Materials Performance

DEC 2018

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 DECEMBER 2018 W W W.MATERIALSPERFORMANCE.COM CM CORROSION MANAGEMENT will be set to zero) through the electrode. For the no-deposit and sand deposit tests, the maximum localized corrosion rate was found to be lower than 3 mpy and no UDC was observed on the electrode's surface. For the field deposit, a high localized corro- sion rate was measured, between 365 to 1,780 mpy. These results were also confirmed with maximum localized depth measurements (Figure 5). The maximum localized depth FIGURE 2 CMAS, average general corrosion rates measured against immersion time under no deposit and •eld sludge deposits. The synthesis brine was purged continuously with H 2 S/CO 2 gas at 48 °C. FIGURE 3 Photos of exposed CMAS probe and weight-loss coupons with corrosion rates measured by weight-loss coupons along with multi-electrode array experiments under no deposit and •eld sludge deposit. The synthesis brine was purged continuously with H 2 S/CO 2 gas at 48 °C. measured in all tests increased with increas- ing immersion time; however, the corrosion rate measured under field deposit exhibited the greatest depth, which is ~14 µm. The maximum localized depths measured for the no deposit and sand deposit were 9 and 4 µm, respectively. The results revealed that localized and general corrosion rates mea- sured using the CMAS instrument are in good agreement with weight-loss coupons (Figure 3). Scanning electron microscopy (SEM) images were taken on corroded cou- pons (Figure 6). It is worth noting that only the coupons under the field sludge deposit were severely corroded and localized corro- sion was seen clearly on the coupon's sur- face. This indicates that the high localized corrosion rate had taken place on this cou- pon, which agrees with the degree of corro- sion attack measured by the CMAS, as pre- viously shown in Figure 2. The SEM results also showed that no UDC was observed on coupons tested under the sand deposit, which confirms the earlier assumption that sand inhibits CS with the presence of a sour environment. Conclusions The corrosion behavior of CS under dif- ferent deposits was thoroughly studied in a sour environment using CMAS and weight- loss coupons. It was noticed that when actual field sludge was deposited on the CS surface, significant general and localized corrosion rates were observed. For the sand deposit test, the general and localized cor- rosion rates were found to be very low, even lower than the no deposit test. No UDC was observed on coupons tested under the sand deposit, meaning that sand inhibits corro- sion of CS in a sour environment. Acknowledgment The authors wish to acknowledge Saudi Aramco management for the financial sup- port of this work and for their kind permis- sion to publish the results of this study. References 1 J.A.M. de Reus, E.L.J.A. Hendriksen, M.E. Wilms, et al., "Test Methodologies and Field Verification of Corrosion Inhibitors to Address Under Deposit Corrosion in Oil and Gas Production Systems," CORROSION 2005, paper no. 05288 (Houston, TX: NACE International, 2005). 2 J. March, J.W. Palmer, R.C. Newman, "Evaluation of Inhibitor Per formance for Prot ection against Localized Corrosion," CORROSION 2002, paper no. 02288 (Houston, TX: NACE, 2002). 3 A. Turnbull, D. Coleman, A.J. Griffiths, "Effective- ness of Corrosion Inhibitors in Retarding Propaga- tion of Localized Corrosion," CORROSION 2002, paper no. 02274 (Houston, TX: NACE, 2002). 4 C.M. Menedez, V. Jovancicevic, "Novel Approach for Assessing Inhibitors Performance Against Local- ized Corrosion," CORROSION 2003, paper no. 03374 (Houston, TX: NACE, 2003). 5 M.M. Salama, "Inf luence of Sand Production on Design and Operations of Piping Systems," CORRO- SION 2000, paper no. 00080 (Houston, TX: NACE, 2000). 6 Nayef M. Alanazi, A.M. El-Sherik, A.H. Rasheed, et al ., "Corrosion of Pipeline Steel X-60 Under Field-collected Sludge Deposit in a Simulated Sour Environment, Corrosion 71 (2015): pp. 305-315.

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