ML19208A889
| ML19208A889 | |
| Person / Time | |
|---|---|
| Site: | Washington Public Power Supply System |
| Issue date: | 07/10/1979 |
| From: | Renberger D WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| GO1-79-380, NUDOCS 7909180204 | |
| Download: ML19208A889 (11) | |
Text
T/G Y
pp Washington Public Power Supply System A JOINT OPEkATING AGENCY P
O. Dos 960 3000 Geo. WasMsNcrom Way Ric ML AN3 W A S HIN G TON 99352 PHONE (509) 375 5000 Docket flos. 50-460 and 50-513 July 10,1979 G01-79-380 U.S. fluclear Regulatory Commission Suite 202, Walnut Creek Plaza 1990 fl. California Boulevard Halnut Creek, CA 94595 Attention:
Mr. R. H. Engelken O
M /y
'i' p1
.J f 2 u, Q 7
Subject:
WPPSS flVCLEAR PROJECTS fl0S.1 & 4 2 4 N-IE BULLETIll T10. 79-2&,- REVISI0il fl0.1 g'(i '
" PIPE SUPPORT BASE PLATE DESIGilS jy g
i USIflG CONCRETE EXPANSI0tl At1CHOR BOLTS" g, ')
sf Q
Dear Mr. Engelken-
'E' d '
The Washington Public Power Supply System has reviewed the subject IE Bulletin and submits the attached infonration in response.
Please contact me should you have any questions in regard to this response.
Very truly yours, d
tLt4 eM L. Rew &
D. L. REtlBERGER Assistant Director-Technology DLR:FJ:ct Attachment 355174 t
7900180 ggy p/9-56
Attachment NRC IE BULLETIN 79-02, REVISION 1 PIPE SUPPORT BASE PLATE DESIGNS USING CONCRETE EXPANSION ANCHOR BOLTS It should be noted that only ten (10) Seismic Category I pipe supports (through June 22,1979) which utilize concrete expansion anchors have been installed on WNP-1 and none on UNP-4. The majority of pipe supports (approximately 80%) do not require concrete expansion anchors and are attached by bolting into embedded inserts or welding to existing structural members, supplementary steel, or embedded structural shapes.
- 1) VERIFICATION THAT BASE PLATE FLEXIBILITY WAS ACCOUNTED FOR IN CALCULATlhG ANCHUR BOLT LOADS The original design calculations for determining anchor belt loads did account for the effects of base plate flexibility but.:ot to the extent specified in Item 1 of IE Bulletin 79-02 and not to the extent of considering increased anchor loads due to prying action.
Calculations for all Seismic Category I pipe supports are therefore being reviewed with the assumption that the base plate is flexible unless the distance i im the edge of the support member to the edge of the plate is less u,_.. two times the thickness of the plate (i.e.,
the base plate is rigid). When base plates have been determined to be rigid, the compressive force is assumed to act at the center-line of the anchor bolt on the compression side of the plate.
(See ). When base plates are assumed to be flexible, anchor bolt loads are determined in accordance with the calculation basis described in Attachment 1.
This design approach includes considera-tion of prying action in causing additional anchor bolt loading.
The original design calculat.ons utilized the fomulas given in with the exception that there was no factor for prying action and the moment arm "h" was equal to d+(a+b).
2 For those Seismic Category I supports which have already been designed, anchor bolt loads will be recalculated utilizing the approach described in Attachment 1.
All future designs will utilize this same approach in det.:rmining anchor bolt loads.
Recalculations which indicate maximum allowable anchor bolt loads have been exceeded (See Item 2 of this response.) will be rectified by appropriate pipe support redesign, refabrication, and/or field modification as required to meet the maximum allowable design load.
The current schedule for recalculating anchor bolt loads on exist-ing designs calls for a January,1980 completion.
Sh8E/U
F. Jafarey July 3,1979 Page 2 of 9 E14-NS P-7 9- 037 2.
VERIFICATION OF MIrlIMUM SAFETY FACTOP. FOR BOLT DESIGN LOADS WNP-1/4 utilizes Hilti-Kwik Bolts exclusively for all Seismic Category I pipe supports with concrete expansion anchors.
The original design calculations required that the design tension load be less than or equal to the maximum allowable design load (MADL) where the fMDL is defined by:
fM )L = Fu SF Where, Fu = ultimate static capacity of the anchor based on the manufacturer's static test for the applicable strength of concrete SF = safety factor of 4 for Hilti-Kwik Bolts (shell type anchors are not utilized for Seismic Category I supports on WNP-1/4)
When both shear and tension act on the anchor a straight line shear-tension interaction is assumed as follows:
+
1.0 a
a Where: T = Design Tension Load V = Design Shear Load T = fMDL in Tension a
V = fMDL ir. Shear a
Based on test data generated on 'JNP-2 and WNP-1/4 it became apparent that wedge type concrete expansion anchors (Hilti-Kwik Bolts) slip well below the yield strength of the bolting material and utilizing one-fourth of the ultimate static capacity of the anchor (based on the manufacturer's static test data) does not provide a safety factor of four against slip.
