Steam Ship

Problem: A steam freighter – sailing the Pacific corridor - had experienced aggressive pitting and through wall corrosion of its steam condenser tubes, salt water intrusion impacted operating efficiency and reliability. The steam condenser was located in the bowels of the ship and many factors had to be evaluated as a condenser tube repair evolved. Among the priorities were the potential impact of ship maintenance and transport schedules, and the financial impact of non-routine maintenance.

Consultation: Curran International evaluated sample condenser tubes and found corrosion cavities containing crystalline chlorides, calcium and sulphides. Substantial pit fields were found surrounding multiple through-wall pits of the steam condenser tubes. Further evaluation was performed of the scaled areas, and active corrosion cells were found where scale was partially removed.

Solution: Working within the limited available schedule for ship maintenance, Curran International developed a project scope to clean existing scale and corrosion, and coat the full length ID of 20’ long steam condenser tubes. All aspects of coating were to be performed in-situ; containment during surface preparation and forced curing of the epoxy material were considered in advance of crew deployment.
Curran International has years of experience to clean condenser tube IDs and tubesheets to SSPC-SP5. A proprietary method was used to coat full length tubes with a thin film of epoxy, forcing the material into pitted cavities and sealing tubes. The duration from the project start to final cure was less than 9 days.

Results: When the steam condenser was returned to service the ship’s engineer reported a 25% improvement in “overboard” sea temperature ΔT, and an improvement in vacuum was realized. After a 12-day crossing it was noted “…the main condenser is tight….The boiler chlorides have not gone up at all…This will save us $$$ in the long run.”