While drilling in bouldery / soft formations, the wall of the hole might slough or cave, resulting in stuck bit and difficult string retraction. The casing is then put into the hole to wall it off. Flush Coupled Casing is thin wall tubing with box connections at both ends. Couplings with pin threads connect the casings. Any size casing will fit into next larger size & its ability to pass the corresponding size core bit & reaming shell. Flush coupled casings are light in weight thus resulting in deeper drilling depths with the same capacity of machine.
UEW manufactures the following "X" SERIES CASINGS:
Flush Jointed casing has a heavier wall thickness than flush coupled casing and an integral pin and box connection. Flush jointed casing makes up flush on both the inside and outside diameters. The heavier wall section provides internal and external mating shoulders for the threaded portion to butt against, providing twice the contact area of flush coupled casing and helping threads from climbing under heavy torque load.
UEW manufactures the following "W" SERIES CASINGS: