Mitigating Sulphur-Induced Corrosion in RCC Structures: A Case Study of Sulphur Pit Rehabilitation (C2026-00245)

Ravindra Lanjewar, Somnath Sadhukhan

RCC sulphur pits in Sulphur Recovery Units are designed to store molten sulphur at around 140°C. However, exposure to aggressive sulphur compounds often leads to serious deterioration of concrete and embedded reinforcement, posing a recurring challenge across refineries globally. To address this, BPCL Mumbai Refinery undertook a comprehensive investigation and repair strategy to restore and enhance the durability of its sulphur pits.
Initial inspections revealed water seepage through acid-resistant brick joints, traced to groundwater ingress through the RCC. Upon removal of insulation and acid brick linings, extensive sulphur-induced damage was observed manifested by concrete softening, cracking, and reinforcement corrosion.
A detailed condition assessment was carried out using advanced NDT techniques including Ultrasonic Pulse Velocity, Ground Penetrating Radar, Rebound Hammer Test, Core Sampling, Petrographic Analysis, and Half-Cell Potential. The results confirmed widespread degradation.
Based on the findings, a targeted rehabilitation strategy was implemented, including sulphur attack mitigation, crack sealing, corrosion inhibition, structural strengthening, and application of protective coatings. This initiative not only restored the structural integrity of the sulphur pits but also significantly enhanced their long-term resistance to chemical attack. The case demonstrates the importance of early diagnosis and specialized repairs in extending the life of RCC structures in harsh environments.