ML20148G637

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Rev 0 to Minimum Pipe Submergence to Prevent Vortexing Calculation
ML20148G637
Person / Time
Site: Waterford Entergy icon.png
Issue date: 12/01/1995
From:
ENTERGY OPERATIONS, INC.
To:
Shared Package
ML20148G625 List:
References
EC-M95-012, EC-M95-012-R00, EC-M95-12, EC-M95-12-R, NUDOCS 9706060072
Download: ML20148G637 (14)
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Text

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i W3F1-97-0111 i SUPPLEMENT TO ,

NPF-38-179 ATTACHMENT A 1

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CALCULATION EC-M95-012, Rev. 0 .l l

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9706060072 970603 ,.

PDR ADOCK 05000382:

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i 1 NMEERDE NRM NER EEE 5:h#ENTERGY B13.18 (Original R-Type or R-Type from Attachment VII)

CALCULATION NO. EC-M95-012 REV. NO. 0 .

TITLE Minimum Pipe Submergence to Prevent Vortexing Calculation l SUBJECT Vortexing in storage pools and vessels due to pump operation.

AFFECTED SYSTEMS CSP THIS CALCULATION SUPERSEDES COMPUTER SOFTWARE USED CODE VERSION DISK CALCULATION CLASSIFICATION:

O Non-Quality Related @ Safety Related O Quality Related: Important to Safety CALCULATION PERFORMED UNDER:

@ Waterford 3 Procedures .

O Supplier Approved Quality Procedures hk CALCULATION STATUS:

@ Final - List Pending Calculation (s) and/or Calculation Changes Incorporated O Void O Superseded - New Calc. No.

O Pending (Not Currently Installed)

O Partially Installed Initial Date  !

O Completely Installed Initial Date O Canceled Initial Date ,

Prepared By: Date: // - a s - 95 l

' ENG NEER Verified / Reviewed By: 44h /g>(4. Date: // p Approved By: Date: / / Y

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SUPERVISOR N0ECP-011 Rev. 2 Form 1, Rev. I (Page 1) .

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Watedord 3 Design Engineering Calc. Ns. EC-M95-412 General Computational Sheet TABLE OF CONTENTS 1.0 Pu rp o se. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ........................................I 2.0 C o nclu sio n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... ....1 3 . 0 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . .. . . . . . . . .................................2

' 4.0 Input Criteria .. . ..... .. .... . .. ............................................................3 5.0 As sumpti o ns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 6.0 Method o f Analysi s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 7.0 C alculation C omputation. . ... . . . . .. .. .. .. . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . . . . . . . . . .. . . .. . . . .. 4 7.1 Condensate Storage Pool (CSP) .. ..... .. .. .. .................... . ..... . . .......... .. 4 8.0 Att a c hment s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Attachment 1: Goulds Pump Manual Section 16B-3 (4 pages)

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. l Wrterford 3 Design Engineering Cale. Ns. EC-M95-012 General Cornputational Sheet RECORD OF REVISION )

REVISION CHANGE DESCRIPTION OF EFFECTIVE PAGES NUMBER REVISION / CHANGE DATE AFFECTED 0 Initial Release 12-1-95 1-6

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Waterford 3 Design Engineering Calc. N2. EC-M95-012 General Cornputational Sheet j

1.0 PURPOSE The purpose of this calculation is to determine the minimum Condensate Storage Pool water i level to prevent air entrainment, due to vortexing during pump operation, into the suction a piping of the Emergency Feedwater Pumps.

This calculation can be used as input for determining the correct low level alarms for the Condensate Storage Pool.

2.0 CONCLUSION

The minimum liquid level and corresponding liquid level percentage for the Condensate

. Storage Pool to prevent vortexing into the pump suction is provided in the following table.

l Storage Tank Minimum Minimum Water Level Water Level %

Condensate Storage Pool 1.2 ft 5.7%

, i This conclusion is based on an Emergency Feedwater Pump flowrete of 350 GPM two hours after the pump has been staned and the installation of strainers EFWMSTRN0001A and B over the pump suction piping.

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. j Watedord 3 Design F- '- ".ag Calc. N2. EC-M95-012 )

General Computational Sheet

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3.0 REFERENCES

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1. . Waterford 3 SES Condition Report 95-0657
2. Goulds Pump Manual Third Edition l
3. Crane Technical Paper No. 410, Flcw of Fluids Through Valves, Fittings and Pipe  !

