ML20059G629

Responds to Rai,Requested During 930713 Conference Re ASME Class 1 Block Forged Tees Installed at Vogtle Electric Generating Plant

ML20059G629
Person / Time
Site:	Vogtle
Issue date:	01/14/1994
From:	Mccoy C GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LCV-0226, LCV-226, TAC-M81760, TAC-M88385, NUDOCS 9401250006
Download: ML20059G629 (16)

Text

• cega Power comoany A0 lrwres Cemer Pwknn Pott OH.ce Bar 129s O rmsr ynam Alarmma 3^.201 klet t,r.ne 205 877 7122 m

C. K, McCoy Georgia Power v4 e en vie r4. om Jyy% Yrtym a i W EOtlihefD 2 CCl?iC 0 byMV m January 14, 1994 LCV-0226 Docket Nos. 50-424 50-425 TAC Nos. M88385 M81760 U. S. Nuclear Regulatory Commission ATTN.: Document Control Desk Washington, D. C. 20555 Gentlemen:

VOGTLE ELECTRIC GENERATING PLANT REQUEST FOR ADDITIONAL INFORMATION ASME CLASS 1 BLOCK FORGED TEES The issue concerning ASME class I block forged tees was first reported by Georgia Power Company (GPC) pursuant to the requirements of 10 CFR 21 and 50.55(e), on December 15,1988. On November 14,1991, the NRC staff met at the Vogtle Electric Generating Plant (VEGP) to discuss the 10 CFR 50.55(e) report. During a conference call on July 13,1993, the staff requested additionalinformation concerning the ASME class 1 block forged tees installed at VEGP. GPC has since taken several actions to respond to the staffs request for additionalinformation.

The actions taken include revising the ASME Section III Class 1 Stress Analyses, eliminating the root cause for this issue by revising the piping material classifications drawing, and eliminating the potential for installing block forged tees that were in the warehouse stock on ASME class 1 piping. Enclosure 1 includes responses to the staffs request for additionalinformation.

The designs of the large tees were also independently reviewed by a mutually respected ASME Code expert to verify compliance with the applicable portions of the ASME Code and ANSI B16.9. Enclosure 2 documents this review.

Sincerely 0 #1 'O C. K. McCoy iOO6: 51 9401250006 DR 940114 p ADOCK 05000424 f" PDR j l

Georgia Powerkn U. S. Nuclear Regulatcry Commission Page 2 CKM/JLIlgmb-Enclosures cc: Georgia Power Company Mr. J. B. Beasley, Jr.

Mr. M. Sheibani NORMS U. S. Nuclear Reculatory Commission Mr. S. D. Ebneter, Regional Administrator Mr. D. S. Hood, Licensing Project Manager, NRR Mr. B. R. Bonser, Senior Resident Inspector, Vogtle LCV-0226 i

i i

703775

w i ENCLOSURE 1 -

REQUEST FOR ADDITIONAL INFORMATION REGARDING ASME CLASS 1 BLOCK FORGED TEES

1. Request:

Identify the materials of the block forged tees in question and the schedule or wall thickness.

Response

As demonstrated in Mr. Rodabaugh's report, (Enclosure 2), for a given type of tee, the large bore tees would have less margin than the small bore tees. Also, ASME class 1 tees would have even less margin than similar sizes of class 2 or 3 tees because of generally higher stress levels, less margin in the calculations, and a larger percentage weight deviation due to the block forged tees per span of pipe. Also, there are no explicit requirements to address wall thickness variations for class 2 or 3 tees. Thus, the large class 1 tees are the limiting case.

The base material for the ASME class I large bore tees is SA-182. The piping thickness for the 12",10" and 8" lines is schedule 140, and for the 6" and smaller lines is schedule 160. Thus, a 12" straight tee would be schedule 140, and a 10" x 6" reducing tee would be schedule 140 by schedule 160.

2. Regunt; Provide a copy of the teleconference notes with Mr. E. C. Rodabaugh that document his concurrence on this issue. i

Response

Subsequent to your request for additional information, we contracted with Mr. E. C.

Rodabaugh to review the information on this subject in detail, and issue a report providing his assessment of the ASME code compliance issues. A copy of his report (Enclosure 2) is more detailed and pertinent than the 1987 teleconference notes with Mr. Rodabaugh on this issue.

El-1

-i

i l

t ENCLOSURE 1 (CONTINUED)

REQUEST FOR ADDITIONAL INFORMATION REGARDING ,

ASME CLASS 1 BLOCK FORGED TEES

3. Request:

Show evidence that the seismic analyses were performed using the actual weight of the block forged tees.

