BSEN877 Gray Cast iron pipe Epoxy Cast Iron Pipe Flat and straight ; high strength and density without defect;easy to install and maintain ; long lifetime ,fireproof and noise resistant; environmental protection Outside of the pipe is zinc sprayed (130g/m2) and an grey color epoxy coating ,approx 60μm.(as you requirement) SML Cast Iron Pipes are suitable for installation inside or outside buildings. When Grey Cast Iron Pipe was been installed outside the buildings, it will notget rust with the protection of the coating.