Materials Performance

AUG 2017

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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62 AUGUST 2017 MATERIALS PERFORMANCE NACE INTERNATIONAL: VOL. 56, NO. 8 CM CORROSION MANAGEMENT • Enhanced control of corrosive agents' concentration (or residual concen- tration), such as oxygen, carbon diox- ide (CO 2 ), and hydrogen sulfide (H 2 S) • Improved water control for oil sys- tems and dehydration processes for gas systems Thus, a remedial action is intended to either reduce the incumbent corrosion rate, diminish the environment's corrosiv- ity, or both . In any case, the time until component failure can be significantly prolonged depending on the effectiveness of the applied action(s). Therefore, the o c cur ren c e of fai lure (s) c o ul d b e si g - nificantly delayed in some cases until the next planned operational shutdown or e ven to th e end of an asset 's design ed operational life. Carrying Out a Repair/ Replacement Action In some cases, the item under inspec- tion/assessment is deteriorating so fast or has degraded to the point that it is too late for effective remedial action. Consequently, a repair or replacement has to be planned and implemented. B e f o re p r o c e e d i n g w i t h a ny su c h actions, howe ver, a f itn ess-for -ser vice assessment is necessary to determine how much longer (if at all) the component can operate before it fails. The resulting time- lin e provides a deadlin e for repair or replacement. This is of paramount impor- tance; once the operator or the integrity management contractor has determined that a repair or replacement is needed, repeatedly postponing implementation (most commonly for operational reasons) can actually lead to component failure or leakage. Ideally, when it has been determined that a repair/replacement is required, that action should be planned to coincide with the next scheduled operational shutdown. Such an approach will eliminate all the per- tinent post-failure costs 1 (Figure 2). How- ever, if the component is not considered fit-for-service or expected to remain fit-for- service until the scheduled shutdown, then earlier action to carry out the necessary remedial work is required. FIGURE 2 Corrosion cost categorization, using the failure time as a chronological reference point for classifying different corrosion cost types. 1 FIGURE 3 Critical factors affecting the corrosion failure preemption process. replacement action; or both successively. Both action types are explained in detail: Implementing a Remedial Action Sometimes when the prediction com- ponent has been carried out, there is an indication of areas, locations, or features that are going to develop into a failure in the foreseeable future due to the high incumbent corrosion rates or the high fluid corrosivity. The occurrence of these failures could be significantly delayed by markedly reducing the corrosion rate or reducing the fluid corrosivity. Examples include: • Improved chemical treatment with corrosion inhibitor(s) • Enhanced control of process param- eters such as pH, temperature, f low rate, and pressure • Improved or more regular cleaning/ pigging of a pipeline

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