Refined Globe Valve Thrust Prediction Model to Bound Midstroke ...
Refined Globe Valve Thrust Prediction Model to Bound Midstroke ...
Refined Globe Valve Thrust Prediction Model to Bound Midstroke ...
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<strong>Refined</strong> <strong>Globe</strong> <strong>Valve</strong> <strong>Thrust</strong> <strong>Prediction</strong><br />
<strong>Model</strong> <strong>to</strong> <strong>Bound</strong> <strong>Midstroke</strong> <strong>Prediction</strong>s of<br />
AOV Margins<br />
Zachary Leutwyler<br />
Dr. M. S. Kalsi<br />
Kalsi Engineering<br />
Tenth NRC/ASME Symposium on<br />
<strong>Valve</strong>s, Pumps and IST<br />
July 15, 2008<br />
Slide #1 #
• Introduction<br />
Objectives<br />
Background<br />
Two-point Two point thrust prediction model<br />
KEI <strong>Bound</strong>ing <strong>Thrust</strong> Zone (BTZ) <strong>Model</strong><br />
• KEI Flow Loop Testing<br />
• KEI Flow Loop Test Results<br />
• Comparison of BTZ prediction with Test Data<br />
• Conclusion<br />
Outline<br />
Slide #2 #
Identify key limitations of Two-point Two point model<br />
Objectives<br />
Identify improvement gained through<br />
implementing the <strong>Bound</strong>ing <strong>Thrust</strong> Zone (BTZ)<br />
Identify Key fac<strong>to</strong>rs governing the “general general”<br />
nature of globe valve thrust w.r.t. w.r.t.<br />
position<br />
Overview of BTZ model and model validation<br />
Slide #3 #
Background<br />
March March 2000 – NRC Issued RIS 2000-03 2000 03 “Resolution Resolution<br />
of Generic Safety Issue 158: Performance of<br />
Safety-Related<br />
Safety Related POVs Under Design Basis<br />
Conditions” Conditions<br />
Prior Prior <strong>to</strong> RIS 2000-03 2000 03:<br />
• NRC and INPO conducted surveys and identified<br />
common cause failures with AOVs that can lead <strong>to</strong><br />
safety concerns, reac<strong>to</strong>r scrams, reduced plant<br />
efficiency<br />
– NUREG/CR-6654 NUREG/CR 6654 & NUREG-1275 NUREG 1275 Vol. 13<br />
– INPO SER 1-99 1 99<br />
Slide #4 #
Background – Continued<br />
• EPRI conducted an AOV AOV pilot pilot program program (1996-1999) (1996 1999) teaming with<br />
four utilities <strong>to</strong> develop AOV evaluation methodologies<br />
– EPRI AOV Evaluation Guide TR-107322 TR 107322, , issued May 1999<br />
– Where applicable, EPRI MOV PPM validated methodologies<br />
where used for AOVs<br />
– Several Industry AOV issues identified, including three issues<br />
related <strong>to</strong> globe valves<br />
1) EPRI MOV PPM models were not applicable for flashing (two-<br />
phase) or compressible flow. flow.<br />
<strong>Valve</strong> fac<strong>to</strong>rs as high as 1.6 - 2.35<br />
were found during in-situ in situ plant tests for steam flow application<br />
(INPO OE-11440) OE 11440)<br />
2) No validated models exist for predicting globe valve disc side<br />
loading/friction force<br />
Mid-position position loads may be greater than fully seated loads under<br />
dynamic conditions due <strong>to</strong> flow-induced flow induced forces<br />
3) Mid<br />
Slide #5 #
Background - Continued<br />
EPRI refined and validated models <strong>to</strong> address issue 2) for balanced disc<br />
globe valves only (NUREG/CP-0152, (NUREG/CP 0152, Vol. 3), July 2000<br />
EDF/KEI addressed side-load side load and cavitating/flashing flow effects for an<br />
unbalanced globe valve through experimentation and CFD (ASME PVP<br />
conference July2008 , PVP2008-61238)<br />
PVP2008 61238)<br />
The methodology <strong>to</strong> address mid-position loads being greater or equal<br />
than fully seated load developed and incorporated in AOV evaluation<br />
software by KEI in 2000.<br />
The methodology is addressed in this paper<br />
Slide #6 #
The two-point two point model is the common<br />
industry approach<br />
- Suitable for MOVs, MOVs,<br />
but not for AOVs<br />
Limitations<br />
Established by predicting the thrust at<br />
the closed and open position.<br />
<strong>Thrust</strong> at closed position is predicted<br />
by imposing the peak thrust at the<br />
closed position – peak thrust may be<br />
