ML20058M607
| ML20058M607 | |
| Person / Time | |
|---|---|
| Site: | Perry  |
| Issue date: | 09/29/1993 |
| From: | Shields S ATWOOD & MORRILL CO., INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9310060263 | |
| Download: ML20058M607 (1) | |
Text
s Valve and Flow Controi Equipment Specialists Power Plant. oil & Gas & Marine & industnal Servke i
Atwood and Morrill Co., Inc.
Designers and Manufacturers Since 1900 285 CANAL STREET SALEM.. MASSACHUSETTS 01970 PHONE 508 744-5690 - 508 744-5691
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FAX 508 741-3626 508 745-0576 TELEX 94 0299 i
September 29,1993 Document Control Desk cc: B. Sullivan U.S. Nuclear Regulatory Commission P. LaPointe Washington, DC 20555 A. Webber
Subject:
Cracking of Hardfacing in MSIV Poppets Supplied by A&M
Reference:
A&M Notification dated June 24,1993
)
Gentlemen:
j l
As discussed wtih Larry Campbell of Vendor Inspection, this letter will furnish additional information to that provided in the reference notification.
J Further investigation and analycis has determined that the root cause of the cracking experienced in the hardfacing of MSIV poppets supplied to CEI Perry Nuclear Station was excessive thickness of.
Stellite #21 welded onto the nose cone and seat area. This excessive thickness resulted from weld repairs to the hardfacing in that area.
Other factors contributing to the cracking may have been insufficient pre-heat prior to welding, lack of post weld heat treatment and thick base metal.
Corrective actions taken to prevent recurrence are as follows:
1.)
The nose cone and seat area have been redesigned to provide a thinner, more uniform finished thickness of hardfacing, while continuing to meet design requirements for poppet guiding and seating.
2.)
A review has been made of the pre-heat temperatures used for the hardfacing operation and it is felt that the previous practice of 60 F min. pre-heat (sufficient to re. move moisture) is adequate.
3.)
Post weld heat treatment will be performed for major repairs to hardfacing in the nose cone and seat area.
4.)
Because the poppet is part of the pressure boundary, base metal thickness must be maintained in order to meet ASME Code allowable stress criteria.
Subsequently, additional MSIV poppets have been hardfaced incorporating the above listed actions without any evidence of cracking.
I trust the information provided is sufficient.
Please advise if you require more.
V truly our f
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V.P. Engineering
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