Temperature °Controls Pty Ltd ACN: 075 298 592 ABN: 966 501 901 83
Sydney (Head Office): 7 Yamma St, Sefton, NSW 2162 Australia Ph: 61 2 9721 8644 Fax: 61 2 9738 9339
Melbourne: 8/280 Whitehall St, Yarraville VIC 3013 Australia Ph: 61 3 9687 0000 Fax: 61 3 9687 1900
Brisbane: 28a 121 – 125 Kerry Rd, Archerfield, QLD 4161 Australia Ph: 61 7 3373 8424 Fax: 61 7 3821 3693
W: www.temperature.com.au E: [email protected]
1661 ALL
THERMOWELL CALCULATIONS TO THE NEW
ASME PTC 19.3 TW 2010
Thermowells are used to protect Thermocouples, RTD sensors and Bimetal Thermometers
when measuring temperatures in high pressure or hostile corrosive applications in pipelines.
Thermowells are machined from solid barstock materials which are suitable for the process
medium and temperature, and supplied with a process connection, threaded, flanged or weld–
in to meet the specific installation requirements. As the flow of the medium ( Fluid or Gas )
in the pipeline passes by the thermowell it forms a turbulent wake ( known as Von Karman
trail ) that generates a vibration in the thermowell proportionate to the diameter of the
thermowell and velocity of the medium. The thermowell must be constructed sufficiently
rigid so that it’s vibration frequency does not equal the frequency of the Von Karman trail,
where the thermowell would vibrate to the point of breaking off.
The American Society of Mechanical Engineers ( ASME ) have developed a Performance
Test Code ASME PTC 19.3 TW-2010 for use to provide mathematical proof that the
material chosen and the mechanical design will not fail given the effects of the operating
conditions. The ASME PTC 19.3 TW 2010 wake frequency calculation is used for one piece
thermowells in tapered, straight or stepped stem designs from solid barstock materials,
process connections include, weld in, Flanged, Threaded and Van Stone styles, all with a
surface finish of 0.8 um Ra or better. To ensure compliance with this latest standard,
Temperature Controls have implemented a computer program to perform wake frequency
calculations on barstock thermowells to ASME PTC 19.3 TW 2010 verifying that the
specified thermowell dimensions are adequate to withstand the service conditions of
temperature, pressure, velocity and vibration. Individual Tag number calculations can be
performed as part of a quotation for supply of thermowells with the customer providing the
specific process data. A certificate of compliance is issued as part of our Quality Assurance
documentation with order shipment.
Support collars or velocity collars are used to support the stem inside the shielded length of a flange mount thermowell to theoretically reduce the insertion length. The ASME 19.2 2010-TW standard does not support the use of velocity collars as the collars do not assure a rigid support plane and so the thermowell stem will be subjected to a hammering effect brought on by the constant vibration. Positioning of thermowells It is generally believed that a temperature element must be centred in the pipe, however in practice so long as the temperature sensor is within the middle third of the pipe there is no reason to expect any decrease in measuring accuracy. Thermowells that fail to meet pressure, stress or frequency requirements as per ASME PTC 19.3 TW-2010 may be modified to reach a passable solution with modification to:- Material; an alternative material with increased mechanical properties. Insertion Length: Reducing the unsupported stem length will improve the force to natural frequency ratio. Tip Diameter: Increasing the tip diameter on a tapered stem thermowell will improve the thermowell strength, or change to a straight stem design. Fillet Radius: Increase the fillet radius to improve strength but consider the flange gasket face surface area.