ResponyJ The actual weights of the block forged tees are not available, but were conservatively estimated by reviewing dimensional measurements taken in the field. The estimated weights were then compared to those used in the piping system analysis. The deviations between the actual weights and the as analyzed weights were then compared to the total weight conservatively calculated for the pipe span. This comparison was repeated for all class 1 piping sizes with block forged tees. The results of the comparison were reviewed by Westinghouse and were found to be  :

acceptable by industrial standards and general practices. No revision of the piping stress analysis was necessary due to this weight effect. The class I stress reports were ,

revised to incorporate a discussion of this block forged tee evaluation. J

4. Reauest: I State explicitly that the ASME Code class 1 rules including stress indices, are satisfied .

for lines with block forged tees.

Response

The block forged tee geometries were reviewed with respect to ANSI B16.9 overall [

dimensional and design proof test requirements. In addition, the applicability of the ASME Section III Code stress indices was also determined. The results of these reviews concluded that the overall dimensional and design proof test requirements of ANSI B16.9 for the tees of concern were met. Having shown compliance with ANSI B16.9, the stress indices and stress intensification factors prescribed in the ASME F Code for B16.9 tees may be used in formal compliance with the ASME Code. The effects of the block forged tee wall thickness variations on the thermal transient stresses and the associated impact on cumulative fatigue usage factor were also evaluated. In addition, the weight deviation of block forged tees was reconciled. The ASME Code class I rules including stress indices, are therefore satisfied.

i El-2 i

y 1

ENCLOSURE 1(CONTINUED)

REQUEST FOR ADDITIONAL INFORMATION REGARDING ASME CLASS 1 BLOCK FORGED TEES

5. Request:

Verify that the block forged tees, especially the NPS 12" x12" tee, satisfy paragraph 9 of the ANSI B16.9 burst test requirement.

Response

Mr. Rodabaugh's report, (Enclosure 2), provides verification that the tees including the NPS 12" x 12" tee, meet the ANSI B16.9 burst test requirements, and are in formal compliance with the ASME Code. Since this was the largest straight tee and thus would be expected to have the least amount of margin, Mr. Rodabaugh suggested that UT wall thickness measurements be made on this tee at the next scheduled refueling outage, similar to those made for several other tees. While not required for compliance with either ANSI B16.9 or the ASME Code, GPC has agreed to take these measurements and evaluate them to insure that there is no pressure capacity concern.

6. Request: ,

Provide the root cause evaluation and the procedure to control the ASME class 1 -

block forged tees in the warehouse.

Response

The root cause was previously identified to be a misinterpretation of the VEGP,

" Piping Material Classification" document, AX4DR001. Specifically Note 4 to Table 2 that stated, "All special forged laterals or forged tees are to be forged and machined i according to details that have the purchaser's concurrence." The word "special " was  ;

meant to require block forged tees to have the purchasers concurrence, but was interpreted by the tee suppliers to mean that tees not meeting the overall dimensions of ANSI B16.9 would need the purchasers concurrence. The word "special" has been  ;

deleted. This note now requires all forged laterals and forged tees to be forged and  ;

machined according to details that have the purchaser's concurrence.

To remove the concern ofunknowingly removing a block forged tee from the warehouse and installing it in a safety system, GPC has removed all class 1 piping tees from the warehouse stock. This eliminates the need of putting special controls on the block forged tees. A review was also performed which verified that none of these tees i had been installed in safety systems since VEGP has been in operation. l El-3 _

I 1

i i

i E. C. Rodabaugh' I 7025 Scribner Vay r November 12, 1993 Dublin, Ohio 43017 614-792-9142 ,

Mr. Bill Ramsey Southern Company Services, Inc. ,

P. O. Box 2625 ,

Birmingham, AL 35202

Subject:

Vogtle B16.9 Tees .de from Block Forgings'(Block Tees) f

Dear Mr. Ramsey ,

This letter report summarizes my review of the subject tees.

(1) Scope The tees evaluated in this letter consist of:

Run Branch Supplier

.NPS Sch. NPS Va]1 10 140 6 160 Ladish 12 140 6 160 Custom Alloy 12 140 12 140 Custom Alloy.

• 10 140 6 160 Custom Alloy L Part (2) of this letter reaches the conclusion that, to meet  ;

Godell) require me nt s , evidence must exist that the block tees meet .the i requirements of B10.9(2), Section 9 " Design Proof Tests". Having - '

shown compliance with B16.9, the Stress Indices and Stress Intensification Factors prescribed in the Code for B16.9 tees may be used in formal compliance with the Code.

