ML19031B396
| ML19031B396 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 03/11/1976 |
| From: | Mittl R Public Service Electric & Gas Co |
| To: | Vassallo D Office of Nuclear Reactor Regulation |
| References | |
| Download: ML19031B396 (3) | |
Text
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Public Service Electric and Gas Company 80 Park Place Newark, N.J. 07101 Phone 201/622-7000 United States Nuclear Regulatory Commission Washington, D. c.
20555 Attention:
Gentlemen:
NRC LETTER,OF FEBRUARY 3, 1976 DOCKET NOS. 50-272 AND 50-311 As noted in your letter requesting additional.information, the major changes in requirements involve radiographic inspection technique.
The original edition of B31-7 was deficient in this area as evidenced by the need for ANSI B31 Code Case 72.
(Copy attached)
The ANSI committee recognized tl::iat the radiographic requirements of B31.7 were not suitable for field radiography of thin wall and sma~l diameter piping butt welds.
The incor-poration of Code Case 72 without change into the 1971 edition of Section III ASME Boiler and Pressure Vessel Code and its retention up to the present edition demonstrates that it pro-vides a realistic approach to field radiography.
The requirements of Cocie Case 72 were incorporated into our radiographic technique in 1971.
Virtually, all of the field butt welds were radiographed with this technique.
This would include all nuclear classes.
In addition, radiographs of Nuclear Class III cement lined pipe were difficult to interpret.
The 1970 addenda to B31.7 allowed 100% magnetic particle inspection in lieu of random radiography.
This provision was also incorporated into Section III 1971 Edition.
The service water system has Nuclear Class III cement lined pipe that utilized this alternate inspection method.
Our use of a later code was restricted to inspection and did not involve requirements from Section III such as materials, stress calculations, etc. that could modify our original design.
Consequently, other requirements from a later Code would not be
~pplicable.
Therefore, we believe that the integrity of our
- .*fie.la' 1-ields has not been compromised and that we have complied
- with our *FSAR commitment to use ANSI B31.7 wherever possible.
JER,*RHD ':'pa*c The Energy Pnople
,~~;:7;;rrs, R. L. Mittl General Manager - Projects Engineering and Construction Department 95-2001 (400M)
ANSI B31 CASE 72 August 1970 l~TERPRETATIO~S OF UllJE FOR PRESSLRE pu>1:-..;G Case 72 (Reopened)-Radiography of Piping Inquiry:
In view of the special prob-lem~ involved in the radiography of welds in pipe and o.ther similar contig11ra,tions wluit addit.iona.1 requirements or modifica-tions t.o the req11irements of AN8I B:H.7-1969, N11dear Power Piping, Appendix B-1 mny be used'?
Reply: It is the 'opinion of the Com-mittee for B3 l. 7 Nuclear Power Piping, that under the circmnst.ances indicated below, the following modifications of the requirements of B:H.7 Appendix B-1 may be used as alternatives in the mdiography of circumfP.rential butt welds in it.ems sttch as pipe, tu.biug, fittings, and nozzles.
1 Except as permitted in Par. 3 below and in Table I, radiographic exati'ima.tion of circumferential butt welds shall be per-formed with ~ingle wall viewing oniy.
The radiation may pass through one or both walls.
Where the source is located outside, a minimum of 4 exposures sepa-ra.tcd by 90 deg a.re required for ~ingle wall viewing.
2 Where radiation passes* through one or two walls and it is impractical to place the penetrameter inside the cylinder, the penetrameter may ho placed on the film side, except as required in 3 below.
3 Welds in items such as pipe, tubing,*
fittings and nozzles with an outside diam-eter of 31/ 2 inches or less may be ra.dio-graphed using a technique in which radia-tion passes through two walls and the weld in both walls is viewed for acceptance on the same film. The penetrameter shall be placed on the source side. The angle of offset of the radia.tion beam from the plane of the weld centerline shall be the mini-mum required to separate the images of the source side and film side portions of the weld sq that there is no overlap of the areas to be interpreted. A minimum of two exposures taken at 90 deg to each other shall be made for each weld joint.
Where the ratio of OD to ID is 3 to 1 or greater, the weld may be radiographed with the radiation beam located s11ch that the images of both walls are superimposed, in which case at le~.t 3 exposures shall be made at 60 deg to each other.
4 Penetrameter thickness and essential hole size requirements for the radiographic technique~ described in 1, 2, and 3 above are preaented in Table I.
5 Where there are direct contradictions between the requirements of Appendi:c B-1 and:this Case, as in the penetrameter hole size selection, the alternate provisions of the Case shall apply.
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ANSI 831 CASE 72 August 1970 INTERPRETATIONS OF CODE FOR PRESSURI!; PIPl~G Table I Penetrameter Requirements for Radl98f&OhY of Citcumferentlal Butt Welds li't Items Suc;!1 a~
Pip", Fitting.;, T ubi**f., and Nozzles Single Wall Penetrameter Essential Hole Thickness Range (in.)
Designation Thickness (in.)
Designation Dia (in.)
0 to 0.375 10 0.010 4T 0.040 Over 0. 375 to 0.625 12 0.012 4T 0.048 Over 0.625 to 0.875 15 0.015 4T O.OGO Over 0.875 to 1.00 17
. 0.017 4T 0.068 Over 1.00 to 1.50 25 0.025 2T 0.050 Over 1.50 to 2.50 30 0.030 2T 0.060 Over 2.50 to 3.00 35 0.035 2T 0.070 Over 3.00 to 4.00 40
- 0. 040 2T
- 0. 080 Over 4.00 to 6.00 50 0.050 2T 0.100 Reprinted from July 1970 MECHANICAL li:NGJNEERJNG u publication of The Am&rican* Society of. Mechanical En-
~;i'leers, United Engineerlng C<rnter. 345 East 47th Street, New Yori<, N. Y. 10017.
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