Hangbo Alloy Group
Shanghai · Est. 2012
Erosion-corrosion attacks nickel alloys in pumps, seawater, and FGD slurry. Understand the mechanism and which grades survive abrasive, corrosive flow.
Erosion-corrosion is the accelerated loss of metal when a flowing, often particle-laden fluid strips away the protective surface film faster than it can reform. In pumps, seawater cooling systems, and flue-gas-desulfurization (FGD) slurry lines, the abrasive action of droplets, sand, or gypsum particles keeps opening fresh metal to the corrosive medium, so the part thins and punctures far faster than either erosion or corrosion would alone. This guide covers the mechanism, the plant locations most at risk, and the nickel alloys specified to survive abrasive-corrosive flow.
The protective passive film (chromium oxide, molybdenum-rich, etc.) is what lets stainless and nickel alloys sit in corrosive fluid for years. Erosion-corrosion begins when fluid velocity, turbulence, or entrained solids mechanically remove that film at a local spot - a bend, a pump impeller eye, a nozzle. Once the film is gone, bare metal corrodes rapidly; the flow then sweeps away the corrosion product, and the cycle repeats. The result is a characteristic horseshoe-pattern or angled groove pointing in the flow direction.
Two factors set the rate: fluid energy (velocity, turbulence, particle size and loading) and film repassivation speed (chromium and molybdenum content, pH, oxygen). High velocity plus low alloy resistance is the dangerous combination.
Erosion-corrosion shows up wherever a corrosive fluid moves fast or carries solids:
Resistance comes from a film that reforms fast and a matrix that resists abrasion:
Alongside alloy choice, control velocity, add erosion shields at bends, and keep solids loading down - design and material together set service life. The PREN and pitting guide explains the chromium-molybdenum chemistry behind film stability.
Pure erosion is mechanical wear by particles or cavitation in clean fluid; erosion-corrosion adds a corrosive medium that attacks the bare metal once the film is stripped. In a neutral, non-corrosive fluid a hard alloy may survive; in seawater or acid slurry the same part fails fast because corrosion joins the attack. The PREN guide covers the corrosion side of the film.
For seawater with sand or high velocity, copper-nickel 70-30 is the traditional choice for pipes and fittings, while Inconel 625 is used where higher strength and broader corrosion resistance are needed. Monel 400 also serves in many marine pump bodies.
Lower fluid velocity at bends and nozzles, fit erosion shields or wear pads, reduce entrained solids by filtration or desanding, and avoid turbulent geometry. For pumps, match the alloy to the medium using our offshore subsea and heat-exchanger tube guides.
As a dedicated nickel alloy manufacturer serving marine, oil & gas, chemical processing, power generation sectors, Hangbo Alloy Group supplies the grades discussed here across all standard product forms with full ASTM/ASME documentation and EN 10204 3.1 certification. Our material is specified for applications where corrosion resistance, high-temperature strength, and traceable quality are non-negotiable. See our production & testing facilities for more on how every heat is verified.