A combination of pipe stress due to poor anchoring & sulfuric acid buildup from SO2 rich gas caused the flanges on this composite expansion joint belt to separate from the duct. If this happens on a positive pressure duct you introduce unintended & unmonitored emissions. If the duct is negative pressure you’re bringing ambient (cold) air into your process (which is already full of SO2 – speeding formation of sulfuric acid H2S04) and increasing parasitic load on your fans.