Water Chemistry-Driven Degradation of Cement-Mortar-Lined Desalinated Water Pipelines

This article investigates water chemistry-driven degradation mechanisms in cement-mortar-lined (CML) steel pipelines conveying desalinated water following the transition from multi-stage flash to seawater reverse osmosis (SWRO) desalination. Field case histories demonstrate that destabilized post-treatment chemistry—characterized by low alkalinity, insufficient calcium hardness, predominantly negative or near-zero Langelier Saturation Index, and elevated chloride concentrations—promotes calcium leaching, loss of cement alkalinity, and increased CML permeability. These processes compromise steel passivation and create aggressive crevice conditions at the CML/steel interface, resulting in localized corrosion, volumetric expansion of corrosion products, debonding, and lining delamination. The findings clearly indicate that controlled water stabilization is a critical prerequisite for the long-term integrity and reliability of CML-lined transmission pipelines conveying SWRO-produced water.1