29.06.2007

Safety fears grow over spurious tower crane components

Following extensive analyses and tests, leading tower crane manufacturers are becoming increasingly worried that the use counterfeit replacement parts may result in the collapse of a crane.

Some manufacturers claim that tests on parts produced by Chinese based counterfeiters has revealed greatly reduced tensile strength, much lower impact toughness and inadequate weld joints.

Until recently, most spurious tower crane components have been produced in Asia – mainly China and Korea – but with counterfeit part production growing in Europe, the potential for a problem is growing.

“Some counterfeit components are easy to spot, some even the manufacturer has difficulty identifying,” said Christoph Schneider, tower crane project manager for Liebherr-Werk Biberach GmbH. “We believe that using these parts may result in the collapse of a tower crane.”

Liebherr is one manufacturer that has carried out extensive tests on counterfeit components using university and material test labs. It found that most components are dimensionally quite accurate however the lesser quality of the material did not meet the minimum static safety requirements.

“Yield points in tensile tests are significantly below what is required and the low temperature tests showed many unsuitable for work in cold weather becaming very brittle,” said Schneider.

Weld quality was another area of concern.
“Weld joints, particularly on transverse connections were not up to standard, in some cases only 50 percent of the transfer cross-section was present,” he said.

“When the crane is in operation, the crane torque therefore causes high levels of stress, leading to cracks in the weld joints. If this was to go unnoticed for too long, it could result in the complete destruction of the transverse connections and cause the crane to overturn.”

Corner posts and corner post linkages were also tested with some failing with just one third of the loading required by the original component.

“It should also be remembered that operators that use counterfeit components are in effect using a new crane and must therefore assume responsibility for its compliance with European regulations and certify its conformity,” he said. “Without knowing the properties of the crane or the spurious components, this would be very difficult.”