https://www.pipenipples.com/king-nipples/ Applications of King Nipple Fittings King Combination Nipples, also known as KC Nipples, are a versatile hose coupling for transitioning from a hose to pipe, equipment, valves, or strainers. These end connections are mainly used for fluid service. NPT, BSPT male thread is standard. King combination nipples, a kind of threaded nipple in pipe fittings, are also available in a grooved end or with a beveled end for welding.