ML20209D901
| ML20209D901 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 01/27/1987 |
| From: | Russell J TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML20209B481 | List: |
| References | |
| 222.2(B), 222.2(B)-R01, 222.2(B)-R1, NUDOCS 8702040569 | |
| Download: ML20209D901 (13) | |
Text
TVA EMPLOYEE CONCERNS REPORT. NUMBER: 222.2(B)
SPECIAL PROGRAM REPORT TYPE:
SEQUOYAH ELEMENT REVISION NUMBER:
1 TITLE:
PIPE SUPPORT WELD DESIGN Box Anchors with Excessive Welding PAGE 1 0F 12 REASON FCR REVISION:
1.
To incorporate comments by SRP, TAS, and TVA; to include TVA's corrective action plan information (see Section 10); and to comply with current format.
PREPARATION PREPARED BY:
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SIGNATURE DATE SIGNATURE
- DATE APPROVED BY:
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ECSP MANAGER DATE MANAGER '0F NUCLEAR POWER DATE l
CONCURRENCE (FINAL REPORT ONLY)
- SRP Secretary's signature denotes SRP concurrences are in files.
TVA EMPLOYEE CONCERNS REPORT NUMBER: 222.2(B)
SPECIAL PROGRAM REVISION NUMBER:
1 PAGE 2 0F 12 1.
CHARACTERIZATION OF ISSUE (S):
Concern:
Issues:
0W-85-003-001 "The box anchors on the 3/4" a.
Welding on box anchors for 3/4-inch and 1" stainless pipe (no and 1-inch diameter stainless steel further location details piping is over-engineered.
known) are over-engineered.
CI is concerned that when 'all b.
The overheating due to large weld size that metal is welded on', the will affect the pipe material pipe has to get so hot that it (addressed in Generic Employee Concern could adversely affect the pipe Report WP-15-SQN).
material. CI has no further information."
2.
HAVE ISSUES BEEN IDENTIFIED IN ANOTHER SYSTEMATIC ANALYSIS? YES NO X Identified by Not Applicable Date Not Applicable Documentation Identifiers:
None.
3.
D3CUMENT NOS., TAG NOS., LOCATIONS OR OTHER SPECIFIC DESCRIPTIVE TUENTIFICATIONS STATED IN ELEMENT:
Box anchors on 3/4-inch and 1-inch diameter stainless pipe.
4.
INTERVIEW FILES REVIEWED:
Review of interview files for concern # OW-85-003-001 shows the following information:
K-Forms: 001, 002, 003, and 004 5.
DOCUMENTS REVIEWED RELATED TO THE ELEMENT:
See Appendix A.
0262D - 01/16/87
TVA EMPLOYEE CONCERNS REPORT NUMBER: 222.2(B)
SPECIAL PROGRAM REVISION NUMBER:
1 PAGE 3 0F 12 6.
WHAT REGULATIONS, LICENSING COMMITMENTS, DESIGN REQUIREMENTS OR OTHER APPLY OR CONTROL IN THIS AREA?
See Appendix A.
7.
LIST REQUESTS FOR INFORMATION, MEETINGS, TELEPHONE CALLS, AND OTHER DISCUSSIONS RELATED TO ELEMENT.
See Appendix A.
8.
EVALUATION PROCESS:
a.
Reviewed a sample of box anchor drawings for 3/4-inch and 2-inch-diameter stainless steel pipe.
b.
Reviewed anchor design criteria for weld requirements.
l c.
Reviewed box anchor details and their calculations for weld size calculated and specified, d.
Evaluated findings for oversize weld.
9.
