| Date | January/February 2005 |
| Volume | 11 |
| Issue | 1 |
| Return to Journal Index | |
January/February 2005 Inspectioneering Journal Article Index
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January/February 2005 Inspectioneering JournalBy John Reynolds at Intertek
Amine cracking is a form of stress corrosion cracking, which is related to alkaline and carbonate stress corrosion cracking. Amine cracking is often intertwined with wet H2S and carbonate cracking, as amines, carbonates and wet sulfides often exist together in amine treating systems.
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January/February 2005 Inspectioneering JournalBy John Reynolds at Intertek
Corrosion fatigue is closely related to mechanical and vibration fatigue cracking, except that it is initiated and accelerated by a corrosion mechanism, especially one that gives rise to pitting, from which cracks often initiate. But that corrosion mechanism need not be very severe in order to give rise to corrosion fatigue. Probably the best known case of corrosion fatigue, in a lightly corrosive environment, stems from deaerators in boiler systems.
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January/February 2005 Inspectioneering JournalBy John Reynolds at Intertek
HTHA falls into multiple categories of corrosion mechanisms, including environmentally assisted cracking, hydrogen assisted cracking, and high temperature degradation. Sometimes HTHA is confused with low temperature hydrogen cracking mechanisms that result from hydrogen being driven into steels by aqueous corrosion reactions.
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January/February 2005 Inspectioneering JournalBy John Reynolds at IntertekHydrogen stress cracking occurs when corrosion from acids like wet hydrogen sulfide or hydrofluoric acid (HF) cause atomic hydrogen to penetrate hardened or higher strength steels and cause stress cracking.
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January/February 2005 Inspectioneering JournalBy John Reynolds at Intertek
Polythionic Acid Stress Corrosion Cracking (PASCC) is an affliction of many refineries processing sulfur containing feedstocks, and since that is the norm these days, most refiners reduce their susceptibility to PASCC by selecting resistant alloys orby neutralizing exposed surfaces during shutdowns.
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January/February 2005 Inspectioneering JournalBy Julian Speck at TWI Ltd., and Brigdet Hayes at TWI
The number of FFS assessments carried out by inspection engineers is expected to increase in the future, as operators "sweat" their ageing process equipment. The parameters required for assessments can be quite complex and interdependent. Therefore, a multidisciplinary peer review (involving stress analysts, NDE experts and materials engineers) is often necessary before acting on the findings of the even the most regular FFS assessment. Operators and inspection engineers using FFS assessments would do well to learn from previous failures. Author:
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January/February 2005 Inspectioneering JournalBy Hegeon Kwun at Southwest Research Institute, and Glenn Light at Southwest Research Institute
Nearly ten years ago the magnetostrictive sensor (MsS) technology was reported in this journal (July/August 1996 Issue, Volume 2 Issue 4) as a method to detect corrosion in insulated piping. At that time, the MsS Technology consisted primarily of the longitudinal guided wave mode introduced into the pipe with a coil wrapped around the steel pipe with a coil wrapped around the steel pipe and a number of large magnets setting up an axially oriented magnetic baising field in the area of the coil. The longitudinal mode worked well for dry, unfilled pipe. However, in liquid filled pipes, the longitudinal mode didn't work well because it interacts with the liquid, producing extraneous signals that, in turn, cause difficulty in analyzing data.
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January/February 2005 Inspectioneering JournalBy Bob Stakenborghs, P.E. at Evisive Inc.
Several years ago, a need was identified to develop an improved nondestructive inspection method to volumetrically inspect dielectric materials. Specifically, an inspection method for detecting defects in rubber expansion joints was needed to assist in preventing leeks in large electric power plant steam condensers. In response to this demand, a microwave based inspection technique was developed and patented by Evisive, Inc. Once the technique was developed and tested, it was found to be a powerful NDE technique that had uses for many dielectric materials, the technique can also be successfully used on composite materials containing conductive components but whose construction makes them overall nonconductors or bulk dielectrics, for example, carbon filter composites.
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