Composite Repair Principle
Pressure-pipe corrosion and mechanical damage reduce wall strength so the line cannot bear the design pressure. Under internal pressure, radial expansion produces circumferential tensile stress in the wall; thinning (e.g. corrosion pits) creates stress concentrations that exceed the material's tensile strength and trigger rupture and leakage.
Composite repair delivers three effects: lower the stress at the defect, lower the strain at the defect, and restore pressure capacity.
Galvanic Corrosion
A 0.1 mm epoxy coating between the carbon-fiber layer and the steel pipe insulates carbon from steel, eliminating galvanic corrosion of the host wall.
High-Temperature Service
For pipelines operating above 80 ℃, replace the standard epoxy with a high-temperature epoxy system. The composite cures and bonds while the bondline remains stable at sustained service temperature.
Repair Workflow
- Survey: pipe OD, wall thickness, grade, operating and design pressures, temperature, coating type, location, defect type and dimensions
- Design: per ISO 24817 or ASME PCC-2, calculate ply count and wrap length
- Surface prep to St3, solvent wipe and dry
- Apply repair compound to level the defect
- Wrap impregnated cloth layer by layer; roll out air
- Cure, recoat for corrosion protection, back-fill