For near surface geothermal drilling and the subsequent installation of the widely used double U heat pipe a combination of drill string with an inner rod diameter of 89 mm and 2 3/8” API thread and outer casing 152 mm is commonly used.To increase the inner diameter (33 mm with 2 3/8” API regular and 44 mm with 2 3/8” API internal flush) for flush drilling, KLEMM Bohrtechnik has designed a completely new drill string under the brand name DRILL PLUS.
Drill rods DRILL PLUS G 95 (inner diameter 59 mm)
e.g. in combination with outer casing diameter 152 mm
Drill rods DRILL PLUS G 114 (inner diameter 85 mm)
e.g. in combination with outer casing diameter 178 mm
The casing is distinguished through its large flushing area and very robust threads with easy screwing / unscrewing.
Besides the application within the geothermal drilling industry, the DRILL PLUS casing is increasingly being used in the special foundation industry e.g. for double head drilling with down the hole hammer.