Testing of the applicability of corrosion monitoring techniques in various corrosive environments

U ovom diplomskom radu ispitivana je mogućnost primjene dvije tehnike korozijskog monitoringa, metodom korozijskih kupona i LPR metodom. Mediji u kojima su provođena ispitivanja metodom korozijskih kupona bili su: talog sirove nafte, sirova nafta, granica faza sirove nafte i plinovite faze iznad sirove nafte, te plinovita faza iznad sirove nafte. LPR metoda koja je primjenjiva u vodljivom mediju ispitana je u 3,5% otopini NaCl. U svim je medijima ispitano djelovanje tri vrste inhibitora označenih sa A, B i C dodanih u dvije koncentracije od kojih je jedna pogodna za kontinuirano, a druga za šaržno doziranje. LPR metodom simulirano je praćenje učinka dodavanja inhibitora u odzračenu otopinu 3,5% NaCl i efekt zadržavanja inhibitora na površini nakon prestanka doziranja. Eksperimenti su pokazali da tri inhibitora sa sličnom namjenom pokazuju znatne razlike u djelotvornosti ovisno o sustavu u kojem se primjenjuju. Dokazano je da su za primjenu u sustavima sa sirovom naftom u sve trifaze djelotvorni inhibitori A i B i to posebice u niskim koncentracijama pogodnim za šaržno doziranje. Inhibitori A i C pokazali su visoku djelotvornost u 3,5% otopini NaCl te vrlo visoku djelotvornost i nakon prestanka doziranja. Zaključak rada je da se za potrebe korozijskog monitoringa trebaju odrediti uvjeti sustava, kao i promjene koje se dešavaju unutar sustava i tome prilagoditi metode mjerenja. Istraživanje je pokazalo i značaj preliminarne laboratorijske ocjene inhibitora prije upotrebe u realnom sustavu, čak i kada je riječ o izboru između proizvoda istog proizvođača, jer neodgovarajući odabir može rezultirati nepostizanjem maksimuma djelotvornosti koja osim o vrsti inhibitora ovisi i o karakteristikama sustava u kojem se inhibitor želi primijeniti.In this work the applicability of two corrosion monitoring methods, weight loss method, and LPR method, was tested. Mediums in which testings were conducted are: crude oil sediment, crude oil, crude oil and vapor phase boundary and vapor phase. LPR method that is applicable in conducting medium was tested in 3.5% NaCl solution. Activity of three inhibitors, marked as A, B and C, added in the concentrations of which one was suitable for continuous dosage and other one for batch dosage was tested. Performance of added inhibitors in deaired solution of 3.5% NaCl and surface retention efect after dosage were monitored with LPR method. Experiments showed that three inhibitors with similar applicability show significant differences in effectiveness depending on the system they were applied in. It was proven that in the systems with crude oil in all three phases inhibitors A and B were effective, especially in low concentrations suitable for batch dosing. Inhibitors A and C have shown high effectiveness during and after dosing in 3.5% NaCl solution. Conclusion of this work is that for corrosion monitoring to be effective one should need to determine system conditions, as well as changes that are taking place in the system and adjust measurements as such. Research has shown significant preliminary laboratory evaluation of inhibitors, even when they are from the same manufacturer, because inadequate choice can result in failure to reach maximum efficiency of inhibitor, which depends not only on type of inhibitor but the characteristics of system in which inhibitor is applied to