Materials Performance

JUN 2019

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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52 JUNE 2019 W W W.MATERIALSPERFORMANCE.COM CM CORROSION MANAGEMENT T This article is meant to highlight the impact of routine surrounding con- ditions as well as unusual neigh- borhood events on the integrity of process equipment and piping. We cannot disregard the role of a neigh- borhood's influence on the probabil- ity of material damage mechanisms, failure modes, and applicable con- sequences. Further, it discloses a real incident of corrosion under insulation: highlighting the potential mitigations and viable preventive actions. Finally, it presents a neighborhood-influenced model of a fired heater (reformer) with sensitivity analysis for various damage mechanisms along with their prob- ability and consequences. To date, environment-assisted damage mechanisms have been studied in various detail, in terms of their mitigation, suscep- tibility, monitoring, and critical factors that can trigger and drive these mechanisms. The damage mechanisms in this category mainly include environmentally assisted cracking and environmental corrosion that subsequ ently re sult in various fai lure modes, such as pitting, rupture, cracks, etc. O n th e o th er h a n d , c er t ai n d a m a ge s happen due to neighborhood conditions and may or may not require conditions like those reported in the previously mentioned environment-assisted damages. Modern inspection practices for process equipment, such as heat exchangers, tanks, vessels, and piping, involve the consider- ation of applicable material damage mecha- nisms. 1 The decision-making is dependent on the assessment of applicable failure modes, such as loss of thickness, pitting, localized corrosion, rupture, etc. Moreover, risk-based inspection (RBI) programs have recently emerged, broadening the canvas of inspections to the applicable risks and esti- mation of associated probabilities as well as impacts. 2-3 Case Study An oil refining unit was ready for start- up after successful maintenance turn- around that involved inspections, repairs, and box up works. The turnaround work was completed in accordance with antici- pated checklists and inspection plans. Dur- ing start-up, an 8-in (23-mm) low carbon steel A106 Grade B (UNS K03006) insulated line containing finished hydrocarbon prod- uct showed evidence of leakage. The line was covered with glass wool insulation and cladding to retain the heat of the hydrocar- bon ser vice. The hydrocarbon product leaked out of the pipe, seeping out of the insulation and reached the outer cladding surface. Due to high flammability and criti- cality of the line toward the start-up mile- stone of the refinery, the whole plant was depressurized to inspect and repair the leakage issue. Insulation was stripped off, followed by inspection of the pipe loop PHORGOTTEN PHENOMENON Neighborhood—An Influential Factor for Material Damages Ah MA d r A z A k h A n r A n A A nd z oheir F A rh A t, Dalhousie University, Halifax, Nova Scotia Canada

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