Plastic rainwater storage tanks can become damaged with age. When a plastic rainwater tank cracks, you need to repair the crack to conserve the rainwater and to keep the crack from growing to a point that you need to replace the tank. To create a permanent repair to your plastic rainwater tank, you need to fuse the crack with heat. A hot air plastic welder will fuse the crack, creating a strong repair. Here are some instructions for repairing a plastic rainwater tanks.
1. Drain the water from the plastic rainwater tank so that the water level is two to three inches below the repair area.
2. Determine the type of plastic your rainwater tank is made from by finding the three-letter identification code stamped on the surface and then referencing the identification code in the plastic identification guide. In the identification guide there will be a welding temperature listed along with the plastic melting temperature.
3. Set the heat of the plastic welder, turn the plastic welder on and allow the plastic welder to warm up while you prep the repair area.
4. Put on your safety glasses.
5. Create a 1/16-inch groove over the repair area with the carbide beveling tip attached to the die-grinder. Run the groove 1/2 inch past each side of the repair area. This will ensure that the stress is relieved from the repair.
6. Hold the speed tip of the plastic welder on one end of the repair area and feed a length of plastic filler rod into the rod guide of the speed tip.
7. Apply downward pressure on the plastic filler rod and pull the plastic welder toward you. Keep a constant eye on the area where the plastic filler rod meets the surface of the repair area. If you notice the surface of the repair area turning brown, increase the speed you are pulling the plastic welder. Slow down your pulling speed if you notice there is no bead of melted plastic flowing in front of the area where the plastic filler rod meets the surface of the repair area.
8. Clip the plastic filler rod with the side-cutting pliers when you reach the end of the repair area. Fuse the end of the plastic filler rod to the surface of the plastic rainwater tank.
9. Allow the welded area to cool to air temperature before allowing any water to enter your rainwater storage tank.