Damaged plastic gas tank, hit by prop.
Permanent fix for PPG fuel tanks | Thanks to Alex Varv
If your gas tank gets damaged, it’s frequently almost impossible to fix since no glue that we’re aware of permanently adheres to the polypropylene material.
Epoxy Repair
Various epoxies, such as JB weld, can be used for a temporary repair. Clean the glued area with brake cleaner and sand the surfaces to be glued with 200 grit sandpaper (or similar). Mix the glue and hold the glued surfaces together with weight or tape wrapped around the tank.
Glue repairs won’t last, though. At least one pilot had epoxy-repaired his tank only to have all the fuel leak out in his car when the epoxy failed a day later.
Weld Repair
Caution: You’re working with a gas tank. Before dealing with hot tools, especially those using propane, make sure the gas tank is completely cleaned out and has no fumes!
Polypropylene plastic can be repaired through plastic welding. Alex found that the material does not become brittle at the weld, or at least not appreciably so.
If you have a welding tool, that obviously makes it easier, but it can be done with a heat gun ($10 Harbor Freight) and hot knife ($25 CableOrganizer.com).
Using the hot air gun, heat up the areas to be welded together until they become clear and a little more. Then use the heat knife to fuse the two pieces together.
This method can also be used for repairing the surround of fittings.
Thanks to Alex Varv for experimenting with this method and sharing it with the community.
Chicago Electric Plastic Welding Kit with air motor and temperature adjustment. Available from Harbor Freight.