ML20059E519
| ML20059E519 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 08/19/1993 |
| From: | AFFILIATION NOT ASSIGNED |
| To: | |
| References | |
| OLA-2-I-MFP-073, OLA-2-I-MFP-73, NUDOCS 9401110250 | |
| Download: ML20059E519 (17) | |
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Item /ActivityCentrifugal Chargine Pump 2-1 8"I*'*"**
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Description of mencenterumaces Investigation of an increasing vibration trend revealed'aldeg'raded!abtbr'to I \\
oumo couoline.
This is considered a nonconformance oer OAP IS.S." paragraph l
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Plant Conditions 111. Cause of Problen V.
Correettee Actions A
II. Innscription of Problem IV.
Analysis of Problem VI. Additions) Inferestion L
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MANAGEMENT
SUMMARY
On June 30, 1992, an increase in vib' ration'on. Centrifugal, Charging Pump (CCP) 2-1 was identified by Predictive Maintenance (PM).
Investigation into.the cause of-the increased vibration included obtaining a gear lube sample from the motor-to-speed increaser coupling.
While attempting to take the gear lube sample, the coupling. sleeve on the speed increaser side of the pump was stiff-due to hardened lubricant..However, the coupling sleeve was moveable and was subsequently freed.
l PM work order #C0101385 was issued to replace _this coupling
~
as part of the PM program.
While ECCS trains 1-1, 1-2,'and 2-2_have not experienced coupling problems, this'was the third occurrence involving CCP 2-1._
The previous cause of excessive coupling wear was due to misalignment of the motor with respect to the speed increaser.
l This draft dated March 12, 1993 contains the minutes from l
the TRG meeting held on March 5 1993. -
This NCR will be distributed for comments, signed-off and sent to the PSRC.
NCR closure ECD: July 7, 1993.
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E1 ti aebaa e 92NCRWP\\92MMNO31.PGD Page 1
of 15
o, NCR DC2-92-MM-NO31 Rev. 00 March 12, 1993 NCR DC2-92-MM-NO31 Centrifugal Charging Pump Coupling I.
Plant Conditions Unit 2 was in Mode 1 (Power Operation) at 100% power.
II.
Descriotion of Event A.
Summary:
On June 30, 1992, a coupling sleeve on Centrifugal Charging Pump (CCP) 2-1, was found to be stiff.
The coupling was subsequently replaced.
B.
Background:
The CCP motvr is connected to a speed 'ncreaser that in turn drives the pump.
The motor output to speed increaser input shafts are connected by a " Fast" gear-type coupling.
This coupling allows for an angular misalignment of 1/2 degree between the shafts.
C.
Event
Description:
On June 30, 1992, an increase in vibration on CCP 2-1 was identified by Predictive Maintenance (PM).
Investigation into the cause of the increased vibration included obtaining a gear lube sample from the motor-to-speed increaser couplina.
While attempting to take the gear lube sample, the coupling sleeve on the speed increaser side of the pump was found to be stiff apparently due to hardened lubricant.
However, the coupling sleeve was moveable and was sub.equently freed.
Possible causes include misalignment and hardened lubrication.
On July 3, 1992, Work order #C0101385 was issued to replace this coupling.
While CCP's 1-1, 1-2, and 2-2 have not experienced coupling problems, this was the third occurrence involving CCP 2-1.
The previous cause of excessive coupling wear was due to misalignment of the motor with respect to the speed increaser.
D.
Inoperable Structures, Components, or Systems that Contributed to the Event:
None.
92NCRWP\\92MMNO31.PGD Page 2
of 15 l
1 I
NCR DC2-92-MM-NO31 Rev. 00 March 12, 1993 E.
Dates and Approximate Times for Major Occurrences:
1.
June 30, 1992: CCP motor coupling sleeve was found stiff but moveable.
The sleeve was freed and the coupling was replaced.
F.
Other Systems or Secondary Functions Affected:
None.
G.
