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原文传递 ACCELERATED LOW WATER CORROSION OF STEEL PILINGS IN SEAWATER

题名：	ACCELERATED LOW WATER CORROSION OF STEEL PILINGS IN SEAWATER
作者：	Ashok KUMAR; Larry D. STEPHENSON
关键词：	ACCELERATED; LOW WATER CORROSION ; STEEL PILINGS ; SEAWATE
摘要：	The corrosion of steel pilings in seawater was investigated, for the past 25 years, at two field locations in the United States, one in the Gulf of Mexico at La Costa Island, Florida, and the other in Buzzard’s Bay, Massachusetts. Three rows of 22 test steel H piles, 20.3 cm x 20.3 cm and 12.2 meters long, were installed in 1974 at the Buzzards Bay, Massachusetts, test site, where the test temperature varies from –1° C to +19° C. The steel H-plies, which were coated with various coating systems, such as, coal tar epoxy, polyurethane, flame sprayed zinc and aluminum. Several of the piles were left uncoated for baseline comparison. Sacrificial cathodic protection was provided by anodes to some of the bare and coated steel pilings. Annual inspections were conducted and a row of pilings was pulled out after 5 years and detailed inspections were conducted. The results of the study at Buzzards Bay, Massachusetts were compared with a similar study conducted at Lacosta Island, Florida. The results of the long term coating evaluation showed that flame sprayed aluminum coating with a topcoat sealer performed best in the cooler temperature at Buzzard’s Bay and the thick polyester glass flake coating was the best performer in Florida. Coal Tar epoxy coatings, with zinc rich primers, performed well at both locations. The average corrosion rates, at the two test sites, were determined by measuring the thickness of the flange after the steel piles were pulled out for detailed evaluation. The exposure of the piles in the marine environment was divided into vertical zones in which corrosion requires separate consideration: atmospheric zone, splash zone, tidal zone including inter-tidal low water zone, continuous seawater immersed zone, and embedded or below seabed zone. Measurements indicate that, in some cases, concentrated corrosion was encountered, where the corrosion rates were more than twice as much within 1 m below the mean low water line, compared to corrosion rates in other regions of the immersed zone. This phenomenon, termed “accelerated low water corrosion (ALWC),” is a rapid form of microbial assisted corrosion. The solutions include thicker steel, protective coatings, cathodic protection and design considerations.
总页数：	Proceedings of the 30th PIANC-AIPCN Congress. Sydney Australia. 22-26 Sept. 2002. pp12
报告类型：	科技报告