1 / 14

FPSO Research Forum Forum Discussion

FPSO Research Forum Forum Discussion. OTRC, College Station USA April 2003. Corrosion issues and challenges. Optimal vs. minimal requirements. Corrosion protection Corrosion margins Coating types Maintenance, repair & planning strategies Repair or replace? Now or later?

reina
Download Presentation

FPSO Research Forum Forum Discussion

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. FPSO Research ForumForum Discussion OTRC, College Station USA April 2003

  2. Corrosion issues and challenges Optimal vs. minimal requirements • Corrosion protection • Corrosion margins • Coating types • Maintenance, repair & planning strategies • Repair or replace? • Now or later? • Owner/Operator vs. Class vs. Regulatory • Balancing economic vs. safety vs. environment • Different environmental & operating conditions DNV Houston background

  3. Corrosion protection

  4. Corrosion Protection • Coating: • Critical but expensive: • Application (fabrication schedule impact) • Inspection (construction and in-service) • Class focus during operation but not (normally) NB • Note: Cannot coat steel with steel • Anodes • Significant weight and cost. Can we optimize? • Impressed current Which provides the best economic return? CAPEX vs. OPEX DNV Houston background

  5. Maintenance, repair & planning strategies

  6. Corrosion impact • Leaking: • Gaseous vapors  explosion • Pollution • Fatigue: • Lives halved in corrosive environment(corrosion is located at HS) • General corrosion has less impact • Yield strength: • typically small impact Typically local impact only DNV Houston background

  7. Corrosion impact - Buckling tk = 3.0mm (ballast tank) = 14% of actual plate thickness 2 – 3mm reduction in main deck plate will reduce buckling capacity 10-15% DNV Houston background

  8. DNV’s acceptance criteria options Thickness measurements Pass/fail No action • Repair to As-built • Easy to determine • Quick (WSD) • Repair to WWT • Requires simple calc • Medium time (WSD) • Repair to Site • Rigorous calc • Time consuming (LRFD) Which is the cost effective solution? DNV Houston background

  9. Import Thickness Measurements Thickness Measurements Color Coded Model DNV Houston background

  10. Compare against requirements “As-built” or “As Measured” Plot Thickness Distribution Curves (S-Curves)(Tanker Structure Cooperative Forum & DNV) Prediction of Steel Diminution • Generate repair specifications • Establish volumes, weights, areas & staging • Store all collected information for analysis and later re-use DNV Houston background

  11. Different environmental & operating conditions

  12. Different environmental & operating conditions 90% of future FPSOs are forecast to be in non-harsh environments but… What is a "harsh" environment for corrosion? DNV Houston background

  13. Questions for discussion • Should we focus on: • Corrosion protection systems? (Preventative), or • Monitoring, recording & decision making systems? (Reactive) • What information do we need: • Corrosion margins • Corrosion rates • How do we address and rank the variables? • Cargo type, temperature, steel type, etc. • How do we incorporate into the Life Cycle: • Design • Fabrication inspection • Inspection and Maintenance Planning • Repair decisions • Feedback / Industry updates (ownership) DNV Houston background

  14. Reference DNV Guidelines • Classification Notes 72.1 Allowable Thickness Diminution for Hull Structure, November 2000(currently being updated) • RP Corrosion Protection of Ships, 2000 • Classification Notes 33.1, Corrosion Prevention of Tanks and Holds, July 1999. DNV Houston background

More Related