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4. Waterford 3 Engineering Calculation EC-S89-003 Rev.1, EFW Requirements
5. Waterford 3 Engineering Calculation EC-M84-001 Rev. 6, Tank Volume vs. Level Tables
6. Waterford 3 DBD-003 Rev. O, Emergency Feedwater System
7. Waterford 3 SES Drawing 1564-G-905 Rev. 5
8. Waterford 3 SES Drawing 1564-G-906 Rev. 3
9. Waterford 3 SES Drawing 1564-G-907 Rev. 9
10. Waterford 3 SES Flow Diagram 1564-G-160 Sh. 6 of 6 Rev. 6
11. Waterford 3 SES Isometric Diagram 4305-6636 Rev. 9 I

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Waterford 3 Deden 5' Calc. N2. EC-M95 412 General Cosapidadonal Sheet 4.0 INPUT CRITERIA The results of calculation EC-S89-003 [4] are interpreted to dete nune the required flowrate ,

into the steam generators at the time the Condensate Storage Pool is nearing a low level. -

The interpreted required flowrate is the rate at which water is pumped into the steam ,

generator which results in an increasing steam generator level. The pump capabilities are l provided in the Design Basis Document [6]. l The CSP and subcomponent dimensions are located on the storage pool drawings [7, 8, 9].

In addition the piping configurations are shown on the isometric diagram [11). ,

The Goulds Pump Manual [2] provides a method for determining the required minimum submergence to prevent vortexing. Attachment 1 provides excerpts from this manual.

5.0 ASSUMPTIONS A. The shape of the vessel does not affect the required minimum pipe submergence.

B. The suction piping strainers act to reduce fluid momentum and prevent vortering.

6.0 METHOD OF ANALYSIS This analysis uses standard engineering conversions to determine the fluid velocity through the suction piping inlet strainers based on volumetric flowrate through the surface area of the mesh.

Once the velocity is determined, the graph contained in the Goulds Pump Manual [2], shown in Attachment 1, provides the minimum screen submergence.

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Waterford 3 Design Erginearbig Cale. Ns. EC-M95 412 i L General Cesaputational Sheet l 1  !

P 7.0 CALCULATION COMPUTATION

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j 7.1 . Condensate Storsgs Pool (CSP) i The repired flowrate from the Condensate Storage Pool (CSP) into the Emergency i Pcdwater (EFW) Pump suction piping is 350 GPM based on engineering calculation ,

t EC-S89-003 [4]. This calculation shows that two hours after starting the pump, a i 3

flowrate of 350 GPM into the steam generator will increase the water level in the steam generator. With an initial water level of 81% and a continuous flowrate into the l steam generators of 700 GPM, the CSP water level will be approxunately 41% (8.6 ft)

{ after two hours of pump operation [4, 5].

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., Each train of suction piping has a strainer, EFWMSTRN0001A or B, to prevent debris

from entering the piping system. When the water level is above the top of the strainer, i the strainers will reduce the momentum into the suction piping, thereby, reducing the
required minimum submergence to prevent vonexing.

In order to determine the effectiveness of the strainers, the fluid velocity through the l mesh must be determined. This velocity can then be compared to the graph provided

in the Goulds Pump Manual [2] to determine the required minimum submergence of the strainer.

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The strainer drawing [9] shows that the strainer height is 12.25 inches. The diameter t

i of the strainer is equal to the nozzle diameter plus 2.5 inches [9]. Since the suction j piping is 6 inch Schedule 40, the diameter of the strainer is approximately 8.5 inches.

Therefore, the overall surface area of the strainer can be calculated as follows.

A = x(8.5)(12.25)+ (8.5)* = 383.86 in f

[ The top rim of the strainer is supported by 0.75 inch angle bar [9]. There are four 2 inch wide by 12.25 inch high plates located every 90* around the perimeter of the j strainer [9]. The total surface area consumed by the supports is calculated below. j i i 2 2 s L A, = x(8.5)(0.75)+f8.5 _7 )+(4)(2)(12.25) = 136.29 in

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- l Waterford 3 Design Engineering Calc. N2. EC-M95-012 General Computational Sheet l

The strainer wire is 0.0625 inches diameter and provides a 0.25 inch square mesh [9].

In order to determine the percent of free area available to flow water through the mesh, one wire diameter is added to the length and width of one hole (0.0625 + 0.25 = , ;

0.3125 inches) so that the total area of one hole plus the wire can be calculated. The j z

total area of one hole plus wire is therefore equal to 0.09766 in (0.3125 x 0.3125).

2 The total free area through one hole is equal to 0.0625 in (0.25 x 0.25). Therefore, the percentage of free area available for flowing through the mesh is 64%

(0.0625/0.09766).

