ML20084P167
| ML20084P167 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 05/15/1984 |
| From: | Finneran J, Iotti R, Stevenson J AFFILIATION NOT ASSIGNED, EBASCO SERVICES, INC., TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | |
| Shared Package | |
| ML20084P084 | List: |
| References | |
| OL, NUDOCS 8405170434 | |
| Download: ML20084P167 (17) | |
Text
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Attachm:nt-1 i
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, May 15, 1984 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of )
) Docket No. 50-445 and TEXAS UTILITIES ELECTRIC ) 50-446 i
- ) (Application for (Comanche Peak Steam Electric ) Operating Licenses) 1 Station, Units 1 and 2) )
AFFIDAVIT OF J.C. FINNERAN, R.C. IOTTI AND J.D. STEVENSON i REGARDING ALLEGATIONS INVOLVING j AWS VS. ASME CODE PROVISIONS "
We, J.-0, Finneran, R.C. Iotti and J.D. Stevenson, being first duly sworn, hereby depose and state as followsl-(Finneran) My name is John C. Finneran. I am the Pipe Support Engineer for the Pipe Gupport Engineering Group at Comanche Peak Steam Electric Station ("CPSES"). In this position, I oversee the design work of all pipe support design organizations for Comanche Peak. I have previously provided testimony in this proceeding. A statement of my professional and educational qualifications was received into evidence as Applicants' Exhibit 142B.
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., 1 Except as otherwise indicated each affiant attests to all parts of this affidavit.
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8405170434 840516 l PDR ADOCK 05000455 9 ppR
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N (Iotti) My name is Robert C. Jotti. I am Chief Engineer, Applied Physics for Ebasco Services, Inc. A statement of my professional and educational qualificTtions is attached to Applicants' letter of May 16, 1984, to the Licensing Board.
(Stevenson) My name is John D. ,Stevenson. I am the President and Managing Partne'r of Stevenson a d Associates.
My educational and professiona*1 qualifications are attached to Applicants' Motion for Summary Disposition of Certain CASE Allegations Regarding 'AWS and ASME Code Provisions Related to Welding (April 15, 1984).
Q. Are you f amiliar with CASE's allegations that there are several design related provisions. included in the AWS Code 1
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4 which are not considered by, the.33 rte Code nor used at CPSES, t'
specifically"Multiplicationfaptorandreductionfactors joints," "Limita'ckons on angularity 'for for skewed "T" skewed "T" joints," " Calculations for punching (actually a reduction factor for the weld) shear on step tube joints,"
and " Design procedure for joint of tube to tube with Beta equal to 1.0"? /
A. Yes, we have evaluated these four design related items which CASE has characterized as AWS Code provisions not considered in ASME requirements or in CPSES design practices.
Q. In an overview fashion what did<your evaluation entail?
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A. We first examined the AWS Dl.M Code to determine if there f
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( were any AWS code provisions,related to the item.
We also l examined the AISC Specification fur,the Design, Fabrication
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i i s e and Erection of Structural Steel for Buildings, since the AWS Code,is intended to be complementary with a specidica-tion for design and construction of steel structures (see Section l'.1 of AWS Dl.1). Next we examined applicable k portions of the ASME Code, e.g.,Section IX (Welding and ,
c Brazing Qualificacions) and Subsection NF (Component g e Supports) and Appendix XVII (Design of Linear Type 2 Supports by Linear Elastic and Plascic Analysis) of Section III.
Finally, we examined design practices used at CPSES., ,
Q. Do the AWS and ASME Codes contain all the information necessary to design a weld joint? -
A. No. Design of structural steel including welded connecti[qs or joints should consider not only the detailed welding
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p,rovisions of applicable codes such as ASME Section IX or .
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AWS DI.1, but also the complementary requirements of other Codes [(e.g., ASME Section III in the case of ASME component
,anpports). In addition, a properly designed welded cNnnection also requires the training, experience and skill of the design engineer to provide structural design
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adequacy. See for example the Forward to the Commentary to the AWS Dl.1 Code which states in pertinent part that "It I
should be recognized that the fundamental premise of the o
Code is to provide general stipulations applicable to any o
situation and to leave sufficient latitude for the exercise of engineering judgement." Considering the infinite variety and combination of welded joints or connection
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configurations together with types of welds possible, no published standard can possibly cover all possibilities. In the final analysis, the engineer designing the weld joint nust be relied upon to assure the st'ructural adequacy of the design.
Q. Describe the results of your evaluation of the
" multiplication factor and reduction factors for skewed "T" weld joints"?
A. AWS Code requirements regarding multiplication and reduction factors for skewed T-weld joints are contained in Appendix B of the AWS Code, which sets forth limitations on effective throat thickness for fillet welds in skewed T-joints designed in accordance with the AWS Code. This is but one of the parameters effecting the load capacity of the joint.
