Condensation problems in paper and pulp bulk transport ships

The use of GrafoTherm is the same product as Kefa, but in different countries, different product names are used.  We have met the inventor and we are authorized to use his product name Kefa and sell his manufactured Kefa product line.

Kristian Gerhard Jebsen Skibsrederi use GrafoTherm in their Gear Bulk ships for transportation of paper and pulp.

The first series of three bulk ships were built in 1990/91. When in 2000 a new series of similar ships were to be built GrafoTherm was specified as condensation protection, due to the good experience of the product.

The Problem

Paper pulp release large quantities of water during the transport. This water condenses in the roof of the garage and drips down on the cargo. To avoid damage the Gear Bulk ships are supplied with high capacity dehumidifiers, to keep the indoor air below dew point.

At loading and unloading the doors must be opened and then the dehumidifiers do not work any more. Especially wintertime, during cold weather, the humidity released by the paper pulp forms large quantities of condensation in the roof. Not until the doors are closed the dehumidifiers can start working again and even then it takes time before the indoor air is below dew point and during that period dripping continues.

 Jaeger Arrow has got a special problem. The ship loads paper pulp in north Canada and in wintertime is on the Atlantic Ocean and enters the warm and humid Gulf Stream the inside of the garage is exposed to a condensation chock. The steel walls of the hull are still very cold and condensation water literarily pours down the hull sides.

The Solution

A 2 mm thick GrafoTherm Standard Marine coat was sprayed in 4 coats in the roof and 6 metres down the hull sides. The corrosion protection was a dull zinc rich epoxy that gave a good adhesion to the GrafoTherm coat. The application took place in January and to create the necessary conditions for the drying and film forming process, the deck was covered with tarpaulins, under which hot air was blown. Also the inside of the garage was heated.

The Result

During loading and unloading GrafoTherm acts as a buffer, which absorbs and stores the condensation water, thus preventing it from dripping and running. When the ship is loaded and the doors are closed, the dehumidifiers can start working. GrafoTherm releases the accumulated water in the form of vapour to the air.

The condensation water may freeze to ice during the loading, but that constitutes no problem. GrafoTherm will hold for that stress. Due to the micro porous structure of GrafoTherm the evaporation of water is almost three times as fast as from a metal or painted surface.

Also the condensation problems at the entrance of the Gulf Stream are taken care of by the GrafoTherm treatment.