Port cranes raised

Ten ship-to-shore cranes have been raised ten metres by Shanghai Zhenhua Port Machinery Company (ZPMC) at the Port of Los Angeles in order to accommodate larger ships.

The project was managed by ZPMC North America, in collaboration with the original equipment manufacturer (OEM). It involved structural fabrication of new leg sections and frame bracing, which was carried out at ZPMC’s Shanghai facility.

An important part of the project included benchmark weighing of one raised crane to determine the new, as-built weight and centre of gravity.

The weighing procedure included: lifting the crane utilising ZPMC’s self-propelled modular trailers; placing 16 Straightpoint wireless compression load cells, supplied by Lifting Gear Hire (LGH), in pairs under the eight intermediate gantry equalisers on specially designed pedestals; and lowering the crane down to rest on the load cells. The crane was lifted off the load cells between trials to allow for three distinct weighing evolutions.

The initial as-built weight of the crane, as provided in historical documents, was 1,185te. Post-construction weighing indicated the raising added 193te, for a total pre-ballast weight of 1,378te. Concrete ballast was added according to OEM specifications and resulted in a post-ballast weight of 1,414te and shift of the operational centre of gravity approximately 1m toward the rear of the crane.

LGH also provided an SP wireless tablet with data logging software and USB wireless base station. The data logging software provided user-configurable screens, recording the physical location of the load cells and collection of data. Centre of gravity software collected data over three trials of weighing to calculate an average. A report was automatically created upon completion of the tests, including each load cell’s load, location, calculated centre of gravity and standard deviation of weight data.

John Molidor, director of projects and market development at Straightpoint, said, “It was great to witness the application in person and get a first-hand impression of the 16 load cell system delivering safety and accuracy to such a landmark project. We enjoyed working with LGH and ZPMC North America to deliver the state-of-the-art solution.”