Analysis of SPMT Transport of Large Onshore Modules

Usage of onshore process plant modules includes transportation from a fabrication yard to a jobsite via a combination of water and land routes. Large modules (larger than 1,000 m) are normally transported over land using self-propelled modular transporters (SPMTs) in order to spread the module’s weight uniformly over a large area of the transportation path. SPMTs utilize hydraulic cylinders to lift and lower modules, and to achieve uniform wheel loads that transfer the module’s weight to the road. A suitable analysis is needed to consider this uniform wheel loading and to check against the hydraulic cylinder’s permissible stroke, spine beam permissible stresses, and deflections within the module. This paper describes a balancing approach for a SPMT analysis that is used by several companies. The discussion describes the method itself and includes how hydraulic-type reactions are modeled. One key element is specifically examined, the rigidity of the module and the resulting effect from SPMT-imposed support. The results of field measurements are presented in support of the approach.