Part (3) of this letter describes'the evidence that the block tees do meet the requirements B16.9. Section 9 " Design Proof -Tests" .

Part (4) ci this letter goes beyond fornal Code compliance and gives evidence that specific block tees installed-at Vogtle would be j expected to meet the require ments of B16.9 Section.9, " Design Proof Tests". This part also discusses the pressure capacity margins of the  ;

block tees, relative to design pressure and temperature.

Reierences are indicated by [ x) ; the list of references is ,

included as Part (5) at this letter.

l Part (6) of this letter summarizes my conclusions.

I

)

E2-1

c.

i (2) Background f

In early 1987 it was discovered that tees, ordered to B16.9 and '

manuf actured f rom either block f orgings or f rom closed die forgings, were installed in Vogtle Units 1 and 2. Ve will use the term " block forgings" as' including both types of forgings.

B16.9, in Section 7 " Surf ace Contours", says: " Fittings made f rem block f orgings may be supplied subj ect to agreement between  ;

manuf acturer and purchaser. " Apparently, there was some mis-communication between Vogtle and fitting suppliers regarding this

" agreement" However, the signi2icant point in this 3atter is that- 4 B16.9 does not prohibit use of block forgings.

B16.9, in Section 5, " Ma t e r i a l" , requires that fittings shall be in accordance with SA-234, SA-403, or SA-420, These material specifications do not prohibit the use of block forgings for subsequent machining to B16. 9 requirements such as center-to-ends and welding end dimensions. Further, these specifications do not specify any surface contour controls.

The Code does not specify any suriace contour requirements on j B16.9 tees. Thus, tees made f rom block f orgings may be evaluated by i the Code guidance for B16.9 tees: provided the tees meeet all

• requirements of B16.9; in particular, Section 9 " Design Proof Test". l B16.9, Section 2 " Pressure Ratings, Par. 2.2 " Design of Fittings" is:

i "The design of fittings may be established by mathenatical analyses centained in nationally recognized pressure vesssel or piping codes or, at the manuiacturer's option, by proof testing in accordance with Section 9 of this Standard. The design of fittings  ;

that cannot be qualified by such analyses shall be. established by proof testing in accordance with Section 9."

The Code, footnote to Tables NB/NC/ND-3132-1, states: " Analysis per ANSI B16.9, paragraph 2.2, is acceptable only for caps and reducers." )

i Thus. to assure compliance with the Code, it is necessary to have l evidence that the requirements of B16. '9, Section 9, " Design Proof  ;

Test", have been met. The available evidence is described in the -j following part (3) of this letter. '

Havine shown that block tees meet all recuirements of the Coce I relative tb tees purchased to BlO 9, the Stress Indices and Stress Intensification Factors prescribed in the Code for B16.9 tees may be ]

used in f ornal compliance with the Code.  ;

I I

E2-2 I

1

'Y *

, , i Evidence of Meeting Section 9 cf E16.9 i (3)

(3.1) Ladish 10x6 Tees i The following.is quoted from Ref. L 31 : letter trom Bob Schmidt (Ladish) to Grissom (Soutern Company Services), 10/13/1993.

"Below is a listing of the tees from solid forgings that we. burst  :

test for the Navy: i 1/2" S/80 304 Tee (and A105) l 1" S/80 304L Tee i 1x1/2x1 S/80 304 Rtee ,

lx1x1/2 S/80 304 Rtee ,

lx1x3/4 S/80 304 Rtee  !

1-1/2 S/80 304L Tee (and A105) l' 2 S/80 304 Tee 2 S/160 304 Tee l

2x2x1/2 S/80 304 Etee .

2x2x1 S/80 304 Rtee {

2-1/2 S/80 304 Tee 3 S/40 A105 Tee  ;

3 S/100 304 Tee 'l 4 S/40 304 Tee I 4 S/120 304 Tee  !

6 XS 304 Tee s 6 S/160 304 Tee S S/120 3 0.' Tee None of these tests failed at iss than the calculated pressure and I all were machined f rom the sat; fergiag type blanks used to provide your 10x6 and 2x1 reducing tee," ]

It may be ncted that a 10x6 Sch. 140 (Run) tee is not included -l in the above list Relevant aspects of Section 9 of B16.9 concerning ,

extrapolation of burst test data are: j (a) Untested. tees must be "similar" or "of the same pattern" ac the j tested tees. The pertinent Ladish statement is: "all were machined R f rom the same forging type blanks used to provide.your 10x6... tees." l l

(b) One test 1#tting may be used to qualif y similar fittings no smaller than one-half nor ' larger than two times the ei e of the test-fitting. The test on a nonreducing. fitting qualifies 1or reducing fittings of the same pattern

.I Thus, the Ladish test of an 8x8 tee qualifies sizes from 4 to 16; )

including the 10x6 tee, j 1

(c) The untested fitting must have a t/D ratio not less than one-half I r.c r more than three t imes the t /D. of the test titting.  !

For NFS 6 Sch. 120, t/D = 718/8.625 = 0.083. For NPS 10, Sch.

140 t/D = 1.000/10.75 = 0.093; well within the range of extrapolation permitted by B16 9.

I l

1 E2-3 .

-- ~.- -. . . . .- ~. . . . . - -

1

-- -1

~

l 1

1 l

.j l

Thus, the evidence indicates that-the Ladish 10x6 tee has been .

-qualified per B16.9. Section 9 Design Proof Tests. Indeed, the I

lengthy list of burst tests and the state ment that "None of these tests failed at less than the calculated (per B16.9) pressure..." is j very reassuring that Ladish is well aware of.the significance of the ' '

l

" .nesign Proof Test" Section of B16.9.

(3.2) Custom Alloy, 12x6, 12x12 and 10x6 Tees Reference I41, Custom Alloy, letter dated 9/28/93, provided documentation of a burst test on an NPS 6x6, Sch. 160 tee. This test.

was run on 6/18/87 in response to a request f rom Southern Ccmpany ,

Services. The test burst pressure was well above the calculated-(per B16.9) burst pressure. ,

t The tested tee was stated to be "manuf actured f rom open die block forging".

i The following is quoted from Ref. 1 53, Custom Alloy letter dated 10/30/93. ,

1) Enclosed is a dimensioned drawing of the burst tested' tee which .li was recovered f rom an old drawing file. It is my opinion that the tested tee was in fact nachined to these dimensions.  ;

3) During the time that block tees were produced, all tees were j designed with the contours as shown on the attached drawing.

.j The " attached drawing" is labeled "S 'ight Tee (Block), 6 NPS x SCH. ". The drawing is neither numbered ar dated. The words "all ,

tees were designed with the contours as sh a on the attached drawing" is unlikely to be true ior the tees furnist.J for Vogtle. Ve [

interpret the words to mean that the contours shown on the attached drawing were scaled up for the larger sizes of tees furnished for Vogtle. t r

The three criteria for extrapolation of burst test data, .

analogous to those discussed in (3.1), are:

(a) Untested tees must be "similar" or "of the same pattern" as the  ;

tested tees, The pertinent Custom Alloy statement is: "During the time that block tees were produced, all tees were designed with. ,

contours (pr esu ma bly , scaled up) as shown on the attachec drawing." -)

Ib) Cne test f itting may be used to quality similar fittings no j smaller than one-hall nor larger than two times tne cire et the test.

21tting. The test on a nonreducing :itting qualifies 1or reducing fittings of the same cattern. ,

Thus, the Custen Alloy test of the 6x6 tee cual111es tees with.  !

run sizes f rom 3 to 12: including the 12x6, 12x12 and.10x6 Custom Alley tees. r t

'I .

4 h

E2-4  !

i

(c) The untested fitting must have a t/D ratio not less than one-half j nor more than three times the t/D of the test fitting.  ;

i For NPS 6. Sch. 160, t/D = .718/6.625 = 0.108. For NPS 12 Sch. ,

140, t/D = 1.125/12.75 = 0.086; for NPS lo, Sch. 140, t/D =  ;

1.000/10.75 = 0.093. These t/D's are well within the range of '

extrapolation permitted by B16.9.

• Thus, the evidence indicates that the Custom Alloy 12x6, 12x12 and 10x0 tees have been qualified per B16.9 Section 9 " Design Proof Test".

While in formal compliance with the Code, the Custom Alloy data.

is less complete than.the Ladish data. This aspect, in part, motivated the supplementary checks discussed in the following Part (4) of this letter.

(4) Supplementary Checks of Pressure Capacity  ;

Par. 2.2 of B16.9 says: "The design of fittings may.be j established by mathematical analyses contained in nationally recognized presure vessel or piping codes...". Ve are not aware of '

any national (USA) pressure vessel or piping code that provides an analyses method that purports to estimate the burst pressure of tees. 1 However, VRC Bulletin 335I6) does provide a method to estimate the burst pressure of tees. The following page is page 55 of VRC 335.