The design criteria for the maximum allowable load on Hilti-Kwik Bolts was therefore revised as shown in Attachment 2.
Design loads calculated in accordance with Attachment 1 must be less than the maximum allowable load shown in Attachment 2.
This approach accounts for shear-tension interaction, minimum edge distance, and proper bolt spacing.
3.
DESIGN REQUIREMENTS FOR ANCHOR BOLTS SUBJECT TO CYCLIC LOADS No specific calculational requirements for seismic loads or high cycle operating loads exist for anchor bolts other than identified in Note 2 of Attachment 2.
As a general rule, the use of concrete expansion anchors is discouraged for high cycle operating loads.
3.38170
F. Jafarey July 3,1979 Page 3 of 9 E14-NSP-79-037 All anchors will have an initial preload tension applied which is greater than 1.5 times the maximum allowable design load identified in Attachment 2.
T!:e method of obtaining bolt pre-tension will be torquing or the use of calibrated Belleville washers.
Final determination of the pretensioning method will be based on tests to be conducted by UE&C.
Concrete expansion anchors for Seismic Category I hangers / supports currently being installed are torqued to the following minimum values after nuts have been turned a minimum of three turns past the finger tight position:
MOP.!!al SCLT CIA *:ETER MINIMUM INSTALLATI0fi TORQUE 1/2-inch 30 ft. lbs.
5/8-inch 60 ft. lbs.
3/4-inch 130 ft, lbs.
1-inch 155 ft. Ibs.
1 1/4-inch 230 ft. lbs.
If torque vs. preload to be tests conducted by UE&C indicateo that the minimum torque values identified above do not provide the required proload tension, anchor bolts installed to the above torque requirements will be re-torqued as required to achieve proper preload or fitted with a calibrated Belleville washer.
4.
VERIFICATION THAT DESIGN REQUIREMENTS HAVE BEEN MET FOR EACH ANCHOR BOLT BASED ON EXISTING QC DOCUMENTATION The installation of concrete expansion anchors is controlled by the installing contractor's (J. A. Jones.- Contract 211 and 257) installation procedures and inspection procedures.
The inspection of concrete expansion anchors is included in JAJ-ITI-005, Paragraph 4.3 which includes the inspections and documentation (refer to Attachment #3) necessary to verify that the design requirements have been met for each anchor bolt in the following areas:
4a)
Cyclic Loads Have Been Considered (i.e, Anchor Bolt Preload Is Equal To Or Greater Than The Bolt Design Load As indicated in the response to Item #3, all concrete expansion anchors are torqued to the minimum values shown.
Torque is verified by the installing Contractors quality control by checking the torque on a minimum of two bolts on each assembly.
Utilizing the formula for determining required wrenching torque values to obtain a given bolt preload, the maximum allowable design load for tension per Attachment 2, and preliminary torque vs. preload data, a comparsion between contractor's minimum installation torque and 3hb1.77
F. Ja fa rey July 3,1979 Page 4 of 9 E14-NSP-79-037 the calculated torque required to obtain an anchor bolt preload of 150% of the MADL is as follows:
BOLT DIAMETER CONTRACTOR's MINIMUM TORQUE FOR 150%
INSTALLATI0il TORQUE MADL (TEf1SION-ALL LOADS) 1/2-inch 30 ft, lbs.
23 - ft. lbs.
5/8-inch 60 ft. lbs.
42 - ft. lbs.
3/4-inch 130 ft. lbs.
84 - ft. lbs.
1 - inch 155 ft. lbs.
149 - ft. lbs.
1 1/4-inch 230 ft. lbs.
240 - ft. Ibs.
Subsequent to completion of the WNP-1/4 torque vs. preload testing ?rogram, installation torques will be revised as re-quired to assure a minimum preload tension of 150% the MADL.
Anchors which have not been torqued to the minimum values established by torque vs. preload tests will be re-torqued as required or fitted with calibrated Belleville washers.
4b) Specified Design Size And Type Is Correctly Installed i.e., Proper Embedment Depth)
Refer to Attachment 3.
The installing Contractor's in-spection checklist includes an inspection hold point to verify that the proper hole depth and diameter exists prior to installation of the expansion anchor.
This approach eliminates any incentive to modify the anchor to accommodate hole depths which are less than the minimum specified.
Additionally, expansion anchors are identified with a length code number by the manufacturer so that bolt length can be verified visually af ter installation.
