Investigating cathodic disbonding of external buried pipeline coatings in the presence of sulfate reducing bacteria

This paper presents work down to assess the effect of sulfate reducing bacteria (SRB) on cathodic disbonding of buried pipeline coatings. Cathodic disbonding tests were performed according to ASTM G8 and in a specific SRB culture media. Results revealed that bacterial growth affected by applied potential. Scanning electron microscopy (SEM) micrograph showed the presence of SRB under the cathodic protection conditions. The black color as a result of iron sulfide formation due to the SRB activity was clearly observed via a digital camera but visible pitting not detected on the surface. The radius of cathodic disbonding area was reduced in sterile culture medium compare to the ASTM G8 electrolyte. When SRB were added to the culture medium the average radius of cathodic disbonding area increased. Effect of exposure time on cathodic disbonded area was evaluated and results revealed increasing the average cathodic disbonding radius with the time.