Corrpro Implements In-Situ Pipeline Repairs in Hawaii

In early 1996, Corrpro completed coating, depth-of-cover, and GPS surveys for a Hawaiian pipeline operator. The pipeline operator wanted to obtain a general coating condition report for his fuel transfer pipeline system, with GPS coordinates of the lines for updating existing company mapping records. The existing transfer system, which consisted of four separate pipelines, had no history of leak failure. The cathodic protection system had been routinely surveyed by recording "On" potentials only. During the Corrpro C-Scan, "Over-the-Line" survey, several suspect coating areas were reported and some low cathodic protection potentials were noted during detailed "On/Off" surveys. Three of the worst areas were selected for excavation to correlate survey results and confirm actual line conditions.

The correlation excavations were accomplished by Corrpro Canada's Pipeline Services group. The team's objectives were to excavate the selected sites to determine if the low cathodic protection potential levels and suspect problem coating areas had resulted in corrosion pitting and, if so, to what extent. The initial excavations discovered a corrosive mixture of native soils, brackish water, and hydrocarbons (from an undetermined source) which enveloped the lines and had caused serious and extensive degradation to the external pipe coatings. Further investigation unveiled approximately 1000 feet of affected pipeline within the right-of-way. Corrpro's Pipeline Integrity team and the pipeline operator discussed the discovery and drafted an action plan to remedy the situation. The plan consisted of excavating the entire affected area, treating contaminated soil, removing the degenerated coating, hydro testing the lines, assessing the pitting and implementing appropriate repairs as necessary. A separate engineering study was also conducted by Corrpro to determine what external protection method would be most effective in this environment.

The Integrity Program ultimately resulted in successful hydro tests in each of the four pipeline segments. Several sizable corrosion pits and some mill defects were observed and noted after thorough line cleaning was completed. Anomalies within the predetermined client safety margin were reinforced with Corrpro's ProWrapT , a fiberglass composite, pipe reinforcement tape system.

It is noteworthy to acknowledge that ProWrapT reinforcement material is easily applied in wet or dry environments and is resistant to a vast array of chemical products. It is also considered to be a permanent repair method when applied according to the manufacturer's specification. Pipeline anomalies repaired with ProWrapT have been tested and proven to perform above standard pipe yield specifications.

Due to the harsh environment, Corrpro recommended that the operator install an enhanced cathodic protection solution. After the system was installed and the lines were lowered into the ditch, the right-of-way was cleaned to original condition and the cathodic protection system was energized. The pipeline operator is currently evaluating the need for an "in-line" inspection of the entire pipeline system.