Corrosion Inspection in Preload

Case Study 4: Trident XII Mumbai High - Corrosion Inspection in Preload/ Ballast Tanks

Client: Our client is one of the largest offshore drilling contractors in the world. The company has the most versatile fleet of mobile offshore drilling units that help companies extract oil and natural gas.

Need: Preload tanks often suffer from corrosion and several other factors, which damage its surface resulting into accidents. Corrosion of the surface lowers the life of preload tanks. Hence, these should be inspected for corrosions regularly. Our clients identified the need for corrosion inspection in preload/ ballast tanks. The tanks form an important part of the rig's structure and are regulated by the respective classification societies. If they are not maintained to their best possible corrosion level, then the rig will have to go in for steel renewal, which will be additional cost for the company.

Challenge: The most important challenge was to find a service provider that would perform a rigorous and accurate inspection of the preload/ ballast tanks.


  • OCS Services being a significant player in the marine and offshore services arena, was chosen by the client, and was contracted to perform a corrosion inspection in preload/ ballast tanks in order to chalk out a scope for total corrosion maintenance in – situ.
  • The inspection was carried out by OCS on 16th and 17th September 2009.
  • The final inspection report was submitted to rig management for further recommendations.

Pictures of the corrosion inspection: