Moisture Damage

For many years, thousands of containerized cargoes are damaged by moisture problems. When the containers arrive at the destination, metal is found to be rusty or oxidated, cartons become soft and moldy, bulk coffee, cocoa, beans may be damp, musty…,such losses sometimes costs several million dollars. It is caused by two main reasons: Container Rain and Cargo Sweat.

Moldy_Rain
(click to enlarge it)
(click to enlarge it)

Musty Agriculture Products

Four Areas of container moisture damage:

1. The ceiling and inner walls of the container, the condensation is known as “Container Rain”

2. The surface of cargo, the condensation is known as “Cargo Sweat”

3. The container floor. There are two kinds, iron floor is cold, wooden floor contains moisture inside. They both easily make the pallets moldy.

4. The container doors. The outside wet air easily goes through the crack of the container door and causes high relative humidity.

Container_Rain
(click to enlarge it)
(click to enlarge it)

Container Rain

Moldy_Pallet
(click to enlarge it)
(click to enlarge it)

Moldy Pallets

Water vapor content in the air at different temperature and RH

RH
T(℃)
100% 90% 80% 70% 60% 50% 40% 30% 20% 10%
65 160.3 144.3 128.2 112.2 96.2 80.2 64.1 48.1 32.1 16.0
60 129.6 116.6 103.7 90.7 77.8 64.8 51.8 38.9 25.9 13.0
55 103.9 93.5 83.1 72.7 62.3 52.0 41.6 31.2 20.8 10.4
50 82.7 74.4 66.2 57.9 49.6 41.4 33.1 24.8 16.5 8.3
45 65.2 58.7 52.2 45.6 39.1 32.6 26.1 19.6 13.0 6.5
40 50.9 45.8 40.7 35.6 30.5 25.5 20.4 15.3 10.2 5.1
35 39.2 35.3 31.4 27.4 23.5 19.6 15.7 11.8 7.8 3.9
30 30.0 27.0 24.0 21.0 18.0 15.0 12.0 9.0 6.0 3.0
25 22.8 20.5 18.2 16.0 13.7 11.4 9.1 6.8 4.6 2.3
20 17.1 15.4 13.7 12.0 10.3 8.6 6.8 5.1 3.4 1.7
15 12.7 11.4 10.2 8.9 7.6 6.4 5.1 3.8 2.5 1.3
10 9.3 8.4 7.4 6.5 5.6 4.7 3.7 2.8 1.9 0.9
5 6.8 6.1 5.4 4.8 4.1 3.4 2.7 2.0 1.4 0.7
0 4.8 4.3 3.8 3.4 2.9 2.4 1.9 1.4 1.0 0.5
-5 3.2 2.9 2.6 2.2 1.9 1.6 1.3 1.0 0.6 0.3
-10 2.1 1.9 1.7 1.5 1.3 1.1 0.8 0.6 0.4 0.2
-15 1.4 1.3 1.1 1.0 0.8 0.7 0.6 0.4 0.3 0.1
-20 0.9 0.8 0.7 0.6 0.5 0.5 0.4 0.3 0.2 0.1

According to the above table we can calculate moisture content in the air in the containers/cartons before shipment.
Total water vapor= unoccupied space in the container* = water vapor in every cubic meter air at relevant temperature and RH(from the table it can be found)

Statement:
The calculation simply tells how much water vapor in the container/carton before shipment. It does not include the water vapor from other sources(such as cargo, container wood floor, pallets and the packaging material inside the container.)


Temperature, Rainfall and Rainfall Days Records

BEIJING SHANGHAI
Temperature Total Days Temperature Total Days
Month Lowest Highest Rainfall Rainfall Month Lowest Highest Rainfall Raining
/day /day mm Days /day /day mm Days
Jan -9.4 1.6 3 2 Jan 0.5 7.7 39 9
Feb -6.9 4.0 6 3 Feb 1.5 8.6 59 10
Mar -0.6 11.3 9 4 Mar 5.1 12.7 81 13
Apr 7.2 19.9 26 5 Apr 10.6 18.6 102 13
May 13.2 26.4 29 6 May 15.7 23.5 115 13
Jun 18.2 30.3 71 9 Jun 20.3 27.2 152 14
Jul 21.6 30.8 176 14 Jul 24.8 31.6 128 12
Aug 20.4 29.5 182 12 Aug 24.7 31.5 133 10
Sep 14.2 25.8 49 7 Sep 20.5 27.2 156 12
Oct 7.3 19 19 5 Oct 14.7 22.3 61 9
Nov -0.4 10.1 6 3 Nov 8.6 16.7 51 8
Dec -6.9 3.3 2 2 Dec 2.4 10.6 35 7
GUANGZHOU XIAMEN
Temperature Total Days Temperature Total Days
Month Lowest Highest Rainfall Lowest Month Lowest Highest Rainfall Lowest
/day /day mm /day /day /day mm /day
Jan 9.8 18.3 43 8 Jan 9.7 16.8 37 8
Feb 11.3 18.4 65 11 Feb 9.8 16.5 65 13
Mar 14.9 21.6 85 15 Mar 11.9 18.8 99 17
Apr 19.1 25.5 182 16 Apr 16.1 23 147 16
May 22.7 29.4 284 18 May 20.3 26.7 152 16
Jun 24.5 31.3 258 19 Jun 23.3 29.4 196 14
Jul 25.3 32.7 228 16 Jul 25.3 32.4 140 10
Aug 25.2 32.6 221 16 Aug 25.2 32.2 155 10
Sep 23.8 31.4 172 13 Sep 23.8 30.7 117 11
Oct 20.5 28.6 79 7 Oct 20.5 27.4 29 3
Nov 15.7 24.4 42 6 Nov 16.4 23.4 37 5
Dec 11.1 20.5 24 5 Dec 11.7 19.1 25 4

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