Merchant couplings are also known as wrought iron couplings, but are actually made from merchant steel according to ASTM A865. The female threads are NPS straight tapped to 2" and taper tapped in larger sizes. Standard couplings are black steel dipped in rust preventative up to 2" and phosphate coated in larger sizes. Deep chamfers allow for easy assembly. Half couplings are chamfered at one end only.