DISCUSSION, FINDINGS, AND CONCLUSIONS:
Chronology:
02/07/78:
Detailed design criteria WB-DC-40-31.15 for piping anchors installed in Category 1 Structures, Rev. 2, issued 02/17/78:
Box Anchor Standard Drawings (47B100-1 thru 4) issued 02/19/78:
Support Modification Request SMR 63-426 issued 06/01/78:
CEB-MEI-76-27, Proposed Design for Box Anchors, Rev. 1, issued 04/22/83:
SQN pipe support design manual (PSDM) Section 7.11,
" Pipe Anchors," Rev. O, issued 10/08/85:
TVA receives the employee concern 04/07/86:
Generic Employee Concern Evaluation Report No.
WP-15-SQN, Design Consideration for Box Anchors, Rev. O, issued 0262D - 01/16/87
-=-
TVA EMPLOYEE CONCERNS REPORT NtlMBER: 222.2(B)
SPECIAL PROGRM REVISION NUMBER:
1 PAGE 4 0F 12 Discussion:
An anchor on a piping system structurally separates two sides of a piping run and secures the desired point in a relatively fixed position.
The loads imposed by both sides of the piping run are carried by the anchor.
Sequoyah (SQN) has used various types of standard anchor details such as box anchor, flued head anchor, trunnion anchor, tube steel anchor, and tee anchor. The box anchors are intended for use in ASME Class 2 and 3 and ANSI B31.1 piping systems and smaller than or equal to 1-inch-diameter Class 1 piping systems (App. A, 5.b and 5.f).
The standard box anchor drawings provide information for design, selection, and load capacity. The largest enveloping set of loads for each pipe size is used to develop these standard box anchor drawings. The following two types of box anchors are used at SQN:
a.
P-series: this type is used on pipe running parallel to walls or floors, b.
T-series:
this type is used on pipe passing through wall or floor sleeves.
Both P and T types of anchors can be fastalled on a carbon or stainless steel piping system. A structural tube of carbon steel material (in two halves) with two end plates is used for P-type anchors, while only two plates and no structural tube are used for T-type anchor.
One plate (called the front plate) is welded to the process pipe, and the other plate is installed to fit snugly around the pipe.
General notes 2 and 3 of standard box anchor drawing 473100-1/R0 (App. A, 5.e) specify ASTM-A240 type 304 plate material for stainless steel pipe anchor and ASTM-A36 plate material for carbon steel pipe anchor.
The CI is concerned about the weld that joins the front plate and the process pipe.
The standard box anchor drawings were reviewed to verify this weld. A full penetration weld in combination with fillet weld is specified on the drawings. This weld is larger than other anchor component welds. The CI has perhaps noted this difference in the weld sizes and, therefore, infers that the weld to the process pipe is excessive. The sizing of this weld is influenced by the following factors:
0262D - 01/16/87
TVA EMPLOYEE CONCERNS REPORT NUMBER:
222.2(B)
SPECIAL PROGRAM REVISION NUMBER:
1 PAGE 5 0F 12 The largest enveloping set of loads (maximum possible) a.
for each pipe size was used in weld design for standard box anchors (refer to Note #14 of dwg. 478100-1, R0).
If unique weld calculations are performed, most of the cases will require smaller sizes of weld than that provided on the standard box anchor drawings.
b.
The weld design between the process pipe and the front plate is governed by the ANSI B31.1 code per Figures 1 and 2 of the anchor design criteria (App. A, 5.c).
The weld design for the other anchor components is governed by the AISC code. Weld allowables for ANSI 831.1 code are smaller than AISC code allowables.
When welding)to a pressure boundary surface (e.g.,
c.
process pipe, the full penetration weld is required per paragraph 1.2 of Appendix I of anchor design criteria (App. A, 5.c) which states:
"The weld attachment to the pipe shall'be by means of a full penetration beveled groove weld. with a minimum effective throat dimension specified in reference 9
... (App. A, 5.f)... as illustrated in Figures 1 and 2."
The above requirements of full penetration weld are consistent with paragraph 1-727.4.7(d) of Nuclear Power Piping USA Standard B31.7 code and NB-4433 and NC-4433 of ASME Section III Code. For nuclear Class 2 and 3 piping the code allows the use of partial penetration weld or fillet weld in place of full penetration weld.
