When CS Energy, an Australian energy company based in Queensland, needed to create a safer work environment at a power station, it turned to Giant Inflatables Industrial of Melbourne to design and fabricate an inflatable solution.
Plant technicians were looking to solve a safety issue for workers in the confined spaces of electrostatic precipitators, which help control fly ash emissions. CS Energy’s best practice for workers to enter confined spaces is the “double block and bleed method,” which requires at least two isolation points and their connecting vent valve to be locked open to the atmosphere. Due to the precipitators’ design, only one isolation point had been used previously, but plant managers wondered if an inflatable bag could provide a gas-tight seal that would act as a second block on the inlet and outlet.
Besides the pandemic making all but the initial consultation impossible, Giant Inflatables Industrial faced several challenges, including the high operating temperature of the duct (240 degrees F) and the fact that airflow in the duct could not be reliably closed, so designers had to allow for the unit to deploy (from fold down to inflation) and locate with significant back pressure.
Giant Inflatables Industrial devised an 11.5-foot square inflatable using a composite construction of PVC-coated polyester and Mylar®-coated fiberglass that is suited for high temperatures, but is also light enough that it could be folded and deployed through a small manhole and inflated inside the duct.
“We chose the Erez PVC-coated poly material for its weight-to-strength ratio and its high-temp specs,” says David Abramowitch, technical design director at Giant Inflatables Industrial. “We chose the Mylar-faced fiberglass to protect the hot face against a temperature spike blast that could occur from the downstream steam generator. The Mylar face protects from radiant heat while the fiberglass offers high-temp capacity to protect the inflatable envelope. As a composite package it’s then easy to work into a reliable and compactable unit.”
Once inflated, the unit was fixed into place using a highly engineered anchorage system compromised of a tie-point winch solution built to withstand the high-velocity air pressure coming through.
The project earned a Health and Safety Innovation Award in the “project or site-wide innovation” category at the Queensland Generator Safety Forum in April. Giant Inflatables Industrial is also fabricating a similar product for a steel manufacturer in India that will work at an even higher temperature.
Client/contractor: CS Energy
Assistant engineering specialist: Chris Ross
Design and fabrication: Giant Inflatables Industrial
Fabric: PVC-coated polyester(Erez ER720) and Mylar®-coated fiberglass (Future Thermal 406MY)
Photo: Giant Inflatables Industrial