Surface level gauges fabricated from AISI Type 316 stainless steel (316) wire Failed after only a few weeks of operation in underground storage tanks at the Hanford Site. The wire failure was determined to be due to chloride ion assisted corrosion of the 316 wire. Radiation-induced breakdown of the polyvinyl chloride (PVC) riser liners is suspected to be
the primary source of the chloride ions. An extensive literature search followed by expert concurrence was undertaken to select a replacement material for the wire. Platinum (Pt) -20% Iridium (Ir) alloy was selected as the replacement material from the candidate materials, Pt-20 %Ir, Pt- 10%Rhodium (Rh), Pt-20 %Rh and unified numbering system (UNS)
alloy N06022. The selection was made on the basis of’ the alloy’s immunity towards acidic and basic environments as well as its adequate tensile properties in the fully annealed state.
Keywords: single-shell tanks, surface level gauges, stainless steel, polyvinyl chloride, corrosion, noble metal alloys, Hanford