Analysis of rigging assembly for lifting heavy industrial modules

摘要

Modularization of heavy industrial plants is a standard mode of operation utilized to reduce costs, site congestion, and schedule. The standard module is 6 m wide, 24 to 36 m long, and up to 7.5 m high (20 ft wide, 80 to 120 ft long and 24 ft high) with weights ranging from 50 to 160 tonnes. On-site traditional rigging arrangements are costly to adjust for dimension and center of gravity and have inherent safety risks in handling the rigging. Additionally, the modules are often over-designed because of uncertainties in the load redistribution due to lifting. The aim of this work is to design a new system, improving upon the limitations of the traditional system. To achieve this goal, a thorough understanding of the traditional system is required. In this paper, finite element 'analysis was used to analyze the load redistribution due to lifting of three module types with different sizes under various extreme loading scenarios. The results show that load redistribution depends primarily on the triangular assembly of the traditional rigging independent of the module type, size and loading. Secondly, an adjustable and functionally very flexible engineered module lift frame was designed to handle the variety of loading and dimensional conditions and reduce module stresses exerted due to lifting. It is comprised of two main running beams, adjustable interconnecting cross braces, sliders for longitudinal flexibility in connection points, and supporting slings to a common upper point. Finite element analysis was used to confirm the module lift frame loading resistance and to determine its limits under a variety of extreme loading scenarios. There are significant improvements in the module load redistribution forces as compared to traditional rigging.