If corrosion control elements are not properly followed per engineer guidelines, it could result in property damage, injury, and even worse, death. Virtually every gas code requires corrosion protection of metallic pipe fittings installed underground; NFPA 54 7.1.3 and ICC 404.8. The DOT disallows unprotected underground steel gas pipe; DOT 192.455. Before installing natural gas connections, contact the local city inspector for applicable city, state & national codes that apply.