What is Monel K-500 used for?

Monel™ K-500 (UNS N05500) is a nickel-copper alloy, age-hardened to achieve two to three times the strength of Monel 400. It retains these excellent mechanical properties up to about 650degC. It also exhibits excellent corrosion resistance in both chloride-containing and chemical environments. The combination of physical and mechanical properties means that it is widely used in a host of demanding applications.

Langley Alloys holds a comprehensive stock of Monel K-500, ranging from 5/8” (15.875mm) to 10” (254mm) diameter solid bar. At times during our company history, we cast our own ingots for further processing, but these days work closely with our mill partners to provide a competitive offering.

Bar sizes around 1” (25.4mm) seem to be most popular amongst our customers who manufacture fasteners. Given the universal application of fasteners, these may find their way into marine atmospheres, pumps and valves, as well as components in the chemical processing industry.

Slightly larger size bars, typically 1-2” (25.4-50.8mm) are most commonly being ordered by valve manufacturers, to produce stems in a variety of valve types. Aluminium bronze is a common material choice for the cast bodies of valves used to handle seawater and chemicals, with Alloy K500 providing similar resistance to corrosion. However, its high strength and toughness over a range of operating conditions reduce the likelihood of damage to the stem through misuse or ‘sticking’ of the valve in operation.

Mid-range bar sizes, typically 3-4” (76.2-101.6mm), are being purchased for a wider array of applications. We are aware of Alloy K500 being used in the fabrication of specialist marine and naval hardware through this combination of high-strength and durability in a seawater environment.  In these sizes, it can also be used to produce pump shafts, most commonly for firefighting and seawater-lift pump systems. Propeller shafts are a target application, but less common, with duplex and super duplex stainless steels being more widely used due to their significantly lower cost.

Larger bar sizes, between 6-10” (152.4-254mm), are most commonly being used by our customers in valve production once again. However, at this size of starting stock, they are being machined into the bodies of valves, usually for service in the chemical process industry due to the wide range of mediums this alloy can resist.

Other applications claimed for Alloy K500 include drill collars and instrumentation used in oil well drilling equipment, due to its resistance to seawater and sour gas environments. Claims are made for its use in aerospace applications, chemical processing equipment hardware such as doctor blades and mixers, springs and pump sleeves and wear rings.

Monel is a trademark belonging to Special Metal Inc and is applied to a family of nickel-copper alloys.