Eccentric casing Systems Drilling through formations with loose, unconsolidated material always comes with problems such as the bore hole cave-in collapse. How to avoid these problems? With years of field practice and research, Team whole had developed its eccentric casing system application for strata with silt, sand or small size pebbles. With its simple structure,easy operation and reliable performance, this system can advance the casing easily for depth within 30 meters. And it's retrievable with long service life. Concentric Casing Systems Usually the land surface of the earth is covered with loose, unconsolidated material such as soil, clay, silt, sand, gravel and boulders, which varies in depth from a few centimeters to hundreds of meters. Use concentric system can drill this complex formation very well. The systems are available through the whole product range the smallest being for 114 mm (4 1/2") casing and largest size available at the moment is for 1220 mm (48") casing.