Weld Nuts Weld nuts combine a welding flange with a female threaded nut. This provides a threaded mounting point that can be welded into place. Tab Weld Nuts in multiple configurations, also Hex Projection, Round Base Styles, and Square Weld Nuts. Square Weld Nuts are designed to create a robust, permanent fastening when welded to another metal surface. Each Square Weld Nut features four projections (located on each corner of the nut), which allows the nut to be bonded to the surface through welding.