Bis-phenol A Formaldehyde Phenolic Epoxy Resin Internal Coating Used for Drill Pipes

Electrochemical impedance spectroscopy(EIS), scanning electron microscopy(SEM) and autoclave experiment were used to study the failure law of of bis-phenol A formaldehyde phenolic epoxy resin coating on pipeline steel N80 at different temperatures. The specimens were immersed in 3.5% (mass fraction) NaCl solution saturated with hydrogen sulfide and carbon dioxide(H2S/CO2). The EIS shows that with increasing temperature(50 ℃, 70 ℃ and 90 ℃) , the coating failure was slowed down. After 16 hours autoclave experiment, the apparance of the coating was normal(without blistering, cracking and significant change in surface color) and the coating was well adhered; The SEM results were in agrement with the EIS results.