ML19290A085
| ML19290A085 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/28/1978 |
| From: | Pletke L, Rise D, Rogers L BABCOCK & WILCOX CO. |
| To: | |
| References | |
| TASK-TF, TASK-TMR 181-01, 181-1, PROB-780428, NUDOCS 7909140261 | |
| Download: ML19290A085 (11) | |
Text
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BWNP-2034 1 (8-78)
SITE PROBLEM REPORT TRANSMITTAL
- CLEARED ****
25 To:
Change Control For Distribution File: 13-4 - 18 l ' # /
S. H. Klein - Quclity Assurance Contract No. :
620-00 o (s Central Engineering Filesi SPR:
If I b-l 4 I b. Le Task Engineer (s)
Title:
C.ldeb failao 2A a
g-1 Lk.h%ct
- Project Manager R.C.P Mob Y
t Date:
> M 77 Status Code:
C L. r P.c L : ':
P. E. Perrone s'. R. Bohart - Intl. Support B. A. Karrasch - Plant Integration Attached is one copy of Site Problem Report No.
18l which was processed on Contract 620-00 O fo This SPR has been reviewed for generic applicability and this problem w/is r,c; considered applicable to other contracts.
REMARKS:
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Clutch Failure er 2A ?.0? Mccor m.
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A - -- ' '-j - - - - - y DESCRIPTION OF P P.0 9 L E H :
on 13 March the following events o: curred: P.cP2A vas shut down at 0820 for OTSG data, El aul 22 were still r2n.ing.
Atte= pts to start 2A vere unsuccessful and in order to complete f.hb data Al was sth:ted at 1216. ~After 8 minutes
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run time with ' cree other pumps, smoke was noticed cc=ing fro = the 2A motor E
and a loud vibration noise was cc=ing frc= the upper part of the notor.
O It was 1~ticed that the shaft was turning but the direction was not reported.
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STATUS-ACTION TO DATE. I NCLUD i tt G P ERSO N S CON T ACT ED:
Contacted,Tohn Derpsey, Bill Spangler, Tom Scott, & Allis-C%al ers representative.
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Renoved the C'_naged clutch and shipped to Marland in Lacrange, Illinois and sent the hub to Allis-Ch- a-c ' -,nufactu-ing plr._nt in Qisconsin. The motor rotor keyway shows impac; da= age followins hub removal. Allis-Chalmers c'.icpatched
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FAILUPI A'i.U.YSIS OF FIACTOR COOL /J:T PL 2 ANTI-PIVERSE DEVICE APPlL 17, 1978 lm.................................,..,...,.
SECTION A DESCRIPTION OF EVE::T:
On Maaday, March 13, 1978, the Three FJ.le Island II B&W service personnel reported a loud knocking noise heard near the upper portion of the A-2 Allis Chal=ers Reactor Coolant Pu=p Motor. The =otor was turning in the I
reverse direction while being propelled by back flow from the other pt ps.
is hl The anti-reverse device was vistm11y inspected and found to be extensively i
A desaged. The device was re=oved and sent to the Marland one Way Clutch Co.
at La Grange, Illinois for disasse=bly and inspection. The upper portion of the cotor shaft in the drive key area was slightly damaged - requiring in-place repairs.
. SECTION 3
~~ INSPECTION OF DAMAGED DEVICE:
The "UEN anti-rotation housing was split in the area of the drive key 1.
where it engages the fixed upper stub shaft.
The drive key had rotated within the housing /for what appeared to be 2.
several revolutions, judging f rom the, a=ount of up-set metal.
The bolts which secure the upper and lower portions of the zurn coupling 3.
The three housing were either badly distorted or co=pletely sheared.
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f Failure Analysis __
4 April 17, 1978 l
Pare 2 bolts not co=pletely sheared hud to be cut with a torch in order to dis-asse=ble the unit.
'4.' The flange ToTueeting the- ~up;ier and' lower = urn coupling housing was 3
.. bent and split, indicating very high upset. forces had been applied, both radially and axially.
5.
The one inch diameter dowels which position the fixed stub shaf t to the stor housing were badly distorted from excessive radial force.
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6.
Two drive keys which resist rotation of the fixed roller cam relative to i
t the zurn coupling were offset and rotated out of their normal position, 3
- g choving c cessive torque.
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7 The pipe nipple which supplies oil to the fixed roller cam was sheared l:
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off flush where the tapered pipe thread ter=inates its engage =ent with j;
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the can stub shaft.
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8.
The four pipe elbows which distribute flow to the roller cage were. rotated g
out of position. Icpact marks were noted on the elbour. The elbows
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vere all turned in the direction they would have tu ned when the nor= ally
,,,,, stationary, can would be rotating and allowing them to strike a stationary object such as the broken section of the pipe nipple.
The direction of g p!
rotation was reverse from the cotors shafts normal rotation.
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9.
The clutch roller cage was tested for freedom of ro.ation and no tight U
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f spots or friction was observed which vould interfere with its motion.
