conference 2015 technical

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.

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2015 Industrial Refrigeration Conference & Exhibition

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© 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.



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



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.



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.



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.



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.



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.



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



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.



Figure 6. Shows an insulator cutting a section of new insulation for installation as a replacement for old ice-laden insulation.



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.



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.



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



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.



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



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.



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.



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



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



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



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.



$-‐

$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.



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



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.



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.



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.



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%



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


n Draw


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


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


n Draw


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


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



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