Safety of rope-guided conveyance systems

ABSTRACT

The guide rope factor of safety (FOS) currently set in regulations in various countries is unduly conservative and constrains the maximum attainable depth for shafts using rope guides. It limits the amount of guide rope tension that can be imposed, which is important for controlling the lateral motion of conveyances. A lower FOS would lead to more constraint of lateral conveyance motion and therefore safer winding, but this implies a design trade-off of apparent rope safety versus conveyance guidance safety. This paper considers the safety of rope-guided shaft systems and questions whether the above trade-off is appropriately set. Rope safety, the role of guide ropes, and constraints on increasing guide rope tension are discussed. Precedents for review of rope FOS are recalled. The paper provides a motivation for reducing the regulated guide rope static FOS, which will give designers more flexibility in configuring rope-guided systems and will reduce capital costs—potentially significantly if the design is on the boundary of these constraints. Following precedents for a lower rope FOS, it is proposed that, if adopted, this reduction is made with the obligation to meet a code of practice for guide rope installation, inspection, and maintenance.

RÉSUMÉ

Le facteur de sécurité du câble de guidage (FOS, de l’anglais factor of safety) actuellement fixé dans les réglementations de différents pays est indûment conservateur et limite la profondeur maximale atteignable pour les puits utilisant des guides à câble. Il limite la tension du câble de guidage qui peut être imposée, ce qui est important pour contrôler le mouvement latéral des moyens de transport. Un FOS plus faible entraînerait une plus grande contrainte du mouvement latéral du moyen de transport et donc un enroulement plus sûr, mais cela implique un compromis de conception entre la sécurité apparente du câble et la sécurité du guidage du moyen de transport. Cet article examine la sécurité des systèmes de puits guidés par câble et se demande si le compromis susmentionné est correctement établi. La sécurité des câbles, le rôle des câbles de guidage et les contraintes liées à l'augmentation de la tension des câbles de guidage sont abordés. Les précédents concernant l'examen des FOS des câbles sont rappelés. Le document fournit une motivation pour réduire la FOS statique réglementée des câbles de guidage, ce qui donnera aux concepteurs plus de flexibilité dans la configuration des systèmes guidés par câble et réduira les coûts d'investissement - potentiellement de manière significative si la conception se situe à la limite de ces contraintes. Suivant les précédents concernant la réduction de la FOS des câbles, il est proposé que, si elle est adoptée, cette réduction se fasse avec l'obligation de respecter un code de pratique pour l'installation, l'inspection et l'entretien des câbles de guidage.

KEYWORDS:

• Capital cost, Code of practice, Guide rope factor of safety, Mine shaft safety, Rope guides

MOTS-CLÉS:

• code de pratique, coût du capital, facteur de sécurité du câble de guidage, guides-câbles, sécurité des puits de mine

ACKNOWLEDGMENTS

The authors thank their colleagues for their helpful critique of this paper and Worley Limited for permission to publish this paper.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the authors.

REVIEW STATEMENT

This article was reviewed and approved for publication by the Health and Safety Society of the Canadian Institute of Mining, Metallurgy and Petroleum.

ETHICS APPROVAL AND CONSENT TO PARTICIPATE

There are no ethical issues associated with this manuscript.

Additional information

Notes on contributors

M. E. Greenway

M. E. Greenway, FIEAust., FAusIMM, holds the degrees BSc Eng (Mech) and DPhil (Oxon). After graduating, he worked at Oxford University in wind engineering. In 1979, he joined Anglo American Corporation of South Africa in Johannesburg, where he was responsible initially for research and development projects, including shaft steelwork dynamic behavior, rope guide performance, and winder rope oscillations. He progressed to become Consulting Mechanical Engineer. In 1995, Malcolm emigrated to Australia, joining consulting engineers Sinclair Knight Merz in Perth. He is now retired.

S. R. Grobler

S. R. Grobler graduated with a Master’s degree in mechanical engineering from the University of the Witwatersrand in South Africa in 1990. He joined Anglo American Corporation and worked on research projects in shaft hoisting systems and failure investigations on mining equipment. In 1996, he joined Australian consulting firm Sinclair Knight Merz, which subsequently merged with Jacobs Group, which in turn merged its mining business with Worley Services. Steve left full-time employment in 2021. He has experience in dynamic analysis of mine shaft fixed steel guides and rope guides, finite element analysis, simulation modeling, fatigue analysis, and field measurement of vibration and stress on structures and machines. Steve is experienced in condition assessment of steel wire hoisting and guide ropes—including magnetic flux leakage inspection—and was a National Association of Testing Authorities accredited wire rope inspector for 22 years.