Method of Discovery:
During a PM Repetitive Task (RT) Work Order to trend CCP 2-1 vibration history, it was found that the vibration in CCP 2-1 was increasing. Investigation of the increased vibration trend identified the worn coupling.
H.
Operatcr Actions:
None.
I.
Safety System Responses:
None.
III. Cause of the Event A.
Immediate Cause:
Hardened lubricant caused the coupling to be stiff.
B.
Determination of Cause:
See attached root cause analysis.
C.
Root Causes:
Inadequate alignment criteria due to:
1.
Vendor recommendations not clearly stated (use of left or right lead to misunderstanding).
2.
Alignment tolerances and data not specifically called out on the work order.
The WO stated to align per vendor manual.
3.
No alignment data sheets provided or utilized.
92NCRWP\\92MMNO31.PGD Page 3
of 15
(
5 NCR DC2-92-MM-NO31 Rev. 00 March 12, 1993 4.
No witness or evaluation done by Mechanical Maintenance engineering of the alignment results to determine the acceptability.
5.
Actual relative thermal movement between shafts different that what is indicated by the manufacturer's cold offset recommendations.
D.
Contributory Causes:
1.
The grease type presently used is not as durable for this applications as the special grease available from the coupling manufacturer.
Several plants and coupling specialists have found the coupling manufacturer-grease to provide better service in severe service applications.
2.
The technique for cleaning and lubricating this type of coupling during preventive maintenance (PM) can vary greatly.
The outer flange cannot be pulled back to allow good cleaning, inspection, and repacking of the coupling at the gear teeth.
IV.
Analysis of the Event A.
Safety Analysis:
The Predictive Maintenance group periodically monitors various plant components to aid in the early detection of potential problems.
Part of this predictive maintenance is to monitor the vibration history of CCP 2-1.
Noting a change in CCP 2-l's vibration history, the pump was inspected to determine the cause of the increased vibration.
Upon investigation of the pump vibration, the motor-to-speed increaser coupling was found to have excessive wear.
This event demonstrate the effectiveness of the Predictive Maintenance program. The PM program discovered a potential problem while the pump was still able to perform its safety function and the coupling was replaced prior to any failure.
Therefore, the health and safety of the public were not affected by this event.
I i
92NCRWP\\92MMNO31.PGD Page 4
of 15 1
1
w NCR DC2-92-MM-NO31 Rev. 00 March 12, 1993 B.
Reportability:
1.
Reviewed under QAP-15.B and determined to be l
non -confe rming in accordance with Section 2.1.3.
2.
Reviewed under 10 CFR 50.72 and 10 CFR 50.73.per-NUREG 1022 and determined to be non-reportable.
3.
This problem will not require a 10 CFR'Part 21 report, since it does not involve defects in vendor-supplied services or spare parts in stock in the warehouse.
l 4.
This problem will not be reported via an INPO Nuclear Network entry.
5.
Reviewed under 10 CFR 50.9 and determined to be not reportable since this event does not have a significant implication for public health and.
safety or common defense and security.
6.
Reviewed under the' criteria of AP C-29 requiring the issue and approval of an OE and determined that an OE is not' required.
V.
Corrective Actions i
A.
Immediate Corrective Actions:
The coupling on CCP 2-1 was freed and replaced.
B.
Investigative Actions:
1.
Non-conformance reports will'be investigated to-identify previous failures of gear-type couplings.
RESPONSIBILITY: T. Berube (PTRC)
DEPARTMENT:
Regulatory Compliance Tracking AR:
A0269974, AE #01 STATUS:
RETURN.
92NCRWP\\92MMNO31.PGD Page 5
of 15
i NCR DC2-92-MM-NO31 Rev.'00;
)
March' 12, 1993 l
2.
Investigate maintenance history 1'acords to l
determine previous failures-of gear type coupling.-
l This should include any indication ~of. grease-i degradation.
I RESPONSIBILITY: D. Delfino (PGMP)
DEPARTMENT:
MechanicalfMaintenance Tracking AR:
A0269974,1AE #02-STATUS:
RETURN.
