Development of an effective method for internal pipeline corrosion control in the presence of CO2

Abstract

This paper reports on progress in developing an effective method for internal pipeline corrosion control in the presence of CO2. The inhibition effect of talloil diethylenetriamine imidazoline (TOFA/DETA imidazoline) on corrosion of mild steel API X65 in CO2-saturated 3 wt. % NaCl solution was investigated by: linear polarization resistance (LPR), potentiodynamic sweep (PDS), electrical resistance (ER) measurements, and atomic force microscopy (AFM). Novel top-of-the-line corrosion (TLC) mitigation method was verified in an innovative glass cell set-up and in a large scale flow loop. It was demonstrated that TOFA/DETA imidazoline can successfully protect the mild steel surface from corrosion in CO2-saturated 3 wt. % NaCl with the inhibition efficiency up to 92%. The TLC rate of mild steel, as measured in the vapor phase using the ER probe, was reduced effectively by periodic treatment by the foam containing TOFA/DETA imidazoline corrosion inhibitor in both glass cell and the large scale flow loop. The corrosion inhibition efficiency was calculated to be higher than 90 % and the inhibition effect lasted up to 50 h.

U ovom radu je dat pregled dosadašnjih rezultata razvijanja efikasne metode zaštite cevovoda od unutrašnje korozije u prisustvu CO2. Efikasnost organskog inhibitora, imidazolinskog derivata smeše viših masnih kiselina i dietilentriamina, TOFA/DETA imidazolina za zaštitu niskougljeničnog čelika API X65 od korozije u 3 mas. % NaCl rastvoru zasićenom sa CO2 ispitivan je primenom metode linearne polarizacione otpornosti, metode polarizacione krive, metode određivanja gubitka mase na osnovu električne otpornosti, metode mikroskopije atomskih sila. Nova metoda zaštite od korozije u uslovima kondenzacije je ispitivana u staklenoj ćeliji kao i u sistemu sa višefaznim tokom fluida, posebno konstruisanom za ispitivanje uticaja operativnih parametara na koroziju čelika u uslovima kondenzacije. Na osnovu dobijenih rezultata merenja vršenih u tečnoj fazi potvrđeno je da je inhibitor TOFA/DETA imidazolin dobar i efikasan inhibitor za koroziju niskougljeničnog čelika u rastvoru 3 mas. % NaCl zasićenom sa CO2 uz izmerenu vrednost efikasnosti inhibicije preko 92%. Pena sa TOFA/DETA imidazolinom efikasno smanjuje brzinu korozije čelika u gasovitoj fazi uz efikasnost inhibicije od oko 90 % i vreme trajanja izvedene zaštite od korozije do 50 h.