Ballast Line Repair

Overview

Internal corrosion was found in a ballast line in the cargo tank of an FPSO. This ballast line required an in service repair without the use of hot work. As the internal rate of corrosion was high, the repair was designed to accommodate future corrosion which may lead to a through wall defect.

Technowrap™ composite repairs are the only class approved composite repair by both ABS and Lloyds.

Scope

The line had the following specifications:

Structure	Ballast Line
Surface Preparation	Sa 2.5
Class Approval	ABS & Lloyds
Design Pressure	600 kPa
Design Temperature	300C
Application Temperature	100C
Design Life	10 years
Wrap Length	6 meters
Pipe Diameter	550mm
Geometry	Wrap onto bulkhead - vacuum bag consolidation
Corrosion Type	Internal
Defect Details	50 mm circumferential (through-wall)

Solution

The solution to this project was:

• Technowrap 2K™ HA system used
• Vacuum bag consolidation used at the complicated bulk head region geometry
• Detailed QA/QC procedures captured repair details for future reference

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Benefits

The benefits of executing this solution were:

• Lines remained live during repair, maintaining production at the FPSO
• No hot works required in extremely sensitive operating environment
• Repair effectively installed a new glass reinforced epoxy pipe over the existing pipe work
• Repair allowed for future internal corrosion to cause a 50mm circumferential through wall defect (full section loss over 50mm of pipework)
• The Applicator's extensive vacuum bagging experience ensured appropriate consolidation of the wrap over the complex geometry of the repair
• Technowrap 2K™ HA system provides temperature resistance up to 90°C and excellent chemical resistance to immersion in a wide variety of hydrocarbons