The total free area available for flow into the suction piping can calculated by subtracting the surface area of the supports from the total surface area and multiplying by the percentage of free flow area available as follows.

2 2 Au = (383.86- 136.29)(0.64) = 158.44 in = 1.10 f1 The fluid velocity through the mesh is calculated as follows.

l v= 350 88I/m. m

= 0.71ft /

2 7.48052 _ gal (1.10 ft 60se/cmin

. Referring to the t;raph in the Goulds Pump Manual (Attachment 1), velocities below 1.5 ft/sec are not included on the graph. Therefore with a velocity of 0.71 ft/sec, it is only required that the strainer remain submerged to prevent vortexing. Allowing for a 2 inch margin of error in the height of the screen, the minimum water level in the CSP

' to prevent vortexing mto the EFW suction piping is 14.25 inches (1.2 ft) which corresponds to a liquid level of 5.7% [5].

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e e Waterford 3 Design Fr_' _s Calc. N:. EC.M95-012 General Computadonal Sheet 8.0 ATTACHMENTS

  • 1 1

Attachment 1: Goulds Pump Manual Section 16B-3 (4 pages)  !

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. . . ATTACHMENT 1 (Page 1 of 4) 168-3 Pipmg Design The design of a piping system can have an smportant ,'h -t on Higher velocities willincrease the friction loss and can result in the successful operation of a centnfugal pump. Such ws as troublesome air or vapor separation. This is further complicated sump decign, suction piping design, suction and discharge pipe when elbows or tees are located adjacent to the pump suction size, and pipe supports must all be carefully considered. nozzle, in that uneven flow patterns or vapor separation keeps e ing g er. s upseu vraulic Selection of the discharge pipe s ze is pnmanly a matter of am a p ss e ca am, and ocesswa a

economics. The cost of the vanous pipe sizes must be compared to the pump size and power cost required to overcome the a res t resulting fnetion head.

" ** '"U'"**" ' "# D #"'" '" "

The suct:on piping size and design is far more important. Many su tion line can be a source of trouble. The suction pipe snould centnfugal pump troubles are caused by poor suction conditions.

be exactly honzontat, or with a uniform slope upward from the TM suction pipe should never be smaller than the suction sump to the pump as shown in Fig.1. There should be no hagh connection of the pump, and in most cases should be at least spots where air can collect and cause the pump to lose its one size larger. Suction pipes should be as short and as straight prims E;contne rather than concentnc reducers should always as possible. Suction pipe velocities should be in the 5 to 8 feet be used.

per second range unless suction conditions are unusuaisy good.

CHECK AIR POCKET BECAUSE ECCENTRIC REDUCER ECCENTRIC VALVE GATE iS NOT USED AND BECAUSE SUCTION ,

REDUCER -

VALVE PIPE DOES NOT SLOPE GRAOuALLY GATE

\ g*, ~3 UPWARo FROM SUPPLY VALVE 80: I I -

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>cz GATE VALVE SHOULD NOT BE BETwEEN VALVE CHECK VALVE AND PUMP

.=:1 FOOT VALVE fiF USED)

, (239-81 1)

STRAINER (t a) CORRECT (1C) WRONG CidECK ECCENTRIC VALVE REDUCER s' . w y }

(ogN aAD'US g f_ h )

GATE SUCTION PIPE SLOPES

  • UPwARoS FROM SOURCE
  1. ALN OF SUPPLY I

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3 FOOT VALVE (IF USEDI l

, - STRAINER

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. (1b) CORRECT Fig.1 Air Pocketa in Suction Piping 407 f(410D ,

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if an 4lbow is r* Quired at the suction of a doubtw suction pump, necesstry for some ATTACHMENT reason to use1 a nonzontaj Page 2 of 4) elbow, it should

  • l l lt should b3 in a vertical position if at all possible. Where it is be a long radius elbow and thsre should be a minimum of two 3

diemstsrs of straight pips between the elbow anc the purno as j shown in Fig. 2. Fig. 3 shows the effect of an elbow directly on

{ the suction. The liquid will flow toward the outsics of the elbow

{ y g and result in an uneven flow 6stnbution into the two inlets of

  • the double suction impeller. Noise and excessive axial thrust 3 (

i d )l will result.

l 3* tj l M l ECCENTRIC l i AEDUCER-WITH 'j rg

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TOP HOAl20NTAL , $g,g [ h M A I 'WlUl

-O-i i e' EBOW MUST BE b ~

VEATICAL WHEN '