It gives two " criteria" equations. These equations have been used to check block tees in which the wall thicknesses were measured by UT.;

see Ref. [73.

Table 1 identifies the specific tees that were examined. The UT measured thicknesses, T, Tx and t are identified by Figure 1. The ,

" pad" length, Lp, where a measurable pad existed, was. estimated from .

the photographs identified in the column in Table 1 headed " Photos",

For the two tees where a pad existed. Lp was about 2 inch. The.

thickness T, used in the VRC 335 evaluations, was taken to be ,

ti+Tx)/2; e.g., for Tee 3 T(VRC335) = (1.00+1.15)/2 = 1.07 inch.

• Table 2 shows the results of the VRC335 evaluations. For all except tee X. T/Tr = ratio of burst pressure of tee to the burst pressure of the designated run pipe, is greater than 1.00; i.e., the tees would be expected to meet Section 9 of B16.9. Tee X, by VRC335 Eq. (1), has T/Ir slightly less than 1.00.

!able 2 also shows the results of the VRC335 evaluations of e' C.A 0, the 6x6, Sch. 160 tee tested by Custom Alloy. The thicknesses.

ter VkC335 evaluation indicated in Table 2 were obtained f rom the i drawing p*ovided by Custom Alloy, see Ref. [ 5) . The VRC335. evaluations  !

inoicate this tee would be expected to be stronger than the designated..

run pipe, thus, in the burst test, failure would be expected to occur

n c r.e of the Etraight pipes attached to the tee for bur st testing.

j E2-5 I

~!

l 6

I

[

mate tensile strength to establish allowable stresses, j-- 4  ;

i.e., ASME Section III, Class 1; ASME Section VIII. _-  ;

Div. 2 and ANSI B31.1, # l i The following 8.3 provides suggestions for a test program to investigate the change in performance ob. , i tained by pad reinforcements. {

~

8.2 Recommended Addition to ASME Section VIII. L Div.I t.dd to UG-36, following present (g): ,'

(h) Pipe Connections Under Internal Pressure. Pipe /

connections, as defined and limited in Appendix 1-9, g may alternatively meet the rules in Appendix 19 in- 3 7 .

stead of those given in UG 3G through UG-46.  ;  !

Add to Appendix 1, following present 1-8: t  !

1-9 Alternative Rules' for Pipe Connections under Internal Pressure _ __ ___-~ '

(a) Nomenclature:These rules are applicable to configurations shown in Fig.19.

2 d - mean diameter of branch pipe,in.

d.O u L < M u / 4-r D '= mean diameter of cylindrical vessel,in. m 4 , , ,., 3f,,,g,9 4, ,

t . = wall thickness of branch pipe,less corrosion allowance,in. .

'2

t. = wall thickness of nozzle, less corrosion allow. Dg.1-9-ConHgesuons covered t>y enerneuve rules t ance, in.

T = wall thickness of vessel,less corrosion allow- t ance, in. those conducive to corrosion or stress-corrosion -

T, = PD/2S,in. cracking, may significantly reduce the cyclic j P = design pressure, psi pressure espacity. Significant fabrication de- -

S = allowable stress, Table UCS.23 fects w uld also reduce the cyclic pressure ca- .

L = axiallength of nozzle with thickness t.,in. pacity.)

t.w = nominal wall thickness of ANSI B36.10, std. (c) Criteria Equatfor.s: The limits expressed by wt., for NPS 510, = 0.375 in, for NPS >10; or the following equations shall be met.  ;

d > 24 in. 2 + 2(d/D)88(t /T)La + 1.25A by-A = (d/D)JII/T 5 2.95(T/T,)

1 + (d/D)"(t,,/T)"

(b) Scoper These rules apply under the following

[A(r /T)2 + 228(t./T)(d/D) + B] A + 155 i conditions:

8 ~'

(1) The pipe connection is in a cylindrical vessel 108A + {228(d/D)' + 228] A + 152 located not less than 0.5(DT)W from any other 2: (0.93 + 0.005A)(T,/T) (*)

oss structural discontinuity such as a head or A = 162 for to/T $ 1.000; A = 54 for t,/T > 1.000 (2) The spacing between the edge of the opening B = 210 for to/T 51.000; B = 318 for t,,/T > 1.000 and any other opening is not less than two times I their average diameter; see Fig. UG 42. (d) Minimum Nozzie Thickness:Regardless of t. i (3) The pipe connection is circular in cross section that satisfies (c), to shall not be less than (7/8)t.w i and its axis is normal to the surface of the vessel, through an axiallength of E..

