ML20024D178

Final Deficiency Rept SDR 5 Re Cold Formed back-to-back Channel Shop Welding.Initially Reported on 780307.Rev to Matl Specs & Actual Load Analysis Completed on 780324.Repair of Supports Previously Installed to Be Completed by 780801

ML20024D178
Person / Time
Site:	Limerick
Issue date:	04/05/1978
From:	PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20024D173	List: ML20024D172 ML20024D178 ML20024D193
References
10CFR-050.55E, 10CFR-50.55E, SDR-5, SOR-5, NUDOCS 8308030273
Download: ML20024D178 (7)

Text

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e April 5, 1978 f

Mr. Boyce Orier, Etrector Office of Inspect 1 bn and Enforcement, Region i:

United States Nuc1)ar Regulatory Connission '

f 631 Park Avenue -

King of Prussia, Pa. 19406 .

Subject:

Significant Deficiency Report $

Cold Formed Back-to,Back r%nn.1 Shop Welding Deficiency - W nAl Report Limerick Generating Station - Units 1 and 2 NRC Construction Pennits Nos. CPPR-106, -107

Reference:

Telecen of March 7, 1978 (H. R. Walters, '

PICo. to R. McGaugby, NRC)

Pile: QUAL 2-10-2 (SDR $ )

Dear Mr. Grier:

Attached is our final report on the above subject deficiency Weh was reported to US'RC per the referenced telecon in accordance with 10CFR50 55(e).

If there are any questions on this matter, we would be pleased to discuss thec with you.

Sincerely, Copy to: Dr. Ernest Volgenau, U313C Attachment r k

e 8308030273 930727 gDRADOCK 05000352 PDR

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1 FINAL REPORT COLD FORMED BACK-TO-BACK CHANNEL SHOP Mi1 DING DEPICIENCY AT LDERICK GENERATING STATION

' UNITS 1 & 2 Philadelphia Electric _ Company March' 1978 s

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TABLE OF CONTEIES PAGE

1.0 INTRODUCTION

1

2.0 DESCRIPTION

OF DEFICIENCIES 1

. 30 ANALYSIS OF SAFHIT IMPLICATIONS 2

4.0 CORRECTI E MEASURES 2 50 CONCLUSIONS 3 6.0 FIGURES - BACK-TO-BACK CEWNELS 4 1a - TYPICAL USE OF BACK-TO-BACK CHANNELS 1b - CROSS SECTION OF BACK -TO-BACK CHANNELS O

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1.'O Introduction .

1.1 In compliance with 10CFit50 55(e) this Final Report; is issued on the problem of cold formed back-to-back channel shop welding

. deficiencies. This significant deficiency was reported via Telecon to NItc Itegion I on March 7,1978.

1.2 This report describes the deficiencies, analyzes safety implications, sungnarizes results of test programs, and discusses corrective measures taken to prevent re-occurrence of the problem; and describes measures taken in the field to remedy problems on supports already in place.

1 3 The material on which theuc weld deficiencies has occurred consists of cold formed, channel shaped members of material conforming to AS M A-570-72, Grade C, hot dip galvanized per AS M A-386-73 or ASTM A-153-73, after spot welding in a back-to-back configuration to form composite members. Class I electrical raceway supports are field fabricated from stock member len6ths. Typical raceway support configurations are shown in Figure ia, and Figure 1b shows a typical cross section of the members. .

2.0 Description of the Deficiencies 2.1 The back-to-back channel members are procured from catalog designations, and are available from several manufacturers.

Catalogs contain section properties of the composite, spot-welded members, and specify spot weld spacing.

2.2 The deficiencies described herein occurred on material purchased from Super-Strut, Inc., of Oakland, California, and fabricated at their Goshen, Indiana, plant.

23 Inspection and limited testing of back-to-back channels being used on site, and procured from another supplier has indicated thus far that the deficiencies noted herein are related only to caterial procured from Super-Strut, Inc.

2.4 On about January 10, 1978,'a support was observed to contain back-to-back channels which had failed spot welds. Another support was noted to include a member which did not contain any spot welds in a 12" length. The catalog description specifies spot welds spaced at 2" to 3". An unused 24" long section was observed to have separated as a result of weld failure. A qualitative review of the material at the site indicated sufficient evidence of weld deficiencies and weld spacing irregularities to warrant a more quantitative review. Accordingly, fifty-five samples, representing three sizes of back-to-back channels, were randomly taken from field stock of material furnished by Super-Strut, Inc. Specimens containing three spot welds were cut from these samples, and the welds were teste'd in tension to failure by an independent laboratory. Failures occurred at loads ranging from 550 pounds per 3 welds, to 11,450 pounds per 3 wolds.

Super-Strut,'s acceptance criteria had been set at 8000 pounds per 3 wo3 ds .

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c 2.5 At the time the deficiencies wara discovered, approximately

' 1100 sppparts for Q-listed racoway had bsen erected.

3 0. . Analysis of Safety Implications 31 'Ib assure composite action of the back-to-back channel nenbers, spot welding'is provided at the interface of the two channels.

The load capacity of the menbors is based on structurally adequat,c welds spaced in accorda6cc with the specifications contained in the manufacturer's catalog.

32 Welding deficiencies, in spacing of welds in excess of the manufacturer's catalog specification, or in the quality of wold, would zwsult in a reduction in the load capacities of the members involved.

h.O' Correctivo Measures.

h.1 A site fabrication and erection hold was placed on all raceway supports on January 18, 1978. This hold was released on February 3,1978, on the condition that any strut material used for fabrication of now supports, and strut in supports already installed, be stitch welded to develop adequato composite member strength, without dependence on existing spot welds. Maximum load capacity of the strut was used as the basis for detemining weld spacing, pending completion of a more detailed analysis based on actual loading.

(see Figure 1b, notes 1 and 2). Instructions were issued to the field describing the procedures to be used for this repair welding.

h.2 A shipping hold was placed on all field procured back-to-back channel material, pending development of fomal test / inspection ,

acceptance criteria and production monitoring.

h.3 Or. February 23, 1978, a survey was made of the Goshen, Indiana, faci.11 ties of Super-Strut, Inc. It was observed that a neu automatic welding nachine has been installed at that' facility, uhich should eliminate the deficiency in weld spacing. However, prior to release of the shipping hold and acceptance of any new material from Super-Strut, Inc., that supplier 'will be required to demonstrate a level of quality control adequate to assure that the deficiencies addressed to in this report will not recur.

h.h To assure structural adequacy, all material procured from Super-Strut, Inc., that has been delivered and/or installed prior to the discovery of the deficiencies noted herein will be repaired, detemined by analysis to be acceptable, or replaced by new, qualified material.

h.5 Additional material will be procured only from suppliers that have been found acceptable by survoy, and are implementing an approved weld testing and inspection program, h.6 The appropriate material specification is being revised to include test / inspection acceptance critoria and production monitoring requirementsc 2 of h m

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50 Conclusions

'5.1 'ihe revision of material specifications, and actual load

, analysis was completed 11 arch 24,1978. The repair of supp3rts previously installed will be completed by August 1,1978.

52 Implacentation of the correctivo measures stated herein will minimize the recurrence of weld deficiencies during fabrication of strut material.

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NOTES: . .1

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1. SPACING OF WELD EASED ON MAXIMUM LOAD CAPACITY OF STRUT. .

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2. SPACING OF WELD AS REQ'D. BY ANALYSIS BASED ON ACTUAL LOADINGS. .' .

. .y 3-FIG. Ib BACK-TO - BACK CHANNEL CROSS SECTION 9

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