Manufacturers busy as demand soars for float glass

New production facility in Dubai challenges traditional suppliers.

The demand for construction materials in the UAE has rocketed over the past five years. To meet the demand, the emirates have had to import the majority of construction products, but things are changing fast.

Suppliers are racing to take advantage of the booming local market by building facilities closer to this demand. According to MEED the volume of cement production capacity alone increased by 21.4 millions/tonnes a year to a total of 74.5Mt, with a further 11 Mt a year scheduled to come on stream by the end of the year.

With demand rates growing at 14 per cent a year it is not surprising that local manufacturing capacity is racing to keep up.

Demand is rising for float glass, used to clad the thousands of new buildings planned for the Dubai skyline.

Until late 2007 all float glass used in the UAE's buildings was imported and processed locally, but recently suppliers have been changing their strategies.

US firm Guardian, the UAE's dominant float glass supplier, built the UAE's first float glass manufacturing facility in the emirate of Ras Al-Khaimah in 2007 and now local firm Glass LLC (LLC means PLC) is about to challenge the traditional supplier through its new facility.

"Regional demand for float glass has been increasing at an average of 10 per cent per year and in the past three years it has been at 20 per cent plus," says general manager of Emirates Float Glass, Narendra Mohanty.

$1 trillion investment Emirates Float Glass was set up to build and operate a 1,200-tonnes-a-year float glass facility through two production lines.

The first one is now complete. "There are committed investments [in the region] for at least the next five years, amounting to at least US$1 trillion. Glazing accounts for 3 per cent of that and depending on the type of glass used it could be up to 5 per cent," says Mr Mohanty.

Glass LLC is traditionally a glass processing specialist which would buy float glass from the likes of Guardian, San Gobain and Asahi, then temper and coat it as required by contractors.

This strategy ensured it won about 20 per cent of the UAE's market share for the high performance glass used in many of the emirate's residential and commercial tower blocks.

But from later this year it will be able to supply its own companies rather than buying from international providers and wants to take its market share up to 50 per cent.

"Our own processing companies – Emirates Glass, Saudi-American Glass and Lumiglass – can potentially use 100 per cent of our output. But we will be supplying other local companies as well as exporting plate glass outside the Gulf Cooperation Council," says Mr Mohanty.

The factory has been ready to produce glass on its first production line for several weeks, but is being held up by the need to secure various approvals before the local authority will connect its gas supply.

"We're waiting for gas and electrical connections to be made," explains Franco Nespoli, resident project manager for contractor Ianua. "Then we'll be able to start the furnace and, over the course of about 21 days, bring it up to full temperature – 1,500-1,600 deg C.

"It takes about four weeks to start firing," adds Glass LLC general manager Faisal Rashid. There are no objections to the scheme so we are all set and close to making the connections."

Thermal expansion

The factory infrastructure it has to adjust to the high temperatures in the building. "One of the critical things during that period will be maintaining the correct geometry of the furnace roof," says Mr Nespoli.

The furnace roof is a shallow vaulted structure, acting in compression. As thermal expansion takes place, the crown of the vault lifts but screw adjustment at the lower edges of the roof will allow compensation for this movement, maintaining the roof's geometry.

Construction of the second line will start next month, eventually giving the company the ability to maintain clear glass production on one line and tinted glass on the other.

"Waste glass from the tail end of one campaign (batching order) is stored in hoppers below the building and recycled into the production process when the next campaign in that tint comes around. Clear glass is fed straight back into the furnace," explains Mr Nespoli.

The factory has been built in Abu Dhabi, enabling it to use gas as a feedstock rather than the more expensive fuel oil often used outside the emirate.

In case of emergency the firm has a contingency plan. "The plant stores enough fuel to maintain production for 24 hours if normal supplies are cut," says Bassem Iskandarani, project manager for consultant Mott MacDonald.

But the main priority is obtaining a connection so the firm can start providing float glass to its own firms and beyond.

FLAT TO FLOAT

• Each float glass plant refines its own process and the exact method for each facility is usually a closely guarded secret. But in general the process, developed by Pilkington, has six main phases.
• Furnace Sand limestone, soda ash, dolomite, iron oxide and salt cake are mixed together and melted at temperatures of 1,500 deg C.
• Float bath Glass flows gently on to the mirror-like surface of molten tin, starting at about 1,100 deg C and leaving the float bath as a solid ribbon at 600 deg C. The speed of the flow controls the thickness of the pane.
• Coating Coatings that change the optical and thermal properties of the glass can be applied at this point. This process is known as chemical vapour deposition (CVD).
• Annealing This is the process of slowly cooling the glass. If the temperature falls too quickly, considerable stresses are developed, which can cause the glass to break when it is cut.
• Inspection This allows the manufacturer to refine the process if too many flaws (such as bubbles) are apparent, or to direct the cutter (next stage) to cut around them.
• Cutting Glass is sized according to the order placed by the customer.