DTE Energy Coal Mill Bunker Silo/Tank refurbishment consisted of removing the existing cladded carbon steel straight wall shell materials and replacing them with all new fully stainless steel materials. This project was performed on an around-the-clock basis to minimize the downtime for the customer. Work all had to be completed in the tight confines of the inside of the plant surrounded by many other tanks, piping, catwalks, structural, scaffolding, and other contractors. This project was completed safely and ahead of schedule for our customer.
This project was very challenging and rewarding to complete due to the extremely tight confines of the area around the exterior of the tank, as there was only approx. 2 feet of space between the tank we were refurbishing and the next tanks in the battery, and the very tight around-the-clock schedule with which we were working. This repair/modification required us to demo all the existing 18-foot diameter by approx. 49-foot tall straight wall carbon steel shell plates that had been cladded with stainless steel towards the inside of the tank as there is a permanent structural steel grid that contains the tank and is stitch welded to the shell plates on the outside in a grid. All rigging had to be hung through access holes cut in the tank’s roof and all demolished steel then had to be lowered and taken out through an access hole established at a lower cone in the bottom of the tank. Once the straight shell was demoed, we then reinstalled the new 1/4″ thick, Stainless Steel shell in reverse operation of the demo process, starting from the bottom and working our way to the top. Pole scaffolding was utilized on the exterior to create access to allow our crews to safely make all stitch welds to the existing structural members and finish all shell full penetration butt welds. Tank builders scaffolding was built and jumped multiple times by our trained crews on the interior for all rigging, fitting, and internal welding to ensure the schedule could be met while maintaining a safe job site. Once the straight shell was replaced, we reattached our new Stainless Steel shell to the thicker cladded roof and lower cone that was not demolished, safely removed all scaffolding, rigging, and tooling, and then turned the tank back over to the customer for many more years of continued operation.