as far away 30% from the seating<br />
position<br />
Two--point Two point model model may not bound all<br />
thrust profiles and may result in non-- non<br />
conservative conservative margin margin predictions predictions for<br />
AOVs<br />
Two-point Two point <strong>Model</strong><br />
Slide #7 #
BTZ - Enhanced <strong>Model</strong><br />
Peak thrust magnitude is predicted<br />
the same as Two-point Two point model, but<br />
“knee knee” position is defined by the<br />
user <strong>to</strong> bound the thrust curve.<br />
BTZ bounds F DP throughout the<br />
stroke, thus eliminating non-<br />
conservative margin predictions for<br />
AOVs<br />
<strong>Bound</strong>ing <strong>Thrust</strong> Zone<br />
Slide #8 #
<strong>Bound</strong>ing <strong>Thrust</strong> Zone - Applicability<br />
When is BTZ necessary?<br />
<strong>Valve</strong> Parameters<br />
• Flow Over the Disc<br />
• Opening Stroke<br />
Actua<strong>to</strong>r Parameters<br />
• Spring return (i. e., not<br />
applicable <strong>to</strong> double acting<br />
without spring actua<strong>to</strong>rs)<br />
Notes:<br />
Potential non-conservatism<br />
non conservatism<br />
can exist regardless of<br />
actua<strong>to</strong>r action (i. e., reverse<br />
or direct).<br />
• Actua<strong>to</strong>r action only<br />
determines if the air stroke<br />
or spring stroke corresponds<br />
<strong>to</strong> the opening stroke<br />
Slide #9 #
Notes (Continued):<br />
<strong>Bound</strong>ing <strong>Thrust</strong> Zone - Applicability<br />
Closing stroke generally not a<br />
problem since actua<strong>to</strong>r<br />
capability decreases in the<br />
closing direction – minimum<br />
margin at seating position<br />
Slide #10 # 10
<strong>Thrust</strong> Components<br />
Disc DP Force, F DP<br />
Stem Rejection Force, F P<br />
Side-load Force, F US<br />
Static Forces, F P<br />
Packing<br />
Bellows<br />
Static Pis<strong>to</strong>n Seal<br />
Friction<br />
Sealing Load, F SL<br />
Closing Stroke<br />
Opening Stroke<br />
Introduction<br />
<strong>Thrust</strong> Components<br />
FC = FDS + FP + FUS + FSR + FDF + FDP + FSL<br />
FO = FDS + FP + FUS + FSR + FDF + FDP<br />
Slide #11 # 11
Key Fac<strong>to</strong>rs<br />
Key Fac<strong>to</strong>rs Influencing FDP DP vs. Position<br />
Balanced/Unbalanced Trim affects<br />
magnitude<br />
Maximum Disc Head Diameter vs.<br />
Seating Diameter<br />
Disc Head-<strong>to</strong> Head <strong>to</strong>-Body/Cage Body/Cage Wall<br />
Clearance<br />
Trim Trim Flow Flow Characteristics<br />
Characteristics<br />
(focus (focus of of testing) testing)<br />
Fluid Media<br />
Operating Conditions (e.g. DP, Q,<br />
T, & Cavitation/flashing)<br />
Slide #12 # 12
Example of Geometric<br />
Dependency<br />
(e.g., Seat Based vs. Guide Based)<br />
Unbalanced Unbalanced Disc<br />
Clearance Clearance between Disc<br />
Head and body/cage wall<br />
is small ( (lower lower Figure) Figure)<br />
Key Fac<strong>to</strong>rs - Continued<br />
Wide<br />
Clearance<br />
Narrow<br />
Clearance<br />
Slide #13 # 13
Key Fac<strong>to</strong>rs - Continued<br />
Area Based on D seat<br />
Example of Geometric Dependency<br />
(e.g., Seat Based vs. Guide Based)<br />
Narrow clearance restricts flow and<br />
causes high static pressure <strong>to</strong> act on the<br />
disc face<br />
Once disc opens, area on which pressure<br />
acts increases from Dseat seat <strong>to</strong> Ddisc disc diam.<br />
The increase in Area and preservation of<br />
DP Close causes an increase in F DP<br />
As such, F DP initially increases as the disc<br />
moves from the seat untill ~ +25%<br />
open, then decreases as DP drops below<br />
DP<br />
DPclose close<br />
Area Based on D disc diam.<br />
Slide #14 # 14
Test Specimen<br />
4” <strong>Globe</strong> <strong>Valve</strong><br />
Unbalanced Trim<br />
4 3/8 inch Port<br />
Flow Under<br />
Equal Percent or Quick Open Trim<br />
(established by the Cage)<br />
Quick Open Equal Percent<br />
KEI Flow Loop Testing<br />
Slide #15 # 15
Measurements/Instrumentation<br />
<strong>Thrust</strong> (using a Crane ForceLink<br />
