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A quick warning about those new ceramic fiber blankets versus the old asbestos ones | Foundry Workers - Pinecone Attack

A quick warning about those new ceramic fiber blankets versus the old asbestos ones

We had to reline a core oven at the plant last month and the new guy brought in a roll of the modern ceramic stuff. I insisted we use the old asbestos blanket we had in storage, just to compare. After one full heat cycle to 1600 degrees, the ceramic blanket shrank nearly two inches and developed hard spots. The asbestos lining held its shape perfectly. The foreman said, 'That's why we kept the old stock.' Has anyone else run into this with the newer materials?

3 comments

3 Comments

anthony_lane553mo ago

quote: "That's why we kept the old stock" Yeah, but the real question nobody's asking is how long did that asbestos blanket actually last in service? Because I've heard stories from old timers about them holding up for decades, not just a few heat cycles. The ceramic stuff might fail fast, but I'm wondering if the asbestos just fails slower over a longer period. Did you check for any warping or cracking after a few months of continuous operation, or was it just a single test run? I'm asking because that "held its shape perfectly" line could be a case of survivorship bias if you only ran it once. The real test would be putting both blankets through a full year of daily cycles and seeing which one actually fails first.

faiths126mo ago

Honestly thought all the new materials were straight upgrades. Your post shows a real world problem I never considered. That much shrinkage could cause gaps and hot spots in a lining. Makes you wonder what other "improvements" actually perform worse under real heat stress. Did the ceramic blanket get brittle too, or just shrink?

roseb476mo ago

Yeah, that 3% shrinkage spec on the new stuff sounds fine until you see the actual gap it leaves in a 20 foot run. You're right on the money, faiths12, about the hot spots. The blanket got so brittle after a few cycles I could snap pieces off by hand. Makes me feel like a real chump for trusting the data sheet over my own eyes.