Where are corrosion coupons typically installed to monitor corrosion rate?

• A. In process control rooms.
• B. In access hatches for periodic inspection.
• C. In pipelines or vessels to monitor corrosion rate by weight loss.
• D. On the exterior of buildings.

Answer: (C)

Corrosion coupons are small metal samples placed in the actual service environment so their weight loss over time reflects the true corrosion rate. They must be exposed to the same fluids, temperature, and chemistry as the equipment being monitored. That exposure is best achieved inside pipelines or vessels where the corrosive conditions exist, providing an accurate measure of how fast material is corroding. Retrieving coupons can happen through access points, but the key is the coupon’s location in the process environment, not in control rooms or on exterior surfaces where the conditions differ.