Temperature & Humidity in Ocean Containers

Temperature & Humidity
in Ocean Containers
Results from a one year study of ocean container
temperature and humidity conditions for shipments
between Asia, Europe and North America. Highlights
include port, sea, rail transport and storage conditions,
as well as a number of unexpected conditions.
David Leinberger, CPP, CPLP
Senior Packaging Engineer
Xerox Corporation
26600 SW Parkway Avenue, MS: 7063-201
Wilsonville, OR 97070 USA
Tel: 503-685-3717
Email: david.leinberger@xerox.com
Education: BS and MS from Michigan State University.
Activities: Member of ISTA, IoPP, ASTM, Western Packaging
Association.
Achievements: IoPP CPP, ISTA CPLP-Professional.

Abstract
Ocean Container Temperature and Humidity Study
David A. Leinberger, 2/27/2006
This paper summarizes the results from a twenty-month study of ocean container
temperature and humidity conditions for shipments between Asia, Europe and North America.
While this study focused on ocean containers, the recorded conditions include sea, truck and rail
transportation as well as periods of storage that may occur during a normal container shipment.
A distribution of all data along with a detailed look at the extreme conditions is provided. Effects of
container position on the ship and recorder position within the container are presented. The
effect of the container contents is also discussed.
Routes
The goal of this study was to understand the temperature and humidity conditions for
three of our common transportation routes. We monitored shipments from a facility just south of
Nagoya, Japan to a facility near Portland, Oregon USA and to another facility in Oostrum, The
Netherlands. The route from Japan to Portland is a rather direct route across the Pacific Ocean.
The route from Japan to The Netherlands weaves around Singapore near the equator, around
India, through the Suez Cannel, through the Mediterranean Sea, into the Atlantic Ocean and
finally up the English channel to the Netherlands. There can be a number of stops at ports along
this route. We also monitored a third route between a facility south of Yokohama, Japan to a
facility in Memphis, Tennessee, USA. This route includes train transportation from a west coast
port to Memphis. All three routes are outlined in figure 1.
Figure 1. Routing Map
Destinations:
Netherlands
Memphis
Portland
Ocean Container Temperature and Humidity Study
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Seasons
Date recording began in April 2004 and continued through January 2006. 160 shipments
are included in the analysis. The recordings are broken down by month for each route in figure 2.
While we recorded throughout the year, some months have more recorded data than others.
Recorded Days
600
500
400
300
200
100
0
Equipment / Setup
Figure 2: Distribution of Recordings - Three Destinations
Netherlands
Memphis
Portland
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
HOBO U12-011 data loggers from Onset Computer Corporation were used for this
study. They have a temperature range of -4º to 158ºF [-20º to 70ºC] with an accuracy of ±0.6ºF
[±0.35ºC] from 32º to 122ºF [0º to 50ºC]. The relative Humidity Measurement range is 5% to 95%
RH, with an accuracy of ±2.5% from 10% to 90% RH. (1) Recorders were programmed to capture
temperature and humidity readings every 10 minutes. This allowed for up to 113 days of
recording which exceeded the longest trip length.
The recorders where mounted to the outside of corrugated boxes using an adhesive
pouch. A portion of the pouch was removed around the recorder to allow unrestricted airflow.
Operators were instructed to install the recorder as high as possible on the top box of the last row
at the door of the container during the loading process. Recorders where installed away from the
sidewalls, but facing the container door. See figure 3 for data logger installation. The recorders
where removed as part of the unloading process and returned for data collection and reuse.
Ocean Container Temperature and Humidity Study
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Figure 3: Diagram of Data Recorder Location
Typical Conditions
A normal shipment consists of three distinct stages. The first stage includes the time
from container filling until the container is loaded onto a ship. This includes road transportation
and brief periods of storage. Daily cycles of temperature and humidity are common. For
example, figure 4 includes temperature swings of 40° F [22°C] during the first stage of a shipment
from Japan to Portland.
Temperature F and
Relative Humidity %
120
110
100
90
80
70
60
50
40
30
20
10-May-
05
15-May-
05
Figure 4: Typical Shipment
Japan to Portland
Japan Ocean Netherlands
20-May-
05
Temperature
Relative Humidity
J
25-May-
05
Date
30-May-
05
Ocean Container Temperature and Humidity Study
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Recorder
04-Jun-05 09-Jun-05
48
43
38
33
28
23
18
13
8
3
-2
-7
Temperature C

