Butt weld (BW) fittings, connect with pipe to transport natural or propane gas, water, steam, and air to residential, construction, and manufacturing applications. Butt weld fittings form pipe joints with strength, fatigue, corrosion resistance, and temperature compliance. These beveled fittings are welded to the ends of same thickness pipe. Uncoated black steel fittings, also called black malleable iron, are made from corrosion-resistant ungalvanized steel with a scaly, dark-colored iron oxide coating. Butt weld fittings come in a variety of sizes and shapes.