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Information Notice No. 92-68: Potentially Substandard Slip-On, Welding Neck, and Blind Flanges
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C. 20555 September 10, 1992 NRC INFORMATION NOTICE 92-68: POTENTIALLY SUBSTANDARD SLIP-ON, WELDING NECK, AND BLIND FLANGES Addressees All holders of operating licenses or construction permits for nuclear power reactors. Purpose The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert licensees to problems with potentially substandard slip-on, welding neck, and blind flanges. It is expected that recipients will review this information for applicability to their facilities and consider actions, as appropriate, to avoid similar problems. However, suggestions contained in this information notice are not NRC requirements; therefore, no specific action or written response is required. Description of Circumstances On July 9, 1992, the NRC staff met with a representative of The National Board of Boiler and Pressure Vessel Inspectors (Board) to discuss the Board's investigation of problems associated with flanges that originated from the People's Republic of China. The Board has received numerous reports of flanges marked "China" that contain cracks, inclusions, and slugged weld repairs, and that were constructed from two pieces of material. The suspect China flanges were sold to U.S. suppliers through several trading companies. Three of the trading companies identified were: Billiongold Company Limited of Hong Kong, Tain Gong Company, and Shanxi Province Overseas Trading Corporation. The suspect flanges were marked as forgings that complied with the requirements of the American Society for Testing and Materials (ASTM) Standard A-105, "Specification for Forgings, Carbon Steel, for Piping Components," and the American National Standards Institute (ANSI) Standard B16.5, "Dimensional Standards for Steel Pipe Flanges and Flanged Fittings." However, the suspect flanges were manufactured with ring-inserts welded to the inside diameter of the flange and the outer surfaces were machined. Consequently, a visual inspection would not detect either the welding or the two-piece construction. Other flanges were found with slugged weld repairs to the flange hub and still others failed to meet the material specification requirements for thermal treatment, mechanical properties, or chemistry. 9209030274. IN 92-68 September 10, 1992 Page 2 of 2 Discussion The Board determined that one Chinese flange manufacturer, of the several known factories that supply the U.S., shipped more than 110 tons of ASTM A- 105, ANSI B16, China flanges to this country. The Board stated that over 7,000 flanges are being removed from refineries and petro-chemical plants as a result of failures that occurred during welding, bolting, and hydrostatic and pre-operational testing. The Virginia Electric and Power Company informed NRC staff that China flanges are installed in two of its fossil power plants and others are in its warehouse. At the time of discussion, Virginia Power had not determined whether any suspect China flanges are installed in its nuclear power plants. The NRC does not have evidence that any suspect China flanges have been installed in U.S. nuclear power plants. However, specific examples and discussions of the problems are attached for information. A potentially substandard "China" flange can pass between two or more distributors before reaching the end-user facility. A nuclear power plant could buy a commercial grade China flange from a distributor to dedicate the flange for safety-related use, or safety-related components or subassemblies that contain China flanges could be supplied by licensee-approved manufacturers or fabricators. Establishing and verifying procedures to trace procured equipment and material to the original manufacturer or mill is an important prerequisite to inspecting and testing during the dedication process. It is possible for a licensee to install potentially substandard or defective equipment or material if it does not adequately verify that the product can be traced to the original manufacturer. This information notice requires no specific action or written response. If you have any questions about this matter, please contact the technical contact listed below, one of the Board representatives listed on the attachments, or the appropriate Nuclear Reactor Regulation (NRR) project manager. ORIGINAL SIGNED BY Charles E. Rossi, Director Division of Operational Events Assessment Office of Nuclear Reactor Regulation Technical contact: Steven M. Matthews, NRR (301) 504-3191 Attachments: 1. 1992 Board article, "Failure Analysis of a Slip-On Flange." 2. Selected 1992 Board "NBBInfoletters." 3. List of Recently Issued NRC Information Notices.
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