Porausputki

Porausputki, or drill pipe, is a tubular steel component of the drill string used to bore boreholes. It transfers drilling fluid from the surface to the bit, provides structural support for the downhole assembly, and resists bending, torsion, and compression during drilling. It is employed in oil and gas, geothermal, mineral exploration, and civil engineering boreholes.

Construction. Drill pipe is typically steel, manufactured as seamless or welded tubes with hardened tool joints at each end for connections. Tool joints extend the ends and are designed for wear resistance. Materials range from standard carbon steel to alloyed or corrosion-resistant grades for aggressive fluids. API specifications govern dimensions, tolerances, and connections to ensure interchangeability.

Sizes and standards. Common joint lengths are around 9.5 meters, with outer diameters from roughly 2 3/8 to 5 inches depending on the operation. API 5DP covers drill pipe, while associated standards cover casing and tubing to ensure compatibility of connections and performance across equipment.

Applications. The drill pipe transmits rotation to the bit and channels drilling mud to the downhole area, helping to cool the bit and carry cuttings to the surface. It forms the upper portion of the drill string in oil, gas, geothermal, and hard-rock drilling.

Maintenance. Regular inspection is essential to detect wear, pitting, or corrosion; thread damage requires repair or replacement. Protective coatings and proper handling minimize damage. When damaged beyond tolerance, sections are retired and replaced to prevent failure under load.