ML20126C071

Rev 0 to Operations Manual,Section H7.3, Integral Welded Attachment Evaluation Criteria for Prairie Island Nuclear Generating Plant

ML20126C071
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Site:	Prairie Island
Issue date:	07/19/1990
From:	NORTHERN STATES POWER CO.
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References
PROC-900719, NUDOCS 9212220341
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f j, GRAIRIE ISLAND NUCLEAR GENERATING PLANT NORTHERN STATES POWER COMPANY H PROCEDURES

",. TITLE:

j 9[ } ] 1:6% NUMBERt i'

[,;g INTEGRAL WELDED ATTACHMENT H7.3 i I5 EVALUATION CRITERIA b- m: 0 s isection - . .'.~

FOR THE PRAIRIE ISLAND i 4 NUCLEAR GENERATING PLANT Page 1 of 21 n

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9212220341 921211 PDR ADOCK 05000282 PDR P

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c H7.3 Rev. O Table of Contents Page 2 f12A 1.0 DEFINITIONS 1

2.0 INTRODUCTION

1 3.0 CODE REQUIREMENTS 1 4.0 ANALYSIS AND DESIGN CRITERIA 2 4.1 Weld Criteria 2 4.2 Pipe Stress Screening Criteria 2 4.3 Detailed Local Stress Criteria 3 5.0 EVALUATION HETH000 LOGY 6

6.0 REFERENCES

7 No. of Paaes

( APPENDIX A: IWA Evaluation Flow Chart 2 APPENDIX B: Configuration 1-9 10

1 11 7 . 3 -

i Rev. O Page 3 i 1.0 TEFINITIONS l /fx The following definitions / abbreviations will be used throughout this procedure.

l l

d, = Nominal Diameter of Trunnion D, = Nominal Diameter of Run Pipe i r - Mean Radius .

! I j_ R, = Radius of Run Pipe i

! T, - Thickness of Run Pipe 1

[ ,, = Weld Stress f: ,, - Pipe Stress or Punching Shear

,, = Local Membr:ne Stress au - General Membrane Stress l

j! ,, - Bending Stress l

l S, -

Material Allowable 9 Hot Temperature

) S: -

Material Allowable 9 Cold Temperature (70"F)

. C.

1 2.0 INTR 00VCTION The objective of this procedure is-to outline a method for the systematic i evaluation of integral welded attachments (IWA) at Northern States Power

! Prairie Island Nuclear Plant. This method may be used for the evaluation of

new IWA designs or existing IWA's. The intent of the evaluation is to

' demonstrate that the IWA designs comply with the requirements of the piping codeofrecord,USASB31.1.0,Ref.(1).

r 3.0 CODE RE0VIREMENTS-F The design requirements for integral type structural- attachments is stipulated in Subparagraph 121.3, Chapter II - Part 5 of USAS B31.1.01967. -

" Consideration shall be given to the localized stresses induced in the )iping_

component by the integral attachment". Part-(b) states: " Welds shall Je-proportioned so that the shear stresses shall not exceed 0.8 times:the-applicable S values shown-in the allowable stress tables."

9

H7.3 '

Rev. O Page 4 4.0 ANALYSIS AND DESIGN CRITERIA

(^ )

The following criteria is used to determine the acceptability of an IWA for each of the nine (9) configurations listed below.

1. Axial Lugs IA. Radial Lugs IB. Radial and Axial Lugs

2. Circumferential1y Reinforced Axial Lugs

3. Circumferential Plate with Stiffeners

4. Plate at Elbow

5. Trunnion

6. Trunnion at Elbow (Stanchion)

7. Saddle An illustration of each of the above configurations along with the applicable weld stress equations are given in Appendix B.

4.1 Held Criteria

a. Sustained loads (Gravity + Thermal) a w I 0.8 S,

b. Intained + OBE loads 1

,, s 1.2 (0.8) 5, = 0.96 S,

( c. Sustained + DBE loads a w 1 1.8 (0.8) S,= 1.44 S, 4.2 Pioe Stress Screenina criteria " Punching Shear" The equation for a, is given with Configuration 1 and is applicable for all nine (9) configurations. (SeeAppendixB)

The screening guidelines are as follows:

4.2.1 Trunnions - (Configuration 5 & 6)

Trunnions should be located away from discontinuities by more than

1. 5 VR t '. Otherwise, the effect of proximity needs to be addre,s s e,d . t 4.2.1.1 Anchor Tvoe Trunnions An anchor is a six (6) way restraint, anything less is considered a non-anchor.

a. if 0.201 d, < 0.40 and R. 1 32, then D, T, ap 10.30 S, (IWA is acceptable)

11 7 . 3

,,, Rev. O l' age 5

b. if 0.40 5 d, < 0.60 and R, s 16, then D, T,

,, s 0.40 S, (IWA is acceptable)

c. if 0.60 1 dt and A s 12, then D, T, e, s 0.60 S, (IWA is acceptable)

d. if 0.60 s da and 12 < R. 5 24, then D, T,

,, s 0.40 S, (IWA is acceptable)-

l 4.2.1.2 Non-Anchor Tvoe Trunnions for 0.20 s i D,

,, s 0.15 S (IWA is acceptable).

