ASME-Imp 1998 Thermo Well

7/31/2019 ASME-Imp 1998 Thermo Well

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THERMOWELL VIBRATION

When fluid flows past a thermowell, the change in fluid momentum createsa turbulent wake behind the well. Vortices form in this wake, and shed fromalternate sides of the well. The vortex shedding frequency (or Wake

frequency) is linear with flow velocity and inversely proportional tothermowell tip diameter.

These shedding vortices impose on the thermowell, a periodic forcecomprising two components (i) a lift force, normal to direction of flow,oscillating at the wake frequency, and (ii) a smaller drag force, parallel toflow, oscillating at twice the wake frequency.

These vortex-induced forces, which cause thermowell vibration, arenormally small with the magnitude of the vibrations generally negligible.However, as the wake frequency (fw) approaches the natural frequency (fn)of the thermowell (within 20%), it can shift and lock-in to the naturalfrequency. When fw = fn, the thermowell goes into resonance, andvibrating forces increase rapidly. The resultant vibrations can causemechanical failure of the well.

The Murdock calculations (and companion ASME PTC 19.3) consider onlythe oscillating lift force as the cause of thermowell vibration. The ratio ofwake to natural frequency is restricted to a maximum of 0.8 to eliminate thepossibility of resonance.Although the oscillating drag force is small, it can force the thermowellinto resonance at lower velocities because it occurs at twice the wakefrequency. For high-density fluids (liquids and high pressure steam), theMurdock analysis is not adequate. When the oscillating drag component isincluded, the velocity rating can be reduced by up to 50%.

The calculations included herein are modified to include in-line resonancedue to the oscillating drag force, correction for the magnification ratio anduse of the actual natural frequency of the well rather than the estimatedvalue.

The results of these calculations should only be used as a guide in theselection of the correct thermowell. Other variables, like corrosion, shouldbe evaluated and influence the decision.


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Tag #:

Date:

Rev:

U

B

d

A

FLUID DATA CONSTANTS

Air Kf 2.01 t/A 0.01

To 150 K1 0.079 t/B 0.01

Po 200 K2 15.7 FA 3.5

V 39 K3 2.679 FB 3.5

v 1.052

Well Material 304 fn 424 Hz

U 10.00 fw 137 Hz

d 0.500 r 0.32

B 0.750 Fm 1.12

A 0.760 Um 15.7 in

w 0.112 Vm 96 ft/sec

E 50.0 Pm 3167 psig

S 40.0 Ls 42.09 in

Max Stress Velocity Vs 164.1 fps

thermowell design. Thermo-Kinetics assumes no responsibility for failure of a well based on the results of these calculations,

and accepts no liability direct or consequential, arising from error or misinformation supplied herein, or due to program misuse.

These calculations are performed according to the paper "Power Test Code Thermometer Wells" by J. W. Murdock, and also

meet the requirements of ASME PTC 19.3-1998. The program supplies results which should only be used as a guide for

Thermowell Velocity Rating(Program Ver. 4.2a)

Company:

Project No:

WELL DATA

Fluid

Operating Temperature F

Reference:

Operating Pressure

Fluid Velocity

ft/sec

Bore Diameter

psi x 103

Magnification Factor

Max Length @ V (r=0.8)

Max Velocity @ U (r=0.8)