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It should be noted that this cage should be nearly free of all friction y
which could interfere with its complete freedom to rotate.
Any friction I Lp (q
high enough to overco=e the engaging force of four scall springs which
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.f. D. De=psey'to R. K. Kennedy
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Failure Analysis April 17,1978 -
Page 3 advance the cage to its roller locking position would allow t.he motor shaf t to rotate in reverse.
If this friction vere to d1=inish while The the motor was rotating in reverse, the clutch would then engage.
device, once triggered, has very littic, if any, slippage. The poten-tial torsional noment developed while atte=pting to instantly stop the t
rotating 39,000 lb. rotor approaches infinity.
The outer roller race was then checked for freedom of rotation in the l
10.
over running direction and found to be free to rotate while a clunking noise. could be heard.
The outer race (rening me=ber) was then checked several dozen times'in 11 It various positions for positive locking against reverse rotation.
engaged every ti=e with no detectable back-lash.
12 The four springs which function to engage the roller cage inits locking 4
I position were all in place and properly lock vired. :.They were of proper tension and can definitely be ruled out as the cause of the =alfunction.
- 13. The stationary can and roller cage asse=bly were then. lifted out of the rotating outer race. A small metal chip was found at the bottom of the It was approxi=ately 1/16 inches long by 3/16 inches wide outer race.
by 0.010 inches thick. It was determined to be magnetic.
14.
Two rather severe gouges were found in the lover portion of the outer
_dinneter of.the alu=inus magnesiun alloy roller cage.
The two gouges i
vere approxinately opposite of _ each other, being l80* apart.._
- n One gouge O(
spanned approximately 90* of the circu=ference, while the other was
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.7. D. De=psey to R. K. Kennedy Failure Analysis AprL' 17,1978
.pgge 4-
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spproximately 45' in length. Both weEe of a nature to indicate that a foreign particle had entered at the top and was discharged at the bottom while the outer race was rotating in the nor=21 over running direction which is counter clockwise when viewed from the top. (See Attachments A, B, & C.)' All da= aging forces had been applied in the reverse (Locking) direction which is clockwise when viewed from the top.
- 15. All 22 rollers had two light scratches around their circu=ference about 1/8 inches apart and approx 1=ately 1 1/2 inches fro = the top of the rol-1er. There were corresponding scratches on the outer race and on the roller cam. I really feel these scratches were the result of two s=all
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abrasive particles being embedded in the' outer race which would account for the scratches being transferred to the rollers and then to the cam l
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- 16. The Kaydon ' bearing ' housing had a cut cark at an angle which lined up pe5fectly with the ' gouge" = arks previously observed at the botton o the
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roller cage.
(Attachment 3) It should be noted that the roller cage has a register fit engaging with the Kaydon bearing housing.
The Kay-don bearing is provided to allow for friction free rotation of the roller In the event the Kaydon bearing locks up,'the slip fit between cage.
i 8
the cage and the bearing housing allows double protection against I
cage lock-up. Several nicks and dings were noted on this ' slip fit sur-
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. face. Hand testing determined the friction resulting from these nicks
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vould still allow the springs to advance the cage properly, however, this was a very marginal situation, as small particles could have been
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,;. D. Denpsey to R. K. Kennedy Failure Analysis April 17, 1978 Page 5 j
present which later flushed away.
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- 17. The outer race pilot shaf t which functions to provide concentric posi-d tioning of the fixed roller can and the outer race was polished well and showed no signs of distress.
18.
Several further atte= pts to lock up the roller cage by tilting it were unsuccessful. The cage was finally locked in a position which would allow free reverse rotation of the outer race (runner) by hand rotating I
the roller cage to the disengaged position and inserting a c=all 1/8 inck allen vrench between the cage and can surface.
This merely de=on-strated that a foreign object lodged in the proper position could fail
[
the unit and allow reverse rotation.
t SECTION C ANALYSIS OF FAILURE:
l l1.
5ased upon the series of operational events, inspection of the failed device, review of the design, and the process of clini,ation, B&iT has i
I concluded that the failure was caused by te=porary sticking of the roller cage.
2.
hn Attachrent A, a cut away sketch of the principal working me=bers of the device is shown. 1; hen the cachine is running counter clockwise in the nor=al direction (over running), the rollers are moved away fron the locking can (down the ra=p) and very little friction is applied
. to restrict f ree rotation of.the outer race relative to the stationary j
i to rotate the roller If the =_achine is stationary, four springs act
)
cam.
(
When the machine is j'
cage to engage the rollers with the stationary cam.
subjected to a reverse torque (clockwise when viewed from above) the 357
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r J. D. Denpsey to R. K. Kennedy
[
Failure Analysis April 17, 1978 Page 6 rollers are forced by friction to move up the cam ra=p.