4.2.2 Lugi - (Configurations 1, 2, 3, 4, 7)

When more than one (1) lug is used, the separation distance f.. will be compared to 1.5 R, t, 4.2.2.1 Axial-Luas

,,10.40 S (IWA is acceptable)'

4.2.2.2 Radial lu,gi

,, s' 0.15 S, (1WA~ is acceptable)-

4.3 Detailed local Stress criteria Supports with.IWA's not meeting the criteria set forth in Section 4.2 will be evaluated on an individual basis using methods applicable to -

pressure vessels ~or pi)ing. For lugs the WRC 107 methodology as outlined-in 4.3.1 may_se used. Two different methods are used for trunnions:

- WRC 107 for r _ s 0.5. .

r,

• H7.3 Rev. 0 Page 6

- Rodabaugh for r_10.5 r,

4.3.1 WRC 107 METHODOLOGY

~; The Welding Research Council Bulletin 107 outlines a method of calculating local stress on a thin walled ves'sel. Per ASME B&PV Code,Section III, Table NC-3321-2, Ref (6]. The WRC of 107 stresses can be categorized into the following:

et - Local Membrane Q Secondary Bending F - Peak 3 The acceptance criteria below is taken from ASME B&PV Code Class 2 vessel rules which only consider ,t, ,, and ,, (see definitions). To calculate the local membrane stresses using the WRC 107 methodology, set the stress concentration factor for bending, K equal t (au + ,,) is being used here to designate tb,e gross )o zero.ipe stresses which include the i pressure stresses and tle stresses induced by the moments in the pipe as predicted by the piping analysis. The limits are as follows:

d

a. Level A (Gravity + Thermal)

,e + (,u + ,,) i 1. 5 S o

( b level B (Gravity + Thermal + OBE)

,e + (,u + ,,) i 1.8 S,

, c. Level D (Gravity + Thermal + DBE)

,e + ( au + ,,) s 2.4 S, If the trunnion in question is an anchor, then the WRC 107 3

' are the total stresses (except for pressure). Gross pipe stresses are accounted for in WRC 107 in this case and the 4

M/Z pipe stresses from the piping analysis need not be added.

4.3.2 Rodabauch Methodoloav The method of WRC 107 cannot be used for geometries with Trunnion to pipe radii greater than 0.5 without severe extrapolation. A different method, based on recent work by Dr. E.C. Rodabaugh on laterals will be used. In general, the geometries in this category are the larger trunnions, typically anchors, dominated by moments. Since the trunnion to the pipe is similar to a lateral, without the weakening of the hole, the Rodabaugh approach will be used. Proper use of this paper requires some background from WRC

( l

H7.3 j.. Rev. O j Page 7 j Bulletin 329, Ref. [8]. This second approach is therefore limited to anchors or restraints with primarily moment

.f loadings. The loading will be treated as "Homent Loading on the Branch" as explained in E.C. Rodabaugh's paper. The following indices are required:

C3 - 1.5 ( B ) * ( I )'# ( 1 )( I ) ; > 1.5 for I < 0.9 T R T r, R

=0.9-(R)'d (I);I=1

[

T r, R j B3 - 0.5 C 3 i > 1.0 i

i -C 3  ; > 2.1 l These are for "As-Welded" intersections. For anchors, the j stress is then i

Bn _fL where Zb = ,r't per NB-3683.1 l!

Zb or Y i M

Zb i

j ..

Depending en the loads t,eing considered.

l4 In calculating stres'ses due to loads', conservatively use the smaller of Branch /Run section. Since the loads on-the anchor are the sum of the two sides, they are of like sign for seismic and usually of like sign for thermal, although l

i this should be verified. :This means only.the loads on the Branch need to be used in the " Tee" evaluation.-

For seismic, the run moments are always assumed to add' l - absolutely. There is no need to add run moment-stresses.to i - 0 if the two run the " tee",

moments aresince of-likeASME sign. Since codegravity states that M loads are usua .

