How to Design a Fillet-Welded Lap Patch

Arc welds are common for fillet-welded lap patches.

Fix holes in tanks, boats and other metal structures by designing your own fillet-welded lap patch -- a piece of metal that lays on top of the metal it's being welded to. Designing a lap patch like this is a relatively easy project that requires little measuring and arithmetic. Performing the actual weld will require knowledge of using welding equipment, which is much more involved than knowing what size of piece needs to be welded to make the patch.

Things You'll Need

• Welding gloves
• Welding jacket
• Welding face shield
• Measuring stick
• Sheet metal
• Band saw
• Wire wheel
• Arc welder,
• Welding rods, 6013

Instructions

1. Measure the size of the hole that you need to patch, using your measuring stick. Add 1 1/2 inches to the length and width of these measurements.

2. Cut your sheet metal with your band saw to the measurements determined in the last step. Clean this piece of metal with your wire wheel.

3. Clean the metal surrounding the hole you need to patch, with your wire wheel. This will ensure that the fillet-weld will be strong.

4. Position the piece of sheet metal over the hole that needs to be patched, so it is covering three-quarter-inch of metal on all four sides. Weld it down to finish the patch. Clean the weld with your wire wheel, when you are finished.

Tips & Warnings

• Always wear the proper safety attire when welding.

References

• "Practical Blacksmithing and Metalworking", Percy W. Blandford; 1988
• Miller Welds: Guidelines for Shielded Metal Arc Welding