دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: a collar or coupling of tool steel, threaded internally, that can be used to retrieve pipe from the well on fishing jobs;the female counterpart of a taper tap. The die collar is made up on the drill pipe and lowered into the hole until it contacts the lost pipe. If the lost pipe is stuck so that it cannot rotate, rotation of the die collar on top of the pipe cuts threads on the outside of the pipe, providing a firm attachment. The pipe is then retrieved from the hole. It is not often used because it is difficult to re- lease it from the fish should it become necessary. Compare taper tap.

n: See box tap.

n: the value of dielectricity assigned to a substance. A substance that is a good insulator has a high dielectric constant, whereas a poor insulator has a low one. The dielectric constant of oil is lower than that of water, and on this principle a net-oil computer operates. die nipple n: a device similar to a die collar but with external threads.

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.