Cart Black Steel Nipples (Sch 40) Schedule 40 black steel nipples are for use in gas piping and non-potable water installations. View cart “2″ x 6″ Black Steel Nipple (Sch 40)” has been added to your cart. 1/8" Black Steel Nipples (0) All Black Steel Nipples (Sch 40) (128) 1/2" Black Steel Nipples (22) 3/4" Black Steel Nipples (22) 1" Black Steel Nipples (21) 1-1/4" Black Steel Nipples (21) 1-1/2" Black Steel Nipples (21) 2" Black Steel Nipples (20)