of -25°F to a high of 60°F. The replacement pipe insulation system
includes a continuously sealed polyvinylidene chloride (PVDC) film vapor retarder,
sealed with matching tape and new aluminum jacketing for protection.
The quoted price, from the insulation contractor, to perform this insulation removal
and replacement is about $550,000. This price includes contractor labor for removal
and disposal of the original insulation, purchase of the new insulation, sealant, PVDC
film vapor retarder, aluminum jacketing, labor to install the new materials, and
contractor overhead.
A separate energy analysis showed annual thermal energy savings, by re-insulating
the roof top refrigerant pipe, of 3,149 million Btuh. This results in an estimated
89.4% load reduction on the insulated pipes. A Life Cycle Cost Analysis concludes
that with a refrigeration system Coefficient of Performance less than 2.75, this
insulation replacement would have a lower LCC than leaving the original, ice-laden
Technical Paper #1 © IIAR 2015 27
Case Study – Economic Justification for Replacing Ice-laden Refrigerant Pipe Thermal Insulation with New Insulation
and wet pipe insulation in place. At higher values of COP, leaving the original, ice-
laden pipe insulation system in place would have been more cost effective.
It is recommended that either insulation manufacturers or the refrigeration
industry test wet and ice-laden insulation materials, of the types used on ammonia
refrigeration pipes, for thermal conductivity as a function of moisture content.
This will allow economic analyses, such as this, to be more refined, with fewer
assumptions. It is also recommended that mechanical designers specify insulation
vapor retarder and jacketing materials that are recommended by the 2014 revision of
Chapter 7 of the IIAR Ammonia Refrigeration Piping Handbook (Ref. 1). Additionally,
it is recommended that mechanical designers use software that models simultaneous
heat and mass transfer to improve predictions of water vapor transmission into
refrigeration pipe insulation. Doing so will provide the opportunity to make
improvements in water vapor control strategies for pipe insulation systems.
28 © IIAR 2015 Technical Paper #1
2015 IIAR Industrial Refrigeration Conference & Exhibition, San Diego, CA
Figure 14. Shows several refrigerant pipes, all but one of which have a new pipe insulation system. Dents from the severe hail storm, which brought the degraded condition of the original insulation to the facility owner’s attention, still show on the old aluminum jacket protecting the largest pipe, to the left of the photo.
Technical Paper #1 © IIAR 2015 29
Case Study – Economic Justification for Replacing Ice-laden Refrigerant Pipe Thermal Insulation with New Insulation
References:
1. IIAR Ammonia Refrigeration Piping Handbook, Chapter 7, “Insulation for
Refrigeration Systems,” 2014.
2. ASTM C578–Specification for Rigid, Cellular Polystyrene Thermal Insulation
3. ASTM C1427 – Specification for Extruded Preformed Flexible Cellular Polyolefin
Thermal Insulation in Sheet and Tubular Form.
4. ASTM C1136–Specification for Flexible, Low Permeance Vapor Retarders for
Thermal Insulation.
5. ASTM C1729–Specification for Aluminum Jacketing for Insulation.
6. Cammerer, W.F.: “Der Feuchtigkeitseinfluss auf die Wärmeleitfähigkeit von
Bau- und Wärmedämmstoffen.” Bauphysik 9 (1987), Heft 6, Seite 259-266.
7. Cremaschi, Lorenzo (2012), “Methodology to Measure Thermal Performance of
Pipe Insulation at Below Ambient Temperatures,” ASHRAE Research Project RP-
1356.
8. Properties of Water, taken from the Website: http://people.ucsc.edu/~bkdaniel/
WaterProperties.html.
9. Properties of ice, taken from the Website: http://www.engineeringtoolbox.com/
ice-thermal-properties-d_576.html.
10. 3E Plus®, Version 4.1 Computer Program (available for download at www.
pipeinsulation.org), provided by the North American Insulation Manufacturers’
Association (NAIMA).
11. Lindeberg, Michael R., Engineering in Training Review Manual, Sixth Edition,
Chapter 2, Table 2.1.
