Fittings, flanges, and unions for piping systems are constructed out of various types of metals. Forged carbon and alloy stainless steel fittings, flanges, and unions make up the largest segment of the market and accounted for about a quarter of sales as of the year 2000. This segment of the market consists of socket-weld or threaded-type fittings, flanges, and unions, which had an estimated market value of $220.4 million in 2000; butt-weld flanges accounted for about $125 million in sales; and butt-weld fittings, around $131 million in 2000.
Fittings and flanges made of copper, brass, or bronze represent the second-largest segment of this market. These products accounted for about 21% of sales in 2000. These fittings, flanges, and unions can be constructed of either cast brass or bronze, or wrought copper or alloy. Wrought copper and wrought copper alloy fittings, flanges, and unions made up the majority with $290 million in sales in 2000, or 71.4% of the copper, brass, or bronze fitting, flange, and union segment. Copper is an excellent conductor of electricity, while brass fittings are used for feed-water pipes where hard water makes steel pipes undesirable.