Corrosion Rate (Mass Loss)
Calculate the corrosion rate by the mass-loss method, CR = 87.6 × W ÷ (D × A × t), from the mass loss W (mg), the material density D (g/cm³), the exposed area A (cm²) and the exposure time t (hours). The result, in mm/year, is the average speed at which the metal is consumed by corrosion — the key parameter to predict the service life of structures, piping and equipment and to set the corrosion allowance in design. Rates below 0.1 mm/year are usually acceptable. Enter the mass loss, density, area and time.
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Taxa de corrosão por perda de massa
O método de perda de massa (perda ao peso) é a forma mais antiga, simples e confiável de medir corrosão: pesa-se um corpo de prova limpo, expõe-se ao meio agressivo por um tempo conhecido, depois remove-se cuidadosamente os produtos de corrosão e pesa-se de novo. A diferença é a massa corroída. A taxa de corrosão converte essa perda numa velocidade de penetração uniforme: TC = 87,6 × W ÷ (D × A × t), com W em mg, a densidade D em g/cm³, a área exposta A em cm², o tempo t em horas e o resultado em mm/ano (a constante 87,6 faz a conversão de unidades). Expressar a corrosão como penetração por ano é o que permite ao engenheiro dimensionar: define-se uma sobreespessura de corrosão (corrosion allowance) que será consumida ao longo da vida prevista do equipamento. Como referência, taxas abaixo de ~0,1 mm/ano são geralmente consideradas de boa resistência; acima de ~1 mm/ano, o material é inadequado para a maioria das aplicações. Atenção: essa taxa pressupõe corrosão uniforme; formas localizadas (pite, frestas) podem perfurar muito mais rápido com perda de massa pequena. Informe a perda de massa, a densidade, a área e o tempo.
Related Tools
Thickness with Corrosion Allowance
Calculate the total thickness to specify for a pressure-vessel component including the corrosion allowance, t_total = t_calculated + CA, from the minimum pressure-calculated thickness t_calculated (mm) and the corrosion allowance CA (mm). The thickness from the ASME formulas is the MINIMUM needed to resist pressure — but the vessel will operate for DECADES, and corrosion (and erosion) will consume wall material over time. If the vessel were made exactly at the minimum thickness, the first corrosion would already leave it below safe. So a CORROSION ALLOWANCE (CA) is added — a 'sacrificial' over-thickness, typically 1.5 to 6 mm, sized for the expected corrosion rate times the design life (e.g., 0.1 mm/year × 25 years = 2.5 mm). Thus the thickness specified for fabrication is the structural minimum plus the corrosion allowance. Over life, inspection (by ultrasound) measures the REMAINING thickness; when corrosion consumes the whole allowance and the thickness approaches the structural minimum, the vessel must be repaired or retired. The corrosion allowance is like a 'life reserve' built into the wall. Enter the calculated thickness and the corrosion allowance.
Sacrificial Anode Life
Calculate the life of a sacrificial anode, life = (mass × capacity) ÷ (current × 8760), from the anode mass (kg), the material's current capacity (A·h/kg), the protection current drained (A) and the 8760 hours in a year. The result, in years, shows how long the anode (zinc, aluminium or magnesium) will provide protection before being consumed and needing replacement — essential in designing galvanic cathodic protection of tanks, pipelines and marine structures. Enter the mass, the material capacity and the current.
Corrosion Thickness Loss
Calculate the cumulative thickness lost to corrosion, δ = CR × t, multiplying the corrosion rate CR (mm/year) by the service time t (years). The result, in mm, is the depth of material consumed over the period — direct input to assess the integrity of piping, tanks and structures and to decide on inspection, repair or replacement. Compared with the corrosion allowance set in design, it shows how much of the margin is already used and estimates the component's remaining life. Enter the corrosion rate and the service time.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.