The paper covers the Engineering, Design, Material Selection, Certifying Authority Requirements, Manufacture, Testing and Installation of two large Duplex Stainless Steel (DSS) manifolds for the NAM Underground Storage project, at Langelo near Norg in the Netherlands. Early in 1995, Fluor Daniel B.V.(FDBV) in Haarlem, acting as managing contractor for NAM B.V. awarded a contract to supply two manifolds in DSS for the project to Wyman-Gordon (W-G) in Livingston, Scotland.