This fiberglass/teflon composite expansion joint belt is on the stack-breach where a long run of duct work connects to the chimney. Even though this power plant is fueled by low-sulfur natural gas (as opposed to coal), there’s still SO2 gas in the stream and when it runs through the long duct the temperature drops below dew-point, causing the SO2 to combine with moisture in the ambient air and create H2SO4 (sulfuric acid). In this case the expansion joint hardware is acting like a heat-sink and increasing this effect. We’ll solve this problem by using Interep CustomFlex Insulation on the outside of the expansion joint to keep temperatures above dew point while still allowing for movement.

This fiberglass/teflon composite expansion joint belt is on the stack-breach where a long run of duct work connects to the chimney. Even though this power plant is fueled by low-sulfur natural gas (as opposed to coal), there’s still SO2 gas in the stream and when it runs through the long duct the temperature drops below dew-point, causing the SO2 to combine with moisture in the ambient air and create H2SO4 (sulfuric acid). In this case the expansion joint hardware is acting like a heat-sink and increasing this effect. We’ll solve this problem by using Interep CustomFlex Insulation on the outside of the expansion joint to keep temperatures above dew point while still allowing for movement.