Extending the Life of Existing Pipelines through the Use of a Retrofit Cathodic Protection and Internal Lining Program

摘要

This paper provides a presentation of a life extending system ("Anode Retrofit Program") for existing water mains by examining the planning, design and specification requirements. Included is a case study from the District of Columbia Water and Sewer Authority (DC Water) in Washington, DC. First, a discussion of the proper design and construction considerations for cathodic protection (CP) of water and wastewater transmission pipelines is basic to any asset management strategy. This includes the importance of understanding: 1. Environmental conditions, 2. Interior and exterior pipe conditions, and 3. CP design considerations. The second part of this presentation of an Anode Retrofit Program for cathodic protection of an existing steel main in Washington, DC. DC Water conducted an anode retrofit project as part of a water main repair on a 48-inch steel water main at the Brentwood Reservoir. The prime objective of corrosion control is to maintain a pipeline system free of corrosion at the lowest cost thereby extending the life of the asset. Washington, DCs corrosion control program have proven to be beneficial in the reduction of leaks while extending the useful life of the asset. In recent years the question regarding the use of linings or cathodic protection alone, or in combination, has been evaluated for the best economic choice, especially when viewed in terms of the life cycle of the asset. When corrosion protection is added to an existing pipeline asset that has a documented leak history, as part of an Anode Retrofit Program (ARP), it is possible to estimate the additional expected life. This provides decision makers with valuable data that can be used as part of a life cycle cost analysis for making informed decisions.