Cover: The use of preservation treatments for hydrostatic test waters is a crucial practice to provide protection of subsea pipelines against corrosion. The potential effects of seawater ingress into 316L lined pipes filled with treated seawater during subsea tie-in operations on corrosion performance were investigated. Fluorescence imaging shows microorganisms attached to 316L coupons exposed to treated seawater in the event of oxygen ingress into the system. 3D optical surface images show typical pits found on 316L exposed to treated seawater in the presence of high concentrations of oxygen. Pit profiles were determined from optical microscopy to measure pit depths. The entry of seawater into the system can introduce aggressive species such as oxygen which is shown to have a negative impact on the biocidal and oxygen scavenging efficiency of the chemical treatments and a detrimental effect on pitting corrosion.
More detailed information can be found in: L. L. Machuca, L. Murray, R. Gubner, S. I. Bailey, Evaluation of the effects of seawater ingress into 316L lined pipes on corrosion performance, Materials and Corrosion 2014, 65, 8.