12. Whole Building Design Guide, section on Life Cycle Cost Analysis (LCCA),
available on-line at: http://www.wbdg.org/resources/lcca.php.
30 © IIAR 2015 Technical Paper #1
2015 IIAR Industrial Refrigeration Conference & Exhibition, San Diego, CA
App
endi
x A
, Tab
le 1
. Hea
t ga
in s
avin
gs fo
r ro
of s
ecti
on M
3.1
of t
he fo
od p
roce
ssin
g fa
cilit
y, p
ipe
syst
em b
y pi
pe s
yste
m
20 |
Page
Appe
ndix
A, T
able
1: H
eat g
ain
savi
ngs f
or ro
of se
ctio
n M
3.1
of th
e fo
od p
roce
ssin
g fa
cilit
y, p
ipe
syst
em b
y pi
pe sy
stem
List of A
mmonia Refrigeration Pipes o
n Draw
ing M3.1 at Food Processing Facility
Pipe Size
(inches)
Temp (°F)
% defrost time
Old insulatio
nNew
insulatio
nOld insulatio
n New
insulatio
nOld insulatio
nNew
insulatio
nOld insulatio
nNew
insulatio
nOld insulatio
nNew
insulatio
nOld insulatio
nNew
insulatio
nL (ft)
Q/L (B
tuh/lf)
Q/L (B
tuh/lf)
Δ Q (B
tuh)
L (ft)
Q/L (B
tuh/lf)
Q/L (B
tuh/lf)
Δ Q (B
tuh)
L (ft)
Q/L (B
tuh/lf)
Q/L (B
tuh/lf)
Δ Q (B
tuh)
L (ft)
Q/L (B
tuh/lf)
Q/L (B
tuh/lf)
Δ Q (B
tuh)
L (ft)
Q/L (B
tuh/lf)
Q/L (B
tuh/lf)
Δ Q (B
tuh)
L (ft)
Q/L (B
tuh/lf)
Q/L (B
tuh/lf)
Δ Q (B
tuh)
3/4 x 1
2421.28
4.66
399
3/4 x 2
1 x 1
7222.23
4.8
1255
603.09
2.64
271 x 2
01 1/4 x 1
6827.46
6.23
1444
104
3.82
3.42
41.6
1 1/4 x 2
01 1/2 x 1
126
28.01
4.9
2912
126
3.89
3.44
56.7
1 1/2 x 2
024
146.5
9.97
3276.72
2 x 1
7832.14
7.32
1936
784.47
4.02
35.1
2 x 2
036
166.2
11.8
5558.4
2 1/2 x 1
180
36.28
8.4
5018
180
5.04
4.61
77.4
2 1/2 x 2 1/2
142
90.16
6.29
11910
3 x 1
9441.85
9.93
3000.48
3 x 2 1/2
36191.2
13.39
6401.16
4 x 1
4 x 2 1/2
4 x 3
5 x 1
764.88
1.21
278.92
5 x 2 1/2
7619.88
2.88
1292
180
130.9
10.46
21679
6435.13
7.29
1781.76
5 x 4
6 x 2 1/2
258
39.78
8.35
8108.94
6 x 4
8 x 4
76143.9
10.2
10161
7635.58
7.11
2163.72
10 x 4
12 x 4
Sub-‐Totals with
defrost
548
12,559
761,292
624
517
9614,534
398
42,383
492
14,584
Total load w/ o
ld insulatio
n103,589
Btuh
Total load w/ n
ew insulatio
n17,720
Btuh
Percent load reduction
82.9%
Total load savings
85,869
Btuh
Total Pipe Length
2,234
feet
Total Δ energy use
752
MMBtus/yr
3050
60-‐25
Liquid
MT Liquid
Hot G
asSuction
+15 deg Suctio
n15
+30 deg Suctio
n30 3.1%
3.1%
0%0%
4.6%
3.1%
Technical Paper #1 © IIAR 2015 31
Case Study – Economic Justification for Replacing Ice-laden Refrigerant Pipe Thermal Insulation with New Insulation
App
endi
x A
, Tab
le 2
. hea
t ga
in s
avin
gs fo
r ro
of s
ecti
on M
3.2
of t
he fo
od p
roce
ssin
g fa
cilit
y, p
ipe
syst
em b
y pi
pe s
yste
m
App
endi
x A
, Tab
le 3
. tot
als
from
App
endi
ces
I-A
and
I-B
21 |
Page
Ap
pend
ix A
, Tab
le 2
: hea
t gai
n sa
ving
s fo
r roo
f sec
tion
M3.
