Underwater Testing of a Typical Ambient-Cure Epoxy Resin for Composite Repairs of Structural Piping and Vessels

The rehabilitation of piping and pressure vessels is well suited to the field application of carbon fiber/epoxy composites. Ambient-cure resins are ideal for repairs performed in atmospheric conditions. However, the ability for ambient-cure resins to set in alternative environments is critical to their proliferation. The goal in the described experimentation is to determine if one type of ambient-cure resin can be shown to be equally as effective when cured in an aqueous environment as in ambient atmosphere. This paper details the testing of an ambient-cure polymer matrix composite cured underwater. Experimentation consists of testing of panels cured in laboratory settings and burst hydro testing of repaired pipe components. Test coupons are fabricated and cured for 48 hours at ambient water temperatures. After curing, the coupons are tested for indicators of performance. Hardness, total strain, and tensile strength are measured and compared to ambient cure data for the same polymer composite. Elbow joints and tee joints containing a through wall defect are wrapped underwater using the same carbon fiber and epoxy resin used for the panels. A thermoplastic stretch film is applied immediately after installation underwater. The pipes are pressurized after curing and the burst pressure and wrap hardness are measured.