Maxwell Aluminium Domed Floating Roof Tanks (DFRT) are a good alternative to steel for fixed-roof tanks
Maxwell Continental Tank Serv Engineering has combined experiences from the past with their research and development, through which it has produced increasingly innovative products for reducing above ground storage tank (AST) emissions.
Maxwell Aluminium Geodesic Dome Roof covers for storage tanks are innovative clear-span structures custom designed to each individual tank within the requirements of international and local regulations.
And it’s not just about the new and interesting, when old technologies and products are to be revitalised or re-used it always can be reviewed and when needed altered to be made more efficient.
Aluminium, used for major above ground storage tank (AST) components, has
advantages and disadvantages when compared to the conventional steel materials of construction.
For fixed-roof tanks, refiners can save money and gain improved quality if they consider the advantages of aluminium over steel.
An AST that includes a floating roof and is covered by a fixed roof is considered an internal-floating roof tank (IFRT). An existing external floating roof tank (EFRT) can be converted to a covered IFRT by retrofitting it with a fixed roof or aluminium dome roof cover. Although the EFRT may have a lower initial cost than the IFRT, it may not have the lowest total ownership cost when long-term operating costs, maintenance costs, and potential risks are considered.
The factors which favour building or retrofitting EFRTs with fixed roofs are incident prevention, environmental protection, safety, and reduced long-term maintenance and operating costs.
Covered tanks eliminates rainwater entry, where rainwater;
• Can sink floating roofs if roofs are not drained or if drain plugs
• Add to water bottoms which may increase disposal/treatment costs or cause product contamination
• Accelerate bottom corrosion
Next to rain water, snow and freezing can cause floating-roof mechanical failures or
Covered tanks eliminates roof drain, roof drains;
• Uses more vertical space to allow sufficient hydraulic head
• Are a potential for serious external spills if the drain is not properly operated
• Increases the potential for liquid on roof if roof drain is damaged
Covered tanks requires only a primary seal * (Although EPA, EN and some local districts have stricter requirements) , where EFRT tanks requires primary plus secondary seal which requires more vertical spacing to accommodate secondary seal
Summarised Clear-span Aluminium Geodesic Dome Roof (AGDR) tanks have more
advantages than steel dome/cone column-supported SCR tanks. The AGDR is usually the
most favourable option for the retrofit of an existing EFRT with a new fixed
roof. For new tank construction, or replacement of an existing dome/cone roof, an evaluation should consider the initial bid price as well as other
fundamental variables, like:
• Operating capacity savings
• Initial coating cost and long-term maintenance
• The elimination of columns and their related problems: emissions, penetration seal, bottom corrosion, maintenance obstruction, settlement, and incident risk costs.