Profile: Pennine Systems Ltd. manufactures vitreous enameled flue pipes. Our products include flexible flue liner, single wall stainless steel, cowls & bird guards, log stores, and weather vanes. Vitreous enameled flue pipe is suitable for oil, gas and solid fuels, and domestic heating appliances. Finished products have an internal and external vitreous enamel coating to offer extremely high resistance to heat and toxic or corrosive gases.