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Mechanical properties and applications of INCONEL alloy C276

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INCONEL alloy C276 is a versatile nickel alloy that’s utilised across a number of different environments. We look at the key industries that benefit from the high-performance alloy’s mechanical properties and its common applications within those
INCONEL alloy C276 has been around for over 50 years, and its use shows no sign of decline. It offers outstanding corrosion resistance to some of the most volatile environments on earth, making it an indispensable material.
 
Its strengths lay in its unique makeup, heavy in nickel, chromium and molybdenum, as well as controlled amounts of tungsten. It also has deliberately controlled low levels of carbon to minimise carbide precipitation during heat treatment and welding.
 
The precision and expertise practised in its development and manufacture ensures it has mechanical properties that keep it in demand for a number of industrial applications. Here we explore some of the key industries that utilise the material and the areas in which it is most commonly employed.
 
Oil and gas
The oil and gas industry presents many difficult environments. In particular, the recovery of sour gas (natural gas) can throw up many problems for design engineers when it comes to material selection.
 
Sour gas is highly corrosive, due to the presence of large amounts of hydrogen sulfide. This chemical compound is poisonous, corrosive and flammable, making it very difficult to handle. If natural gas contains more than 5.7 milligrams of hydrogen sulfide, it’s considered ‘sour’, which applies to an increasing number of natural gas fields. Natural gas will also include carbon dioxide and chlorides, compounding the difficulties faced. The gas is highly corrosive to carbon and alloy steels, causing brittle failure due to sulfide stress cracking or stress-corrosion cracking.
 
The properties of INCONEL alloy C276 make it a good choice of material for use in these sour gas environments. It is highly corrosion resistant to even the most aggressive of external media. Thanks to its unique chemical balance, with high levels of nickel, chromium and molybdenum, the alloy can resist corrosion from sour gas, even in deep wells where the temperature is high.
 
As such, INCONEL alloy C276 is often used for various downhole and surface components, as well as tubing.
 
Nuclear industry
Another industry where environments can be volatile, toxic and highly corrosive is the nuclear industry. As well as aggressive media, there are also high temperatures to contend with. It’s a tricky environment and any materials used have to be strong, highly corrosion resistant and durable. If a material is compromised, it can have vast safety implications.
 
Nuclear waste containers, for example, need to be constructed in materials that can withstand corrosive attack by their contents. The high concentration of molybdenum and tungsten in INCONEL alloy C276 means that the alloy has superior resistance to crevice attack and localised corrosion, making it a great option for storing nuclear waste. The alloy is commonly used in nuclear reactors and nuclear power plants for various key components.
 
The material is also useful in innovative and conceptual designs that will drive the nuclear industry forwards. For example, in a supercritical water reactor (SCWR) that operates at supercritical pressure, internal conditions would be particularly harsh. One research article looked at the ‘Corrosion Behaviour of Alloy C-276 in Supercritical Water’ in relation to its potential use in a SCWR system.

Power generation and pollution control
INCONEL alloy C276 crops up as a material of choice in a number of applications within power stations. For example, it’s often used for flue gas desulphurisation components like ducts and fans, louvers and gas valves, dampers, scrubbers, chimney stack linings and containment housings.
 
Flue gas desulphurisation (FGD) systems are used to control air pollution from electric power plants and is an essential, but corrosive, process. The scrubber liquors and gas condensates are generally high in chlorides, which can present problems in many alloys due to its very corrosive nature. There are also issues surrounding the elevated temperatures often present in these kinds of systems; higher temperatures can increase the rate at which corrosion occurs.
 
FGD systems are also prone to fluctuating between wet and dry conditions, where surfaces become wet with the acids present, then the temperature increases and essentially boils the acids. All of this puts a lot of pressure on the materials used.
 
INCONEL alloy C276 is known to withstand higher chloride content than other alloys, without exhibiting localised corrosion. It’s also less prone to corrosion as the temperature increases than other materials. C276 is therefore a reliable and proven good choice for these FGD systems within the power industry.
 
Chemical, pharmaceutical and food processing
Processing plants present varying but equally difficult conditions, where material selection has to be determined by a number of factors, such as the presence of aggressive chemicals, elevated temperatures and high pressure.
 
INCONEL alloy C276 has been shown to be a good option in chemical processing where certain chemicals or substances are present. This includes ferric and cupric chloride ions, chlorine, hypochlorite, chlorine dioxide, organic acids, acetic anhydride, seawater and brine.
 
Within the chemical, pharmaceutical and food processing, the high-performance nickel alloy has been used in the manufacture of mixing vessels, reaction chambers, heat exchangers, transfer piping and valves and pumps.
 
In more aggressive environments, such as the pulp and paper industry, or in waste-fluid treatment plants, the alloy can be employed in the most volatile parts of the system with good results. This is thanks to its mechanical properties, which make it resistant to general corrosion, stress corrosion cracking, pitting and crevice corrosion.
 
INCONEL alloy C276 has proven itself to be a popular and endlessly versatile material. If you’re looking for a high-performance nickel alloy for your next project, it’s certainly worth exploring this useful option. If you want to discuss your project requirements with one of our expert sales team members, get in touch with us today.