In those cases where anchors do not have the it.ngth identifying code number the actual installation of the anchor into the hole is witnessed by the Contractor's quality control inspector.
It should be noted that WNP-1/4 uses only Hilti-Kwik Bolts for all Seismic Category I pipe supports which require concrde expansion anchors.
In addition to bolt hole depth and diameter, bolt size, and bolt length, inspection parameters also include verificat' a of the following (refer to Attachment 3) to substantiate that anchor bolts have been properly in-stalled:
PARAMETER INSPECTION PROCEDURE-PARAGRAPH Full thread engagement (JAJ-ITI-005 - 4.3.4)
Nut not shouldered out (JAJ-ITI-005 - 4.3.4)
Spacing and edge distance correct (JAJ-ITI-005 - 4.3.2)
Conformance with detail (JAJ-ITI-005 - 4.0
$$81.N
- f. Ja farey July 3,1979 EI4-flS P-79-037 Page 5 of 9 8
5.
COMPLETION OF ITEMS 1-4 FOR OPERATIflG PLAllTS flot applicable to WNP-1/4.
6.
COMPLETION OF ITEMS 1-4 FCR INSTALLED PIPE SUPPORT BASE PLATES WITH CONCRETE AtlCHOR BOLTS Seismic Category I pipe supports are supports used in ASME-III, Class 1, Class 2, and Class 3 piping systems.
As of June 22, 1979 the following Seismic Category I pipe supports which utilize concrete expansion anchors for attachment have been installed on WN P-1 :
SUPPORT fiUMBER ASME CODE CLASS CSS S G-16 2
CSS-14-SG-21 2
CSS-14-RG-22 2
2 CSS-14-SG-23
~
3 ESA-7-RG-6 IAC-11-SG-2 3
IAC-11-RG-3 3
flSW-12-SG-3 3
flSW-22-SG-2 3
flSW RG-83 3
Concrete expansion anchors for these supports were installed in accordance with JAJ-WI-010.1 and inspected in accordance with JAJ-ITI-005.
Existing QC documentation verifies that anchor bolts have been properly installed with respect to the following:
o minimum anchor embedment o
anchor hole diameter o
anchor length o
anchor diameter o
anchor to anchor spacing o
anchor to edge distance o
anchor torqued o
full thread engagement A verification analysis has been performed for the 10 installed pipe supports.
The analysis used a 5.33 factor of safety and took into account prying action and shear-tension interaction.
(Previous analyses used a factor of safety of 4, and accounted neither for prying action nor shear-tension interaction).
The verification analysis shows that two hangers require design mod-ification; namely, CSS-14-RG-22 and NSW-12-RG-3.
The modified designs arescheduled to be available September,1979.
Installation of ASME-III hangers will continue.
An analysis similar in scope to the verification analysis described above will be performed on those hangers which utilize concrete anchor bol ts.
If a design modification is required on a hanger, the hanger will be placed on " hold" until the exact modification
.%81.7.9
F. Jafarey July 3, 1979 E14-14SP-79-037 Page 6 of g i
required has been specified and hardware available to implement the modification, i.e., the modified design will be installed.
Testing to obtain torque vs. preload data is scheduled to commence during July,1979, with completion in time to support a January, 1980 resolution to all existing designs as stated in Item 1.
Attachments h5F:KJC:si 358180
A.T.TACHi4EtlT #1 - AtlCHOR BOLT LOAD CALCUATION BASIS Page 7 of 9 I f, sx.
Gecq M
h-a-~ b Og i
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esar l
L I
I a
.*S l
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_ ___ ci.
i 5
q h-b -'-
- b. 2 3
h'
-y_
I IM Ph iNi th+ N)
N2 Ydi Where: T = Anchor Design Tension Load V = Anchor Design Shear Load f4 = 140 ment Acting on Connection F = Shear Acting on Connection P = Axial Force Acting on Connection Il = fiumber of Tension Anchor Bolts lN = Total Number of Anchor Bolts 2
i = Index to Identify Base Plate Flexibility i = 1 for Rigid Base Plates i = 2 for Flexible Base Plates hi = I40 ment Arm h = Centerline Distance Between Bolts lh = d + 2t not to exceed h1
^1 C(i= F$ctor to Account for Prying Action for
. Base Plate Flexibility d = 1.0, cLg= 1.2 t
NOTE' Where the connection is subject to biaxial loading the above design approach must be repeated for the other principal plane and the absolute sum of the bolt reactions combined.
[hib.Ud.
...s.
ATTACHMENT 2 - MAXIMUM ALLOWABLE DESIGN LOADS Page 8 of 9 DESIGN CRITERIA FOR HILTI KWIK BOL15 I
2 3
PART NO.
