Analysis of a corrosion under insulation failure in a carbon steel refinery hydrocarbon line

• Failure of the pipe had occurred as a result of CUI, the rate of corrosion was consistent with published data.
• The wall thickness had been reduced to a level that would not support the internal pressure.
• The proximity of the pipe to the walkway bracket was not in compliance with published guidance.
• Water had entered the lagging through a breach in the jacketing/lagging made to accommodate a walkway support bracket.
• The investigation has focussed industry and regulator attention on the issues associated with lagged pipework and CUI.