' small, they will be assumed to have same sign. -If thermal run moments are cancelling, the evaluation needs to be-

! modified to account for this. .The-acceptance limits are-as

follows

i l a. Sustained loads (Gravity + Pressure) i B, PDo + B3 M i 1. 5 ' S. -

! 2 t, 1, B, 0l5 l- b. Sustained + OBE' Loads Po,.0, + B 3 M s 1.8 S, t

4 t, Zb u- -v- -----e,e 9-y-v-g -i=%--^-- ty-v-.,-ga.,--%.y a-,mw- t ,.w- ,y,:.-. .ir. gew-a---7g -n 9 rw-s q'w-ww-*--- me en e g 9-** r

.- _ ,_- -- _. -= _- - . _- . _- -

11 7 . 3

,- Rev. O Page 8

c. Sustained + OBE toads

(' Po.,0, + B 3 4 t, M

Zb s 3.0 S,,

d. Thermal (Fatiaue) Loads i M _ s S, = 1. 25 S, + . 2 5 S,,

j Zb 5.0 EVALVATION METHODOLOGY 1

The evaluation methodology for a new or existing IWA's is outlined in the flowchart in Appendix A. From the flowchart it is seen that the nine (9) l configurations of IWA's fall into two (2) categories: Lugs and Trunnions. '

q

a. Classify the IWA into one of the nine (9) configurations. This will l also determine whether the IWA is a Lug or Trunnion. If the IWA cannot l be classified as one of the nine (9) configurations, then it will be 4

2 considered non standard. These configurations will need to be evaluated on a case by case basis using appropriate experience and structural mechanics concepts.

j

b. Based on the configuration, calculate, using maximum loads, the " weld stress" (,,) and the " pipe stress" (a,) for the attachment. For trunnions, also calculate the geometric parameters d, and R.

(.. D, T,

c. Compare weld stress against " Sustained Load" weld criteria (,, 1 0.8 S ). If weld stress exceeds " Sustained Load" limits, then compare weld stresses for the individual load cases with the appropriate weld criteria limits as shown in 4.1 and outlined in the flow chart.

d. Determine acceptability of IWA by comparing pipe stress to the limits specified in Section 4.2. For trunnions, the geometric parameters will determine the pipe stress limits.

e. If the pipe stress exceeds the limits specified in Section 4.0, local stress evaluation can be performed using either WRC Bulletin 107 or the E.C. Rodabaugh approach. The maximum stresses calculated by either of these two (2) methods must be compared to their respective limits based on loads used. See Section 4.3 for the local stress limits for the individual loading conditions. If the local stresses do not exceed these limits, the IWA is qualified and considered acceptable. If the IWA exceeds these limits, then the existing IWA must be modified, or the new design must be changed and the evaluation process re-iterated.

k

,- H7.3 Rev. 0

6.0 REFERENCES

Page 9

{ 1. USAS B31.1.0, " Power Piping", 1967.

2. Impell Calculation 0910-242-001, " Prairie Island IWA Criteria / Evaluation", Revision 0. PINGP Design Change Modification 894915, Feb. 9, 1990.

4 3 Welding Research Council, Bulletin 107, August 1965 l

4. ASME Code Case N-318 3, September 5, 1985

5. ASME Code Case N-392, November 28, 1983

6. ASME B&PV Code,Section III, Division I, Subsection NC, 1989 ED.

l

7. E.C. Rodabaugh, " Stress Indices Pressure Design and Stress Intensificatior Factors for Laterals in Piping, Draft.

8. Welding Research Council, Bulletin 329, December 1987

(

1 l

, Rev 0

, Paga 10 1 of 2 APPENDILA IWA Evaluation Flowchart 4

9

% = N g.,y4 i x ;- # , ' ,aa '; y - 4 6 9

--.1a w,- 4 e.,a -- G L -0A+- n 1 a m a m - A O**

4 .. m a w

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, -fi- J, .

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---+

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=

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!!7. 3 Rey, o Page 12 APPENDIX B Configurations 1 9 t

.. H7.3

]'* - Rev. 0 Fage 13 y C e

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1

. 1 i ADa t tp Configuration l- AXI AL l.UG wE 4

e fr 4 % + ; ; ; / < a lngs

=

'~

f e, =

0.7071 W t o, = f' (penetration welds)

W- 3

g. ,

l Up Wt = Weld thickness

--Weld length (W ) = L- (penet:ation welds) l .

Weld length (W ) = L- (fillet weld,2 sides)

L2

?, =

y- (fillet welds)

L2 S, =

g- (penetradon welds) .

S, = (2*t1 L+L)2 (welded 3 sides) 3 NOTES : ** The number of lugs effect!ve In resisting the load -

not to.ex,ceed 2.

l

• For partial pene*1ation welds l

4 H7.3 F Rev. O Page 14 0

L+

Configuration -l'a - RADI AL LUG Weld length (Wg) = 2L (fillet weld)

( Weld length (Wi ) = L (penetration weld) rF3 fr =  ;

gJ.