2 of
the
food
pro
cess
ing
faci
lity,
pip
e sy
stem
by
pipe
sys
tem
Appe
ndix
A, T
able
3: t
otal
s fr
om A
ppen
dice
s I-‐A
and
I-‐B
List of A
mmonia Refrigeration Pipes o
n Draw
ing M3.2 at Food Processing Facility
Pipe Size
(inches)
Temp (°F)
% defrost time
Old insulatio
nNew
insulatio
nOld insulatio
nNew
insulatio
nOld insulatio
nNew
insulatio
nOld insulatio
nNew
insulatio
nOld insulatio
nNew
insulatio
nOld insulatio
nNew
insulatio
nL (ft)
Q/L (B
tuh/lf)
Q/L (B
tuh/lf)
Δ Q (B
tuh)
L (ft)
Q/L (B
tuh/lf)
Q/L (B
tuh/lf)
Δ Q (B
tuh)
L (ft)
Q/L (B
tuh/lf)
Q/L (B
tuh/lf)
Δ Q (B
tuh)
L (ft)
Q/L (B
tuh/lf)
Q/L (B
tuh/lf)
Δ Q (B
tuh)
L (ft)
Q/L (B
tuh/lf)
Q/L (B
tuh/lf)
Δ Q (B
tuh)
L (ft)
Q/L (B
tuh/lf)
Q/L (B
tuh/lf)
Δ Q (B
tuh)
3/4 x 1
21.28
3/4 x 2
1 x 1
9022.23
4.80
1568.7
120
12.69
2.64
1206
1 x 2
1 1/4 x 1
3627.46
6.23
764.3
6015.68
3.42
735.6
1 1/4 x 2
1 1/2 x 1
8420.33
2.48
1499.4
1228.01
4.90
277.3
144
15.99
3.44
1807.2
1 1/2 x 2
30146.5
9.70
4104.0
12146.5
9.70
1641.6
2 x 1
130
25.28
2.89
2910.7
7832.14
7.32
1936.0
256
18.35
4.02
3668.5
2 x 2
30166.2
11.80
4632.0
30166.2
11.8
4632.0
114
166.2
11.80
17601.6
2 1/2 x 1
9436.28
8.4
2620.7
9420.71
4.61
1513.4
2 1/2 x 2 1/2
30168.9
11.06
4735.2
60168.9
11.1
9470.4
94168.9
11.06
14837.0
3 x 1
202
23.89
5.45
3724.9
3 x 2 1/2
30191.2
13.39
5334.3
12191.2
13.4
2133.7
118
191.2
13.39
20981.6
4 x 1
202
48.96
11.82
7502.3
4 x 2 1/2
4 x 3
60244.9
13.89
13860.6
60205.8
13.9
11514.6
5 x 1
5 x 2 1/2
114
130.9
10.5
13730.2
5 x 4
90210.8
13.3
17778.6
6 x 2 1/2
6 x 4
78232.2
14.9
16946.3
8 x 4
40269.8
17.9
10074.4
10 x 4
54309.9
21.3
15583.3
12 x 4
3.2
202
345.4
24.3
64860.2
Sub-‐totals with
defrost
217.2
4,272
626
27,512
180
31,161
626
145,946
876
12,260
338
52,525
Total load w/ o
ld insulatio
n298,527
Btuh
Total load w/ n
ew insulatio
n24,850
Btuh
Percent load reduction
91.7%
Total load reduction
273,677
Btuh
Total Pipe Length
2,525
feet
Total Δ energy use
2,397
MMBty/yr
4.6%
3.1%
3.1%
4.6%
4.6%
3.1%
Defrost Relief
5030
-‐25
-‐25
45-‐25
MT Liquid
LT Liquid
Suction
LT Suctio
nHo
t Gas
Total load with
old insulatio
n402,116
Btuh
Total load with
new
insulatio
n42,570
Btuh
Total load redu
ction
359,546
Btuh
Percen
t load redu
ction
89.4%
Total Pipe Length
4,759
feet
Total Δ ene
rgy use
3,150
MMBtu/yr
21 |
Page
Ap
pend
ix A
, Tab
le 2
: hea
t gai
n sa
ving
s fo
r roo
f sec
tion
M3.
