Borrstav

Borrstav, in English typically called a drill rod or a segment of a drill string, is a straight, cylindrical metal bar used in drilling operations to transmit rotational torque and axial force from a drill rig to the drill bit. It is a fundamental component in mining, civil engineering, geothermal, and oil and gas drilling, where multiple rods are connected end to end to form a long string capable of reaching the desired depth.

Construction and materials typically include carbon steel, alloy steel, and, where corrosion resistance is required, stainless steel. Borrstavar are manufactured with uniform cross sections and ends that are threaded or machined to accept tool joints or other connectors. Diameters and lengths vary by application, with rod joints designed for easy coupling and disconnection. Surface treatments, such as coatings or case hardening, may be applied to improve wear resistance and longevity. In demanding downhole environments, the rods are designed to withstand bending, torsion, and fatigue loads.

Variants and usage contexts are driven by the task at hand; drill rods are combined with drill bits, stabilizers, and other tools to form a complete drilling assembly. They must be compatible with standard tool joints and connectors to enable easy assembly, disassembly, and replacement. Maintenance focuses on regular inspection for cracks, corrosion, bending, and wear, with damaged rods retired from service. Proper handling, storage, and transport are important to prevent damage and ensure safety.

See also: drill string, drill bit, tool joint, and drilling equipment.