3.
Review "RT" type WOs for as-found lubricant (grease) discrepant conditionsLfor, centrifugal charging pumps and other pump'sjcouplings..
l RESPONSIBILITY: D. Delfino (PGMP)
DEPARTMENT:
-Mechanical' Maintenance Tracking AR:f A0269974, AE #03 l
STATI'S :
RETURN.
THIS AE HAS BEEN REPLACED BY AE # 2 ABOVE.
~
i 4.
Mechanical Maintenance to-document thezas-found-centrifugal charging pump' alignment.
]
-1 RESPONSIBILITY: 'L.
Price-(PGMC)c_
DEPARTMENT:
Mechanical Maintenance
-Tracking AR:
A0269974, AE #04 c
STATUS:
. RETURN.
I 5.
Initiate a NOMIS search for gear-type coupling, failures in pump / motor driven applications.
l l
RESPONSIBILITY: J. Hinds (PGMX) l DEPARTMENT:
Mechanical Maintenance Tracking AR:-
-A0269974, AE #05j STATUS:
RETURN.
l 6.
Initiate a NPRDSfsearch:for.-gear-type. coupling failures in pump / motor' driven; applications.
RESPONSIBILITY:
A. Covillef(PTRE)
)
DEPARTMENT:
Reliability Engineering
-)
Tracking AR:
A0269974,-AE #06:
STATUS:
RETURN-7.-
At the next~available opportunity, instrument CCP 2-1 to determine the actual alignment movement from cold to hot condition.
. Compare' these-results' to the recommended manufacturer's. offset.-
1
-)
92NCRWP\\92MMNO31.PGD Page 6
of015.-
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NCR DC2-92-MM-NO31 Rev. 00 March 14, 1993 PGMP to coordinate this. investigative action with TES.
RESPONSIBILITY:
D. Delfinof(PGMP)'
DEPARTMENT:
Mechanical Maintenance-Tracking AR:
A0269974, AE #07.
l STATUS:
RETURN. -
8.
Review the as-found condition ofithe coupling lubricant and raquest that a sample of the-lubricant be tested.
-RESPONSIBILITY: L.
Price (PGMC)
DEPARTMENT:
Mechanical Maintenance Tracking.AR:
A0269974, AE.#08 STATUS:
RETURN.
9.
Determine if the current specified coupling 1
lubricant is-equivalent.to the latest manufacturer-recommended' lubricant.
l RESPONSIBILITY:
D. Delfino (PGMP)
DEPARTMENT:
Mechanical Maintenance Tracking AR:
A0269974, AE #09 I
i STATUS:
RETURN.
10.
Evaluate the potential thermal offset on this: pump '
configuration and advise if additional-i instrumentation as recommended in.AE #7 is warranted.
RESPONSIBILITY:
C. Beall'(PGMP)
DEPARTMENT:
Predictive-Maintenance Tracking AR:
.A0269974, AE.#10 STATUS:
COMPLETE.
2 C.
Corrective Actions to Prevent Recurrence:'
1.
Revise CCP procedure _(MP'M-8~.2) to include actual movement as determined by on-site' testing.
q 1
RESPONSIBILITY:
L. Price _ ECD: 03/26/92 DEPARTMENT:
Mechanical Maintenance Tracking AR:
A0269974, AE #14 j
Outage Related?
No OE Related?
No NRC Commitment?' No CMD Commitment?
No 92NCRWP\\92MMNO31.PGD Page 7
of 15 f
1
NCR DC2-92-MM-NO31 Rev. 00 March'12, 1993 2.
Lubrication Engineering to initiate the use of' "KOP-FLEX" vendor recommended grease.
RESPONSIBILITY:
H.. Arnold.
DEPARTMENT:
Predictive Maintenance.
Tracking AR:
A0269974, AE #15 Outage Related?
No OE Related?
No NRC Commitment?
No CMD Commitment?- No i
STATUS:
RETURN.