The second stage is the actual time at sea or aboard a ship. This may or may not be the
longest stage during the container’s journey. During this stage, daily cycles of temperature and
humidity are usually very minor or completely non-existent. Temperature changes are gradual,
often occurring over days rather than hours. Occasionally, a single temperature/ humidity cycle
occurs as the ship makes stops along the route, however extreme conditions are rare. Figure 5
includes a slow temperature rise and fall as a winter route takes the ship near the equator and
then north to The Netherlands.
The final stage begins when the container is removed from the ship and continues until
the recorder is removed during the freight unloading process. This may include varying periods
of time spent in customs, on trains, on trucks, and in storage. Daily temperature and humidity
cycles are common and may be extreme.
Temperture F and Relative
Humidity %
90
80
70
60
50
40
30
20
Japan
Figure 5: Typical Winter Shipment
Japan to The Netherlands
Temperature
Relative Humidity
J
Ocean
10
-12
01-Dec-05 11-Dec-05 21-Dec-05 31-Dec-05 10-Jan-06
Date
Ocean Container Temperature and Humidity Study
Dave Leinberger – Dimensions.06
Netherlands
28
23
18
13
8
3
-2
-7
Temperature C

Distribution of Data:
The distribution of maximum and minimum shipment temperatures is included for each
route in Figure 6. Each shipment is represented on this graph by one point at the highest and
lowest recorded temperatures. An example from the graph; 85% of the shipments to Memphis
had a maximum temperature below 120° F [48° C]. Also, 70% of the shipments to Memphis had
minimum temperatures above 32° F [0° C].
Temperature F
Figure 6: Distribution of Maximum and Minimum Shipment
Temperatures
140
130
56
120
110
46
100
90
36
80
70
26
60
50
16
40
6
30
20
10
0
-10
-20
Netherlands:Highest
Netherlands: lowest
Memphis: Highest
Memphis: Lowest
Portland:Highest
Portland:Lowest
-4
-14
-24
-30
-34
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Cumulative % of Shipments
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Temperature C

Extreme Conditions:
Some of the most interesting recordings are the extreme conditions. The highest
recorded temperature occurred on July 25, 2005 during a shipment from Japan to Memphis. The
temperature reached 135° F [57° C] during the third stage of this shipment (figure 7).
Temperature F and
Relative Humidity %
140
120
100
80
60
40
20
Figure 7: Hottest Shipment 135 F [57 C]
Japan to Memphis
Temperature
Relative Humidity
04-Jul-05 09-Jul-05 14-Jul-05 19-Jul-05 24-Jul-05
Date
The lowest recorded temperature occurred on January 15, 2005 also along the
Japan to Memphis route (figure 8). The temperature dropped to –21° F [-29° C], which is slightly
beyond the recorder’s published temperature range.
Temperature F and
Relative Humidity %
100
80
60
40
20
0
-20
-40
21-Dec-
2004
26-Dec-
2004
Figure 8: Coldest Shipment -21 F [-29 C]
Japan to Memphis
Temperature
Relative Humidity
31-Dec-
2004
5-Jan-
2005
10-Jan-
2005
Date
15-Jan-
2005
Ocean Container Temperature and Humidity Study
Dave Leinberger – Dimensions.06
20-Jan-
2005
25-Jan-
2005
53
43
33
23
13
3
-7
30
20
10
0
-10
-20
-30
-40
Temperature C
Temperature C

The shipment with the highest relative humidity occurred during a trip from Japan to
Portland. The relative humidity was recorded at 96% on August 5, 2005 while the container was
on land. Figure 9 shows the detailed temperature and humidity profile. The most extreme
humidity conditions are seen during periods of large daily temperature changes. In this example,
as the temperature slowly drops from 88° F [31° C] to 67° F [19° C] over 9 days, the humidity
increases to 88% before returning to 79%. However, starting on August 4 as the temperature
dropped from 121° F [49° C] to 68° F [20° C] over a 16 hour period, the relative humidity rose
from 32% to 96%. The corrugated boxes seem to absorb moisture fast enough to temper
humidity during slow changes in temperature while at sea. However, rapid temperature changes
seen on land seem to exceed the rate at which the corrugated boxes can absorb moisture.
Temperature F and Relative Humidity %
140
120
100
80
60
40
Figure 9: Highest Relative Humidity 96%
Japan to Portland
Temperature
Relative Humidity
20
-7
11-Jul-05 16-Jul-05 21-Jul-05 26-Jul-05 31-Jul-05 05-Aug-05
Date
Ocean Container Temperature and Humidity Study
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58
53
48
43
38
33
28
23
18
13
8
3
-2
Temperature C

