Found out 90% of furnace brick damage comes from thermal shock not wear

Read that stat in a refractory manual from HarbisonWalker last night and now I'm second guessing every time I've slammed cold scrap into a hot furnace just to save 10 minutes on the clock, anyone else ever actually measure their heatup rates?

3 comments

3 Comments

smith.lee2d ago

I've been in the refractory game since the 80s and I have to push back on that 90% number. Thermal shock is real, no doubt, but calling 90% of damage from it just doesn't match what I've seen with my own eyes. Most of the brick failures I've dealt with came from slag attack and mechanical abuse from charging operations, not from heating and cooling cycles. A furnace that gets run steady at temperature for years will still eat through brick from fluxing and erosion. I think those manual writers have a tendency to oversimplify things to sell their high-end shock resistant products.

aliceharris2d ago

My first furnace job back in the early 90s I pretty much learned thermal shock the hard way, dropped a cold brick into a hot wall and it basically exploded like a grenade. @jessica331 I think you're right that the micro cracking part is what a lot of people miss, even if the big thermal swings don't kill a brick right away they still set it up for slag to eat it alive. But I get where smith.lee is coming from too, I once watched a crew wear out a tundish lining just from jamming scrap in there wrong, no heat cycles needed. I guess I'm just saying that number might be a little high for some shops, but maybe my own experience is just from a different kind of operation.

jessica3312d ago

The 80s experience is legit, no argument there. But that 90% number didn't come from manual writers trying to push shock resistant products. It came from actual studies done by places like the American Ceramic Society and a few big research labs back in the 90s. The thing people miss is that thermal shock isn't just about heating and cooling cycles. It also covers the micro cracking that happens every time any part of the brick sees a temperature gradient, even small ones. Those tiny cracks let slag and flux penetrate way deeper than they would in sound brick. So what looks like pure slag attack at the end often started with thermal shock opening the door. You're right that mechanical abuse from charging does real damage too, but thermal shock is still the biggest single factor in most failure modes.