While the ASME Code does not have explicit requirements governing this area, compensatory requirements have provided assurance of acceptable load carrying capacity.
For example, Appendix XVII (paragraph 223?.c!) of Section III of the 1974 ASME Code required that T-joint basemetal thru thickness allowable tensile stresses be limited to half the normal tensile allowable. This assured that a welded skewed T-joint designed in accordance with this provision would be more conservstive than a similar welded joint designed in accordance with the above noted provisions of the AWS Code. To illustrate the above, consider a 60 skewed T-joint of four inches in length with 1
< w- 4
. e a 1/4 inch heel and toe weld. To determine the load carrying capacity of the weld using the limitations on skewed T-joint effective throats contained in Appendix B of AWS Dl.1, the following equation in Appendix B is used:
F = w/k x .707 x 1 xS a w
where:
w = weld leg length 1 = length of weld S = allowable stress in the weld material a
k = coefficient set forth in Appendix B, Table B F = load carrying capacity of the weld F for (60 ) (limiting) = 1/4 x .707 x 4 x 21,000 = 20,911 lbs.
.71 F for (135 *) (limiting) = 1/4 x .707 x 4 x 21,000 = 11,333 lbs.
1.31
- (shougduse120 to be consistent with 60 acute angle, but used 135 as the limiting more conservative case)
Total load = sum of two load capacities = 32,244 lbs.
To determine the load carrying capacity using the ASME Code provision noted above, and the bounding material used at CPSES (cold rollad tube steel, ASTM A-500), the following equation is used:
F=wx1 xS w ct where:
w = weld leg length.
1,= length of weld l
l k.
t _ _ _ _ _ _ _ _ _ _ _ _ _ - _ . - _ _ _ _ _ _ _ _ _ _ ._. _
S = weld contact surface tensil allowable stress (.3 times the specified minimum yield strength of the plate, Appendix XVII (paragraph 2211(c)) of Section III of the ASME Code)
F= load carrying capacity of the weld F = 1/4 x 4 x 0.3fy = 1/4 x 4 x 0.3 x 42 ksi = 12,593 lbs.
F for Obtuse side = F for acute side Total load = sum of two load capacities = 25,186 lbs.
As can be seen, the load limitations using the ASME provisions are more restrictive than the AWS provisions.
The above discussion is not meant to imply that engineers at CPSES did not use considerations as set forth in the AWS Code. Documentation to the QA Group in August 1982 reflects that weld designers at CPSES were using considerations virtually identical to that noted in Appendix B of AWS Dl.l. See the attached letter CPPA-22,616, which indicates the methods being used by all design organizations at that time (Attachment 1).
(Finneran) To verify the adequacy of these measures, we performed an evaluation of 13 skewed T-joint designs at CPSES selected at random, and in all cases these joints met or exceeded the load capaciti.es required by AWS. The highest stressed weld was only stressed to 39 percent of AWS allowables ( 21 ksi) . See Attachment 2 for a summary of these results as they applied to ASME allowables of 18 ksi.
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It should be noted that the SIT Report at p. 51, after an analysis of skewed T-joints, also concluded that "the design procedures being utilized by the three pipe support design groups for skewed joints are based on sound engineering practice."
In conclusion, the allegations of CASE that design practices at CPSES regarding skewed T-joints is flawed because it does not consider AWS requirements regarding fillet weld throat thickness is without merit.
Q. Would you please describe the results of your evaluation of the limitation on angularity for skewed "T" joints.
A. The AWS Code requirement regarding this issue is set forth in Section 2.7.1.4 of AWS Dl.l. This Section establishes angle limitations for fillet welds used in skewed T-joints.
These limitations do not apply to welds qualified by test.
See Appendix E, Table E-2, to AWS Dl.l. Both the AWS Dl.1 and ASME Codes permit weld procedures without such limitations provided the weld procedure used is qualified by test.
Applicants' practices, as set forth in CPPA-22,616 (Attachment 1), are virtually identical to those set forth in the AWS Code regarding this issue. In addition, as previously noted, ASME Code provisions provided compensatory measures to assure the adequacy of skewed T-joint welds.
I See e.g., Appendix XVII (paragraph 2211(c)) of Section III of the 1974 ASME Code. Evaluations of randomly selected l
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. o skewed T-joint welds (as noted above) provide assurance that l AWS allowables were not exceeded. This conclusion is reinforced by the SIT Report at p. 51.
In sum, CASE's allegations that CPSES' design practice is flawed because it does not consider AWS requirements regarding angularity limitations on skewed joints are without merit.
Q. Would you please describe the results of your evaluation of calculations for punching shear on step tube joints.
A. The AWS Code provisions regarding punching shear are part of empirically derived equations which take into consideration numerous other factors (e.g. , axial and bending stresses in the main member). See Section 10.5.1 of the AWS Code.
