ML20236B351
| ML20236B351 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 10/14/1987 |
| From: | Griffith J, Joyce J, Worthy J TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML20236B339 | List: |
| References | |
| 232.8(B)-01, 232.8(B)-1, 232.8(B)-R, 232.8(B)-R00, NUDOCS 8710260107 | |
| Download: ML20236B351 (7) | |
Text
{{#Wiki_filter:- - _ - _ _ _ _ _ - _ - _
- *, TVA EMPLOYEE CONCERNS REPORT NUMBER:..,232.8(B) i SPECIAL PROGRAM
. REPORT TYPE: SEQUOYAH ELEMENT REVISION NUMBER: 0
- TITLE: PIPINC~AND VALVE DESIGN 1
Criteria for Minimum Pipe Wall Thickness PAGE 1 0F 7 J I i REASON FOR REVISION:
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e TVA EMPLOYEE CONCERNS REPORT NUMBER: 232.8(B) SPECIAL PROGRAM t REVISION NUMBER: 0 PAGE 2 0F 7
- 1. CHARACTERIZATION OF ISSUES:
Concern: Issue: IN-85-545-X06 a. The ASME Section III code formula for "12-1/2% was the criteria esta- calculating required minimum wall blished by Engineer Design for thickness of stainles:; steel Class 1 minimum wall thickness since and 2 piping may be less conservative 1978. One engineer was found than the 12-1/2 percent criterion to be using the less stringent established for WBN units 1 and 2 f ormula contained in Code in 1978. Section NB. The above applies to QA Class 2, and some Class 1, stainless steel pipe in Units 1 & 2."
- 2. HAVE ISSUES BEEN IDENTIFIED IN ANOTHER SYSTEMATIC ANALYSIS? YES N0 X Identified by Not Applicable
() Date Not Applicable Documentation Identifiers: None.
- 3. DOCUMENT NOS., TAG NOS., LOCATIONS OR OTHER SPECIFIC DESCRIPTIVE IDENTIFICATIONS STATED IN ELEMENT:
The concern identifies the Division of Engineering Design and the ASME B&PV Code, Section III, Subsection NB.
- 4. INTERVIEW FILES REVIEWED:
File IN-85-545 reviewed on October 8, 1986, contained only the K-form. t' 0443D(12/03/86)
1, TVA EMPLOYEE CONCERNS REPORT NUMBER: 232.8(B)
]
SPECIAL PROGRAM L REVISION NUMBER: 0 ! PAGE 3 0F 7
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- 5. DOCUMENTS REVIEWED RELATED TO THE ELEMENT:
See Appendix A.
- 6. WHAT REGULATIONS, LICENSING COMMITMENTS, DESIGN REQUIREMENTS, OR OTHER APPLY OR CONTROL IN THIS AREA?
See Appendix A.
- 7. LIST RE0UESTS FOR INFORMATION, MEETINGS, TELEPHONE CALLS, AND OTHER DISCUSSIONS RELATED TO ELEMENT.
See Appendix A.
- 8. EVALUATION PROCESS:.
- a. Reviewed applicable TVA Division of Engineering design criteria-i establishcu for WBN plant and SQN plant ASME Section III Class 1 l and Class 2 stainless steel piping.
- b. Reviewed applicable ASME B&PV Code, Section III subs =tions for minimum pipe wall thickness calculation requirements,
- c. Reviewed SQN FSAR sections pertaining to piping classifications and design.
I
- d. Reviewed typical SQN pipe wall thickness design calculation to verify conformance with code methodology.
- 9. DISCUSSION, FINDINGS, AND CONCLUSIONS: l Discussion:
As stated, the concern appears related to the manufacturing tolerance allowed by ASTM Standard Specification A530 (ASME SA-530) for seamless and welded pipe purchased by schedule number or nominal wall thickness under several ASTM pipe product specifications. The ASTM standard stipulates the minimum actual wall thickness of seamless or welded pipe shall not be more than l 0443D (12/03/86) 1 m_____
,?l. TVA EMPLOYEE CONCERNS REPORT NUMBERi 232.8(B)
.SPECIAL PROGRAM ,l W REVISION NUMBER: 0 PAGE 4 0F 7' 1
.12.5 percent under the nominal wall.thicknessLspecified. in the
-procurement document. This tolerance-is a maximum.and provides one' 1 acceptance' criterion for receiving inspection of commercially available seamless and welded pipe.
The minimum reauired pipe wall thickness is-determined by a prescribed equation in the appropriate piping design code based on the fluid. system' parameters. These design parameters include internal pressure, pipe diameter, and maximum allowable stress for. 1 the selected material at the design temperature. -After the minimum required. pipe wall thickness is determined by the design code i equation, the next heavier commercial wall thickness,is selected I taking into account the manufacturing tolerance allowed in the purchase specification. Thus the piping installed in the plant is assured of having an actual (manufactured) minimum wall thickness equal to or greater than the recuired (designed) minimum wall 1
-thickness.
In certain situa'tions where piping has been procured as a bulk commodity; it could be necessary for an engineer to determine the e adequacy of actual minimum pipe wall thickness available~by .
.) calculating the minimum required wall thickness using the design
. code' equation and the system design parameters for. comparison.
-Typical of such situations would be system modifications or ';
-additions and justification for using pipe with an actual wall 4 thickness less than the minimu.m allowed by the ASTM standard.
l Since the. concern was expressed at Watts Bar, a review was conducted' of the WBN plant design criteria document WB-DC-40-36,
" Classification of Piping, Pumps, Valves, and Vessels," Rev. O, 02/11/75, and Table 3.2-4 of the WBN FSAR. This revealed that WBN 4 committed to the ASME B&PV Code Section III for safety-related systems piping design. There is no evidence to support the allegation of the concern that TVA Engineering Design established for WBN a' piping design criteria more stringent than the ASME code i for determination of minimum required pipe wall thickness.
