At the suggestions provided on my last post, I built a propane forge. The forge works great though the bricks seem to be cracking and deteriorating rapidly. Is that because of the heat? or maybe the humidity? do I need to coat them or something? 

Also, I just picked up some railroad track and a bunch of tongs from a friend in addition to some "SIL-O-CEL" Johns-Manville arch and straight bricks. Does anyone have any knowledge of these bricks? Would they be usable for a propane forge? And also are there any specific ways to use the tongs?

Thanks, Ben

 

I believe those are sound insulating bricks, probably not good for a propane forge.

I'm quite certain they are fire bricks. This article and this article reference them as being high temperature insulation bricks. They are quite old as the packaging says "top for over 90 years" and the company was founded in 1858 which place them being manufactured around 1948.

I read one article that said they were used as sound insulating bricks in large commercial kilns. The only way to tell if they will work in the rapid thermal cycling in a forge will be to try them. Kilns and forges are two different animals. For instance, we have a lot of soft kiln fire bricks which last a long time in the kilns but disintegrate rapidly in the forge. Try them and give us a report on how they work in case someone else may run across them.

I think the way that the IFBs fail in a forge is down to the extreme temperature gradient when the forge starts. I think the hot face gets hot fast and expands, putting the cooler material behind it under tension and starting cracks. When the forge stops, the "hot" face cools quickly, contracting while leaving the warmer material behind it expanded. This puts the cooler material under tension and the cracks propagate from within the IFB material to the surface. 

In industrial kilns, the rate at which the temperature rises is much lower, the temperature gradient is much less and the cracking problem doesn't really arise.

Because IFBs are intended for industrial applications, there is no information provided by the manufacturers on their resistance to rapid thermal cycling. The only information "we" tend to get is anecdotal from others of "us".

Unless you have another, better, use for the bricks, I'd say use them for a forge and report back on how well they work.  

Have you tried contacting the company and asking them?  They are not a product listed on their site, but someone likely knows their characteristics.