I have 3/4" PVC Sch 40 air lines in my shop and have had them for over 15 years with no issues. When I installed them I sanded the connections prior to gluing together.
My Compressor is set at 175 psi.
Wow! You must have been putting some pressure on the system. The tractor is not designed to do dozer work. I'm surprised the metal line busted and not one the hoses. If the dealer doesn't cover it under warranty, it's and easy fix. Get them to order the new line and replace it yourself to save...