The size of the full penetration weld is coverned by the thickness of the plate welded to the process pipe; therefore, the required full penetration weld looks large in size as compared to the wall thickness of the pipe.
A unique box anchor design consists of the standard box anchor design plus the necessary supplementary steel to attach it to the building. This unique design is called " engineered" box anchor design. SQN was requested to provide engineered box anchor details for 3/4-inch and 1-inch-diameter stainless steel pipes to verify the validity of the concern. The following eleven engineered box anchor drawings for 3/4-inch and 2-inch diameter stainless steel pipe were provided by SQN for review:
47A053-702/R1 47A053-704/R1 i
47A053-711/R0 02620 - 01/16/87 I
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TVA EMPLOYEE CONCERNS REPORT NUMBER: 222.2(B)
SPECIAL PROGRAM REVISION NUMBER:
1 PAGE 6 0F 12 47A053-1047/R0 47A053-411/R0 1-H20-ll6/R2 1-H20-117/R3 1-H20-330/R5 2-H20-330/R3 2-H20-368/R2 2-H20-492/R2 All the above box anchor drawings reviewed, except 1-H20-330/R5, specify full penetration weld between the process pipe and the front plate. Anchor drawing 1-H20-330/R5 specifies 1/4-inch fillet weld between the process pipe and the front plate. This weld was changed from full penetration to 1/4-inch fillet weld per the support modification request (SMR 63-426) by construction and was approved by engineering (EN DES). Such change is permitted by the anchor design criteria (App. A, 5.c, paragraph 1.2 (3) of Appendix I) provided an appropriate stress intensification factor (SIF) is considered at the location of the anchor in the piping stress analysis.
In addition, the fillet weld must be sized to carry the design loads. The evaluation team reviewed the piping stress analysis computer input (App. A, 7.k) and found that the required SIF was not considered in the analysis at the location of anchor 1-H20-330/R5 (node point 62). The calculation for anchor 1-H20-330/R5 was not available to verify that the 1/4-inch fillet weld between the process pipe and the front plate was adequate.
Design calculations for eight engineered box anchors (App. A, 5.1),
from the above 11 anchor drawings, were reviewed to verify the calculated weld size and tne weld size specified on the drawings.
For five calculations, since the standard box anchor unit was used, weld size computations were not required. Of the remaining three calculations, two calculations did not document weld size computations. This documentation is desirable but not essential because full penetration weld requires that the minimum strength of j
the weld material be equal to the base metal. The base metal l
sizing computations are documented. The remaining one calculation compares revised and previously applied design loads and does not contain any weld size computation.
As discussed above, the weld specified on the standard box anchor drawings, and in general, on engineered box anchor drawings, conforms to the requirements of the design criteria and code.
l 0262D - 01/16/87 l
TVA EMPLOYEE CONCERNS REPORT NUMBER: 222.2(B)
SPECIAL PROGRAM REVISION NUMBER: 1 PAGE 7 0F 12 Findings:
a.
Weld size (full penetration) specified between the process pipe and the front plate on box anchor drawings is consistent with the anchor design criteria and code requirements.
b.
1/4-inch fillet weld specified between the process pipe and the front plate on box anchor 1-H20-330/R5 is permitted per the TVA anchor design criteria.
However, the requirement for using appropriate SIF is not complied with in the pipe stress analysis.
No calculation for box anchor 1-H20-330/R5 was available to verify that the fillet weld is adequate.
==
Conclusions:==
a.
The concern about over-engineered welds is not valid.
The specified weld sizes are-required per the applicable TVA design criteria and code requirements, b.
The change from full penetration weld to fillet weld for anchor 1-H20-330/R5 does not meet the TVA anchor design criteria requirements.
10.
CORRECTIVE ACTION In its Corrective Action Plan (CAP) ( App. A, 5.j), TVA commits to perform calculations to verify the adequacy of 1/4-inch fillet weld between the process pipe and the front plate for anchor 1-H20-330.
Stress levels in the piping system will be verified to ensure that they are within the code allowables when the stress intensification factor (SIF) is applied at the location of anchor 1-H20-330.
To establish this occurrence as an isolated case, a random sample of box anchors from various systems (including 2-inch-diameter pipe and smaller) will be examined to verify the as-constructed weld.
If a fillet weld is found between the process pipe and the front plate, the use of appropriate stress intensification factor (SIF) in the piping analysis will be verified.
In case the SIF was not considered, further evaluations will be made to determine if the stress levels in the piping system, at the location of the anchor, are within the allowable code limits.
In addition, the adequacy of the fillet weld will be verified.
The sample size will be expanded if a significant number of cases are found where a full penetration 026?D - 01/16/87
TVA EMPLOYEE CONCERNS REPORT NUMBER: 222.2(B)
SPECIAL PROGRAM REVISION NUMBER: 1 PAGE 8 0F 12 weld between the front plate and the pipe is substituted with a fillet weld and the required SIF is not considered in the piping analysis.
The welds found deficient will be strengthened.
Changes in pipe supports are now handled by field change requests (FCRs) and variances.
This should provide the necessary control by Engineering for this type of design changes and should prevent recurrence of the problem.
The evaluation team concurs with this CAP.
i 0?6?D 01/16/87 i
TVA EMPLOYEE CONCERNS REPORT NUMBER: 222.2(B)
SPECIAL PROGRAM REVISION NUMBER:
1-PAGE 9 0F 12 APPENDIX A 5.
DOCUMENTS REVIEWED RELATED TO THE ELEMENT:
a.
Detailed design criteria SQN-DC-V-2.14, " Piping System Anchors Installed in Category 1 Structures," Rev. 0 (06/30/86) (805 860716 500) l b.
SON Pipe Support Design Manual (PSDM) Section 7.11, " Pipe Anchors," Rev. 0 (04/22/83) (No RIMS number) l c.
Detailed design criteria WB-DC-40-31.15 for piping anchors installed in Category 1 structures, Rev. 2, (02/07/78)
(No RIMS number) l d.
Engineered Pipe Anchor Drawings:
47A053-702/R1 1-H20-330/R5 47A053-704/R1 2-H20-330/R3 47A053-711/R0 2-H20-368/R2 47A053-1047/R0 2-H20-492/R2 47A053-411/R0 1-H20-ll6/R2 1-H20-ll7/R3 e.
Box Anchor Standard Drawings:
47B100 - 1/R0 47B100 - 2/R1 47B100 - 2A/R0 478100 - 3/R3 47B100 - 3A/R2 i
478100 - 3B/R0 47B100 - 4/R1 f.
CEB - MEI-76-27, " Proposed Design for Box Anchors," Rev.1 (06/01/78) (No RIMS number) l g.
Generic Employee Concern Evaluation Report No.: WP-15-SQN, R0, " Design Consideration for Box Anchors" (04/07/86) (No l
RIMS number) h.
Support Modification Request SMR 63-426 (02/19/78) (No RIMS l
number) 0262D - 01/16/87
TVA EMPLOYEE CONCERNS REPORT NUMBER: 222.2(B)
SPECIAL PROGRAM REVISION NUMBER: 1 PAGE 10 0F 12 APPENDIX A (cont'd) 1.
Box Anchor Calculations:
47A053-702/R2 2-H20-330/R0 47A053-704/R2 2-H20-368/R0 47A053-711/R2 2-H20-492/R0 47A053-1047/R2 47A053-411/R2 j.
TCAB-063, Corrective Action Plan (CAP) for Element 222.2(B)
(01/17/87) 6.