2 of
the
food
pro
cess
ing
faci
lity,
pip
e sy
stem
by
pipe
sys
tem
Appe
ndix
A, T
able
3: t
otal
s fr
om A
ppen
dice
s I-‐A
and
I-‐B
List of A
mmonia Refrigeration Pipes o
n Draw
ing M3.2 at Food Processing Facility
Pipe Size
(inches)
Temp (°F)
% defrost time
Old insulatio
nNew
insulatio
nOld insulatio
nNew
insulatio
nOld insulatio
nNew
insulatio
nOld insulatio
nNew
insulatio
nOld insulatio
nNew
insulatio
nOld insulatio
nNew
insulatio
nL (ft)
Q/L (B
tuh/lf)
Q/L (B
tuh/lf)
Δ Q (B
tuh)
L (ft)
Q/L (B
tuh/lf)
Q/L (B
tuh/lf)
Δ Q (B
tuh)
L (ft)
Q/L (B
tuh/lf)
Q/L (B
tuh/lf)
Δ Q (B
tuh)
L (ft)
Q/L (B
tuh/lf)
Q/L (B
tuh/lf)
Δ Q (B
tuh)
L (ft)
Q/L (B
tuh/lf)
Q/L (B
tuh/lf)
Δ Q (B
tuh)
L (ft)
Q/L (B
tuh/lf)
Q/L (B
tuh/lf)
Δ Q (B
tuh)
3/4 x 1
21.28
3/4 x 2
1 x 1
9022.23
4.80
1568.7
120
12.69
2.64
1206
1 x 2
1 1/4 x 1
3627.46
6.23
764.3
6015.68
3.42
735.6
1 1/4 x 2
1 1/2 x 1
8420.33
2.48
1499.4
1228.01
4.90
277.3
144
15.99
3.44
1807.2
1 1/2 x 2
30146.5
9.70
4104.0
12146.5
9.70
1641.6
2 x 1
130
25.28
2.89
2910.7
7832.14
7.32
1936.0
256
18.35
4.02
3668.5
2 x 2
30166.2
11.80
4632.0
30166.2
11.8
4632.0
114
166.2
11.80
17601.6
2 1/2 x 1
9436.28
8.4
2620.7
9420.71
4.61
1513.4
2 1/2 x 2 1/2
30168.9
11.06
4735.2
60168.9
11.1
9470.4
94168.9
11.06
14837.0
3 x 1
202
23.89
5.45
3724.9
3 x 2 1/2
30191.2
13.39
5334.3
12191.2
13.4
2133.7
118
191.2
13.39
20981.6
4 x 1
202
48.96
11.82
7502.3
4 x 2 1/2
4 x 3
60244.9
13.89
13860.6
60205.8
13.9
11514.6
5 x 1
5 x 2 1/2
114
130.9
10.5
13730.2
5 x 4
90210.8
13.3
17778.6
6 x 2 1/2
6 x 4
78232.2
14.9
16946.3
8 x 4
40269.8
17.9
10074.4
10 x 4
54309.9
21.3
15583.3
12 x 4
3.2
202
345.4
24.3
64860.2
Sub-‐totals with
defrost
217.2
4,272
626
27,512
180
31,161
626
145,946
876
12,260
338
52,525
Total load w/ o
ld insulatio
n298,527
Btuh
Total load w/ n
ew insulatio
n24,850
Btuh
Percent load reduction
91.7%
Total load reduction
273,677
Btuh
Total Pipe Length
2,525
feet
Total Δ energy use
2,397
MMBty/yr
4.6%
3.1%
3.1%
4.6%
4.6%
3.1%
Defrost Relief
5030
-‐25
-‐25
45-‐25
MT Liquid
