In-service Corrosion Mapping — Challenges for the Chemical Industry

Turcu, Florin; Olympus Europa SE und Co KG; France

Turcu, F.; Olympus Europa; France
Jedamski, T.; Evonik Technology and Infrastructure GMBH; Germany
Treppmann, D.; Evonik Technology and Infrastructure GMBH; Germany

ID: ECNDT-0075-2018
Download: PDF
Session: Oil & Gas 3
Room: H2
Date: 2018-06-12
Time: 09:00 - 09:20

A typical chemical plant represents a challenge for asset condition monitoring with regards to wall thinning and corrosion. The conditions found in a chemical plant, such as elevated process temperatures, phase separations, flow dynamics, and variations in metallographic properties, make corrosion development and dynamics highly unpredictable.

Maintenance is usually performed at regular intervals within a limited time frame and includes both integrity assessment and repair. Interrupting normal activity for maintenance has huge costs to the plant operator, while the lack of predictability of the corrosion process can lead to wall thinning with consequences like vessel implosion or product leaking into the environment.

In-service inspection in these cases can help avoid accidents and minimize downtime for inspection. Industry requirements for in-service inspection include a high probability of detection (POD) of isolated pits, high sensitivity, and good near-surface resolution for the detection of severe wall-loss areas along with high-temperature capabilities. Some of these demands, including near-surface resolution and good sensitivity, can usually be accomplished by spot-testing with thickness gages while high POD can be achieved using ultrasonic phased array technology.

This paper will discuss general corrosion mapping challenges and focus on specific problems that arise during high-temperature inspection with phased array including suitable probes and wedges, coupling, and inspection methodology.