In the glass industry, hot repair of glass melting furnaces is a critical process to extend furnace life, reduce downtime, and ensure consistent glass quality. Despite the widespread use of advanced refractory materials, hot repair remains an essential maintenance practice. This article introduces the three most common hot repair methods used in modern glass furnaces.
The furnace tank wall is usually built with fused-cast 41# AZS bricks installed vertically. This design meets the furnace campaign requirements, but localized erosion still occurs over time. Two widely used hot repair methods are:
Cooling Water Pipe Method
Seamless steel pipes (20–50 mm diameter) are inserted 50–80 mm below the molten glass surface at eroded areas. This cools the local glass, solidifying it and slowing further erosion. Although effective, it consumes additional energy and water, and is limited to the upper wall sections.
External Patch Brick Method
When tank wall bricks are thinned to about 30 mm, an external patch of the same refractory material (typically 150 mm thick) is fixed to the outside wall. Preheating (about 80 °C) is necessary, and the contact surface must be flat with tight joints to ensure effectiveness.
Modern regenerators often use alkali-resistant magnesia-chrome bricks, magnesia bricks, or high-purity zirconia-alumina bricks, allowing the checker packs to last a full furnace campaign. However, batch deposits and build-ups remain a serious issue, as they can block airflow and reduce efficiency.
Hot repair of regenerators focuses on keeping checker channels unblocked, using methods such as:
Mechanical cleaning to remove solid deposits.
Flame-remelting (reverse firing) to burn off glassy build-ups.
Nozzle bricks are special-shaped refractory bricks used in oil-fired glass furnaces. They guide atomized heavy oil mixed with combustion air into the furnace. Exposed to high flame temperatures, they are prone to wear and damage.
Replacement is a straightforward hot repair method:
Remove the burner lance.
Open the small gap above the nozzle brick.
Take out the worn brick.
Insert a preheated nozzle brick (heated near a small furnace or up to 900 °C if required).
Seal the joints, reinstall the burner lance, and resume operation.
Traditional glass furnace hot repair methods are harsh, labor-intensive, and disruptive to production. Today, two modern technologies are improving safety and efficiency:
Hot Gunning Repair
Involves spraying refractory gunning material onto worn areas or sealing holes. While effective, it may risk contaminating the glass melt and disturbing furnace operation.
Oxy-Fuel Spraying Repair
Uses high-temperature oxy-fuel burners to spray fine refractory powders of the same composition as the original material. The powder melts and bonds onto the eroded area, achieving a strong repair layer. This method is highly effective for:
Erosion and wear
Cracks or shifted bricks
Joint sealing and hole blocking
Compared with traditional hot gunning, oxy-fuel spraying offers faster, safer, and more reliable repairs, helping glass plants extend furnace life, improve operating efficiency, and reduce unplanned downtime.
Glass furnace hot repair is essential for maintaining stable production and extending refractory service life. Whether reinforcing AZS tank walls, cleaning checker packs, or replacing burner nozzle bricks, combining traditional methods with modern oxy-fuel spraying repair provides glass manufacturers with a safer, more efficient maintenance strategy.
