Overview
ISO 13589:1998 specifies the dimensions of aerospace bihexagonal (double‑hex) nuts that are self‑locking, have a counterbore, and use MJ threads. The standard covers multiple nut classifications defined by minimum tensile stress at ambient temperature and the maximum service temperature (for example: 1 100 MPa / 425 °C, 1 550 MPa / 600 °C, etc.). Dimensions are given in millimetres and apply after any surface coating but before lubricant application. ISO 13589 is intended for use in the compilation of aerospace product standards.
Key topics and requirements
- Configuration: Bihexagonal (double‑hex) nut with counterbore and MJ thread form; self‑locking achieved by forming the upper portion out‑of‑round.
- Dimensional data: Detailed nominal sizes, wrenching codes and associated maximum/minimum dimensions, provided in figure/table format (mm).
- Classifications: Multiple material/strength‑temperature classes identified by a tensile stress at ambient temperature and a maximum allowable temperature (e.g., 1 210 MPa / 730 °C).
- Measurement conditions: Dimensions and tolerances apply after any surface coating(s) and before lubricant application.
- Tolerances and form: Tolerances of form and position to conform with ISO 8788; thread limits referenced to ISO 5855‑2.
- Interoperability: Dimensions determined to satisfy procurement specifications ISO 5858 (≤425 °C) or ISO 8641 (>425 °C) depending on classification.
- References: Normative references include ISO 4095 (wrenching configuration), ISO 5855‑2 (MJ thread limits), ISO 5858, ISO 8641 and ISO 8788.
Applications and users
ISO 13589 is practical for:
- Aerospace fastener designers and mechanical engineers specifying nut geometry and fit for high‑temperature and high‑strength applications.
- Procurement and quality assurance teams enforcing dimensional conformity for supplied nuts.
- Manufacturers and machinists producing bihexagonal self‑locking counterbore nuts with MJ threads.
- Maintenance, repair and overhaul (MRO) facilities ensuring replacement parts meet aerospace interchangeability and temperature/strength class requirements.
Common application areas include airframe and engine bolted assemblies where controlled locking performance and high‑temperature resistance are required.
Related standards
- ISO 5858 - Self‑locking nuts (procurement spec, ≤425 °C)
- ISO 8641 - Self‑locking nuts (procurement spec, >425 °C)
- ISO 5855‑2 - MJ thread limit dimensions
- ISO 4095 - Bi‑hexagonal drive wrenching configuration
- ISO 8788 - Tolerances of form and position
Keywords: ISO 13589, aerospace nuts, bihexagonal nuts, MJ threads, self‑locking nuts, counterbore nuts, fastener dimensions, aerospace fastener standards.