psig

CALCULATIONS

in

ft3/lb

Wake Frequency

Frequency Ratio

Natural Frequency @ To

lb/in3

Unsupported Length

Root Diameter

Specific Weight @ To

in

in

in

Tip Diameter

NOTES

Max Static Pressure

Max Stress Length

psi x 106

Allowable Stress @ To

Mod of Elasticity @ To

Well taper is less than recommended

Wall thickness is less than recommended


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Code 70F

C.Steel 105 0.284

304 SS 304 0.290

310 SS 310 0.290

316 SS 316 0.290

321 SS 321 0.290

446 SS 446 0.270

F22 SS F22 0.290

ID in Hast B-3 HSB-3 0.334

Q SCFM Hast C-22 HSC-22 0.323

V ft/sec Hast C-276 HSC-276 0.323

Hast C-4 HSC-4 0.323

Hast X HSX 0.297

Inconel INC 0.307

Monel MON 0.319

1 60 100 300 400 500 600 700 Nickel NIK 0.322

0.016 0.016 0.016 0.017 0.018 0.020 0.024 0.037 Titanium TIT 0.163

UNS# 70F 200F 300F 400F 500F 600F 700F 800F 900F 1000F

C.Stl SA-675 105 29.5 28.8 28.3 27.7 27.3 26.7 25.5 24.2 22.4 20.4

HR160 N12160 160 30.6 29.8 29.4 29.1 28.6 28.3 27.8 27.2 26.6 26.0

304 SS S30400 304 28.3 27.7 27.1 26.6 26.1 25.4 24.8 24.1 23.4 22.7

310 SS S31008 310 28.3 27.7 27.1 26.6 26.1 25.4 24.8 24.1 23.4 22.7

316 SS S31600 316 28.3 27.7 27.1 26.6 26.1 25.4 24.8 24.1 23.4 22.7

321 SS S32100 321 28.3 27.7 27.1 26.6 26.1 25.4 24.8 24.1 23.4 22.7

446 SS S44627 446 29.2 28.7 28.3 27.7 27.0 26.0 24.8 23.1 21.1 18.6 F22 SS K21590 F22 30.6 29.8 29.4 28.8 28.3 27.7 27.1 26.3 25.6 24.6

Hast B-3 N10675 HSB-3 31.4 30.6 30.1 29.8 29.3 29.0 28.6 27.9 27.3 26.7

Hast C-22 N06022 HSC-22 29.9 29.2 28.7 28.4 28.0 27.7 27.2 26.6 26.0 25.4

Hast C-276 N10276 HSC-276 29.8 29.1 28.6 28.3 27.9 27.6 27.1 26.5 25.9 25.3

Hast C-4 N06455 HSC-4 29.8 29.1 28.6 28.3 27.9 27.6 27.1 26.5 25.9 25.3

Hast X N06002 HSX 28.5 27.8 27.4 27.1 26.6 26.4 25.9 25.4 24.8 24.2

Inconel N06690 INC 30.3 29.5 29.1 28.8 28.3 28.1 27.6 27.0 26.4 25.8

Monel N04400 MON 26.0 25.4 25.0 24.7 24.3 24.1 23.7 23.1 22.6 22.1

Nickel N02200 NIK 30.0 29.3 28.8 28.5 28.1 27.8 27.3 26.7 26.1 25.5

Titanium R50400 TIT 15.5 15.0 14.6 14.0 13.3 12.6 11.9 11.2

UNS# 70F 200F 300F 400F 500F 600F 700F 800F 900F 1000F

C.Steel SA-675 105 14.3 14.3 14.3 14.2 13.6 12.8 11.9 9.4 5.0

HR160 N12160 160 23.3 20.5 18.3 16.5 15.0 14.1 13.6 13.5 13.5 13.5

304 SS S30400 304 20.0 16.7 15.0 13.8 12.9 12.3 11.7 11.2 10.8 10.4

310 SS S31008 310 20.0 17.6 16.1 15.1 14.3 13.7 13.3 12.9 12.5 9.9

316 SS S31600 316 20.0 17.3 15.6 14.3 13.3 12.6 12.1 11.8 11.5 11.3

321 SS S32100 321 20.0 18.0 16.5 15.3 14.3 13.5 13.0 12.6 12.3 12.0

446 SS S44627 446 18.6 18.5 18.3 18.2 18.1 18.0 17.9

F22 SS K21590 F22 21.4 21.4 20.9 20.6 20.5 20.4 20.0 19.3 15.8 7.8

Hast B-3 N10675 HSB-3 31.4 31.4 30.3 28.8 27.4 26.3 25.4 24.8

Hast C-22 N06022 HSC-22 28.6 26.7 24.6 22.9 21.5 20.4 19.6 19.0 18.6 18.3

Hast C-276 N10276 HSC-276 27.3 24.9 23.0 21.3 19.9 18.7 17.8 17.1 16.7 16.5

Hast C-4 N06455 HSC-4 26.7 24.6 23.0 21.7 20.8 20.1 19.6 19.1

Hast X N06002 HSX 23.3 21.0 19.2 17.7 16.5 15.7 15.1 14.7 14.5

Inconel N06690 INC 23.3 21.1 19.9 19.1 18.6 18.4 18.2 18.0

Monel N04400 MON 16.7 14.6 13.6 13.4 13.2 13.1 13.0 12.7 8.0Nickel N02200 NIK 10.0 10.0 10.0 10.0 10.0 10.0

Titanium R50400 TIT 14.3 12.4 10.3 8.8 7.6 6.5

V = 3.0558Q/ID

MODULUS of ELASTICITY (x 106 psi)

FLUID VELOCITY CALCULATED from FLOW DATA

Specific Volume of Water (ft3/lb) (T in F)

0.017

Flow Rate

Velocity 7.6

Material Code

200

Fluid

Pipe I.D.

