A steel weld-in bung creating a male AN20 port, the largest size offered here. AN20 is reserved for bulk-flow, low-pressure plumbing such as main coolant and header tank connections, large crankcase breather and vent lines, dry sump reservoir feeds and high-capacity fuel transfer. Steel welds readily into mild steel tanks, fabricated reservoirs and chassis fabrications with MIG or TIG, and is the sensible option where corrosion resistance is not critical. Given the diameter, weld in staged passes around the flange and let it cool between runs so the port stays round and the flare seat flat. Fit the AN20 hose end without thread sealant.