PR-201-154500-R01 Composite Repair Load Transfer Study

The objective of this was to evaluate the effect of internal pipe pressure during installation of composite reinforcement systems. Historically, there has been little work evaluating the effect of internal pressure during installation, even though almost all composite installations on transmission pipelines are performed with internal pressure present in the pipe. The focus of this work was specifically limited to reinforcement of pipelines containing simulated corrosion anomalies. Five composite repair technologies from four composite manufacturers were evaluated in this study including:

· Western Specialties Ultra-Wrap (E-glass/epoxy)

· Western Specialties Composi-Sleeve (steel sleeve with E-glass overwrap)

· Citadel (carbon fiber/epoxy)

· Furmanite (carbon fiber/epoxy)

· NRI Steel Wrap (high-modulus carbon fiber/epoxy)

This study used full-scale testing to analyze the load transfer between the composite repair and pipe with internal pressure present during installation and whether this condition impacts the reinforcement provided by the composite repair system. The anomaly configuration evaluated in this study was a machined corrosion defect simulating 50% wall loss in 12.75-inch x 0.375-inch, Grade X42 pipe material. For safety, internal pressure during installation was limited to 50% SMYS (1,236 psig) for the corrosion samples. The composite repairs for the corrosion defects were installed at internal pressure levels of 0 psig, 25% SMYS (618 psig), and 50% SMYS (1,236 psig). Following repair installation, the reinforced full-scale samples were burst tested or pressure cycled to failure to evaluate the repair's performance.

The results and findings of this study provide valuable information to the pipeline industry for addressing an issue of significant interest for many years, and one not previously addressed in a comprehensive manner via full-scale testing.