and a traditional load cell)<br />
Upstream and Downstream<br />
Pressure<br />
Upper Body Cavity Pressure<br />
Flow Rate<br />
Actua<strong>to</strong>r Diaphragm Pressure<br />
Key Parameters<br />
Three DP/Flow rates<br />
Equal Percent and quick open<br />
trim flow characteristics<br />
KEI Flow Loop Testing<br />
Slide #16 # 16
KEI Flow Loop Testing<br />
4-inch 150# unbalanced cage guided globe valve<br />
Slide #17 # 17
Flow Coefficient, Cv<br />
250<br />
200<br />
150<br />
100<br />
50<br />
0<br />
Quick Open - Test Data<br />
Quick Open - Fisher Data<br />
Equal Percent - Test Data<br />
Equal Percent - Fisher Data<br />
Test Results<br />
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%<br />
Disc Position, % Open<br />
Comparison of Experimental versus Published C v Data<br />
Slide #18 # 18
Disc Differential Pressure Force (F DP ), lbs<br />
1600<br />
1400<br />
1200<br />
1000<br />
800<br />
600<br />
400<br />
200<br />
Test Results-Equal Results Equal Percent Trim<br />
Equal Percent Trim<br />
0<br />
0<br />
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%<br />
Disc Position, % Open<br />
Disc Head Force - Equal Percent<br />
<strong>Valve</strong> Differential Pressure<br />
<strong>Valve</strong> DP knee is a good indica<strong>to</strong>r for the F DP knee for BTZ methodology<br />
120<br />
100<br />
80<br />
60<br />
40<br />
20<br />
<strong>Valve</strong> Differential Pressure, psi<br />
Slide #19 # 19
Test Results – Quick Open vs. Equal Percent<br />
Disc Head Force Coefficient<br />
1.2<br />
1.0<br />
0.8<br />
0.6<br />
0.4<br />
0.2<br />
0.0<br />
Equal Percent Trim<br />
Quick Open Trim<br />
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%<br />
Disc Position, % Open<br />
F DP coefficient is dependent on trim flow characteristics<br />
Slide #20 # 20
Key Conclusions<br />
Conclusion from Test Data<br />
FDP DP (and consequently the resultant thrust) for Equal Percent<br />
and Quick Open Trim are significantly different<br />
FDP DP vs. position trend is dependent on Trim Type due <strong>to</strong> DP<br />
and Disc DP force coefficient relationship with position<br />
<strong>Valve</strong> and system resistance governs relationship of valve DP<br />
w.r.t position<br />
Knee location for Equal percent can be as far out as 55%<br />
Open; Quick Open as little as 15%<br />
Slide #21 # 21
Determining Knee Location without Testing<br />
<strong>Valve</strong> Differential Pressure Ratio, ∆PR<br />
1.0<br />
0.9<br />
0.8<br />
0.7<br />
0.6<br />
0.5<br />
0.4<br />
0.3<br />
0.2<br />
0.1<br />
Quick Open<br />
Equal Percent<br />
Linear<br />
0.0<br />
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%<br />
∆P<br />
ratio<br />
∆P<br />
=<br />
∆P<br />
v<br />
sys<br />
Disc Position, % Open<br />
=<br />
K<br />
up<br />
K<br />
+ K<br />
v<br />
v(<br />
x)<br />
( x)<br />
+ Kdown<br />
<strong>Valve</strong> DP ratio can be analytically predicted and used <strong>to</strong> identify knee for BTZ<br />
Slide #22 # 22
BTZ <strong>Prediction</strong> and Test Data Comparison<br />
Disc Head Force, lbs<br />
2000<br />
1800<br />
1600<br />
1400<br />
1200<br />
1000<br />
800<br />
600<br />
400<br />
200<br />
Equal Percent Trim<br />
Running Average Closing Stroke Disk Head Force<br />
<strong>Bound</strong>ing <strong>Thrust</strong> Zone <strong>Prediction</strong><br />
0<br />
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%<br />
Disc Position, % Open<br />
<strong>Prediction</strong>s based on proper location of knee in BTZ<br />
model bound test data<br />
Slide #23 # 23
Conclusions<br />
• BTZ provides bounding prediction of F DP and consequently<br />
the resulting <strong>to</strong>tal thrust<br />
• BTZ eliminates the potential for non-conservative non conservative margin<br />
predictions in AOVs<br />
• BTZ knee location can be analytically predicted using the<br />
valve flow coefficients and system resistance<br />
• Methodology validated by testing and incorporated in the<br />
globe valve thrust prediction model in KVAP software (Kalsi<br />
<strong>Valve</strong> and Actua<strong>to</strong>r <strong>Prediction</strong> software)<br />
Slide #24 # 24