Integrity issue

The weld on a 14 inch weld neck flange from a hydrocarbon cargo line on a FPSO off the west coast of Africa was suffering from preferential internal corrosion. It was proposed to use a Futurewrap composite repair to reinstate the strength and seal the potential threat of a through wall defect. 

Design 

The design of the Futurewrap repair was according to ISO 24817. The design approach was to strengthen and locally leak seal. The design parameters were; internal pressure 2 bar, temperature 400C, design lifetime 3 years. The repair design resulted in a thickness of 5 mm (6 layers) of Futurewrap Glass/LT composite repair with an axial length of 2000 mm.

Installation

The installation steps are shown in the photographs. The potential threat of a through wall defect was dealt with by installing a clamp over the weld. The clamp and flange were then profiled with filler, followed by application of the 6 layers of Futurewrap Glass/LT repair. Full QA/QC measurements were made to demonstrate that the Futurewrap repair was applied in accordance with ISO 24817. 

Summary

A 14 cargo line suffering internal corrosion at a weld neck flange was repaired using a Futurewrap Glass/LT composite repair.  The repair was completed within 5 days allowing the pipework to be returned to its original integrity.