Overview
ISO 8866:1991 - "Rotary core diamond drilling equipment - System C" defines the dimensional, material and tolerance requirements for a complete family of rotary core diamond drilling components designated as System C. System C is a distinct equipment family (not interchangeable with ISO systems A or B) characterized by a series of nesting hole sizes with small clearances between hole wall and equipment, allowing use of thin‑walled casing tubes. The standard covers equipment for drilling holes with outer bit diameters from 35 mm to 112 mm (core diameters ~21 mm to 92 mm).
Key topics and technical requirements
- Scope of equipment: single‑ and double‑tube core barrels (types M, DM, T, DT, DP), diamond core bits, reaming shells, core lifters and cases, core tubes and heads, drill rods and couplings, casing tubes and couplings.
- Material properties: minimum mechanical properties (tensile strength, yield stress and elongation) are specified for manufactured items. Example values in the standard include drill rods with a minimum tensile strength ≈ 690 N/mm², yield ≈ 490 N/mm² and elongation ≈ 12%; drill‑rod couplings at higher values (see standard table).
- Dimensions & tolerances: detailed nominal outside diameters, wall thicknesses and thread forms for each size (tables and figures). Main hole diameters covered: 35, 46, 59, 76, 93, 112 mm (outer bit D).
- Geometric tolerances: requirements for tube straightness and curvature are specified (e.g., maximum deviation from straightness typically 1:2000 of tube length for drill rods and core tubes