Making the grade

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

MONEL alloys – pipes and tubes

01 October 2018

MONEL alloys – pipes and tubes
We take a look in more detail at the pipes and tubes that Corrotherm supplies, focusing on the MONEL product line

Pipes and tubes are among some of the most useful products for industrial applications, employed in everything from the oil and gas industry, to the aerospace and automotive industries. These demanding environments need components that are built to withstand heat, corrosion and pressure. There are a lot of advantages to using nickel alloy pipes for your industrial projects, and there are many Grades available to suit any project’s requirements.

One of the materials used to produce these high-spec pipes and tubes is MONEL. MONEL alloys are produced by blending nickel and copper, alongside additional other elements. They offer both exceptional performance and cost effectiveness. MONEL alloy pipes and tubes come in two key Grades: MONEL alloy 400 and MONEL alloy K-500.

MONEL alloy 400

MONEL alloy 400 is a high-performance alloy that has a 63% minimum nickel content, as well as 28-34% copper. It has significant additions of iron and manganese to give it desirable properties for industrial use. It’s particularly resistant to seawater, which is why it’s often used to carry water in the marine sector. It offers excellent resistance to stress-corrosion cracking in freshwater.

As well as seawater, it’s also highly resistant to hydrochloric and hydrofluoric acids, as well as other corrosive media. Its uses extend into gas storage units and process vessels, as well as in the pulp and paper industry. Due to its ability to withstand high operating temperatures, it’s also a popular choice for heat exchanger piping and the explosives industry.

It’s a solid solution alloy that can be hardened by cold working to make it stronger. In its annealed condition it lacks strength, but it can then be hot worked into a much stronger product, with a full-hard temper seamless pipe offering a tensile strength of 100-130ksi (as opposed to 70-85 ksi in its cold-drawn annealed state).

MONEL alloy K-500

The other MONEL nickel alloy that Corrotherm supplies is MONEL alloy K-500. This is a precipitation-strengthened composition, where titanium (0.35-0.85%) and aluminium (2.3-3.15%) is added during melting to the aforementioned MONEL alloy 400.

This material offers a double whammy of exceptional properties. It has the same excellent corrosion resistance as the MONEL alloy 400, meaning the pipes and tubes lend themselves to similar applications. However, due to the additional elements in its composition, this nickel alloy can be hot or cold worked, then heat treated, to be substantially stronger and harder than the base alloy.

This is useful in oil extraction, marine and chemical processing, seawater pumps and in the pulp and paper industry. Usually, for seawater piping, pipes and tubes are constructed using a combination of both MONEL alloy 400 and MONEL alloy K-500. This gives the best of both alloys. While alloy K-500 is the stronger material, it is more prone to stress-corrosion cracking than alloy 400 in some environments.

Products are manufactured to the strictest of specifications to ensure quality, and can be custom designed in terms of shape, size and thickness to suit any application. If you would like to find out more about MONEL alloys or the range of pipes and tubes that Corrotherm supplies, please Contact Us.

Published in Corrotherm News