(4) D/T 5 250, d/D $ 0.5 8.3 Suggested Future Research Work (5) Design temperature 5650' F

. The usefulness of pad reinforcements is not clearly (6) Materials: Carbon or Low Alloy Steel, with S

, established by available data. Also, the significance of -

per Table UCS.23 not exceeding 17.5 ksi.

the high nozzle stresses given by WRC 297 in relation (7) Nozzle weld to vessel with full penetration weld.

to failure (e.g., cyclic moments) has not been estab-(8) Not more than 5000 anticipated cycles of design lished. The following test program is intended to in-pressure. (The allowable cycles is based on tests vestigate both of these uncertainties, at room temperature with water as the pressur-The test program involves 12 pairs of models in 24 x fring fluid. Inservice environments, such as 0.375 in. (D/T = 63) A106 Grade B vessels (or run pipe). In each of the 12 pairs, one model would be rs. .onn.ctin, e,pm, k.4 c.p.<,ir .r pin. conn.ci nn. 4 n.o u, o without a pad; the other with a pad. Nozzles would be i Eof 44 &.T,

6. pp p.U."'DU="I4"'7n.",*.'n"4%'d.

r.w

.'$ 2,4 and 8 NPS, std. wt., A106 Grade B.The test matrix for "No Pads" is shown below, along with "Expecta-Area Replacement Rules for Pipe Connections 55 E2-6 i

- 1 i

l l

Table 1: Summary of Data on Tees f rom Ref. [ 7] '

Tee- Nominal Supplier Isometric Photos UI Measured Dimensions lio . Size 2K4- T Tx t ha ) Os) (b) (a) (c) (d) (d) (d) 1 12x6 C. A. '1201-036-01 D-2,3,4 1.35 1.35 0.90 {

1 10x6 C. A. 1204-039-02 D-8,9 1.00 1.15 1.00 1 4 -10x6 C. A. 1204-042-01 None 1.15 1.15 0.90 d 5 10x6 L. 1204-045-01 F-2 to 6 1.00 1-.35 0.84 -l X 2x2 T. ---

G-2,3 0 35 0.35 0.43 l I

?

(a ) Per Ref. (73 Att. A. Unit-2 Tea "X" is not listed in Ref. [7), Att. A. It is a Sch. 160 tee; .

o included as an example of the pressure capacity of small size. block tees.

(b) C. A. = Custom Alloy l L. = Ladish T. = Tubeline. H (c) From the indicated Attachments of Ref. [7]

(d) Thicknesses in inches, See Figure 1 and text l

l l

l l

l l'

i E2-7

1

i 4

, .-_n.- -

, 3_ '

l

. . . . . _. . ..,F ,e ,.1 -

i  ;

. . . . }. l , /.. _.

1- - , , .._. , , . .

., , . . . ,. - _ .

• y- '

.~e_-y=--.**1 F"'*"". , ,* T . , , 9'- ," j l 1 I

._ t ., . . . /.z. x .'c . , ,

, . . . . ,., . , , . . . ,_, , /'[ I-[ -.I di

. .,_ ,' i l l I

. - . <.. _._ "__ _ al- ._. ,_ -, , . - . . -, - , - , . . . - - - . - , , .

l

_ _ _ _ . _ . _ . _ . . _ . . _. _ +P ,mI e

_3/Mc b _,

_.k 1,L_. 9_.,-1,-,,.-,_,_.,_, '  !  !

_.._ L n - <

_ , _c. _. _ _., ,

1 i

T .

,__,_,r--- - - r ---- , --

-l ,

+_ ,_ .

m ,

I * .I j '

l t I f I a

I f l - ' l ,

t1 . .  : .

4 I ' I k l f  ! f f

_..,__._____of _. ,

I i

____ a _ , , ,

h h 6 I I l  ! l  ! I l l l

__ ._ i _. _. _ _ _ . .M u n ___, ._,

q __ _,  :

! I I I

IlI 1 i 4 , , , .

..q . , - ~ _ , - . . , - -- - -

i j

- - l i i 1 r i i i l i I , I I-l I "7 >

i '

l ' ' '

i i :1 I i i lijjtI i l l l 1 i i i i i i  ! l i i lj ! l I I liil  ! I II

. i i i n.7zoi i i i i i i ..

. > -'. 4 i , , i , i . 4 . . i ir i i i .

. ; j 4 i i  ;  ;  ; ,

- - - ~

!! , i

!  ; i i ijj: } }! .

