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What are the majorly used materials to perform non metallic composite repairs on piping systems?\nShould there be some qualification done in selecting the one applicable as per site conditions?

ISO 24817 is the guide to provide you with all the details. According to this standard, repair systems are applied to restore structural integrity including external or internal defects or strengthening or stiffening.
Qualifications details could be easily seen within this. On materials front you would find repair classification.

A standard composite repair system is a multi-layer assembly composed of three core material categories:

Reinforcing Fibers (Structural Backbone):
Carbon Fiber: Known for its exceptional tensile strength, high stiffness, and superior resistance to fatigue and creep. It is typically chosen for high-pressure, high-stress, or critical hydrocarbon pipelines.
Glass Fiber (E-Glass or S-Glass): More cost-effective, offering high elongation properties and good electrical insulation (which prevents galvanic corrosion when wrapping steel lines). Widely used for moderate-pressure or utility piping.

Polymer Matrix Resins:
Two-Component Epoxy Resins: The industry standard due to their minimal shrinkage, excellent adhesive bond strength to metals, and broad chemical resistance.
Vinyl Ester / Polyurethane Resins: Utilized in specific applications requiring rapid curing or specialized chemical resistance profiles.

Auxiliary Interfacing Materials:
Adhesive Primers: Applied directly to the prepared metal surface to seal the substrate and maximize interfacial bond strength.
Epoxy Putties / Fillers: High-compressive-strength paste materials used to rebuild lost wall geometry, fill pitting, and smooth out complex surface profiles (such as weld seams, transitions, or pits) before applying the wrap.