DIA.
fMBEDMENT ALLOWABLE LOAD CENTER T0 EDGE DIST. FROM (IN.)
(IN.)
(LBS)
CENTER DISTANCE PREVIOUSLY TENSION SHEAR LPACING (IN.)
DRILLED (WT.& THERM)
(WT.& THERM)
(IN.)
H0LE (IN.)
TENSION SHEAR (ALL LOADS)
(ALL LOADS) 610 740 12 - 512 1/2 2 3/4 1220 1480 6
5 1
890 1070 5/8 - 812 5/8 4 1/2 1780 2140 7 1/2 5
1 1/4 1490 1580 3/4 - 10 3/4 6
2980 3160 9
5 1 1/2 1980 2540 1 - 12 1
6 3960 5080 12 6
2 2565 3395 1/14 - 12 1 1/4 7 1/2 5130 6790 15 7 1/2 2 1/2 NOTES: 1.
Embedment is defined as the distance from the bottom of the anchor to the top of the concrete after the anchor has been set.
2.
Allowable is equal to 9.375% for dead weight and thermal loading or 18.75% for total loading of ultimate strength (interpolated between concrete 0 2000 psi & 4000 psi).
REF: Abbot A. Hands Inc., Testing Laboratories Report #8783-R March 24, 1977.
For dead weight and thermal loads the allowables are based on a factor of safety of 4 against slip and 10.66 against ultimate failure.
For the total loading in-cluding all seismic loads the factor of safety against slip is 2 and 5.33 against ultimate failure.
3.
For center to center distance less than distance in table the capacity is reduced on a straight line basis down to 50% at 6 diameters center to center anchor spacing.
4.
For combined shear and tension use the following interaction formula:
t.*
d}
S (act)
T (act) di 1
CC S (all)
T (all) b*
- Where, 00 S (act) = Shear Load Applied S (all) = Shear Load Allowable T (act) = Tension Load Applied T (all) = Tension Load Allowable k
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INTEROFFICE MEMORANDUM O EDC WNP-1/4 WASHINGTON PUBLIC POWER SUPPLY SYSTEM O enc wNP 2 O EDC WNP-3/5 0 Admin File Date: July 3,1979 GK Dyekman E14-flSP 037 TJ Houchins To:
F. Ja farey AD Edmondson GC Sorens From: fl. S. Porter Fil es : 1/
p flSP/KJC/b g
h a59
Subject:
NRC IE BULLETIfl 79-02, REVISION 1 dJ[
If PIPE SUPPORT BASE PLATE DESIGNS USIflG C0tlCRETE
(
EXPAllSI0tl AllCHOR BOLTS
Reference:
We nate rcvie'.;ed the subject IE Bulletin and our response is summarized in Items 1 through 6 below.4It should be noted that only 10 ~ Seismic Category I pipe supports (through June 22,1979) which utilize concrete expansion anchors have been installed on WNP-1 and none on WNP-4.
The majority of pipe supports (approximately 80%) do not require concrete expansion anchors and are attached by bolting into embedded inserts or welding to existing structural members, supplementary steel, or embedded structural shapes.
1)
VERIFICATI0tl THAT BASE PLATE FLEXIBILITY WAS ACCOUNTED FOR IN CALCULATING ANCHOR BOLT LOADS The original design calculations for determining anchor bolt loads did account for the effects of base plate flexibility but not to the extent specified in Item 1 of IE Bulletin 79-02 and not to the extent of considering increased anchor loads due to prying action.
Calculations for all Seismic Category I pipe supports are therefore being reviewed with the assumption that the base plate is flexible unless the distance from the edge of the support member to the edge of the plate is less than 2 times the thickness of the plate (i.e.,
the base plate is rigid).
When base plates have been determined to be rigid, the compressive force is assumed to act at the center-line of the anchor bolt on the compression side of the plate. (See ). When base plates are assumed to be flexible, anchor bolt loads are determined in accordance with the calculation basis described in Attachment 1.
This design approach includes consider-ation of prying action in causing additional anchor bolt loading.
The original design calculations utilized the formulas given in Attachment I with the exception that there was no factor for prying action and the moment arm "h" was equal to d+(a+b).
2 For those Seismic Category I supports which have already been de-signed, anchor bolt loads will be recalculated utilizing the approach described in Attachment 1.
All future designs will utilize this same approach in deterr.ining anchor bolt loads.
Recalculations which indicate maximum allowable anchor bolt loads have been exceeded (See Item 2 of this response) will be rectified by appropriate pipe support redesign, refabrication, and/or field modification as required to meet the maximum allowable design load.
The current schedule for recalculating anchor bolt loads on existing designs calls for a January,1980 completion.
WP-102 R2 g.,.
.