IN-787, A Low Alloy steel for Offshore Platforms and Ship Hull Plate Applications

Abstract

IN-787, A Low Alloy steel for Offshore Platforms and Ship Hull Plate Applications K.L. Money; K.L. Money The International Nickel Co., Inc. Search for other works by this author on: This Site Google Scholar D.B. Anderson D.B. Anderson The International Nickel Co., Inc. Search for other works by this author on: This Site Google Scholar Paper presented at the Offshore Technology Conference, Houston, Texas, May 1975. Paper Number: OTC-2375-MS https://doi.org/10.4043/2375-MS Published: May 04 1975 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Money, K.L., and D.B. Anderson. "IN-787, A Low Alloy steel for Offshore Platforms and Ship Hull Plate Applications." Paper presented at the Offshore Technology Conference, Houston, Texas, May 1975. doi: https://doi.org/10.4043/2375-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search nav search search input Search input auto suggest search filter All ContentAll ProceedingsOffshore Technology ConferenceOTC Offshore Technology Conference Search Advanced Search AbstractThree years of evaluation in marine environments have demonstrated that IN-787, a 0.9 Ni-0.6 Cr-0.2 Mo-I.2 Cu-O.04 Cb steel, can be used with confidence in the offshore and ship-building industry. Immunity to stress corrosion cracking of IN-787 base plate and weldments in marine environments, even under conditions if hydrogen charging, is a primary advantage. Ease of weldability and galvanic compatibility between weldment and base plate material has been demonstrated. In the sea water splash and spray zone, where critical corrosion most often occurs on steel structures, IN-787 displays acceptable performance.Preliminary test results indicate that IN-787 is amenable to cathodic protection with zinc anodes and requires only low current to maintain corrosion protection of submerged structures after initial polarization has been achieved.This steel develops a tight, adherent corrosion product film in marine atmospheric exposures providing a lower corrosion rate than that of other steels similarly exposed.IntroductionThe use of any carbon or low alloy steel in the offshore or shipping industry should be prefaced by the characterization of its corrosion behavior and mechanical properties. Good tensile strength, weldability, resistance to stress corrosion cracking, compatibility with cathodic protection systems, good low, temperature impact properties and availability of the steel commercially are just a few of the requirements of any steel or alloy for use in a severe marine environment.IN-787 is a steel that achieves these targets. Its mechanical properties and interim results for many of the continuing corrosion tests in natural marine environments are described in this paper.Description of Test SitesThe Francis L. LaQue Corrosion Laboratory of the International Nickel Company, Inc. is situated on Banks Channel at Wrightsville Beach, N. C. The sea water environment is natural, fresh, full strength sea water with an average salinity of 35 ppt, average sea water temperature of 65°F, average dissolved oxygen of 7 ppm and a tidal range of 3-5 feet. All sea water tests described in this paper were performed at this laboratory except the aggressive splash zone studies; which were conducted on a pier on Wrightsville Beach, N. C.The marine atmospheric test site of FLLCL is located 20 miles south of the sea water laboratory at Kure Beach, N. C. along the Atlantic Coast. Using carbon steel specimens it has been demonstrated that the corrosive conditions in the 80-foot lot are 7 to 10 times more severe than in the 800-foot lot. The atmospheric variables in this exposure location, along with several others, have been documented in ASTM STP 435. (1) Both exposure sites are shown in Figure.IN-787 Alloy SystemIN-787 is a precipitation-hardening, high strength steel characterized by good low temperature toughness and excellent weldability at temperatures as low as 80°F. IN-787 utilizes copper as the primary strengthening agent, with low carbon to optimize weldability and toughness. The nickel, nominally 0.85 per cent, provides solid solution strengthening and also increases toughness. Columbium is present for grain refinement with the precipitation of columbium carbide also serving as an additional strengthening agent. Chromium and molybdenum are added to retard auto-aging and thus provide useful strength in heavy sections. Keywords: well integrity, upstream oil & gas, flowline corrosion, steel, engineer, mechanical property, materials and corrosion, beach, subsurface corrosion, riser corrosion Subjects: Pipelines, Flowlines and Risers, Materials and corrosion, Well Integrity, Subsurface corrosion (tubing, casing, completion equipment, conductor) This content is only available via PDF. 1975. Offshore Technology Conference You can access this article if you purchase or spend a download.