316 Stainless steel digester
At the highest end of roof design, the 316 stainless steel skin option is an external beam construction where the roof plates are located below the beams.
This solution is most commonly used in the AD market as gas tight roofs for steel digester tanks operating under pressure, both positive and negative.
This roof is supplied with a 316 stainless steel skin to provide the most robust solution when in contact with the gas space of digester tanks ensuring longevity and a maintenance-free structure.
Aluminium geodesic dome roofs
Balmoral aluminium geodesic dome roofs provide a self-supporting lightweight solution and are used predominantly in potable water, wastewater and for large tank diameters up to 60m.
Constructed in high strength triangulated aluminium sections these dome roofs can be installed on new or existing tank structures. Meeting all current industry standards, they provide corrosion-resistant, low maintenance, reliable weather-proof cover with maximum levels of odour control.
A full range of complementary accessories is available including ladders, platforms and handrails.
Glass reinforced plastic (GRP)
Very similar solution to a coated steel plate roof but provided in a glass reinforced plastic (GRP) material.
This material provides high resistance to corrosion and is generally supplied as either 20-degree pitch or low profile beam and infill solutions. GRP roofs can be sealed, although not gas tight, and manufactured to WRAS standards, meaning suitability for clean water and drinking applications.
Trough deck
Ideally suited for use as a debris roof. This is a low profile roof that is used in low tech applications, such as golf courses or water irrigation.
The roof can be supplied with a fully epoxy coated sub-structure to further enhance its performance capability. If you want to keep it simple, this could be the option for you.
Single membrane
In some respects, a very similar roof to the trough deck system, in so much as it is suitable for low tech applications, such as debris roofs.
Offering a centre column supported fabric roof fixed back to the tank walls. These roofs have been used widely in the agricultural market but have been specified in the water treatment markets.
The single membrane roof can be used for odour control applications so is one to consider if you are looking for tight control on cost while maintaining performance.
Double membrane gas holder
This option is well established in the AD market, offering a low cost option to a sealed, gas tight roof.
Operating with the inner membrane column supported as the gas collection zone, the outer membrane remains permanently inflated so the inner can fill and empty in line with on-site gas production.
This type of roof will never meet the design parameters of a stainless steel digester roof in areas such as pressure but if you are operating with a low pressure rating then this option is worth considering.
Coated steel plate
Balmoral’s coated steel roof comprises of efusion® epoxy coated roof panels supported on top of a full epoxy coated sub-structure.
Offering a fully coated roof structure, the roof is protected against corrosion in every way. This roof can be fully sealed and designed for low pressure applications, so if the contents need to be fully protected, this roof will suit the specification.
A low profile solution, generally at five-degree pitch, but can be designed for higher load scenarios when, for example, permanent personnel access is required.
Corrosion Protection
Tank shell
Balmoral’s cylindrical tank shell design is manufactured using pre-mill galvanized steel, with 305g/m² of zinc coating each side. On occasion, where heavier designs are required, the sheets will be hot dipped galvanized with more than 610g/m² zinc coating on either side. For specialised applications aluminium and stainless steel tank options are available.
All Balmoral tank fittings, flanges and accessories are also hot dipped galvanized as standard with options of epoxy or polyester coatings available. The galvanized coating of the tank shell along with the options of an epoxy performance coating for such applications as potable water or polyester coatings for aesthetic requirements guarantee long durability, low maintenance and extended life-cycle costs of the tank shell. Colour options for the epoxy or polyester coatings are available if required.
On standard galvanized tank designs, the coating of the tank shell doesn’t mean a reduction of the galvanized zinc coatings, the epoxy and polyester coatings are in addition to the galvanizing process.
Galvanized roof purlins are kept out of the stored water to extend the life of the tank roof cover. All nuts, bolts and washers are spun galvanized coated, structural components such as top and bottom angles, wind stiffeners and access manways are hot dipped galvanized with in excess of 610g/m² of zinc coating.
