Through the years I have keep my eyes open for a pvc pipe that would slide over a carbon air tank for protection. I may have stumbled across it. At a job today they are covering parking bollards with a cover. I look them up on line and they make a 7” ID which would work for my tank. I am pondering.
https://www.uline.com/BL_3948/Bollard-Sleeves
https://www.uline.com/BL_3948/Bollard-Sleeves