The existing exhaust stack was comprised of four separate sections (three lower carbon steel sections and one upper stainless steel section). The bottom most section of the stack, located below the roof level, was determined to be adequate based on further analysis and non-destructive examination. The upper two carbon steel sections, located above the roof level of the building, required replacement (due to extreme corrosion) with newly fabricated stainless steel sections. The decision was made to replace the existing middle two carbon steel sections with stainless steel sections during the planned outage. In order to minimize the risks associated with working at height, the decision was made to fully dress the stack at grade and lift the stack to its final position as a single unit. Rally prepared detailed engineering to fabricate the new stack sections off site, reinforce existing sections of the stack and complete all field work.
Rally was responsible for the structural and mechanical engineering in addition to planning and scheduling all aspects of the engineering, procurement and construction management.
This project went straight into detailed engineering with a compressed schedule of three months for engineering, fabrication and construction. Rally issued one Civil/Structural CWP and one Mechanical MR for the pre-fabricated stack sections.