Cranes: Structural Maintenance

Fatigue Cracks on Container Cranes

by Simo Hoite and Mike Jordan of Liftech, Hannu Oja of Konecranes, David Moosbrugger of Kunz, Theo Scheijven and Walter Oostwouder of APM Terminals, and Michael Thanner and James Scanlon of Liebherr Container Cranes.
Published by Port Equipment Manufacturers Association (PEMA).

Liftech is the pioneer of structural maintenance programs for container cranes and has been advocating the importance of performing structural maintenance for decades. Simo Hoite and Mike Jordan of Liftech Consultants Inc. worked with other Port Equipment Manufacturers Association (PEMA) members to develop a new PEMA information paper on the structural examination of container handling cranes. Published February 10, 2016, the paper highlights the danger of fatigue cracks on container cranes and provides practical advice for locating these cracks.

Click here to read the PEMA Information Paper


Structural Maintenance of Dockside Container Cranes

by Michael A. Jordan.

Original: February 1999; Reprinted: May 2008.

Since 1975, the development and use of structural maintenance programs have improved the reliability of heavily used container cranes. The programs, based on the principles of fracture mechanics and probabilistic methods, are designed to locate and detect fatigue cracks.

The booklet explains the fundamental principles of general yielding, fatigue crack growth, brittle fracture, the concepts of stress intensity and fracture toughness, fatigue design criteria, the statistical basis for fatigue criteria, and the selection of inspection intervals. The booklet also gives recommendations for what to do and what not to do when cracks are detected, describes typical crack patterns and good and bad fatigue details, and presents three specific examples of typical cracks and remedies based on actual occurrences.

Crane Useful Life Assessment and Maintenance

by Feroze Vazifdar.

Presented at the TOC Asia 2005 Conference in Hong Kong, China.

This presentation discusses fatigue design philosophy, useful life analysis, structural maintenance, and shows repair examples.

Fatigue cracks occur and can be catastrophic if not repaired in time. Cracking can be controlled with proper design, workmanship, quality control, and a proper structural maintenance program. Structural useful life analysis can be used to predict future cracking so the owner can decide the best course of action.

This article discusses the rationale behind structural maintenance programs for cranes.

Structural Fatigue Happens: Maintain Your Cranes!

by Patrick McCarthy.

Structural maintenance is most efficiently, i.e., cost effectively, achieved through varying inspection intervals for the different crane components, depending on predicted cumulative “damage.” In this sense, cumulative damage refers to fatigue crack growth, not accidental damage.

For a crane structure, maintenance includes frequent visual inspection, periodic non-destructive testing (NDT), and repairing any cracks or damage caused by regular usage or accidents. Regular maintenance is not only essential for a reliable crane but is recommended to justify the allowable stresses. The crane is not designed to last forever with no limits on its fatigue life. This is impossible. Cranes will experience fatigue crack growth and if used indefinitely without inspection will eventually fail. The designer and operator must recognize this.

This article discusses the rationale behind structural maintenance programs for cranes.

Predicting and Prolonging the Life of Used Cranes

by Feroze Vazifdar.

So you have an older crane that has not undergone regular structural inspection—what are your options? You can do nothing and blindly use the crane, which, as we will explain later, is risky. Or you can assess its condition to find out how much structural life remains. Once you know the condition, you can decide how to best use the crane.

Liftech’s techniques of predicting and prolonging the structural life of used cranes are discussed in this paper. Liftech provided this service for quayside container cranes and rail mounted gantry cranes in Hongkong International Terminals, Hong Kong. These cranes will be presented as case studies.

Useful Structural Life Assessment of Dockside Container Cranes

by Kenton Lee, Feroze Vazifdar, and Simon L. H. Wong.

Useful structural life is the remaining time a crane can be operated with an acceptable risk of failure. This time can be extended using a structural maintenance program. This paper and presentation present the methods used to develop a structural inspection program and to evaluate useful life using statistical analysis and the principles of fracture mechanics. A theoretical overview is followed by a case study of useful structural life assessment of eight dockside container cranes for Hong Kong International Terminals.