Evaluation of Coatings Suitability for Buried SS316L Pipelines

Six polymeric coatings viz 3LPE, 3p/2p CAT, PU, VE, LE, and HSS have been selected, and each type of coating has been applied separately on SS316L pipe external surface. The test samples were subjected to Specific Electrical Insulation Resistance (SEIR) test in 0.1 mol/liter of NaCl solution and the Electrochemical Impedance Spectroscopy (EIS) test in 3.5 % NaCl solution. After completion of the tests, SEIR values of PU, 3LPE, and LE are found to be about 2.5×10^9, 8.9×10^8 , and 3.9×10^8 ohm.m² , respectively. In contrast, the electrochemical impedance values at low frequencies (100 mHz) of 3LPE, 3p/2p CAT, and HSS are found to be about 7.9×10^11, 5.4×10^11, and 4.5×1011 ohm.cm2 , respectively. The experimental results are analyzed, and the ranking of coatings has been made based on each test s performance. The overall ranking of coatings is evaluated for the determination of the suitability of the coating for buried SS316L pipelines in the petroleum, petrochemical, and natural gas industries.