These equations, in essence, combine punching shear analyses into a complete local failure assessment of the effected joint. It should be noted that AWS punching shear analysis requirements were introduced to deal with large tubular s tructures (e.g. , of fshore platform supports) with relatively large flange width to flange thickness ratios.
These conditions do not apply to relatively small tubular members used in pipe supports at CPSES. Accordingly, punching shear is not a significant problem at CPSES.
However, on a case by case basis, when the CPSES designer believes it may be appropriate, punching shear is calculated for a given weld joint.
9 O (Finneran) To provide assurance that punching shear was not a problem, I had a punching shear evaluation performed on 12 tubular pipe supports (both stepped and matched connections) selected from the worst cases provided in Case Exhibit 669B. The evaluation reflected no instance where punching shear was a problem, and the highest ratio of actual stress from punching shear to the AWS allowable was
.57. (See Attachment 3. )
It should be noted that Applicants' design process regarding local stress effects (e.g., punching shear) was evaluated by the SIT, and based on a sample of 100 vendor certified supports, was found to be acceptable. (See SIT Report at pp. 54-58, item 4.)
In sum, Applicants' design process reflects adequate consideration of the effects of punching shear, and CASE's allegations are without merit.
Q. Would you please describe the results of your evaluation of design procedure for tube-to-tube joints with betas equal to 1.0.
A. The AWS requirements regarding design of tube-to-tube joints with beta equal to 1.0 are set forth in Section 10.5.1.1 of ;
AWS Dl.l. This section has two equations for determining the allowable capacity for loads normal to the main member:
F 1
= 2t a ex (0.6 Q f F y) (1) I I
where:
F = load capacity of the main member along its sides as determined by web crippling effects t = thickness of branch member tube wall c
a g = width cf loaded area along the tube wall O g = stress interaction factor based on the main member stress level. It ranges from .72 to 1.00 as shown in Table 10.5.1 of the AWS Code F = specified minimum yield strength F
2
= 2t b [Q B f y-0.6y where:
F = 1 ad capacity of the main member along the heel 2
and toe welds b = width of branch tube perpendicular to the main member cross section O = ge metric modifier factor determined from Table B
10.5 as a function of B y = geometic parameter as defined in Figure 10.1.2(M),
AWS Code The AWS Code allowable static load for the connection is F =F7+F2; (Equations 1 plus 2).
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1 The capacity of tube-to-tube connections with beta equal to one is also addressed in the ASME Code in NF Appendix XVII (paragraph 2261.2) of Section III in a substantially similar manner. The ASME formula for the allowable capacity for loads normal to the main member is:
F m
= 2t (N + 2k)(.75F )y (3) where:
2t a is essentially equal to 2t (N + 2k) cx N= length of bearing equal to A k = distance from outer face of flange to web toe of fillet (Finneran) For tube-to-tube connections with beta equal to one, these provisions of the ASME Code are requirements for CPSES.
In sum, the ASME Code contains specific requirements regarding tube-to-tube connections which provide results which are substantially similar to those set forth in the AWS Code. These provisions of the ASME Code are requirements for these type joints at CPSES. Accordingly, CASE's allegations regarding this issue are without merit.
f o 5 J
Robert C. Iotti Sworn to before me this 15th day of May, 1984.
% f% & &:dw Notary Public
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John C. Finneran, .
Sworn to before me this 15th day of May, 1984.
fm& M Notary Public John D. Stevenson i
Sworn to before me this 15th day of May, 1984.
A[M Notary Public Mg Ccmminion Expires January,31,1989
ATTACIIMENT l_
1 XAS UTILITIES SERVICES INL. INDE^, t.D CPP.k22,616 .
OFFICE MEMOR ANDUM DATE:
-- Cordon Purdy/ Quality Assurance Mang. Glen Rose. Texas August 27. 1982 Subject COMANCHE PEAK STEAM ELECTRIC STATION PIPE SUPPORT WELDS AT TUBE STEEL SKEWED JOINTS Ref.: Pipe Support Engineering, ITT Grinnell and NPSI are analyz-ing fillet welds at skewed tube steel joints as follows:
Attachment 1,A,e)l35 Fillet welds at obtuse angles greater than 135 are ignored in design verification, unless the weld exhibits a " mach.
req'd." note.
Attachment 2,B,90(e[135 The effective throat of these fillet welds is calculated by engineering based on the dim.'s of the weld shown.
Attachment 1,C,90pe}60 The effecitve throat is calculated by engineering by multi-plying the leg size (s) by .707.-
ative as the angle approaches 60,This becomes more conserv-
{ Attachment 1,D,60)e45 This is outside the range of a fillet weld. However, many BRH's exist with a fillet weld symbol shown. The weld is actually a "V" groove and engineering calculates the ef-fective throat as such. In the field this is a difficult ueld to measure. Therefore, we've computed the measure-ments at the face of the welds on attachment two for your inspectors convenience.
As noted above, this memo addresses tube steel skewed joints. Pipe connections will be addressed separately.
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