4 3.
Subsequent to the previous alignment.of this coupling, procedure MP M-56,19:" Shaft / Coupling Alignment for Rotating Equipment" was. developed ta) provide detailed instructions.for various~
alignment methods.
This procedura also~ requires recording.the alignment data which~is'rev'swed and approved by the Mechanical Maintenance 1 foreman and the Mechanical Maintenance engineer.
j D.
Prudent Actions (not required for NCR closure)=
l t
t 1.
Provide a detailed inspection criteriaLfor gear type component coupling. -This criteria is to be established prior to the issue of any future RT work orders for these components.
RESPONSIBILITY:
D..Delfino.
DEPARTMENT:
Mechanical Maintenance.
Tracking AR:
A0276090.
-+
STATUS:
ROUTED.-
2.
Select a representative sanyle from the population of pumps being' worked on during 1R5,Tand-inspect their coupling for adequate lubrication,and abnormal wear.
RESPONSIBILITY 5 L. Price-DEPARTMENT:
Mechanical Maintenance.
Tracking AR:
A0276092.-
f STATUS:
ROUTED.
l 3.
Establish a mechanism:for controlling alignment-data sheet.
RESPONSIBILITY:nL. Price: ECD:.01/30/93:
DEPARTMENT:
Mechanical Maintenance'..
Tracking:AR:
A0287500.
92NCRWP\\92MMNO31.PGD Page 8
of 15
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NCR DC2-92-MM-NO31 Rev. 00 March 12, 1993 4.
Maintenance Engineering Predictive Maintenance'to develop guidelines for inspection, evaluation and lubrication of coupling types.
RESPONSIBILITY: H. Arnold ECD: 12/01/92 DEPARTMENT:
Predictive Maintenance.
Tracking AR:
A0287501.
5.
Develop a plan to evaluate other ECCS pumps for actual thermal offset to enhance the alignment process.
RESPONSIBILITY: H. Arnold ECD: 02/15/93 DEPARTMENT:
Predictive Maintenance Tracking AR:
A0287502.
VI.
Additional Information A.
Failed Components:
None.
B.
Previous Similar Events:
i search of Status under keyword Couclina revealed the f.ollowing:
DC2-89-MM-N040 Centrifugal Charging Pump Motor 2-1 Coupling On April 4, 1989, CCP 2-1 motor was making noise and exhibiting excessive vibration.
Upon investigation,-
the motor-to-speed increaser coupling was found damaged.
The root cause was due to the procedure used for maintenance of the motor / speed increaser not containing sufficient details to ensure proper alignment of the shafts during maintenance and for verification after maintenance. 'The corrective ~ actions to prevent recurrence included: (1) development of more detailed alignment instructions and_nore complete post-maintenance testing following shaft, coupling, bearing _
maintenance; (2) expanded alignment instructions were included into the training program.
QC inspectors were included in the training.
l The corrective actions in this previous event did not preclude this event, since these corrective actions did l
not establish a procedure which contains the vendor's base line, (procedure MP M-56.19 was not in existence),
92NCRWP\\92MMNO31.PGD Page 9
of 15 v
e
NCR DC2-92-MM-NO31 Rev. 00 March 12, 1993 no alignment data sheets were in existence, vendor information was ambiguous, difficult to understand, the vendor recommendations were not followed, tolerance and data were not called out.
C.
Operating Experience Review:
1.
NPRDS:
a.
On 5/12/88 at Salem 2, an equipment operator on normal rounds heard an excessive amount of noise coming from the 22 charging pump speed increaser.
Investigation revealed a worn pump and drive coupling in the speed increaser oil pump.
The oil pump and drive coupling were replaced and the charging pump speed increaser returned to normal operation, b.
On 4/4/89, DCPP Unit 2 was at 100% power.
Routine maintenance of CCP 2-1 identified abnormal noise and severe vibrations in the motor such that the pump was declared inoperable.
