Cathodic protection systems must be maintained

An incident of a full bore rupture of an oxygen transmission pipeline occurred in France. Prior to the rupture there were no indications of any leak
The investigation determined that the rupture was caused by the presence of an extended thinning zone of the pipe due to external corrosion. This corrosion was due to:

• The pipe was immersed under the groundwater table during a part of the year. Groundwater brings dissolved oxygen.
• Coating was disbanded, thus cathodic protection was inefficient in this zone (shielding effect).
• The groundwater was renewed by thermal convection in the disbanded area through coating faults, with draining of corrosion products. Thermal convection was due to temperature difference between soil and gas just after compressor discharge

Source: EIGA 2020: Day two recap https://www.gasworld.com/eiga-2020-day-two-recap/2018388.article#.XjPM6yilu6Y.twitter