View Inside The Flue

By Liz Moucka | September 28, 2010

In building what may be one of the last coal-fired electric plants in Texas, Flour Corporation and their subcontractor Hadek Protective Systems BV called upon Spider, a division of SafeWorks, to engineer and install a custom float platform for internal stack access.

Prime contractor on the project, Fluor Corporation, subcontracted Hadek Protective Systems BV to sandblast and install insulation brick and the steel lining for the two 450-foot-tall chimneys. The scope of this work required a powered platform that had enough capacity to provide support and access through all stages of their work in the stacks.

Spider's professional engineers performed site visits in the process of designing a unique 31-foot round float platform equipped with nine SC-1500 traction hoists.

Spider created the powered suspended access business by introducing the well-known Spider basket. SafeWorks is headquartered in Seattle, WA, and maintains 24 operation centers in the major metropolitan areas of North America including Houston and Dallas.

"We had to pre-assemble the platform at the Houston office to make sure it met the dimensions," explained Chris Bates, director — National Accounts & Industrial Access. "In the stack, you have a 4-foot hole you're going through to assemble it into a 31-foot circle. You can't make any adjustments on site. Then it was dismantled and shipped to the job site with all the pieces numbered." The Oak Grove power plant is located in Robertson County, about 150 miles north of Houston near Bremond.

Once on site, the platform had to be reassembled inside the first 450-foot-tall concrete smoke stack. At the 150-foot level where the flue liner enters the stack, a floor with a 4-foot hole in the center served as the reassembly area. Hoists, suspended by wire ropes attached to the grillage atop the stack, lifted each numbered piece of the platform 150 feet upward and threaded it through the 4-foot hole in the floor. Motors attached to the platform would make the platform operational.

The 13,500-pound capacity of the platform was designed to support all workers and their loads. The precise 31-foot diameter enabled the installer to touch the lining wall during work. To meet Hadek's schedule and work processes, Spider designed the large area platform with a 4-foot square access hole in the platform's center to match the 4-foot square hole in the elevated floor. This configuration would allow an independent work basket to transport workers and materials while the platform remained at the work elevation. This was a critical feature since the adhesive material used for the brick installation needed to be mixed at ground level and transported quickly for application.

In addition to managing the hoisted load of the platform itself, Spider's designers implemented numerous special features in the system to meet the work challenges: Grated decking was installed on the platform to allow the abrasive material to sift through the platform during the blasting phase of the project; the top of the stack was outfitted with structural steel to support the 18 wire ropes needed to support the platform; and extensive planning for worker fall protection was addressed, just to name a few.

Spider performed installation and post-project equipment service to fully support Hadek's work in Texas.

"This project exemplifies Spider's ability to engineer and deliver solutions that solve our customers' unique access challenges, but we also navigated training, labor and service needs for this global customer," stated John Sotiroff, vice president, Sales and Distribution. "From the concept initiation, which started with our European team, to the design phase to the platform delivery and assembly, Spider's team rose to the occasion and provided Hadek with a safe, efficient means for getting their work done on time and within budget."

In 2006, TXU Corp. hired Fluor Corp. to handle engineering, procurement and construction services for two units at its Oak Grove coal power plant in Texas. The Oak Grove plant will be constructed at the site of a previously planned power plant that has significant infrastructure already in place.

The Oak Grove project, a nominal 1,634-megawatt super-critical lignite power plant in Robertson County, will have among the lowest sulfur dioxide, nitrogen oxide and mercury emissions in the nation and will be 80 percent cleaner than the average U.S. coal plant, Fluor said.

Unit 1 is expected to be operational in late 2009. Unit 2 is expected to be operational sometime during the middle of 2010. The plants are expected to be able to power about 1 million homes.

Luminant is a subsidiary of Energy Future Holdings (EFH), formerly TXU Corp. In 2007, TXU Corp.'s primary business units were separated into three distinct businesses — Luminant Energy, Oncor Electric Delivery and TXU Energy as part of the merger agreement with the investment group led by Kohlberg Kravis Roberts & Co. and Texas Pacific Group. Luminant is a subsidiary of Energy Future Holdings (EFH), formerly TXU Corp.