Materials Performance

AUG 2018

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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42 AUGUST 2018 W W W.MATERIALSPERFORMANCE.COM popular adage that Alaska only has two sea- sons: winter and construction. This is espe- cially exemplified in the city of Nome, which is only a couple hundred kilometers south of the Arctic Circle. Like many towns in northern Alaska, Nome is difficult to access and the construction season is incredibly short (only three to four months long). This makes project logistics critical and work delays unacceptable. Since there are no big box or large contractor supply stores in Nome, a part or tool needed for a job often must be shipped or flown in from a major city—which may delay work for days to weeks. Safety Sound Bridge, located just out- side of Nome on Nome-Council Road, joins two narrow spits that separate the lagoon- like Safety Sound from the Bering Sea. The bridge is supported by bare steel pipe piles. An existing CP system had reached the end of its service life and needed to be replaced. Due to the lack of alternating current (AC) power to the site and general remoteness of the location that makes operations checks extremely difficult, a galvanic CP system was selected over an ICCP alternative. This replacement system is composed of alumi- num anode sleds attached to each bent on the bridge through test stations accessible from the roadway. Unlike southeast Alaska, the tides in Nome are typically no more than 3 ft (1 m) and aren't a major design concern. How- ever, one design concern on this project that does not appear in the southeast are the yearly ice f loes that occur when the sound freezes each winter. These ice floes can easily tear apart conduit and hardware attached to the sides of the piling. The orig- inal CP system addressed this obstacle with steel channels welded to the sides of the outside piles that were used as a combina- tion ice break and conduit for running anode cables. Not wanting to "reinvent the wheel" with an available working solution, these angles were reused for the replace- ment CP system (Figure 6). Conclusions Durability and maintenance planning in Alaska is not an easy task. Remoteness, low population densities, tight work win- dows, variable extreme climates, and high costs for materials all factor into well- developed plans. Once in place, these plans must be carefully managed and executed to achieve their goals. References 1 ASTM C876, "Standard Test Method for Cor- rosion Potentials of Uncoated Reinforcing Steel in Concrete" (West Conshohocken, PA: ASTM International, 2015). 2 ASTM D4580, "Standard Practice for Mea- suring Delaminations in Concrete Bridge Decks by Sounding" (West Conshohocken, PA: ASTM International, 2012). 3 ASTM C1152, "Standard Test Method for Acid-Soluble Chloride in Mortar and Con- crete" (West Conshohocken, PA: ASTM International, 2012). 4 AASHTO T 358-17, "Method of Test for Surface Resistivity Indication of Concrete's Ability to Resist Chloride Ion Penetration" (Washington, DC: American Association of State Highway and Transportation Officials, 2015). RYAN TINNEA, project engineer with Tinnea & Associates, Seattle, Washington, USA, email: rtinnea@tinnea.net, is a NACE-certified CP4—Cathodic Protection Specialist with 16 years of experience in corrosion consulting that includes work on piers, bridges, water and wastewater pipes and facilities, aquariums, and dams. He has been a NACE member for 13 years a nd cu rren tl y s er ves o n the N AC E International Board of Directors as the director of the NACE Western Area. MADELINE LEE, engineer with Tinnea & Associates, Seattle, Washington, USA, email: madeline.lee@tinnea.net, has corro- sion consulting experience in port and marine facilities, highway bridges, water and wastewater municipal systems, and steel and reinforced concrete structures. She has been a NACE member for three years. ERICH SCHAAL, P.E., deputy port engineer with the City and Borough of Juneau, Docks and Harbors, Juneau, Alaska, USA, serves as a project manager and owners' representative, and works toward proac- tive infrastructure maintenance to extend the working lives of the city's facilities. Subscribe to the Maritime Newsletter www.nace.org/resources/newsletters CATHODIC PROTECTION

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