Keeping it all under one roof
The driving force for change in storage tanks is environmental and safety legislation. The role of roofs and domes is vital as these regulations are implemented. Although legislation over the past few years has not altered their fundamental characteristics, improvements have been made. These allow storage farm managers to go above and beyond mandatory regulations, reducing emissions, increasing safety for workers, and improving durability.
Material of choice In general, roofs come in either aluminium or steel, and are internal or external floating roofs, or fixed roofs, such as domes. The market for floating roofs is roughly split 80:20, with the majority being aluminium and the minority steel, although there are other materials on the market such as glass fibre.
Patterns show aluminium has slowly been replacing steel over the past 20 years. There are a number of economic advantages to aluminium such as lower construction times and lower initial costs. It is also lightweight and compatible with a wide range of materials and can be used with hydrocarbons, in fuel tanks and storage tanks.
'The trend is for aluminium instead of steel internal floating roofs,' says Bill Grimes, sales engineer at US-based floating roof company Allentech. 'It is reliable and some aluminium internal floating roofs (IFRs) have the same emission efficiency as steel.'
Another construction advantage for aluminium is that custom designs can be adapted and retrofitting is easier, both for floating roofs and domes.
Netherlands-based CTS's MD Gert van Meijeren says: 'There are lots of of different grades of aluminium. Each has its own characteristics and applications - it is replacing steel in a big way.'
IFRs fit under a fixed
roof on a tank. External
floating roofs do a similar
job, but are pontoon-type
or double-deck type
covers that rest on the
liquid surface in a vessel with no fixed roof.