The cause was misalignment between the motor shaft and the speed increaser due to inadequate alignment procedures.
The motor-to-speed increaser coupling was-replaced and the alignment procedures are being revised.
In addition, the motor bearings were replaced.
2.
NRC Information Notices, Bulletins, Generic Letters:
A search of the Operating Experience Assessment database revealed the following:
None.
3.
A search of the Operating Experience Assessment database revealed the following:
None.
D.
Trend Code:
Responsible department (Mechanical Maintenance) MM, and cause code A4 (Programmatic Deficiency), B1 (no procedure).
92NCRWP\\92MMNO31.PGD Page 10 of 15
r NCR DC2-92-MM-NO31 Rev. 00 I
March 12, 1993 E.
Corrective Action Tracking:
1.
The tracking action request is A0269974.
2.
Are the corrective actions outage related?
No.
F.
Footnotes and Special Comments:
None.
l l
G.
References:
1 1.
Initiating Action Request A0269779.
i 2.
NCR DC2-89-MM-N040 H.
TRG Meeting Minutes:
1.
On July 7, 1992, the TRG convened and discussed the event.
The TRG concluded that the event was l
not reportable since the equipment was not declared inoperable and could still perfo;q its safety function.
Items discussed were: (1)-How the problem was discovered.
(2) Possible causes including misalignment and hardened lubrication..
(3) The difficulty in the coupling's design to' insure lubrication reaches the gear teeth area._
(4)
Comparison of vendor specifications to the "as found" condition (misalignment). (5) The frequency of the problem on this motor compared to motors on the other three ECCS trains.
Items to be reviewed before the TRG reconvene includo:
Non-Conformance Reports for previous. failures a.
of couplings manufactured by-Fast /Falk.
b.
Corrective Maintenance Work Orders for previous failures of couplings manufactured by Fast /Falk.
" Repetitive Task" Work-Orders for as-found c.
lubricant conditions.
92NCRWP\\92MMNO31.PGD Page 11 of.15 5
NCR DC2-92-MM-NO31 Rev. 00 March 12, 1993 d.
Documentation of as-found pump alignment.
e.
NOMIS search for gear-type coupling failures.
f.
NPRDS search for gear-type coupling failures.
The TRG members agreed to reconvene around the 12th of August, 1992.
2.
On August 19, 1992, the TRG reconvened to review the investigative actions and the NCR write-up.
Review of previous NCRs (AE #1) identified only one similar occurrence of coupling failure.
Review of the responses to AE #5 and #6 found no indication of other nuclear power generating facilities having similar experience wit 4 coupling failures.
Three new investigative actions were agreed upon.
a.
Mechanical Maintenance to review the as-found condition of the coupling lubricant and request that a sample of the lubricant be tested.
b.
Mechanical Maintenance to determine if the current specified coupling lubricant is equivalent to the latest manufacturer recommended lubricant.
c.
Based on a discussion with rece;nized coupling experts, at the next available opportunity, Mechanical Maintenance is to instrument CCP 2-1 to determine the actual alignment movement from cold to hot I
condition.
Compare these results to the recommended manufacturer's offset.
For more information see section V. A. (#7-9)
The TRG agreed to reconvene on September 10, 1992 I
to review the remaining investigative actions, to determine the root cause, and to determine corrective actions to prevent recurrence.
92NCRWP\\92MMNO31.PGD Page 12 of 15
l l
NCR DC2-92-MM-NO31 Rev. 00 2
l March 12, 1993 3.
On September 9, 1992, the TRG reconvened and
~
l discussed the following:
Response to investigative action #9 was inadequate and needs to be expanded to' reaffirm that EP2 is equivalent to the lube the manufacturer l
recommends.
t DCPP does not conduct hot alignments.
Prudent actions include: (1) Provide more detailed inspection criteria for gear type coupling inspections.
(2) From the population of pumos/ motors that are going to be serviced during 1R5, select a representative sample and inspect the couplings for adequate lubrication and abnormal wear.
