Making the grade

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

Focus on INCONEL alloy C-276

21 April 2021

Focus on INCONEL alloy C-276

When a specialist alloy is required and your more frequently used alloys simply will not cut it in a highly corrosive environment, the experts turn to INCONEL alloy C-276, a highly refined specialist alloy that's ideally suited to highly corrosive environments.
Traditionally, alloys such as INCONEL 625, which offer excellent resistance to corrosion from organic and mineral acids, have been ideal for usage in the oil and gas production industries, where they prove themselves time and time again at temperatures of up to 950°C.

These alloys, however, are not able to withstand the harsher and more aggressive environments that exist in the chemical processing and pharmaceutical industries. INCONEL® alloy C-276 offers excellent resistance to sulphuric, phosphoric and hydrochloric acids, and is one of the few nickel alloys that can withstand wet chlorine gas, acid chlorides and chlorine solutions.

INCONEL alloy C-276 Composition

When you take a metaphorical look under the hood, you begin to understand why this alloy is so resistant to the most corrosive and inhospitable environments known to man. The alloy is composed of a blend of nickel and molybdenum, with the addition of tungsten chromium, iron and cobalt. This composition gives INCONEL alloy C-276 a high resistance to general corrosion, stress corrosion cracking, pitting and crevice corrosion.

In addition, the low carbon content of the alloy minimises grain boundary carbide precipitation, allowing it to maintain high resistance within the heat-affected zones of welded joints. This gives INCONEL alloy C-276 additional versatility and longevity - and perhaps it's the key to its success in markets all over the world.

Offshore gains for oil and gas

Not only is INCONEL alloy C-276 proving to be an exceptionally popular choice in the chemical and pharmaceutical industries, but it is also being used ever more frequently in the petrochemical industry - specifically for offshore drilling. Where alloys such as INCONEL 625, MONEL 400 and 316 stainless steel experience corrosion from seawater under crevice conditions, INCONEL C-276 once again stands out as the clear winner.

Corrosion rates for nickel, chromium and molybdenum alloys in the marine environment are very low, both under flowing and stagnant conditions. And in particular, INCONEL alloy C-276 is resistant to stress-corrosion cracking in waters containing chlorides, especially under crevice conditions.

With the costs of INCONEL alloy C-276 being comparable to INCONEL 625, it is increasingly being seen as a viable choice for the long-term processing of crude oil in the Far East and India, where oil reserves are largely offshore, in contrast to the Middle East where oil is predominantly land-based. INCONEL Alloy C-276 is being seen as longer-lasting and more cost-effective than other more traditionally used alloys.

INCONEL alloy C-276 is available as seamless pipe, welded pipes and tubes and fittings in a variety of sizes and thicknesses. If you would like to talk to a member of the Corrotherm team about whether INCONEL C-276 is the right choice for your application, please contact a member of the sales team.

For technical specs on this popular alloy, head over to the ‘Grades’ section of the Corrotherm International website.

Published in Inconel C-276