Making the grade

News and developments in the world of corrosion resistant alloys through the eyes of Corrotherm International

The use of INCOLOY 825 in the oil and gas industry

13 September 2017

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We explore the benefits of this popular INCOLOY alloy for applications in the oil and gas industry.
The oil and gas industry is modernising and advancing, and with that it becomes ever-more important to ensure that the materials selected in new projects and plants can offer exceptional resistance to corrosion, given the extreme environments involved. Alloys used in both onshore and offshore extractions must be both heat and corrosion resistant, and nickel-based alloys from across the INCONEL, INCOLOY and MONEL ranges offer good options that are cost-effective for the manufacture of pumps, valves and process control equipment.

Key alloys in the oil and gas industry

According to Corrosion and Materials in the Oil and Gas Industries (CRC Press, April 2016, Reza Javaherdashti, Chikezie Nwaoha, Henry Tan, “In the oil and gas industry, the two most important nickel alloys are INCONEL alloy 625 and INCOLOY alloy 825”. The latter of these two, INCOLOY alloy 825, is a nickel-iron-chromium alloy, with the significant additions of molybdenum and a small amount of titanium (0.6-1.2%). The alloy is considered the forerunner of modern alloys that contain molybdenum, which imparts strength into the alloy, as well as resistance to pitting and crevice corrosion. The addition of titanium helps to stabilise the alloy against intergranular corrosion. The balanced blend of elements means that the key benefits of this material are its good resistance to both chloride stress corrosion cracking, as well as general corrosion. Chloride stress corrosion cracking (often referred to as simply CSCC) is a type of localised intergranular corrosion on materials that are put under tensile strength, in high temperatures and in an environment that includes oxygen and chloride ions. This can be an issue in the oil and gas industry, which is why nickel alloys are often employed, as the nickel helps to control the material’s susceptibility to CSCC.

Uses of INCOLOY alloy 825

INCOLOY alloy 825 is used alongside other materials in a wide range of applications in the oil and gas industry. Because it is so usefully corrosion resistant under a diverse set of conditions, it can be used across quite a broad range of applications. For example, it can be used for the separation of extracted fluids, in the processing equipment for liquefied natural gas production. It is also useful for flow lines for subsea walls. Other uses include wellheads, cladding for risers and pipes, and casing and tubing. Because it offers a high level of corrosion resistance in both oxidising and reducing environments, it is useful for projects that include sulfuric acid, phosphoric acid, sulfur-containing flue gases, sour gas and oil wells, and sea water. Find out more about the use of INCOLOY alloy 825 and its uses in relation to the oil and gas industry, by getting in touch with a member of our sales team