دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: a tap with a gradually decreasing diameter from the top. It is used to retrieve a hollow fish such as a drill collar and is the male counterpart of a die collar. The taper tap is run into a hollow fish and rotated to cut enough threads to provide a firm grip and permit the fish to be pulled and recovered. See tap. Compare die collar.

a spear-like fishing device with threads to engage ID threaded fish.