What actually ends a campaign, how to measure where your furnace stands, and which repairs buy years of production, most of them without stopping the furnace.
In short: a glass furnace campaign ends when one local area of refractory fails, not when the whole furnace wears out. Extending furnace life means finding that area early, through endoscopy, thermal imaging and regular audits, then repairing it hot, without cooling the furnace and usually without stopping production. Ceramic welding, Hot Tank Repair and hot bottom repairs routinely add one to four years to a campaign that would otherwise have to stop.
Very few furnaces are shut down because the refractory is uniformly spent. Almost always a single zone reaches its limit first and forces the decision:
Each of these is a local problem. That is the whole basis of campaign extension: a local problem can have a local repair.
You cannot extend what you have not measured. A furnace that "looks fine" from the outside can be within months of a forced stop, and a furnace that worries everyone can often run for years more. Diagnosis answers which of the two you have.
A cooled endoscope goes in through existing openings while the furnace runs, and shows the refractory as it actually is: crown, sidewalls, throat, burner ports and regenerator packing. No shutdown, no scaffolding, no guessing from outside temperatures.
Infrared survey of the shell finds hot spots that mark thinning refractory or failed insulation, and gives you a map of where to look more closely rather than a general worry.
Endoscopy and thermal data together, read against furnace age, pull rate and glass type, produce something you can actually plan against: what will fail, roughly when, and what it would take to postpone it.
Hot repair is what makes campaign extension economically obvious. The furnace never stops, so the comparison is not "repair cost versus doing nothing" but "repair cost versus the cost of an unplanned cold repair brought forward by years".
Ceramic welding rebuilds the superstructure: the refractory above the glass line. A powder of refractory oxides and metallic fuel is blown onto the hot surface, burns, and fuses into a dense ceramic mass that bonds to the original block. Crown, breast walls, ports, tuckstone areas and regenerators are all repaired this way, internally with cooled lances or externally to seal joints. It is the single most common way of adding years to a campaign.
HTR renews the glass line and the critical zone immediately above it, exactly where tuckstones break and the steel structure is exposed to heat. This is the repair for the glass-contact zone that ceramic welding does not reach, and it addresses the classic campaign-limiting wear directly.
Bottom wear is the failure nobody wants to discover late. Hot bottom repair installs new refractory into the tank bottom with the furnace hot, using patented bottom lances, and removes the most dangerous single reason for an emergency shutdown.
Campaign extension has a limit, and pretending otherwise costs more than admitting it. When bottom wear is advanced, when the steel structure has lost its geometry, or when the glass quality penalty of running on exceeds the cost of stopping, the right move is a planned cold repair or rebuild on your schedule, not an emergency one on the furnace's.
The value of good diagnosis is that it tells you which situation you are in early enough to choose.
Typically one to four years, depending on which zone is limiting and how early the wear is caught. The same repair applied to thinning refractory extends a campaign far more than it does once a block has been lost, so the gain comes from inspecting early rather than from the repair method itself.
In most cases, yes. Ceramic welding, Hot Tank Repair, crown and block repairs and electrode changes are carried out at operating temperature while the furnace keeps producing glass. Hot bottom repairs and furnace draining also keep the furnace hot, but production stops while the glass is drained. In every case the furnace is never cooled down: that is what defines a hot repair.
A repair process in which a mixture of refractory oxide powder and metallic fuel is blown onto hot refractory. The fuel burns in oxygen and the heat released melts the oxides so they fuse with the existing block. It is used on the superstructure, the refractory above the glass line: crown, breast walls, ports, tuckstone areas and regenerators. The glass-contact zone below is repaired by Hot Tank Repair instead.
By measuring, not estimating. An endoscopic inspection combined with thermal imaging shows which zone is limiting and how much material is left. Localised wear with a sound bottom and structure favours hot repair; advanced bottom wear or a distorted steel structure points to a planned cold repair.
Glass-line corrosion of the sidewall blocks, followed by crown wear and bottom wear. All three are local, and each has a hot repair that addresses it: Hot Tank Repair for the glass line, ceramic welding for the crown and the rest of the superstructure, and hot bottom repair for the tank bottom.
Done properly it protects it. Crown dripping and refractory corrosion are themselves sources of defects, so repairing them removes a quality risk rather than creating one. The materials used in ceramic welding are chosen to match the refractory they repair.
Send us your furnace type, age and pull rate and we will tell you what an inspection would look like, and what it would cost you to wait.