This part of ISO 965 specifies limit deviations and limits of sizes for pitch and crest diameters for ISO general purpose metric internal screw threads conforming to the coarse thread series of ISO 262 (from M8 to M64) having basic profile according to ISO 68‑1.

Internal screw threads according to this part of ISO 965 are intended to mate with external screw threads with maximum size of tolerance position h before hot-dip galvanizing.

Internal threads shall be tapped after the hot-dip galvanizing process has been completed, therefore no galvanizing coating is present on the surface of internal threads.

Products made with thread tolerances according to this part of ISO 965 may show load failure when tested in accordance with ISO 898‑2 without adjustment of the other mechanical properties.

Internal screw threads with thread tolerances according to this part of ISO 965 must not be mated with external screw threads having thread tolerances according to ISO 965‑4 because such combinations will create severe risk of thread stripping.

Internal screw threads with tolerance class 6AX are primarily intended to mate with hot-dip galvanized external screw threads with heavy coating not centrifuged.