Air

2.000

10.0

SPECIFIC WEIGHT (lb/in3)

Code

TABLES

Material

ALLOWABLE STRESS (x 103 psi)

Material


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1/2" 0.840 0.710 0.674 0.674 0.622 0.622 0.546 0.546

3/4" 1.050 0.920 0.884 0.884 0.824 0.824 0.742 0.742

1" 1.315 1.185 1.097 1.097 1.049 1.049 0.957 0.957

1-1/4 1.660 1.530 1.442 1.442 1.380 1.380 1.278 1.278

1-1/2 1.900 1.770 1.682 1.682 1.610 1.610 1.500 1.500

2 2.375 2.245 2.157 2.157 2.067 2.067 1.939 1.939

2-1/2 2.875 2.709 2.635 2.635 2.469 2.469 2.323 2.323

3 3.500 3.334 3.260 3.260 3.068 3.068 2.900 2.900

3-1/2 4.000 3.834 3.760 3.760 3.548 3.548 3.364 3.364

4 4.500 4.334 4.260 4.260 4.026 4.026 3.826 3.826 3.624

5 5.563 5.345 5.295 5.295 5.047 5.047 4.813 4.813 4.563

6 6.625 6.407 6.357 6.357 6.065 6.065 5.761 5.761 5.501 8 8.625 8.407 8.329 8.329 8.125 8.071 7.981 7.981 7.813 7.625 7.625 7.437 7.187

10 10.750 10.482 10.420 10.420 10.250 10.090 10.020 10.020 9.750 9.560 9.562 9.312 9.062

12 12.750 12.438 12.390 12.390 12.250 12.090 12.000 11.938 11.626 11.750 11.374 11.062 10.750

14 14.000 13.688 13.624 13.500 13.250 13.376 13.250 13.124 12.812 13.000 12.500 12.124 11.812

16 16.000 15.670 15.624 15.500 15.500 15.376 15.250 15.000 14.688 15.000 14.312 14.938 13.562

18 18.000 17.670 17.500 17.500 15.376 17.124 17.250 16.876 16.500 17.000 16.126 15.688 15.250

20 20.000 19.624 19.500 19.500 19.250 19.000 19.250 18.814 18.376 19.000 17.938 17.567 17.000

22 22.000 21.624 21.624 21.500 21.250 21.000 21.250 20.250 21.000 19.750 19.250 18.750

24 24.000 23.572 23.500 23.500 23.250 22.876 23.250 22.626 22.064 23.000 21.564 20.938 20.376

26 26.000 25.376 25.000 22.876 25.750 25.000

28 28.000 27.376 27.000 26.750 27.750 27.000

30 30.000 29.500 29.376 29.376 29.000 28.750 29.750 29.000

32 32.000 31.376 31.000 30.750 31.750 30.624 31.000

34 34.000 33.376 33.000 32.750 33.750 32.624 33.00036 36.000 29.376 35.376 35.000 34.750 35.750 34.500 35.000

42 42.000 41.750 41.000

Size O.D.

Pipe Inside Diameter - inches (Welded & Seamless Steel Pipe)

STD302010 40 60 100

SCHEDULE

PIPE DIMENSIONS

XH 80 1205S 10S


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100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

10 0.016 38.85 44.99 51.04 57.04 63.03 69.01 74.98 80.95 86.92 92.88 98.84 104.8 110.76 116.72

15 0.016 0.017 29.90 33.96 37.99 41.99 45.98 49.96 53.95 57.93 61.91 65.88 69.86 73.83 77.81

20 0.016 0.017 22.36 25.43 28.46 31.47 34.47 37.46 40.45 43.44 46.42 49.41 52.39 55.37 58.36

25 0.016 0.017 17.86 20.34 22.78 25.20 27.60 30.01 32.40 34.80 37.19 39.58 41.98 44.37 46.76

30 0.016 0.017 14.81 16.89 18.93 20.95 22.95 24.95 26.95 28.94 30.94 32.93 34.92 36.95 38.90

35 0.016 0.017 12.65 14.45 16.21 17.94 19.66 21.38 23.09 24.80 26.51 28.22 29.93 31.63 33.34

40 0.016 0.017 11.04 12.62 14.17 15.67 17.20 18.70 20.20 21.70 23.19 24.69 26.18 27.68 29.17

45 0.016 0.017 9.782 11.21 12.58 13.94 15.28 16.62 17.96 19.29 20.62 21.95 23.28 24.61 25.94

50 0.016 0.017 8.769 10.06 11.31 12.53 13.74 14.95 16.15 17.35 18.55 19.75 20.94 22.14 23.33

65 0.016 0.017 6.678 7.698 8.667 10.18 10.55 11.49 12.41 13.34 14.26 15.19 16.11 17.03 17.9575 0.016 0.017 0.017 6.645 7.494 8.320 9.135 9.945 10.75 11.55 12.36 13.16 13.95 14.75 15.55