WHAT REGULATIONS, LICENSING COMMITMENTS, DESIGN REQUIREMENTS OR OTHER APPLY OR CONTROL IN THIS AREA?
a.
Detailed design criteria SQN-DC-Y-2.14, " Piping System Anchors Installed in Category 1 Structures," Rev. 0 (06/30/86) b.
SQN Pipe Support Design Manual (PSDM) Section 7.11, " Pipe Anchors," Rev. 0 (04/22/83) c.
Detailed design criteria WB-DC-40-31.15 for piping anchors installed in Category 1 structures, Rev. 2, (02/07/78) d.
ANSI B31.1 - Power Piping Code - 1974 Edition e.
USA Standard B31.7 - Nuclear Power Piping Code - 1969 Edition f.
ASME Boiler and Pressure Vessel Code - Section III - 1974 Edition g.
SQN FSAR Tables 3.2.2-1 and 3.2.2-2, R3 l
7.
LIST REOUESTS FOR INFORMATION, MEETINGS, TELEPHONE CALLS, AND OTHER DISCUSSIONS RELAltu TO ELEMENT.
a.
RFI #SQN-515 (08/26/86) b.
RFI #SQN-521 (08/28/86) c.
RFI #SQN-577 (09/19/86) 0262D - 01/16/87
TVA EMPLOYEE CONCERNS REPORT NUMBER: 222.2(B)
SPECIAL PROGRAM 4
REVISION NUMBER: 1 PAGE 110F 12 APPENDIX A (cont'd) d.
RFI #SQN-650 (10/21/86) e.
RFI # SON-634 (10/15/86) f.
RFI #SQN-685 (11/04/86) 9 RFI # SON-696 (11/06/86) h.
RFI #SQN-710 (11/12/86) 1.
TLB-036 (F01860903604) (09/03/86) l k.
RFI #SQN-723 (11/18/86) 1 i
h 0262D - 01/16/87
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TVA EMPLOYEE CONCERNS REPORT NLMBER: 222.2(B)
SPECIAL PROGRAM REVISION NLMBER: 1 PAGE 12 0F.12 CATD LIST The' following CATD identifies and provides corrective action for the findings included in this report:
222 02 SON 01 (12/11/86; CAP revised 01/17/87) 6 1
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f 02620 - 01/16/87
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til REFERENCE
- ECPS120J-ECPS121C TENNESSEE VALLEY AUTHORITY PAGE 100 FREQUEllCY
- REQUEST OFFICE OF NUCLEAR P0HER Rufi TIME - 12:57:19 O!1P - ISSS - RUM EMPLOYEE CONCERN PROGRAM SYSTEM (ECPS)
RUN DATE - 12/02/86 LIST OF EMPLOYEE CONCERN INFORMATION CATEGORY: EH. DES PROCESS & OUTPUT SUBCATEGORY: 22202 BOX ANCHORS HITH EXCESSIVE HELDING S
GENERIC KEYHORD A H
APPL QTC/NSRS P
KEYHORD B C0flCERN SUB R PLT BBSH INVESTIGATION S
C0!1CERN KEYHORD C HUMBER CAT CAT D LOC FLQB REPORT R.
DESCRIPTION KEYNORD D CH 003-001 EN 22202 N HBN YYYY SR THE BOX ANCHORS ON THE 3/4" AND 1" S HELDING T50172 REPORT TAINLESS PIPE (No FURTHER LOCATION D DESIGN REVIEH ETAILS KNOHN) ARE OVER-E!IGINEERED.
PIPING CI IS CONCERNED THAT HHEN "ALL THAT SEPARATION METAL IS HELDED ON", THE PIPE HAS TO GET SO HOT THAT IT COULD ADVERSELY AFFECT THE PIPE MATERIAL. CI HAS NO FURTHER INFORMATION. NO FOLLOW UP REQUIRED.
l CONCERNS FOR CATEGORY EN SUBCATEGORY 22202 q
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