\

. e, =

0.70[f 1Wt Wet wcW o, = f' g (penetration weld)

W: y, For partial penetration welds e

,5 H7.3

.. Rev. O Page 15

[  ; ,

Fr g

=

Fa e2

/ f f 1 l

+L _>

l >

LJ LJ Configuration ib - RAD: AL & AXI AL LUGS Weld length (Wg) = 2L (fillet welds)

(.-

M, = (Fa5 c2 )+ (F,2 eg) 2 S, =

L .

3-E f

0.7071 W:

=

y

~

, . . H7.3 :

• Rev. 6 Page 16 e

( n l

I F l

f 1r T

1r

) [ "

I

~~l TI -

n 1

, y' h* g bl

<le 4 Li Configuration 2 - CIRCUMFERENTI ALLY REINFORCED AXI AL LUGS .

Weld length (Wg) = 2L + T (conservative)*

• L2 (conservative),,

S, =

y M, = Fx e fr " +  ! # of lug

• f c, =

0.7071 Wg (fillet weld)

NOTES : 'The number of lugs effective in resisting the load -

not to exceed 2.

" The circumferential stiffener is conservatively ignored to maintain similarity to Configuration 1.

l 1

"' H7.3-Rev. 0

• Page 17 A

1

(' 1 I

• p 1 j 4

, t I 4 4

' d. t b - - -6 - - + .4 ,._ y __ .,_ ;

m ssssusms sus (_j

< h= F _

+L1+ ->- +T t

- Configuration 3 - CIRCUMFERENTIAL PLATE WITH

, STIFFENERS Weld length (Wi d = 2Lg x N.S. (fillet welds)

(" N.S. = number of stiffeners Weld length (Wip) = x x O.D. (penetration welds)

(2L + 0. D. )3 - O. D. 3 + x 's O.D.3 6 8 S, = (Blodgett, p. 7.4 -15)

- (2 L + 0.D.) / 2 (2L + 0.D.)3 - O.D.3 x x 0. D.3 J, = + (2I,)

3 4 (Fi + F )

f' =

N.S. x (2L + Wip).

F,

+-

N.S.

1 (2Lg + Wip) i(Mi2+ M,2)-  %

• C. <2D.' 3

( ,

S, J, (conservative)

.-r -

..e- - .- m - - - - *r.-m,.,-m<

'." F '

H7.3 I Rev. O N

j. Page 18

+

(- lw-- e l h

- (O I eg I U l )I ~~

L I

I I

LS -

I Configuration 4 - PLATE at ELBOW

(' Weld length (WI) = determined from plate dimensions and radius of pipe bend.

T = thickness of plate Mg =

(F 2 e2) + (Ft x et) 2 Wi (assumed to be straight)

S, =

6 Wi 3

+ 3Wi T 2 y* ,

6-fr " -+ +

o, = f' (penetration welds)

W: yi ,

f c, = ****

2 x (0.7071) * (W )

• For partial penetration welds

'. i H7.3-g

Rev. 0 Page 19 1

5 gt

(. . + l d ->

l

'h l l TRUNNION

~

I -

I I

[ W '

l i l *a-I 1t- - -- --- - - 1 J =

l RUN PIPE i

i Configuration 5 - TRUNNIONS

{

S, = xxd2 a d3 Jw 4 =

4 i

WI = xxd f

F YM i 2+M 23 32 y (p,2 + p,2) + Mg xf

+

fr = 4 Sw s ( WI lw j

(# of trunnions) f Gw =

(0.7071) x (W ) (fillet welds) fr Ow . 3, (penetration welds)

W: y For partial penetration welds k.

j ,

H7.3 l

.t Rev. 0 Page 20

' (t

f' -

1 l  ! 2 - (L80W

- ' l i '

i I TRUNNION

4. 4- -/

I

[) -

l l l/

I r. m

' 1 I

Configuration 6 - TRUNNION e ELBOW .

8 g, 3 x2d.2 3* ,

4 Iw 4 W1 = x xd ,

'F iM 2i + g,2 32 'q(p 2 + p,2[. Mg 2f -

+ +

fr, y,- _3, Wl Jw ,

(# of trunnions)

(0.7071) x (w,) Wet weMs)

"w = (penetration. welds)

Wg y.

1

(*

• For partial penetration welds '

4.

i

. 11 7 . 3

,, Rev. 0

' Page 2i Fr I

s o

ye

/

0 a l I

N WI s

Ill N N

4 L s i s

• a i

Configuration 7 - SADDLE LUG

~

Weld length (W:) = are length

(~

l 2 T

S, = p (penetration weld) 2 T

S, = p (fillet weld) l M. = F, x e l

l f

l

e, = t' ' (penetration weld)-

l W: y,'

3 -

l l f Gw =

(fillet weld) -

0.7071 x We For partial penetration welds

(

l _ . - - , , , , . ,

+ . , . . _ . . - . . _ , . . - ,