... 2.Application:oilfield equipment 3.WP:High pressure Well head assembly(hammer union) High-pressure union, importing international advanced technology, is ... Sub, Female Sub, Seal Ring;oil field equipmentShanghai Jefa Machinery Co.,Ltd specialize in API 6A products as following:1) Wellheads (casing ... valve, etc)3) Fitting(union, manifold,elbows), bop. Well head assembly(hammer union)