Thermoplastics like polyurethane are quickly repaired by welding the damage with a hot air gun. When you weld polyurethane, the repaired area will be permanently fixed and often stronger than the rest of the tank. To build up the the damaged area, use a filler rod, which is made from polyurethane. The additional filler rod material thickens the repair and therefore strengthens the weld. Like any welding process, heat and speed are the two most important factors when performing the polyurethane repair.
Things You'll Need
- Hot air gun with speed tip
- Fine-tooth triangle file
- Leather work gloves
- Polyurethane filler rod
- Wire cutters
Plug in the hot air gun, turn the heat dial to 575-degrees Fahrenheit and set the hot air gun aside to heat up. This is the optimal welding temperature for polyurethane plastic.
Run the pointed tip of the fine-tooth triangle file along the repair. You want to gouge the area of the repair at least 60 percent of the thickness of the plastic sheet and at least twice as wide as the repair area.
Put on your leather work gloves.
Place the end of the speed tip of the hot air gun in the center of the repair you need to weld on the plastic tank and slowly push a length of filler rod into the guide of the speed tip.
Pull the hot air gun along the repair area, as you push the filler rod gently toward the surface of the polyurethane plastic tank. To ensure that you are pulling the hot air gun at the proper speed, make sure that you see a slight puddle of molten polyurethane in front of the area where the filler rod meets the surface of the plastic tank. If there is no puddle, you are pulling too fast and if you notice the surface of the polyurethane turning dark brown, you are moving too slow.
Cut the filler rod with the wire cutters when you reach the end of the repair area and drag the speed tip along the surface of the plastic tank to fuse the cut end of the filler rod to the surface of the polyurethane plastic tank.
Move the end of the speed tip back to the other end of the repair area and repeat the procedure to run enough passes along the repair area to fill the repair area. To strengthen the repair, you can run an additional pass with filler rod on either side of the repair area.
Allow the repaired area to cool before handling the polyurethane tank to avoid being burned by the welded polyurethane joint.
- Photo Credit Thinkstock Images/Comstock/Getty Images
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