ISO 4309 doesn't give a one-size-fits-all frequency. It gives ranges, and it tells you the inspection regime should reflect the operating duty. Here is the working frequency guide we use when scoping recurring MRT contracts in India.
Daily — visual walk-around
Every duty cycle. Operator or designated maintenance person walks the rope visually, looking for surface broken wires, gross deformation, and obvious corrosion. ISO 4309 expects this baseline.
Monthly — visual periodic inspection
All cranes regardless of duty. A trained inspector performs a more thorough visual check including end-terminations, sheaves, and drum spooling. Photos and a written log accompany the inspection.
Quarterly — MRT on continuous-duty equipment
EOT cranes on multi-shift continuous duty. Mining hoists. Port cranes on high-cycle duty. The 90-day interval is short but the rope wear rate justifies it.
Bi-annual — MRT on heavy-duty cranes
Tower cranes on multi-shift sites. Crawler cranes on long lattice-boom configurations. Mobile cranes on continuous heavy-lift contracts. 6-month MRT interval.
Annual — MRT on standard-duty cranes
Most equipment falls here. Tower cranes on single-shift duty. EOT cranes on intermittent duty. Offshore cranes during scheduled downtime windows. 12-month MRT interval.
Trigger-based — MRT on incident
Unscheduled MRT is required after any rope incident — overload event, shock loading, observed deformation, or unexplained vibration during operation. Don't wait for the next scheduled interval.
How we set up recurring contracts
We start with an equipment list and rope diameter inventory. We propose an inspection frequency based on the duty cycle and equipment type, plus a trigger-based add-on. We track each rope's condition history over time so the recommended replacement intervals become data-driven, not guesswork.
Email wirerope@dgoc.in to set one up.