The SQN plant FSAR commitment to the ASME B&PV Code, Section III, applies to piping items initially procured after April 2,1973. Prior to April 2, 1973 SON plant piping was designed to the ANSI B31.1 Power Piping Code. These piping design code constituents are ; documented in the SON Design Criteria Document SON-DC-V-3.0,
.
- General Design Criteria for the Classification of Piping, Pumps, Valves, and Vessels." Currently ti. SON Engineering Project staff i I
h. 4 0443D (12/03/86) i
'I TVA EMPLOYEE CONCERNS REPORT NUMBER: 232.8(B)
SPECIAL PROGRAM REVI5 ION NUMBER: 0 , a PAGE 5 0F 7 i are preparing verification calculations to docJment the design basis of essential aechanical systems, reliminary versions of typical examples of these verification c.ticulatians were reviewed ' in the course of this investigation and confirm use of appropriate piping design codes identified in the design criteria. On the basis of regulatory and other appropriate system safety criteria, TVA has systematically classified SON plant equipment for application of the ASME B&PV Code, Section III design rules (for items initially procured after April 2, 1973). Code Subsections ND and NC provide rules for the design of Code Class 1 and 2 items ! (TVA Classes A&B) respectively. Under the Code permitted optional use of Code Classes, items classified as Class 2 (TVA Class B) may i be designed and certified under the rules of Subsection NB. Thus , any Code Class 2 pipe wail thickness determinations made under the )' rules of Code Subsection NB, as is implied in the concern, are acceptable and do not represent a safety issue. Findinas:
- a. Piping design criteria established by TVA Division of 4 I
Engineering Design has consistently requirea use of Q'" appropriate piping code rules to determine the minimum , required pipe wall thickness of piping in safety and l nonsafety class systems.
- b. 12-1/2 percent is the maximum permissible reduction of nominal wall thickness allowed by several ASTM standard !
specifications for furnishing seamless and welded carbon steel and stainless steel piping products. l
- c. The manufacturing tolerance on nominal pipe wall thickness specified for material purchase is not an element in the !
piping code equation for determining minimum required pipe i wall thickness and, thus, has no impact on the design j conservatism. j
Conclusion:
The concern is not valid for the safety class piping systems installed at SQN Plant
- 10. CORRECTIVE ACTION:
No corrective action is required. h I 0443D(12/03/86)
1 S-. 'TVA EMPLOYEE CONCERNS REPORT NUMBER: 232.8(B) SPECIAL PROGRAM REVISION NUMBER: 0 PAGE 6 0F 7 APPENDIX A
- 5. DOCUMENTS REVIEWED RELATED TO THE ELEMENT:
- a. TVA Mechanical Design Guide DG-M5.1.3, " Steel Piping Materials, Accessories and System Design Considerations"
- b. SQN Plant Design Criteria SQN-DC-V-3.0, " General Design Criteria for the Classification of Piping, Pumps, Valves and Vessel s"
- c. SQN Final Safety Analysis Reoort, Section 3.0, " Design Criteria - Structures, Components, Equipment and Systems"
- d. Selected Sheets of Piping Bill of Material for SQN Piping Drawing No. 47W450 --Series, " Essential Raw Cooling Water"
- e. ASTM A 312 (ASME SA-312), " Specification for Seamless and Welded Austenitic Stainless Steel Pipe"
- f. ASTM A 530 (ASME SA-530), " Specification for General
.] Requirements for Specialized Carbon and Alloy Steel Pipe"
- g. ASME B&PV Code, Section III, Division 1, Subsection NB -
Class 1 Components; Subsection NC - Class 2 Components; and Subsection ND - Class 3 Components
- h. SQN Plant Pipe Wall Thickness Verification Calculations (Preliminary and Unnumbered) for Auxiliary Control Air and Steam Generator Blowdown Systems
- i. WBN Plant Design Criteria WB-DC-40-36, " Classification of Piping, Pumps, Valves and Vessels" !
- 6. WHAT REGULATIONS, LICENSING COMMITMENTS, DESIGN REQUIREMENTS, OR OTHER ;
APPLY OR CONTROL Ih THIS AREAY !
- a. SQN Final Safety Analysis Report, Section 3.0, " Design Criteria - Structures, Components, Equipment and Systems"
- b. SQN Plant Design Criteria SQN-DC-V-3.0, " General Design Criteria for the Classification of Piping, Pumps, Valves and Vessel s" i ,. c. ASTM A 530 (ASME SA-530), " Specification for General Requirements for Specialized Carbon and Stainless Steel Pipe" 4
0443D (12/03/86) l
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,. TVA EMPLOYEE CONCERNS REPORT NUMBER: 232.8(B)
SPECIAL PROGRAM REVISION NUMBER: 0 PAGE 7 0F 7 APPENDIX A (Cont'd)
- 7. LIST REQUESTS FOR INFORMATION, MEETINGS, TELEPHONE CALLS, AND OTHER DISCUSSIONS RELATED TO ELEMEN1.
- a. RFI #5QN-562 (9/15/86)
- b. TVA Transmittal #115 (9/19/96) l c. Telecon between Mahlman, TVA, and Griffith, Bechtel, (10/17/86)
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.e d
6 04430(12/03/86) _ -__ .}}