Heat temperature isnt necessarly the only factor when it comes to thermal shocking. It also depends on annealing. It only takes one bad batch of poorly annealed glass tubes to be bought up by one of us and literally have it blow up in our faces. One example I can think of is say your pv is in the car on a cold winter day. You come in the house and fire it up. So along with a bad batch of un annealed glass along with the extreme temperature change chances are you'd have extreme thermal shock.
I'm not saying this is not a great idea Dan. I'm just saying we should use quartz tubes. Here is my supplier I use to buy my quartz tubes.
Technical Glass Products: Fused Quartz Tubing
Bedazzle
Supplier and the stepped in here to try and lead us from injury. You would be go to for me when I needed to get more cut. Thanks for info and trying to keep tube out of our eyes!
Sent from unemployment line.