Standard shipping container flooring usually consists of marine hardwood made from Apitong or Keruing. It is usually plywood of around 25mm-30mm in thickness. The hardwood used in containers however is in danger of running out. While still a renewable resource, it takes fifty to sixty years to replace one tree cut down to make container floors. Many container companies have experimented with alternatives. Nevertheless, the production volume of containers fitted with floors using materials other than tropical hardwood plywood has continued to rise slowly. Here at Intermodal Eye we have investigated the other types of floors available:
Bamboo wood is a good resource to use as it is quick to grow and can be produced in similar size boards to plywood. It is the only alternative to hardwood that is produced in any significant volume. According to a recent report by the Container Owners Association (COA) 650,000 TEU of dry freight containers were fitted with bamboo floors in 2012 and the estimate for last year is some 720,000 TEU. The principal manufacturers of these floors are: CIMC, Nantong New Atlantic Forest Industries (NNAFI), Jiangxi Dechang Bamboo Board Company and Fujian Heqichang Bamboo. These floor suppliers have a wide range of customers and their floorboards are used in open top and 45ft European containers as well as 20ft, 40ft and 40ftHC dry boxes. As a bamboo floorboard has the same dimensions as tropical hardwood plywood floorboards, they can be installed in containers without any modification to container production lines and replaced by other plywood floorboards if damaged in service and no bamboo replacements are readily available.
Some companies have tried steel floors in containers, usually consisting of painted steel plates with a non slip pattern. The crossmembers running horizontally underneath the container which support the flooring take much of the load weight. However, because of the gap between, the type of flooring laid on top must be fairly strong as the containers are rated to carry as much as 30 tons. Also quite often, forklifts will be used to run cargo inside.
Refrigerated containers have aluminium flooring usually consisting of “T” section planks running the full length of the container. These planks are slightly raised and allow for air flow to keep the cold air circulating and also prevent any build up of meat by-products. In certain cases reefer containers have flat aluminium chequer plate flooring and this is often found in containers destined for domestic use.
Plastic and Composite Floors
According to the COA, the volume of plastic and composite floors being installed in containers was expected to rise in 2013 – but it did not, and in 2014 the number will be effectively zero. There are (or were) two players in this market – MCI and Conforce – and they took very different approaches. MCI focused on using recycled plastic, as it is cheap and readily available, formed into planks with strengthening longitudinal steel omega sections. Conforce, for their Eko-Flor, use a special thermoset plastic supplied by Bayer which is much stronger than recycled plastic but more expensive. Orders have not been forthcoming because of the unwillingness of buyers to pay a premium of between $140 and $250 per TEU for a composite floor.
Larch / Birch Hybrid Floors
Also in the COA report, it noted that the other significant alternative previously showing growth was a larch / birch hybrid manufactured in Inner Mongolia by CIMC. However, production of just 40,000TEU of these floors took place in 2012 due to the high cost of the raw material, which made volume production unviable. This situation has not improved and CIMC has now ceased production of this type of floorboard.
The production volumes of floors using alternative materials in 2012 and production estimates for 2013 are shown below:
|2011 TEU Volumes||2012 TEU Volumes||2013 Est TEU Volumes|
|Total Alternative Floors||610,000||690,000||720,000|
|Total Dry Container Production||2,775,000||2,460,000||2,400,000 (est.)|
|Percentage of non tropical hardwood plywood||22%||28%||30%|
Source: Containerisation International total production, floorboard manufacturers – production figures
The hunt for alternatives to the tropical hardwood floor goes on and a number of possibilities are being pursued or investigated by various parties. Also in the COA report, it was noted that a new design for a steel floor developed by Hapag Lloyd in conjunction with CIMC. The floor is made of 5 sheets of steel running the full width of the container, each 4ft long with stamped corrugations running longitudinally down the container. These corrugations add strength to the panel allowing the thickness to be reduced to just 3.2mm. An additional 3 cross members have been added but despite this, the use of 3.2mm plate has enabled this new design to be “weight neutral” compared to a 20ft with a plywood floor. Service trials of this design are now underway.