Problem 7.5: A carbon steel coupon density 787 gcm surface
From Chapter 7 Problem Set. Level 2: Applied Thinking.
Question
A carbon steel coupon (density 7.87 g/cm³, surface area 3.5 in²) is exposed for 90 days. Initial weight: 12.4500 g. Final weight: 12.1500 g. Calculate the corrosion rate in MPY and classify it for a cooling tower.
Answer
Show answer
W = (12.4500 − 12.1500) × 1,000 = 300 mg. T = 90 × 24 = 2,160 hr. MPY = (534 × 300) / (7.87 × 3.5 × 2,160) = 160,200 / 59,497.2 = 2.69 MPY. Classification: “Very Good” for carbon steel in an open cooling tower (1–3 MPY range).