ABSTRACT Systematic internal corrosion monitoring of process vessels and associated piping in operating plants as well as fluid analysis from appropriate locations can provide valuable insight into the corrosion status of the equipment and components. At the Kuwait Oil Company (KOC), internal corrosion monitoring activities are carried out in all their facilities which consists of 22 crude processing plants (or gathering centers), 4 gas processing plants (or booster stations); 2 effluent water disposal plants, seawater treatment and injection plant, a vast network of pipelines carrying different products, as well as early production facilities.
Internal corrosion monitoring is conducted with online monitoring equipment that include corrosion coupons, corrosion probes, bio probes, hydrogen patch probes etc. installed at key locations. Fluid analyses activities are also carried out for different processes to determine various key parameters such as pH, conductivity, total dissolved solids (TDS), total hardness, dissolved oxygen content, hydrogen sulfide (H2S) and carbon dioxide (CO2) concentrations, corrosion and scale inhibitor residuals, Iron (Fe) content (total and dissolved), bacterial activity, etc. Corrosion data and fluid characteristics are analyzed for trends and appropriate recommendations issued to asset owners for corrective, preventive measures to mitigate corrosion and also to advise Inspection requirements based on findings.
This paper highlights two cases in KOC, one involving a low pressure (LP) wet separator and another involving an inlet piping to a desalter in two different facilities, where Internal corrosion monitoring results were utilized to undertake pre-emptive non-destructive testing (NDT) inspections using ultrasonic scanning by Automated Ultra-sonic Test (AUT) method and thickness verification of susceptible portions of equipment, nozzles and piping circuits followed by physical verification. In both cases potential disasters and unscheduled plant shutdowns were avoided since in both cases the equipment in question were found to have suffered severe corrosion with wall thickness losses exceeding 50-75%. In both cases the corroded items were replaced before major problems occurred.