Hastelloy C-276 for Superior Corrosion Resistance

Corrosion resistance can be a key design consideration when choosing the material of a heat exchanger. Certain fluid processes may have corrosive environments that can cause stress corrosion cracking to components. Materials that can resist this mode of mechanical failure may be necessary in corrosive environments.

Nickel-based alloys can be an appropriate material choice for applications where corrosion resistance is required. Nickel can retain ductility while increasing strength and hardening ability. Heat exchangers that utilize nickel-based alloys can potentially resist stress corrosion cracking. There are a number of nickel-based alloys available for applications that require corrosion resistance.

Hastelloy C-276 is one of the popular corrosion resistant materials for fluid processing industries. The alloy is composed of a combination of nickel, molybdenum, and chromium with a small amount of tungsten. Nickel typically composes more than 50% of the alloy, but every manufacturer has a slight variation of the amount of material in their alloy composition.

Hastelloy Properties and Manufacturing

Alloy C-276 has excellent corrosion resistance in harsh environments where other alloys fail. This alloy is considered to be a ‘superalloy’ due to its extreme corrosion resistance. The material is commonly used in reactor vessels, piping, flanges, fittings, pumps, and valves in the pharmaceutical industry.

Alloy C-276 is a wrought alloy, which means that the alloy is forged into its final shape. The alloy can be processed through conventional hot working and cold working methods. Hastelloy C-276 can also be processed with electrical discharge machining. The processing method depends on the end application of the heat exchanger and the corrosive environment that it operates in.

Further understanding the properties of alloy C-276 can help you make the right decision around which material to use for your heat exchanger.

Corrosive Properties

Hydrogen sulfide is often present in corrosive environments, such as offshore drilling applications. This chemical compound can corrode certain alloys and materials. This can lead to equipment failure and compromise worker safety. Manufacturers should ensure that the heat exchanger material does not fail in hydrogen sulfide environments.

Hastelloy C-276 has great corrosion resistance in reducing environments and can handle most oxidizing environments. Alloy C-276 can handle hydrogen sulfide rich environments as compared to 825 and 625 alloys. The material can resist pitting, stress corrosion cracking, and various acids, such as hydrochloric, formic, acetic and phosphoric acids. This alloy is one of the only nickel-alloy grades that can operate in wet chlorine gas, hypochlorite, and chlorine dioxide environments.

The material is not suitable for extremely harsh oxidizing conditions, such as hot concentrated nitric acid, due to the amount of chromium present. The alloy can be suitable for most corrosive environments.

Temperature Considerations

Your operating temperature of your processes could compromise the material that your heat exchanger is constructed of. At certain temperatures, even the strongest, most durable alloys may begin to fail. Alloy C-276 can operate in oxidizing environments up to 1,900℉ while still resisting pitting, corrosion, and cracking. The material maintains oxidation resistance at 2,000℉. Hastelloy C-276 can typically operate in high temperature environments.