A new investigative action was assigned to evaluate the potential thermal offset on the CCP configuration and advise if. additional instrumentation as recommended in AE #7 is Warranted.
The TRG agreed to reconvene after completion of the remaining investigative actions.
4.
On December 4, 1992, the TRG reconvened and discussed the following:
Review of the investigative actions for AE # 4 and AE # 11.
The as-left alignment starting from last failure.
There is no base line. called out for alignment, nor there is a procedure.
Poor vendor information, instructions. Ambiguities taken away in the 90's.
Failure to implement the vendor recommendations. Tolerance and data not called out.
DCPP QC not familiar with pump's alignment.
The conclusion is that the misalignment was due to the thermal offset.
Thermal growth can be noted after 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> of operation.
92NCRWP\\92MMNO31.PGD Page 13 of 15-
4 NCR DC2-92-MM-NO31 Rev. 00 March 12, 1993 First root cause:
The base line did not match.the alignment.
I second root cause: The vendor recommendations were not implemented.
l Need to review the previous NCR to determine if the steps in our data-are ineffective.
MP'M-56.19 translates the vendor's recommendat' ns such as use of left and right leads.
Predictive maintenance-does trending on alignment.
I Need to evaluate previous similar events and expend on why the corrective actions.in the.
previous events did not preclude this event.
Two corrective actions to prevent recurrence were initiated as follows:
- 1. -
Mechanical Maintenance'(L. Price) to' revise CCP procedure-(MP M-8.2) toJinclude actualj movement as determined by on-site testing.
CAPR 2.
Predictive Maintenance (Howard' Arnold) to initiate the use of "KOP-FLEX" vendor recommended grease..CAPR Three prudent actions.were. initiated as follows:
l 1.
Mechanical Maintenance (L. Price) to establish a mechanism for con'_ rolling alignment data sheet.
l 2.
Predictive Maintenance (Howard Arnold) to l
develop guidelines for' inspection,' evaluation l
and lubrication of coupling types.
l 3.
Predictive Maintenance'(Howard Arnold)' to j
develop a plan to. evaluate other ECCS. pumps for actual thermal offset to enhance the alignment process.
NCR CLOSURE ECD:
JULY 1,.1993.
i 92NCRWP\\92MMNO31.PGD Page 14 of 15
l 4
NCR DC2-92-MM-NO31'-Rev. 00
/
March 12, 1993 5.
On March 5, 1993,-the TRG reconvened and discussed 1
the following:
Reviewed the write-up.
Reviewed the corrective ^ actions to prevent recurrence.
Reviewed the' root cause. analysis, j
THIS TRG WILL "*T RECONVENE.
THIS MCR WILL BE i
DISTRIBUTED FOR COMMENTS, SIGNED-OFF EMh SENT TO.
PSRC.-' ECD: APRIL 5, 1993. THIS NCR WILL BE TREN
'SEiii TO - OA POR CLOSURE. NCR CLOSURE ECDs JULY 7, 1993.
I.
. Remarks:
None.
J.
Attachment (s):
None.
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1 i
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.e NCR L 2-92-MM-NO31 Rav. 00 March 12, 1993 Centrifugal Charging Pump Coupling ROOT CAUSE ANALYSIS PAGE 1 OF 1 EFFECT CAUSE EVIDENCE BARRIER An increase in vibration on Inadequate aligment Grease Vendor Centrifugal Charging Pump 2-1 criteria.
condition and recommendations not R t cause.
was identified by Predictive vibration clearly stated.
maintenance.
increased.
WHY?
Alignment tolerances and data were not specifically called out'on the work order.-
The WO stated to align per vendor manual.
No alignment data sheets were provided or utilized.
4 WHY?
No witness or evaluation was done by Mechanical Maintenance engineering of the alignment results to determine'the acceptability.
WHY?
Actual relative thermal movement between shafts different that what is indicated by the manufacturer's cold offset i
recommendations.
CC.
CONTRIBUTORY CAUSE.
~
.,