There’s Gold in Those Damage Mechanism Reviews

Editor’s Note: This article is presented from a high level and is not all inclusive. It is meant to help those new to DMRs as a basis to start with justifications and a few helpful tips.

Introduction

I started my career in the mid-1970’s as a chemist.  Shortly thereafter I transferred to the corrosion/materials/inspection group because I would get to crawl through equipment; which sounded a lot more fun than working in a lab. I could get sweaty and dirty and wear cool gear, like parachute harnesses and full face respirators! Working in a large chemical plant in the mid-west, I was fortunate to join a corporation where a lot of importance was placed on inspection and corrosion and materials engineering as a constant collaboration. In fact, both disciplines, which can have a lot of knowledge overlap (i.e., corrosion/materials professionals and inspection professionals), entered vessels regularly. One prime reason for this was mentoring, and it was reciprocal.

When the corrosion/materials engineer entered the equipment with the inspector, he/she educated the inspector about damage mechanisms and how they look in the field. The inspection opportunity also provided quality time together where the inspector could ask the corrosion/materials engineer about various things like:

• What specific types of damage (e.g., chloride SCC, caustic SCC, matrix crazing of FRP, weld sensitization, creep, etc.) to expect in various pieces of equipment. If I have damage of concern but am unable to classify it, how can I know what is causing it and how quickly it will become a problem?
• Where in the unit and component (HAZ, weld, elbow, low flow area, straight run, 6 0’clock position, etc. and mid-wall, ID or OD or all, etc.) is the damage likely to occur?
• What type of morphology or shape (laminar, bulge, blister, planar crack, stepwise crack, stress-oriented crack, de-alloying sponge-like, pinholes, pits, etc.) can the damage exhibit?

Something I found quite valuable was the practice of increased mentoring from the highly experienced corrosion/materials engineer the week after the inspector returned from taking the NACE Basic Corrosion Course.  This reinforced the learning in the real world.  That paid off big for the inspector as it addressed any questions left and misunderstandings after/from the course. It was a start to an extremely valuable journey.

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