Load-Dependent Performance of Repair Techniques for Corrosion-Induced Pinhole Defects in Agricultural Pipelines

Area of Science:

• Materials Science
• Civil Engineering
• Agricultural Engineering

Background:

• Agricultural steel pipelines are vital for irrigation systems but susceptible to corrosion-induced pinholes.
• These defects create stress concentrations, compromising structural integrity and necessitating effective repair strategies.

Purpose of the Study:

• To experimentally evaluate the performance of three repair techniques (hinge clamp, GFRP sleeve, overlay welding) for corroded steel pipelines.
• To assess repair effectiveness under different loading conditions (bending, tension) and damage severities (6%, 10% circumferential).

Main Methods:

• Simulated pinhole defects were introduced into steel pipes.
• Three repair methods were applied: multi-joint hinge clamp, GFRP composite sleeve, and overlay welding.
• Pipes underwent four-point bending and uniaxial tensile tests to mimic in-situ loads.

Main Results:

• Repair effectiveness varied significantly with loading mode and damage severity.
• All repairs restored bending capacity at 6% damage; GFRP sleeve was most effective.
• Overlay welding consistently provided substantial structural restoration, especially under tensile loading.
• Confinement-based repairs showed reduced efficacy beyond 6% damage, particularly under tension.

Conclusions:

• Pipeline repair performance is load-dependent and cannot be solely evaluated by bending tests.
• Overlay welding is a robust repair method, effectively mitigating stress concentrations.
• Load-specific and damage-severity-aware rehabilitation strategies are crucial for buried pipelines.