Pyrex is rated to 950 degrees. I keep it indirect and have never had an issue. If it was directly over the coals it would be a problem. Grill cooked along at 450. In my opinion what does it matter if the heat source is charcoal or gas in my household oven. Keep it indirect and should never be a problem. Now that I say that my luck the next time I cook with it ill probably come out and the glass will have shattered. But hey that's why they have pizza delivery. But I understand your concern. I often use aluminum but when I don't have any I grab the Pyrex.