The very slight pressure angle of 4* to 6* acts to vedge the outer rac.a fir =1y to the can, preventing rotation. The four cage advance springs nust, of necessity, be very light to prevent break down of the lubricating oil film provided to assure friction free rotation of the rollers in the normal over running direction and to allow the cage to be pushed slightly in the direction to allow roller disengagement with the cam If sufficient friction is present to overcome the engaging ra=p.
force developed by the springs, the cage vill stick in a canner to allow rotation in the reverse direction. Since dynamic coefficient g
of friction is known to be significantly-less than static coefficient
- ' __ of friction, the cage may become unstuck while the cachine is rotating backwards. The device, once triggered, has vary littic, if any, slippag'e. This allows stored kinetic-energy from the flywheels to be suddenly applied to the nor= ally fixed cas and anti-rotation me=bers.
We have deter- *-cd this force to be a rMhum of 150,000 ft. Ibs, based upon the amount of da= age incurred.
There is no other known force availabic which can develop a torsional 3.
zocent of this cagnitude. The caximum torque available fr,a back flow
~~'
would be 16,500 ft. Ibs.
4.
A typical unit of this design was subjected to 50,460 reverse torque cycles while loaded to 64,000 f t. lbs," 17,593 cycles at 84,000 ft. Ibs,
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and 100 cycles at 120,000 ft. lbs. Only cinor dar. age censisting of s
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D. De=psey to R. K. Kennedy
. ' railure Analysis 1
April 17,1978 Page 7 shallow indentations of the outer race by the rollers was noted after the series of cycles at 120,000 ft. Ib. Ioading. We therefore must conclude that the excessively high loading was a result of flywheels stored kinetic energy and that the destructive forces were approxi=stely a
l ten times greater than our system can produce without first assu=ing failure of the anti-reverse device.
5.
Returning to cut away sketch Attach =ent A which Ows stop lugs provided to prevent over travel of the roller cage, we can see that lifting of the cage from its nor=al position vould result in forcing the lugs to contact the stationary can slots shown in Attach =ent F and stick the r
. cage.
6.
Two gouges which are described in Section B-14 are shown in Attachments
- A, B, and C, are at an angle and location which would cause a high l
sertical force to lift the cage if debris were present in the location shown. Although the particles of foreign debris were not found lodged
- 4 in this location, they could have easily been flushed away by oil flow and vibration after the failure occurred. The nature of the gouges l
in roller cage and the catching carks on the Kaydon bearing housing shown
- 1 i
in Attachments A and D 1 cave no doubt that the cage was lif ted and debris Indenta-vas lodged in the space between the cage and bearing housing.
tions shown on the horitontal surface of the'fic which has nor= ally 1
i zero clearance can be seen in photo teachment B.
A separate metallurC -
cal report describing the gouge characteristics is attached.
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'f. D. Denpsey to R. K. Kennedy railure Analysis April 17, 1978 Page 8 han effect of the One suggestion offered as possibly a cause rather td in Section 7.
failure was the fracturing of the oil supply line describe of the incident.
EW has concluded that the pipe broke as a result B-7.
Een Moore.*
This is covered in a separate report by SW metallurgist SECION D_
REC 010fEIDZD COREZCIVE ACION:
r key way by Eliminate the upset metal noted on the noter shaf t uppe I
1.
in-place cachining of the key way.
h the oil to elici-Carefully cican up the rotor upper housing and flus Gg 2.
'nate the presence of foreign particles. -
i in cican-Install new anti-reverse device parts taking care to ma nta 3.
11 ness of the unit and area.
dropping in to,
Install a sheet retal baffle to prevent debris from It should be noted that the outer race provides 4.
the roller cage tnnulus.
king in this area to center a co1venient tool shelf when personnel are wor the uppcr bearing follot-ing Pt..-p caintenance.
adjust as Inspect the upper and lower notor bearings and repair or 5.
necessary.
hich alarms when the An audio signal can be provided to the operator w This logic system can be 6
motor is rotating while being de-enerr, ired.
lled speed switches.
provided by using signals fron the presently insta f
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,,,j D. De=psey to R. K. Kennedy
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Failure Analysis.
April 17, 1978 Page 9 f
SECTION E PREVIOUS SUGCESTION ITdICH IS NOT RECO."' ENDED:
l It was suggested that a shear pin type relief device should be provided 1.
which would act to preclude extensive da=2ge to the motor in the event of future failures.
BW has made a pre 1Mnary study of the mechanical
__ arrangenent of such a device. It would be considerably core complicated than one would assume on the surface. The device would consist of a large
. bearing, bearing housing, shaf t adaptor, shear plate,and shear pin nounted upon the upper housing. The problem with employing such a device istheeldov ev-available for the pin to shear relative to the various design fune-
.L tional requirements. For cra=ple, design ~ condition E outlined in Attach =ent H vould allow a very narrow window if absolute certainty of
.the design functional requirements and materini characteristics are known, however, allowing for so=e smil uncertainty applied to the design functional require =ents and nor-,1 caterial property scatter this I
vindow disappears.
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cc:
L. Pictke
- 17. Spangler L. Stanek B. Shif1ct:(2)
L. Rodgers J. Thornhill G. Ward K. Moore J. Phinney L. Weissert m'
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