Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
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.