NEXT TO PUMP l (2a) PERMISSIBLE (2b) WRONG l

i Fig. 2 Elbows At Pump Suction i

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i Fig. 3 Effect of Elbow Directly on Suction l

l l There are several important considerations in the design of a The free discharge of liquid above the surface of the supply suction supply tank or sump. 'It is imperative that the amount of tank at or near the pump suction can cause entrained air to ,

turbulence and entrained air be kept to a minimum. Entrained eriter the pump. Alllines should be submerged in the tank, and air will cause reduced capacity and efficiency as well as vibra. baffles should be used in extreme cases as shown in Fig. 4.

tion, noise, shaft breakage, loss of prime, and/or accelerated I

corrosion.

pump SVCTioN

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i j PAFFLE - ,

i PUMP W sucTloN / **

l Puus g ' RECoHMENDEo suction

  • l j (da) (4b) (4c) I i Fig. 4 Keeping Air Out of Pump I

l 1mproper submergence of the pump suction line can cause a location of the pipe in the sump and the actual dimensions of l j vort:x which is a swirling funnel of air from the surface directly the sump are also important in preventing vortering and/or j into the pump suction pipe, fn addition to submergence, the excess turbulence, i

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' . Fig. 5 can be used as a guide for minimum submergence and ATTAC}NENT 1 (Page 3 of 4) .

sump dimensions for flows up to approximatsly 3000 gpm. Baffles

) can be ussd to hero prevent vortering in cases where it is im-I practical or impossible to maintain the required submergence.

{ Fig. 6 shows three such baffling arrangements. .I 1 _

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N 4a 21 OR '"

AREA (inches): D8 l

Fig. 5 Minimum Suct6on Pipe Submergence and Sump Dimensions h

FLAT BAFFLE

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[' BAFFLE 1 Sloe VIEW SMOOTHS SUCTION PsPE N OUT YORTEx

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SUCTION y .

i j TOP view j (6a) (60)

(6c) j Fig.6 Battle krongements for Vortex Prevention i

j tarde units (over 3000 gpm) taking their suction supply from multiple pump pit. Note that the pipe should always be located i, umps require special attention. The larger the unit, the more near the back wall and should not be subjected to rapid changes ianportant the sump design becomes. in direction of the flow pattern. The velocity of the water in the j area of the suction p> pes should be kept below one foot per Fig. 7 Illustrates several preferred piping arrangements within a second to avoid air being drawn into the pump.

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. c NOT RECOMMENDgTACHMENT 1 (Page 4 of 4) ,

l RECOMMENDED 7

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  • V, = 2 fos & UP V, = 1 fps OR LESS -4 y, f I (F A = L SS THAN g

v 4 V. S = 1 % TO 20 W

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W

/ T ADD WALL THICO -]f j NESS TO Q DIST.

ROUND OR OGIVE - m aims, '

WALL ENDS. GAP W AT REAR OF WALL APPX. D/3 0 -

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MIN a = 45'

.\ PREFERED a = 75*

Fig. 7 Piping Arrangements Within Multiple Pump Pits R1prmted from MYoRAULIO INSTITUTE STANoARos. Twelfth Edition. Copyrtant 19es Dy Hydraul6c Institute.

A b211 should be used on the end of the suction pipe to limit the considered. The amount of submergence required depends upon entrance velocity to 3.5 feet per second. Also, a reducer at the the size and capacity of the individual pumps as well as on the pump suction flange to smoothly accelerate and stabilize the sump design. Past experience is the best guide for determining flow into the pump is desirable. the submergence.The pump manufacturer should be consulted

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The submergence of the suction pipe must also be carefully 16B-4 Stuffing Box Sealing Th3 stuffing box of a pump provides an area in which to seal The function of packing is to control leakage and not to elimi- ,

ag: inst leakage out of the pump along the shaft. Packing and nate it completely. The packing must be lubncated, and a flow m chanical seals are the two devices used to accomplish this of from 40 to 60 drops per minute out of the stuffing box must be ,

f s;01. maintained for proper lubncation. j The mett'.od of lubricating the packing depends on the nature l C "I of the liquid being pumped as well as on the pressure in the A typical packed stuffing box arrangement is shown in Fig.1. stuffing box When the pump stufhng box pressure is above t i

atmospheric pressure and the liquid is clean and nonabrasive, I it consists of: A) Five rings of packing, B) A lantem ring used for th3 injection of a lubricating and/or flushing liquid, and C) A the pumped liquid itself will lubricate the packing (Fig. 2.) When gland to hold the packing and maintain the desired compression the stuffing box pressure is below atmospheric pressure, a lantem ring is employed and lubrication is injected into the for a proper seal, NOGC0 410 s

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