LR Provisional Rules for SPS

Lloyd’s Register, in conjunction with Intelligent Engineering, Ltd, has developed a set of provisional Rules for new construction and ship repair using steel sandwich construction. Entitled Provisional Rules for the Application of Sandwich Panel Construction to Ship Structure, the Rules were approved in early 2006 by a specially convened sub-committee of Lloyd’s Register’s Technical Committee, comprising independent experts drawn from across the industry.

Sandwich Plate System (SPS) is a technology created by UK-based Intelligent Engineering Ltd in which two metal plates are bonded to a solid elastomer core. The elastomer provides continuous support to the plates and stops local plate buckling, eliminating the need for stiffeners. Other advantages of SPS include its high strength-to-weight ratio, high energy-absorption capacity, good thermal and acoustic insulation properties and inherent fire resistance. The material is now well proven for deck and tank top reinstatement, and its breadth of applications is continually expanding.

The new Rules introduce a set of class notations relating to the application of sandwich panel in ship structures. The Rules cover construction procedures, scantling determination for primary supporting structures, framing arrangements and methods of scantling determination for steel sandwich panels.

Alan Gavin, Marine Director, Lloyd’s Register, says: “We have enjoyed a long and fruitful collaboration with Intelligent Engineering since the first application of SPS onboard the Lloyd’s Register-classed ro-pax ferry Pride of Cherbourg. To date we have been involved in over 20 projects involving SPS, comprising 20,000 square metres of repair and reinstatement projects. The steel sandwich concept has now become a viable option for large-scale commercial applications, and the development of these new Rules will allow designers to consider this material alongside traditional shipbuilding materials such as steel.

“The Rules provide a framework for the classification of ship structures built using the sandwich panel concept and the basis for a consistent approach to the approval of such designs. The overall philosophy of the Rules is to ensure that designs utilising steel sandwich construction are equivalent in strength and safety to conventional steel construction. We believe that these Rules will give the industry confidence to embrace SPS even more fully than it already has.”