Overview
ISO 16173:2025 - Ships and marine technology - Jacking system appliances on self‑elevating unit - Rack pinion leg fixation system defines requirements for the design, manufacture, inspection, testing, designation, marking and documentation of rack pinion leg fixation systems used on self‑elevating units. The standard applies to leg fixation systems that establish a rigid mechanical connection between hull and pile legs (rack chocks meshing with pile leg racks) and covers composition, classification, technical requirements and acceptance testing.
Key topics and technical requirements
- Scope and composition
- Covers the mechanical fixation mechanism, power unit (electric or hydraulic) and control system.
- Mechanical parts typically include rack chock, screw and nut, wedge block (if applicable) and hydraulic cylinder.
- Classification
- Structural types: Type A (with wedge blocks) and Type B (without wedge blocks).
- Drive types: Type E (electric power unit) and Type H (hydraulic power unit).
- Design and safety requirements
- Systems must be designed with failure mode and effect analysis (FMEA) to ensure redundancy and that a single-component failure does not compromise unit safety.
- Provision of self‑fixation means to maintain leg height in case of loss of power.
- Strength analyses required for normal holding (unit and pile legs) and severe storm holding conditions.
- Rack chock tooth root ultimate strength: at least 1.1× that of the pile leg rack tooth root.
- Power units must include overload/pressure protection; hydraulic cylinders require robust environmental and safety design.
- Control systems must provide monitoring, alarms and clear indication of complete locking/disengagement.
- Inspection and testing
- Material, surface and internal quality, dimensions, coating/plating inspections.
- Tests specified: pressure tests, safety protection testing, locking/unlocking tests, static load bearing tests.
- Requirements for type testing and production testing to verify performance.
Applications and users
ISO 16173:2025 is intended for:
- Offshore designers and structural engineers specifying leg fixation for jack‑up rigs and other self‑elevating units.
- Manufacturers and fabricators of jacking appliances and rack pinion systems.
- Shipyards, offshore contractors and owners for procurement, acceptance and maintenance criteria.
- Classification societies, surveyors and inspectors performing type approval, inspection and certification.
- HSE and operations teams managing safety, maintenance and emergency procedures for jack‑up units.
Related standards
Normative references cited in ISO 16173:2025 include, for example:
Keywords: ISO 16173:2025, rack pinion leg fixation system, self‑elevating unit, jacking system appliances, rack chock, leg fixation, offshore jack‑up, design requirements, inspection and testing.