One of the most prominent nickel alloys in the INCONEL line is alloy 625 and for good reason. Here, we examine its many uses in a variety of industries and the reasons it’s so popular.
Rarely does a high-performance alloy continue to be widely used across so many industrial applications for so long without being replaced by more modern materials? However, INCONEL 625 defies this pattern and continues to be a common building material that professionals frequently utilize.
The adaptability of Inconel 625 Valves, which allowed it to be utilized in a variety of applications, helped it gain popularity after its development in the early 1960s. It is still highly regarded more than fifty years later as engineers continue to develop new applications for this vital alloy. The nickel alloy is now used for a variety of purposes that go far beyond its original usage in the ultra-critical steam piping.
Over the course of its existence, new processing techniques have been developed, allowing engineers to better comprehend this alloy’s possibilities. For instance, minor compositional modifications and improved milling techniques have extended the fatigue life of thin sheets. 625 filler metals are very well suited for welding different materials together since they are a great option for welding and can handle dilution from other compositions.
PERFECT COMPOSITION
The distinctive chemical makeup of INCONEL alloy 625 gives it favorable qualities. A minimum of 58% of the total alloy must be nickel, making it a high-nickel alloy. Additionally, it contains a significant amount of chromium (20-23%). An outstanding level of corrosion resistance, particularly to oxidizing agents, is imparted by the ideal ratio of nickel and chromium.
The alloy’s extraordinary high strength is due to the presence of molybdenum (8–10%), which also works in concert with the nickel level to offer resistance in non-oxidizing settings. This alloy is resistant to pitting and crevice corrosion due to the molybdenum as well.
KEY PROPERTIES
There are several explanations for why this alloy is so well-liked. It can tolerate a variety of corrosive situations in particular due to the composition of the material. It is almost corrosion-free under gentler circumstances, such as when freshwater or ocean, neutral salts, and alkaline media are present.
Its composition includes chromium, which offers greater resistance to oxidizing chemicals in low-temperature corrosive settings, and molybdenum, which provides resistance to non-oxidizing conditions. Additionally, it can tolerate adverse, high-temperature conditions.
USE IN FUEL REFINING
One of its main uses has been in the refinement of fuel, where excessive corrosion can be a significant issue throughout the entire process. By preventing naphthenic acid corrosion, lowering polythionic acid (PTA) or chloride stress-corrosion cracking, and boosting resistance to oxidizing, INCONEL 625 seamless pipe can be of assistance. Additionally, it lessens high-temperature sulfidation.
Distillation towers at refineries that operate in high-temperature conditions of 220-400°C are susceptible to naphthenic acid corrosion, particularly in transfer lines, nozzles, and return bends. For the construction of distillation towers, INCONEL alloy 625 is frequently used because it has been demonstrated in the industry to have good, long-term resistance to this sort of corrosion.
OTHER APPLICATIONS
The usage of INCONEL alloy 625 is undoubtedly not limited to this. It is frequently used in pipelines for the purpose of collecting sour gas due to the material’s excellent resistance to potable and salt water. The pipelines themselves can be constructed with INCONEL alloy 625 or, as a more cost-effective option, coated with the metal.
The alloy can be used in power plants, offshore topside services, and seawater heat exchangers. Other seawater applications include mooring cables, boat propeller blades, propulsion engines, transducer controls and fittings for submarines, and utility boat exhaust ducts. Additionally, it could be utilized in electrical cable connectors, oceanographic instrument parts, and submerged control components.
