Leapfrog Technology to Standardize Equipment and System Installations. Section 7. Engineering Analysis and Develop Standards

Prepared in cooperation with Vibtech, Inc. and Univ. of New Orleans, LA.

The grillage is the simplest and most common type of foundation. Therefore where it is not possible to mount equipment with weld studs or spools the greatest cost savings can be achieved by standardizing a producible grillage design. In the past grillages have typically consisted of two or more parallel spans of angle iron welded continuously along their length to either deck or bulkhead plating or spanning between deck or bulkhead stiffeners. This is an inefficient method of installation because it typically involves a large amount of welding and fitting. Considering the number of grillages mounting light weight equipment aboard a ship great cost savings can be achieved by instead lifting grillage angles up off of plating and stiffeners with chocks which attach the web of the angle to supporting ship structure. This practice reduces the amount of required welding and simplifies the foundation assembly. Additional savings can be achieved if this grillage is then mounted directly to soft plating or cantilevered off of stiffeners where these practices are feasible. Previous practice unnecessarily avoided landing on soft plate or cantilevering and grillages were almost always bridged to rigid ship structure even though this is typically not necessary with lighter equipment. By obviating this old convention significant cost savings are generated by eliminating the pieces associated with bridging the foundation to ship structure. This greatly reduces the welding cutting and fit-up time associated with a particular foundation.