ML20195G843

Technical Evaluation Rept for Employee Concerns Element Rept 221.6(B), Rev 1, `Pipe Support Design,Observed Bending of Pipe Clamp Ears

ML20195G843
Person / Time
Site:	Sequoyah
Issue date:	12/08/1987
From:	Tai M NCT ENGINEERING, INC.
To:
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References
NUDOCS 8712210058
Download: ML20195G843 (5)

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SEQUOYAH NUCLEAR PCWER PLANT, UNITS 1 & 2 TECHNICAL EVALUATION REPORT FOR EMPLOYEE.CCNCERNS ELEMENT REPORT 221.6(B), REVISION 1

~"PIPE SUPPORT DESIGN Observed Bending of Pipe Clamp Ears" I

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SUBJECT:

This report summari es the NRC audit of TVA's corrective actions for employee concerns regarding SCN pipe support clamp bending for B001 type pipe supports.

e By:

Mohanmad K. Tai Consultant NCT Engineering, Inc.

Date:

December 8, 1987 i

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f'-P NCT ENGINEERING, INC.

1 r-y 9319.1t o*W 9f

SEQUOYAH NUCLEAR FCWER PLANTS UNIT 1 & 2 TECHn CAL EVALUATICN REPORT FOR EMPLOYEE CONCE'ANS ELEMENT REPORT 221.6 (B) REV. 1 "PIPE SUPPORT DESIGN" I.

SUBJECT CATEGORY:

Engineering (20000)

SUBCATEGORY:

Pipe Support Design (22100)

ELEMINT NO:

Cbserved Bending of Pipe Clamp Ears (22106)

CONCERNS:

IN-85-305-001 5

IN-85-305-001 "Over a period of time the bending of ears on small B001 support clamps will cause the A-36 material to yield beyond its yield point.

Clamps are installed in both units.

(WBNP ). "

7

SUMMARY

OF ISSUES The element report interprets this concern into the following two issues:

1.

Excessive torque on bolts caused bending of clamp ears, l

2.

Clamps were modified to prevent this bending but the clamp ma,nuf acturer's concurrence was not cbtained.

III.

EVALUATICN According to the ECTG report, B001 Seismic Category I type supports are used to support drain lines, instrument rensing

lines, sampling

lines, radiation monitoring

lines, and test and process lines

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l containing isolation valves.

These lines are called branch lines.

The supports consist of a stanchion pipe we1ded directly to the run line or to'the clamp which is fastened to the run line.

Similarly the i

I branch line is welded or clamped to the stanchion.

The ECTG report addressed to the adequacy of the branch line and run line clamp for over-torquing considerations.

.l l-l Drawings 478001-14, 14A and -12 specify a torque valve of 5 to 10 ft-lb, depending on the sire of the bolt, for branch line clamps and 100 ft-lb for run line clamps regardless of clamp and bolt si:e..

These drawings were reviewed during the NRC audit of this employee concern.

This torque valve of 100 f t-lb was determined by the ECTG report to be f

excessive, specially for small size clamps.

In order to address this issue, TVA ravi9ed it i drawing number 47B001-12, rev.

5, and issued drawing 47B001-12A which reduced the torque l

valve.for bolts on small si:e clamps.

These torque valves were reviewed during NRC audit and are considered reasonable.

TVA also t

i surveyed (SMI-0-317-48 dated 1/8/87) about 247 B001 type

supports, which according to TVA (confirmed by ECTG) represented about 80% of all the B001 type supports at SCN.

The survey indicated that clamps were used only on 14 of the 247 supports.

TVA replaced bolts for all 1

14 supports.

In order to assess the possible damage to the bolts due to over-torquin'y, TVA also performed magnetic particle examination of the removed bolts and found no evidence cf bolt damage.

In adds: ion, i

static testing of two piece pipe clamps was performed by Singleton Laboratorips, for TVA (RIM No. B258 61216 009).

Test report indicated no adverse effect on the performance of the clamp function due to the bending of clamp ears.

Therefore, based on these tests, over-torquing will not be detrimental to the clamp function. --

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l According to the ECTG report, in order to prevent bending of clamp ears at NBN, stiffeners were welded.

However, ECTG report also states that at

SCM, there was no use of stiffeners, therefore the second issue is not valid.

IV.

CONCLUSICM The ECTG report concluded that the concern was valid that an excessive torque valves were specified for run line clacps.

Based on the review of TVA's corrective actions, it is concluded that the issue has been adequately addressed.

However, at the time of this review, the ECTG had not C0mpleted verification of TVA's' corrective

actions, therefore it is recommended that the final ECTG verification be reviewed when ecmpleted.

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f EN 2211C SER IS ATTACHED TO EN 21510 SER

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