In a 1998 study, costs for corrosion in USA were estimated to be about 276 billion US-$. One way to reduce this gigantic amount of money is to use modern stainless steels and nickel alloys with excellent resistance to various forms of corrosion in corrosive environments like seawater, brines, oil and sour gas wells.
An advanced grade of super-austenitic stainless steel with a reduced content of nickel offers a significant economic advantage over nickel-base CRA’s. As the alloy is readily fabricated by conventional techniques, it is an excellent candidate for a variety of applications in the chemical, petrochemical, mining, oil and gas, and refining industries.
Sulfuric and hydrochloric acids are among the most common chemicals produced.in the process industry. Nickel alloys have been a traditional material of choice. This paper will review the alloys available for this service as well as identify the temperature limits and other conditions that should be considered when selecting an alloy.
Exhaustive testing has been conducted and reported previously on UNS N06055 in corrosion 2014 paper number 4223. These data support the use of UNS N06055 for nuclear applications where resistance-to-cracking during fabrication and resistance to primary water stress corrosion cracking (PWSCC) in service are of paramount importance.
UNS N08935 is a new versatile super austenitic alloy with extreme pitting resistance as indicated by its pitting resistance equivalent number (PREN) of 52. It can be used in a broader temperature range than superduplex and hyperduplex stainless steels, offers good weldability and is more cost-effective than Nickel-based materials which make the grade a good candidate for O&G applications, refineries, and chemical industries.1,2
Several industrial applications including the chemical industry and oilfield technology involve frequently halide-containing streams at elevated temperatures, that challenge the pitting corrosion resistance of metallic materials. Pitting susceptibility becomes not only a reject criterion for materials selection during the design stages of engineering components used in these applications. It also constitutes a significant limiting factor to the service life of these components once in service. Therefore, the characterization of the pitting corrosion resistance of metallic materials including the influence that operational factors can have on material’s susceptibility is crucial.
Alloy 182 is an austenitic (FCC) nickel base Ni-Cr-Fe-Mn weld metal that is used as a weld filler or weld pad metal to join stainless steel reactor internals, reactor instrumentation penetrations and main coolant piping to the low-alloy steel reactor pressure vessel. Stress corrosion cracking (SCC) in alloy 182 dissimilar welds is one of the most important material degradation problems and an ongoing issue in boiling (BWR) and pressurized water reactors (PWR) world-wide with potential safety concerns.
Thermally activated preferential local ordering (unlike atom pairs is greater than that in a random solution) of elements within a lattice, over spatial dimensions that are typically on the order of a few nearest neighbor spacing 20 to 50 Å (2 to 5 nm) is referred as short range ordering (SRO). SRO causes lattice contraction and induces additional stress which is claimed as the driving force for SCC in the alloy 600, alloy 690, and alloy 182.