Single Tube Core Barrel is a tubular component made of cold drawn seamless tube. Water is continuously in contact with the core, causing it to erode.
Single tube core barrels have the lowest core recovery and are typically utilised for core drilling in continuous hard rock formations or non-core drilling where core recovery is not critical. Hard metal strips at the head, hard chrome plated on both ends of the tube with core lifter, blank reaming shell, and blank bit are standard on all single tube core barrels.
Double Tube Core Barrel has a swivel head, which means the inner tube is connected to the core barrel head through bearings, allowing the inner tube to rotate independently of the core barrel.
Water flows between the outer and inner tubes of the twin-tube core barrel. Water can flow via perforations on the inner tube’s lower end. The diamond core bit is the sole spot where the core is susceptible to erosion from this point on.
Triple Tube Core Barrel is used for dam and bridge research, geotechnical study, diamond core drilling, soil investigation, foundation testing of high-rise buildings, and mineral discovery with approximately 100% core recovery. With the assistance of a piston mechanism, air or water is forced into the head, and the third tube/split tube emerges. After that, the upper half of the split tube is raised, revealing the core in its original state.
CORE BARREL SELECTION GUIDE
Core Barrels from the TT Series
Ultra thin wall core barrels are available in 46 and 56 mm diameters, suitable for underground mining. These core barrels need relatively light feed pressure and torque, which means that they use lightweight diamond drills to cut effectively at high rotation speeds.
Core Barrels from the T2 Series
Thin wall core barrels are available in 46, 56, 66, 76, 86 and 101 mm diameters, suitable for general purposes of exploration. These core barrels, especially in harder rock formations, have a relatively small cutting area and therefore allow rapid penetration. Flush water or polymer is needed. Planned for use of metric casing in combination.
Core Barrels from the T6 Series
The T6 series is a continuation of the T2 series, but is more compact in nature and is available with larger diameters of 76, 86, 101, 116, 131 and 146 mm, suitable for general exploration purposes. As the flushing medium, water, mud or air may be used, but oversized bits and head couplings are advised when using air to provide adequate room for the Cuttings for clearing. Planned for use of metric casing in combination. The T6H core barrel is the equivalent of the T6-101 in imperial scale, basically similar in style, but with a slightly smaller O.D. Allowing it to fit inside the HW or HX casing.
Core Barrels from the T6S Series
These core barrels have a split inner tube of aluminium and are intended for use in very loose formations of geotechnical practice. An undisturbed sample is given by the split inner tube combined with face discharge bits. Mud and air flushing is made possible by a large annulus between the inner and outer tubes. The diameters available are 101 and 131mm.
Core Barrels from the WF / WG Series
Geotechnical core barrels, available with N, H, P and S DCDMA diameters. The WF series is built with water or mud as the flushing medium for coring soft formations using face-discharge core parts. Internal discharge core bits are used in the WG series and are built for slightly harder rocks. Compared with metric series T2 and T6, core bits have a relatively wide crown area, and this tends to slow penetration and cause faster bit wear in harder rocks. The head design is very primitive and uses only a single thrust bearing, so that the more advanced core barrels do not rotate as smoothly as the more modern core barrels. They continued to be widely used largely due to clients wishing to specify hole and core sizes according to U.S. and U.K. Standards.
CONVENTIONAL TRIPLE TUBE CORE BARRELS
In site investigation and core exploratory exploration projects, Triple Tube Core Barrels are intended to optimize core recovery. A split steel tube that fits snugly inside the inner tube (e.g. “Triefus” NMLC and HMLC core barrels) or a transparent plastic tube known as the “Coreliner” or “Triplex” device can be used for triple tube core barrels. To turn several double tube traditional core barrels into triple tube forms, clear, semi-rigid PVC “Coreliners” are available. Prior to any core run, these thin PVC tubes are forced into the inner tunnel. The coreliner (which now includes the drilled core) is extracted easily and in “one piece” after retrieving the core barrel from the hole simply by grasping the lower end of the liner and easing it with a pair of pliers out of the inner tube. Even in difficult formations, this technique can provide 100 per cent core recovery. When using coreliners, special core parts, core lifters and core lifter cases are required with a slightly reduced internal diameter.
WIRELINE DOUBLE TUBE CORE BARRELS “W/L”
In deep holes, wireline core barrels are used, primarily because each time the core is retrieved, they significantly reduce the time spent handling the rod string. An overshot system is dropped on a cable and paired directly onto the inner tube assembly, allowing the core after each core run to be easily retrieved. Accessible in sizes B, N, H from DCDMA. Oh. And P. Also available in S scale is a geotechnical variant of the wireline device (‘GBS’), giving cores in excess of 100 mm.
WIRELINE TRIPLE TUBE CORE BARRELS “W/L3”
These are typical wireline double tube barrel modifications, but incorporate a third, split tube. After retrieval, the split tube is drained out of the inner tube, allowing the center to be examined in its in-situ state. Generally used in broken, fragmented formations, using face-discharge core bits when high quality core is needed. The use of a third tube allows the bits to cut a core of a slightly smaller diameter than wireline barrels of double tubes. It is possible to use PVC Coreliners instead of the split inner tube, allowing the core to be kept inside the core box in one piece.