! l 7 ,__.7  ; ,

! 4 I i '

., _ _ . , . . .4 _ . . . _ . . _ . _ . . _ , . . . . . . . _ . _ . . ...._-,_.7 7 _,..,i..~._q.__., _,..,_y I a (

, . . _ , _ .- - , 4.~., . , . _ , , ._.. __, ,.. . . . _ . ,

t ,l i

I t >

i

- , . . . _ , - - . , . . , . _ , p,,,,_,_. . __ ..

_q .~.q . _

._._..__._.._..,'_.._..-_.._ }

l  ! l j c

,., ,_.__.,_' --l

,..,_.,_.7

,__._...._,_,_,_.,,'_.3_....___,_.r, ,

I l

t

. 1 I i 1 l

. . . _ _ . . , _ , - , _ . , _ . . - . 3 ,

,._7_.._,___,_,.-._e._,__., '

,  ; 3 I I l  !

l l l

.' s. .

.r,_...-.-,-... , , , , .

I . *

. .1 ,i s 1 1 1 1 I l l l

~

i i i i 17 i i i i 1 i l 1 E2-8 i 4

-- . . . . - . .. . - . . = . .- . . . .

l l

,l I

-Table 2: Summary of .%TC Bulletin 335 Evaluation of Tees j

'l Tee D T d t Ir T/Ir '

Eq. (1) Eq. (2)  !

(a) (b) (c) (b) (c) (d) (e) (e) )

I 11.625 1.350 5.907 0.900 1.125 1 10

. 1.08  !

(1.125) - ( 0. 718 ) .

3 9.750 1.070 5.907 1.000 1.000 H1.03 1'.09 .!

(1.000) (0.718) 4 9.750 1.150 5.907 0.900 1.000 1.04 1.05 (1.100) (0.718) i l

5 9.750 1.170 5.907 0.840 1.000 1.02 1.02 1.000. (0.718)

X 2.032 0.350 2.032 0.430 0.343 0.98 1 03 *

(0.343) (0.343) i l

i C.A.6 5.907 0.915 5.907 0.915 0.718 1.05 1.13  !

(0.718) (0.718) 2 11.625 1.430 11.625 1.430 1.125 0.99 1.08 I (1.125) (1.125) '

i (a) See footnote (a) to Table 1. See text for discussion of the tees ident if ied as "C. A. 6" and "2".

'f (b) Mean diameters based on nominal dimensions i

(c) First lines wall thicknesses from UT.measuremerts .;

Second lines, ( ), are nominal wall thicknesses *

(d) Nominal. wall thickness of designated run pipe  :

(e) Obtained f rom the Criteria Equations given in VRC Bulletin 335, ]

page 55, solved for T/Tr = ratio of burst-pressure ci tee to the  ;

burst pressure of the designated run pipe. 't b

}

E2-9 -

1

p The Custom Alloy tee did fail in one of the straight pipes. It did so at a pressure equivalent to T/Tr = about 1.2. This suggests that the VRC335 evaluations, which are based on burst tests of carbon steel branch connections, are conservative as applied to block tees made of austenitic stainless steels.

The tee in Table 2 identified as "2" represents the 12x12, Sch.

140 tse installed in Vogtle Unit-1. This unit is in operation, thus UT wall thickness measurements have not been made, it is identified, in Att. A of.Ref. [7] by Isometric 1K4-1201-149-02. It was supplied by Custom Alloy.

The thicknesses of 1.43 inch used for VRC335 evaluations are based on a scale factor of 1.125/0.718 applied to the drawing of the tested Ox6 tee; i.e., for the 12x12, Sch. 140 T=t=

0.915*1.125/.718 = 1.43 inch. It can be seen.in Table 2 that, by '

VRC335 Eq. (1) evaluation, T/Tr = 0.99 Considering the probable conservatisms in VRC335 as applied to austenitic stainless steel block tees, it is quite likely that the 12x12 Sch. 140 tee has the pressure capacity of the designated run pipe. However, the scale-up factor may not be accurate. Thus, we.suggest that at the next scheduled outage ,

of Vogtle Unit 1 UT wall thickness measurements be made on this  :

particular tee.

