Internal corrosion of carbon steel piping in hot aquifers service

Hemijska Industrija

关键词: Internal corrosion;    carbon steel;    hot aquifers;    corrosion models;    inhibitors;    weight-loss coupons;   

DOI  :  10.2298/HEMIND110209023S

来源: DOAJ

【 摘 要 】

Internal corrosion of carbon steel pipelines is a major problem encounteredin water service. In terms of prediction of the remaining lifetime for waterpipelines based on the corrosion allowance, the three main approaches arecorrosion modelling, corrosion inhibitor availability, and corrosionmonitoring. In this study we used two theoretical corrosion models, CASSANDRAand NORSOK M-506 of quite different origin in order to predict uniformcorrosivity of hot aquifers in eight different pipelines. Because of thevarying calculation criteria for the different models, these can give verydifferent corrosion rate predictions for the same data input. This isespecially true under conditions where the formation of protective films mayoccur, such as at elevated temperatures. The evaluation of models wasconducted by comparison using weight-loss coupons and three corrosioninhibitors were obtained from commercial suppliers. The tests were performedduring the 60-day period. Even though inhibitors’ efficiencies of 98% hadbeen achieved in laboratory testing, inhibitors’ availabilities of 85% havebeen used due to logistics problems and other issues. The results, given inmmpy, i.e. millimeter per year, are very consistent with NORSOK M-506prediction. This is presumably because the model considers the effect of theformation of a passive iron carbonate film at temperatures above 80 °C andsignificant reduction in corrosion rate. Corrosion inhibitor A showed abetter performance than inhibitors B and C in all cases but the targetcorrosion rates of less than 0.1 mmpy were achieved for all inhibitors. Thechemical type of corrosion inhibitor A is based on quaternary amines mixedwith methanol, isopropyl alcohol, xylene and ethylbenzene. Based on theobtained results the carbon steel lifetime of 30 years, provided properinhibitors are present and 3mm corrosion allowance, can be achieved for hotaquifers service with presented water compositions.

【 授权许可】

Unknown