April 1, 2008
SPS Overlay protects dredge sideshell
Leading dredging contractor Van Oord chose SPS Overlay to provide side shell protection for its dredge Volvox Iberia (1993). The work was carried out in Ajman, UAE, at a yard which is jointly owned by Keppel, an SPS Overlay licensee.
SPS Overlay was used to reinforce the side shell of the dredge and to provide enhanced impact protection when alongside moored barges.
Van Oord Technical Superintendent Sipke de Vries commented on the repair: "We have used SPS Overlay on various projects previously and are familiar with its benefits. In this case, we were able to strengthen two areas of the dredger's side shell for improved impact protection and we are very pleased with the outcome."
In total 109 sq.m of the side shell was reinforced and strengthened with SPS Overlay. The existing steel was blasted and cleaned. Perimeter bars and new plates were welded in two areas, to create a series of cavities, which were then injected with a fast-setting elastomer.
SPS is a patented construction technology based on a composite material comprising two metal outer plates and a solid elastomer core. The plates are separated and continuously supported by the more ductile core. This gives SPS global strength and stiffness with a much less complex structure that has superior performance characteristics to conventional stiffened steel. SPS Overlay utilizes the existing worn surface, a new top plate and an elastomer core. SPS is a proven and approved technology. Over 100 SPS projects have now been completed around the globe. SPS is approved by the six major classification societies.
Commenting on the side shell protection, Director SPS Overlay Rob Duffin explained: "In this case, the increased stiffness of the SPS Overlay helps to share the load between side shell frame members, distributing the effects of any side shell impacts. The elastomer core provides a continuous elastic foundation for the top plate thereby precluding the risk of any plate buckling, preventing any permanent set and mitigating the effects of concentrated loads."
Meanwhile, Project Engineer Alvin Forster noted the efficiency of the Middle Eastern repair yard. "Steel work was undertaken by yard personnel to a good standard and we were able to complete the injection process efficiently."
He added "In fact the whole project took two weeks. A conventional strengthening would have taken at least twice as long and would have been significantly more disruptive."