Power Generation Case Study: Feasibility of Carbon Fiber and Alternate Repair Methods

Abstract

coal fired Power Generation Facility in the Baltimore relies on a large diameter circulation pipeline stretching half a mile from the boiler to the cooling towers. The line was constructed with mainly 102 Prestressed Concrete Cylinder Pipe (PCCP) containing problematic class IV wire. The plant started experiencing breaks in the nineties with costly repairs and even more costly lost revenue. The plant engineers then devised a proactive inspection and preventive repair program that managed to mitigate breaks but still forced longer outages and costly repairs using post-tensioning loops or concrete encasements. In 2007, a solution was presented which included the use of Fiber Reinforced Polymer, or Fiber Wrap. The advanced composite system was applied on the interior of the pipelines at this facility first in the fall of 2007. After that first successful experience, internal repairs utilizing Fiber Wrap became common practice for dealing with distressed pipes as they were detected year after year. The Power Generation facility went beyond the year to year approach and in 2009 decided to strengthen the entire length under the switchyard to completely eliminate the chance that a break or a leak would shut down the entire plant. The scope of work for this Project, completed in early 2010, was 55 sections, 20 ft long and 102 diameter to complete in 30 days. The project included a very short window for surface preparation of 10 days. The completion of the Fiber Wrap installation and top coating was reached on day 24 of the project, well ahead of a very challenging schedule. Alternative methods of mitigating this critical pipeline problem could have cost up to 5 times the Fiber Wrap option and would have caused major construction to take place under rail lines. The application of Fiber Wrap can be completed in 10–15% of the time required to replace pipelines of this nature. For over a decade Fiber Wrap has been utilized to strengthen and renew pipelines in varying degrees of distress and degradation in the municipal water and power generation market. The process is viable when there is an inability to excavate and a trenchless method must be utilized. Fiber Wrap liners lend themselves well to trenchless rehabilitation where a fully structural solution is a requirement. The Fiber Wrap designs may consider various loading combinations from internal pressure to external loads such as vehicular traffic, or in some cases, train traffic. The Fiber Wrap liner used as a segmental repair in combination with electromagnetic wire break testing for PCCP or Ultra Sonic(UT) testing for steel wall thickness loss may be a more economically feasible repair method when pipeline owners are working with limited rehabilitation budgets. The case study will present a clear contrast of various methods of pipeline repair considering the associated costs of down time, environmental impact, safety and capacity loss. Using the Power Generation facility project as a detailed case study this paper will assist pipeline owners in determining if and when to consider the use of Fiber Wrap. It will present a concise and objective comparison and contrast to traditional pipeline upgrade meant to provide Conference attendees usable information to assist in making these critical operational and financial decisions.