100 0.016 0.017 0.017 4.936 5.588 6.217 6.834 7.446 8.053 8.658 9.260 9.862 10.46 11.06 11.66

200 0.016 0.017 0.017 2.361 2.725 3.059 3.379 3.693 4.003 4.310 4.615 4.918 5.221 5.522 5.823

250 0.016 0.017 0.017 1.861 2.154 2.430 2.693 2.948 3.198 3.446 3.692 3.936 4.179 4.421 4.663

300 0.016 0.017 0.017 0.019 1.767 2.005 2.227 2.442 2.653 2.861 3.066 3.270 3.474 3.676 3.878

400 0.016 0.017 0.017 0.019 1.285 1.477 1.651 1.817 1.978 2.136 2.292 2.446 2.600 2.753 2.905

500 0.016 0.017 0.017 0.019 0.993 1.159 1.304 1.441 1.573 1.701 1.827 1.952 2.076 2.199 2.321

600 0.016 0.016 0.017 0.019 0.795 0.946 1.073 1.190 1.302 1.411 1.518 1.623 1.726 1.830 1.932

675 0.016 0.017 0.017 0.018 0.693 0.829 0.946 1.053 1.154 1.252 1.347 1.441 1.534 1.627 1.718

700 0.016 0.016 0.017 0.019 0.020 0.793 0.908 1.011 1.109 1.204 1.296 1.387 1.477 1.566 1.654

800 0.016 0.016 0.017 0.019 0.020 0.678 0.783 0.877 0.964 1.048 1.130 1.211 1.290 1.368 1.446

900 0.016 0.016 0.017 0.019 0.020 0.587 0.686 0.771 0.850 0.926 1.000 1.072 1.143 1.213 1.283

1000 0.016 0.016 0.017 0.019 0.020 0.514 0.609 0.688 0.761 0.831 0.898 0.963 1.028 1.091 1.154

1200 0.016 0.017 0.017 0.019 0.020 0.402 0.491 0.562 0.626 0.686 0.743 0.798 0.853 0.906 0.9591400 0.016 0.017 0.017 0.018 0.020 0.318 0.406 0.472 0.529 0.582 0.632 0.681 0.728 0.774 0.820

1550 0.016 0.017 0.017 0.018 0.020 0.272 0.357 0.420 0.473 0.522 0.568 0.613 0.656 0.699 0.740

1600 0.016 0.017 0.017 0.018 0.020 0.024 0.342 0.403 0.456 0.503 0.548 0.592 0.634 0.677 0.716

1800 0.016 0.017 0.017 0.018 0.020 0.023 0.291 0.350 0.399 0.443 0.484 0.524 0.562 0.599 0.635

2000 0.016 0.017 0.017 0.018 0.020 0.023 0.249 0.307 0.353 0.394 0.432 0.468 0.503 0.537 0.570

2500 0.016 0.017 0.017 0.018 0.020 0.023 0.169 0.230 0.272 0.308 0.340 0.370 0.399 0.427 0.454

3000 0.016 0.016 0.017 0.018 0.020 0.023 0.098 0.176 0.216 0.249 0.277 0.304 0.329 0.353 0.376

3100 0.016 0.016 0.017 0.018 0.020 0.023 0.092 0.167 0.208 0.240 0.268 0.293 0.318 0.341 0.364

3500 0.016 0.016 0.017 0.018 0.020 0.023 0.031 0.136 0.176 0.207 0.233 0.256 0.278 0.300 0.320

4000 0.016 0.016 0.017 0.018 0.020 0.022 0.029 0.105 0.146 0.175 0.199 0.221 0.241 0.260 0.279

5000 0.016 0.016 0.017 0.018 0.020 0.022 0.027 0.059 0.104 0.131 0.153 0.172 0.189 0.205 0.220

7500 0.016 0.016 0.017 0.018 0.019 0.021 0.025 0.032 0.051 0.074 0.092 0.107 0.121 0.133 0.144

10000 0.016 0.016 0.017 0.018 0.019 0.021 0.023 0.027 0.036 0.050 0.063 0.076 0.087 0.096 0.105

15000 0.016 0.016 0.017 0.017 0.018 0.019 0.022 0.024 0.028 0.034 0.041 0.048 0.055 0.062 0.069

THERMOWELL VELOCITY RATING

(psia)

STEAM TABLES (extracted from ASME Steam Tables for Industrial Use, 1997 Edition)

Temperature (F)

Specific Volume (ft3/lb) (w)

Pressure

Documents

ASME-Imp 1998 Thermo Well