Generator flues|: The product selected would be a twin wall insulated stainless steel pre-fabricated exhaust system. The product is manufactured from a 0.6mm grade 316L inner liner, and a 0.6mm grade 304L outer case with the 37mm void packed of 128kg/m3 high density insulation. The joints are push-fit complete with outer locking band. GE gives a positive pressure resistance of up to 5,000Pa and a continuous high temperature capability of up to 760°C (1000°C Intermittent), GE is the chosen product for industrial applications. Independently tested to BS 476: Part 24 for 4 hours. The product selected gives a positive pressure resistance of up to 5,000Pa and a continuous high temperature capability of up to 760°C independently tested to BS 476: Part 24 for 4 hours.