The Design Pressure f or the subject tees is 2485 psi at a Design ,

Temperature of 650F. For SA-182, Type 304 =aterial, the minimum expected ultimate tensile strength (Table U of Code Part D) is Su =- _

63.5 ksi. For T/Tr = 1.00, the expected burst pressure of tees is:

Run NPS Sch. T D Pb = 2*Su*T/D inch inch psi 12 140 1.125 12.75 11200 10 140 1.000 10.75 11800 Thus, the margin against bursting at the Design Pressure is about ,

11200/2485 = 4.5. This is more than the margin of 3 implied by the Code use of allowable stress = Su/3 for Class 1 components design. ,

The margin increases as the nominal sice decreases; e.g. ,

Run NPS Sch. T D Pb = 2*Su*T/D -j inch inch psi 6 160 3.718 6.625 13800 l 4 160 0.531 4.500 15000 t 2 160 0.343 2.375 18300  !

These comparisons indicate that the block tees would have ,

Code-compatible pressure capacity, even if T/Tr. were less than unity; e.g., for NPS 12 Sch. 140, not less than 2485x3/11200 = 0.67; for-NPS 2,Ech. 160 not less than 2485x3/18300 = 0.41. . This alleviates any real concern about the pressure capacity of small NPS, Sch. 160 block .;

tees.

i 1

i E2-10 q l

l l

-1

l-(5) References

( 13 ASME Boiler and Pressure Code. Section Ill, Div. 1 " Nuclear  ;

Power Plant Components", 1992 Edition.

(2) ASME/ ANSI B16.9-1986, " Factory-Made Vrought Steel Buttwelding Fittings"-

(31 Ladish Co., Inc. Letter Dated Oct. 13, 1993 Subjects Ladish Forged Reducing Tees. Bob Schmidt (Ladish) to Phil Grissom (Southern  ;

Company Services).

[4] Custom Alloy Corp. Letter Dated 9/28/93, Ref. Forged tees from open die forgings, Frederick E. Trach (Custom Alloy) to Phil Grissom (Southern Company Services), Attachment : " Burst Qualification Test ,

Verification", 4 pages.

[ 53 Custom Alloy Corp. Xemorandum Dated 10/30/93, Ref. Fax of 10/19/93; Letter, EC Rodabaugh to Chris Ng, 10/12/93, Frederick N.

Trach (Custom Alloy) to Phil Grissom (Southern Company Services)

At tachme nt s : Custom Alloy drawing,

Title:

Straight Tee'(Block), 6 NPSxSch., no date nor number;.and Custom Alloy drawing.

Title:

Velding End Detail, 6 NPS x Sch. 160, dated 10/23/81, no number. '

C6) Velding Research Council Bulletin No. 335 August 1968, " A Review of Area Replacement Rules for Pipe Connections in Pressure Vessels and Piping", E. C. Rodabaugh. ,

I 7] Intercompany Memo Dated 14-Oct-1993 RE: Vogtle ASME Class 1 Block Forged Tees, From Phillip D. Grissom (Southern Company Service) to E. C. Rodabaugh and Ken Chang, Attachments: 1 A Matrix of Class 1 Large Bore Forged Tees B Custom Alloy Burst Test Report (Ref.-I4])

C Correspondence with Custom Alloy D UT and Photgraphs of Custom Alloy Tee Samples E Ladish Burst Test and Correspondence (Includes Ref. (33)

F UT and Photographs of Ladish Tee ..,

G UT and Photographs of Tubeline 2" Tee Sample I

l E2-11

E

[ ..a m

9 (6) Su mma ry Part (3) of this letter cites the evidence that-the subject block tees at Vogtle meet the requirements of Section 9 of B16.9. Part (4) supplements Part (3) by demonstrating, by use of VRC Bulletin 335, that the block tees at Vogtle would be expected to meet the requirements of Section 9 of B16.9.

Having shown compliance of the block tees with B16.9, the Stress-Indices and Stress Intensification Factors prescribed.in the Code for ,

B16.9 tees may be used in' formal compliance with the Code.

Part (4) of this letter shows comparisons between the Design Pressure of 2485 psi at 650F with the pressure capacity of the block '

tees. This indicates, in particular, that there is no real concern about.the pressure capacity of small size block tees.

As added reassurance, we suggest that at the next-scheduled outage of Vogtle Unit-1, UT wall thickness measurements be made on the Custom Alloy, 12x12 Sch. 140 tee (Isometric 1K4-1201-149-02)

F I trust the preceding will be of use to you in your evaluation of the Vogtle block tees. Please let me.know if I have mis-interpreted any portion of the information you supplied to me or if you have any questions or comments concerning this letter report.

Yours'Very Truly

8. c. M t E. C. Rodabaugh Copy to: Chris Ng (Vestinghouse)

File: Vogtle. Lil E2-12

_ _ __._ - .