LT Liquid
Suction
LT Suctio
nHo
t Gas
Total load with
old insulatio
n402,116
Btuh
Total load with
new
insulatio
n42,570
Btuh
Total load redu
ction
359,546
Btuh
Percen
t load redu
ction
89.4%
Total Pipe Length
4,759
feet
Total Δ ene
rgy use
3,150
MMBtu/yr
32 © IIAR 2015 Technical Paper #1
2015 IIAR Industrial Refrigeration Conference & Exhibition, San Diego, CA
App
endi
x B
, Tab
le 1
. Tab
ulat
ed r
esul
ts o
f Life
Cyc
le C
ost
Ana
lysi
s of
bot
h th
e or
igin
al
pipe
insu
lati
on a
nd t
he r
epla
cem
ent
pipe
insu
lati
on
22 |
Page
Ap
pend
ix B
, Tab
le 1
: Tab
ulat
ed re
sults
of L
ife C
ycle
Cos
t Ana
lysi
s of
bot
h th
e or
igin
al p
ipe
insu
latio
n an
d th
e re
plac
emen
t pip
e in
sula
tion
Cost of e
lectric
ity ($
/ kW
h) =
0.10
$
O&M Cos
ts ($
/ yr) =
10,000
$
Interest ra
te, a
ssum
ed (%
/ yr) =
2%Ho
urs o
f ope
ratio
n / y
ear =
8760
Expe
cted
life of s
ystem (y
ears) =
20Orig
inal In
vestmen
t amou
nt ($
) =55
0,00
0$
P/A (for electric
ity escalation) =
16.351
4
COP, Assum
ed Value
s1
22.5
33.5
4Initial re
placem
ent C
ost
-‐$
-‐$
-‐$
-‐$
-‐$
-‐$
Pres
ent a
nnua
l electric
ity co
sts
103,20
9$
51,605
$
41,284
$
34,403
$
29,488
$
25,802
$
P of fu
ture elect. cos
ts ove
r 20 yrs
1,68
7,62
1$
843,81
1$
675,04
8$
562,54
0$
482,17
7$
421,90
5$
P of fu
ture O&M co
sts o
ver 2
0 yrs
163,51
4$
163,51
4$
163,51
4$
163,51
4$
163,51
4$
163,51
4$
Life Cycle Cos
ts ove
r 20 ye
ars
1,85
1,13
6$
1,00
7,32
5$
838,56
3$
726,05
5$
645,69
2$
585,42
0$
COP, Assum
ed Value
s1
22.5
33.5
4Initial re
placem
ent C
ost
550,00
0$
550,00
0$
550,00
0$
550,00
0$
550,00
0$
550,00
0$
Pres
ent a
nnua
l electric
ity co
sts
10,926
$
5,46
3$
4,37
1$
3,64
2$
3,12
2$
2,73
2$
P of fu
ture elect. cos
ts ove
r 20 yrs
178,66
1$
89,330
$
71,464
$
59,554
$
51,046
$
44,665
$
P of fu
ture O&M co
sts o
ver 2
0 yrs
163,51
4$
163,51
4$
163,51
4$
163,51
4$
163,51
4$
163,51
4$
Life Cycle Cos
ts ove
r 20 ye
ars
892,17
5$
802,84
5$
784,97
9$
773,06
8$
764,56
0$
758,18
0$
Old, orig
inal Insulatio
n
New
Rep
lacemen
t insulation