Effects of Modular Systems on Construction Productivity and Project Management Processes
Authors: Ahmed Zaid 
Published: July 2010

A new method of construction of tertiary supports on offshore platforms is analyzed. Use of new generation modular systems is compared with traditional welded hot rolled steel construction for tertiary supports of a typical oil and gas process platform. Parameters including time of installation, resource-use and effects on other project management aspects are studied in order to compare its performance against traditional welded construction method. Also an empirical model is developed to estimate the time and budget savings when welded steel is replaced with the modular systems.

Introduction

Improving construction efficiency and finding financially optimal solutions is always on the top in the wish-list of owners and project managers, especially in offshore platforms construction where each day lost in construction is each day loss of production of thousands of barrels of oil and cubic meters of gas. Among other major activities, petty installations such as supports for light equipments, utility piping, electrical cable trays and instruments is also considered important for the successful completion of project. Such activities generally expand over almost 30% of project schedule and costs from 5 to 7% of the total construction budget. These tasks although are small-ticket items on budget but are generally one of the main reasons of schedule delays and erosion of contingency budgets. Hence, increased productivity and improved change management processes involving these seemingly inexpensive but painstaking tasks can be of significant help.

System of hot rolled steel sections welded together is one of oldest and well known support system for all levels of loads. Despite the fact that it has a large number of advantages very well known to industry, for light load applications there are some disadvantages that contractors would happily want to avoid even at considerably high expense. Such disadvantages include:Welding on painted surfaces, especially when electrical equipments in the surroundings are already installed/deployedExpensive re-work when caused by design changes and construction errors

Modular Systems

An alternate system was introduced to overcome these drawbacks and achieve significant productivity increase. The system consisted of long channels, small enough to be handled by one person, which can be joined together using bolts or pins in multiple ways to create supports for small scale loadings. The system due to its nature of piece-by-piece construction is called modular system. The system is used in the building construction since many years but is believed not to offer any significant advantage in offshore construction primarily because:It is unable to resist lateral- and dynamic loads as expected on any offshore project.It doesn't satisfy the flexibility demands as expected on offshore platform construction due to use of supports for multiple trades within tight spaces.It doesn't eliminate welding as it relies on brackets to connect tertiary supports to the primary steel. These brackets are typically welded to the primary steel supports. They are installed either prior to paint but in a lot more quantity than needed in order to manage the changes incurred later or post-paint thus having to damage the painted surface and do the long and tedious repair work.