Effect of Position on Ship:
As part of our study, we measured the conditions in multiple ocean containers traveling
on the same voyage. The temperature profiles were usually very close to identical. However, on
a few shipments, there were clear differences in temperature between the different ocean
containers. The largest difference was recorded between two containers traveling from Japan to
The Netherlands. Figure 10 shows how container #2 had a gradual temperature variation along
the ocean voyage. Container #1 shows a much larger variation each day. This container may
have been loaded above deck where the sunlight could affect the container temperature. It is
important to note that the temperature variations while at sea are more moderate than those seen
before and after the ocean voyage.
Temperature F
110
100
90
80
70
60
50
40
Figure 10: Container Temperature Differences From Same Ship
Container 1
Container 2
30
-1
02-Sep-04 12-Sep-04 22-Sep-04 02-Oct-04 12-Oct-04
Date
Ocean Container Temperature and Humidity Study
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39
34
29
24
19
14
9
4
Temperature C

Effect of Position Within Container:
As the study continued, we wanted to understand how temperatures are distributed within
an ocean container. We ran a controlled experiment with data recorders at various positions
within a partially filled ocean container. Figure 11 details the recorder position along with the
temperature profiles over a three-day period. The temperature recorded at the top of the ocean
container was over 35° F [19° C] higher during the afternoon than the temperature recorded near
the bottom. Also, the temperature from a recorder surrounded by the mass of packaged products
was more moderate than the temperatures in the empty area of the container and the
temperature outside.
Temperature F
110
100
90
80
70
60
50
Figure 11: Container Temperature by Location
40
30
20
1: 9" down- tail
2: 48" down- tail
3: 88" down- tail
Outside
A: 5" down- middle
C: 48" down- middle
D: 88" down- middle
B: 26" down- middle
9/26/05 14:24 9/27/05 14:24 9/28/05 14:24
1
2
3
Date/Time
A
B
C
Ocean Container Temperature and Humidity Study
Dave Leinberger – Dimensions.06
D
43
38
33
28
23
18
13
8
3
-2
-7
Temperature C

Effect of Container Contents:
In our recordings, a typical shipment will see an increase in humidity as the temperature
drops within a container. However, at some point, humidity stabilizes and eventually falls even as
the temperature continues to drop. We believe the corrugated boxes in the container slowly
absorbed the moisture from the air preventing condensation at the lower ocean temperatures.
To test this theory, we recreated these ocean conditions using an environmental chamber
and large sealed jars to simulate an ocean container. One jar held fiberboard boxes, while the
other held plastic boxes of the same volume. The jars were exposed to 86° F [30°C], 75%
humidity for 48 hours before being sealed. As Figure 12 shows, the simulated container with the
fiberboard boxes had a much lower relative humidity. Clearly the contents can change the
relative humidity.
Temperature F and Relative
Humidity %
100
90
80
70
60
50
40
Figure 12: Simulated Container Test
Temperature
Humidity-Jar with Plastic Boxes
Humidity- Jar with Fiberboard Boxes
0:00:00 48:00:00 96:00:00 144:00:00 192:00:00 240:00:00
Time
Conclusion:
We now have a much greater understanding of the temperature and humidity conditions
in an ocean container for some of our common shipping routes. While we learned much about
our distribution environment, we also raised a number of questions. Further study focused on
quantifying the affect of certain variables may be useful. Some areas that could be further
explored include: container color and design, position on the ship, type of load, positions along
the length, width and height of the container, position at port, routing differences.
References
(1) Onset computer website:
http://www.onsetcomp.com/Products/Product_Pages/hobo_u12_loggers/u12_logger_specs.html
Ocean Container Temperature and Humidity Study
Dave Leinberger – Dimensions.06
34
29
24
19
14
9
4
Temperature C