THERMOWELL CALCULATIONS TO ASME PTC 19.3 TW 2010
Scope of ASME PTC 19.3 TW-2010
Tapered and Straight Design
Stepped Tip Design
Sample Certificate
Process Data Required for a calculation
Process Medium : Gas or Liquid Type
Velocity
Viscosity
Density
Maximum Temperature
Maximum Pressure
Shielded Length
Pipe Size / Schedule
Not within the scope of ASME PTC 19.3
Thermowells fabricated from pipe
Special surface finish e.g. Knurled
Thermowells with 2 or more piece welded stems
Stems that include flame spray ( stellite )or weld overlay
Ceramic or Non-metallic materials
Design Input Minimum Maximum Minimum Maximum
Unsupported Length U 63.5 mm 609.6 mm 127 mm 609.6 mm
Bore Diameter d 3.175 mm 20.9 mm 6.1 mm 6.7 mm
Tip Diameter B 9.2 mm 46.5 mm 12.7 mm
Support Diameter A 15.8 mm 80 mm
Taper Ratio B/A 0.58 1 N/A N/A
Minimum Wall Thickness 3.0 mm 3.0 mm
Temperature °Controls Pty Ltd ACN: 075 298 592 ABN: 966 501 901 83
Sydney (Head Office): 7 Yamma St, Sefton, NSW 2162 Australia Ph: 61 2 9721 8644 Fax: 61 2 9738 9339 Melbourne: 8/280 Whitehall St, Yarraville VIC 3013 Australia Ph: 61 3 9687 0000 Fax: 61 3 9687 1900 Brisbane: 28a 121 – 125 Kerry Rd, Archerfield, QLD 4161 Australia Ph: 61 7 3373 8424 Fax: 61 7 3821 3693
W: www.temperature.com.au E: [email protected]
ASME PTC 19.3 TW‐ 2010 Process Data required for a calculation
#1661/A
Before we can prepare your calculation we need you to complete the table below. Standard Answer
Material
Flange size / process fitting
Bore (d) = 3.175 to 20.9mm 6.5mm
Process medium – gas or liquid
Velocity m/s
Viscosity
Density
Maximum design temperature
Maximum design pressure
Shielded length (Lo)
(Flanged thermowells only)
(includes standoff and pipe thickness)
Pipe size / schedule (see attached)
Overall Length (L)
Unsupported length (U) 63.5mm to 609.6mm
Lag Extensions (F)
Stem Major - Root diameter (Q) 15.8mm to 80mm
Stem Minor - Tip diameter (B) 9.2mm to 46.5mm
Taper ratio B/A 0.58
Tip thickness 6mm
Fillet (Root) R3 Option R5
Partial penetration weld Standard
Full penetration weld Recommended
Note: Calculating pipe immersion = (L) – (Lo) – (F) = pipe immersion
INSTRUMENT
CONNECTION
MINOR
STEM
U
(UNSUPPORTED LENGTH)
STD
TIP THICKNESS (t)
BORE (d)
FILLET RADIUS
STD R3 OPTION R5
MINIMUM
25mm
(L)
OVERALL LENGTH REQUIRED FOR CALCULATION
B
LAGGING EXTENSION (F)
FULL PENETRATION WELD
PARTIAL PENETRATION WELD
CONDITIONS
SCALE : NTS
SIZE : A4 DATE : 13/04/12
TITLE
DRAWING BY R.B
TEMPERATURE CONTROLS PTY LTDSYDNEY : 7 YAMMA ST SEFTON , NSW 2162PHONE : (02) 9721 8644 FAX : (02) 9738 9339
THIS DRAWING IS OUREXCLUSIVE PROPERTYAND MUST NOT BECOPIED OR HANDEDTO ANY OTHER PARTIESWITH OUT WRITTENPERMISSION. IT SHALLBE RETURNED UPONREQUEST
Qual
ity S
yste
m
QualityEndorsedCompany
Certificate No:QEC 14412AS/NZS 9001:2000
MELBOURNE : 8/280 Whitehall StYARRAVILLE VIC 3013
PHONE : (03) 9687 0000 FAX : (03) 9687 1900EMAIL :[email protected]
ASME-PTC-19.3-TW-2010
Flange Size 150# 300# 600# 900 / 1,500# 2,500#1” 16.1mm 19.1mm 23.9mm 35.4mm 41.4mm1 ½” 19.1mm 22.6mm 28.9mm 38.4mm 50.9mm 2” 21.1mm 24.1mm 31.9mm 44.9mm 57.4mmFlange (F) 57mm 57mm 80mm 80mm 90mm
MATERIAL FLANGED TAPER DESIGN BARSTOCK THERMOWELL
SPECIFY SHIELDED LENGTH (Lo)
(PIPE SIZE REQUIRED FOR CALCULATION)(INCLUDES STAND OFF AND PIPE THICKNESS)
A (Q)STEM
MAJOR
U(UNSUPPORTED LENGTH)
STD
TIP THICKNESS (t)
BORE (d)
FILLET RADIUSSTD R3 OPTION R5
MINIMUM25mm
(L)OVERALL LENGTH REQUIRED FOR CALCULATION
B
LAGGING EXTENSION (F)
FULL PENETRATION WELD
PARTIAL PENETRATION WELD
Report Information
Customer: Temperature Controls (Sample copy) Date / Time:
Tag Numbers: 0 Reference #:
Process Fluids: Gas
Pipe Size / Schedule: 6" STD
Max Temperature (T) / Pressure (P): 60 °C / 1960 KPa
Fluid Flow Rate: 34122.636 in^3/s
Fluid Velocity (v): 30 m/s
Fluid Density: 7.12 Kg/m^3
Fluid Viscosity: 0.123 centipoise
Density (Pm): 0.29 lb/in^3
Elastic Modulus, E(T): 28300000 psi
Allowable Stress (S) / Fatigue Limit (Sf): 16700 psi/9100 psi
In-Line Reson. Velocity(VIR): 42.85 m/s Von Mises Stress (Root): 76.11 psi
Bending Stress at VIR (So.max) 15253.09 psi
Dynamic Stress at V (So.max) 86.68 psi
Thermowell Configuration Frequency Limit: 0.40 Reynolds # (Re): 46941
Flanged Frequency must be below: 238.03 [Hz] Strouhal # (Ns): 0.1887
Tapered Installed Natural Freq (fnc): 595.08 [Hz] Scruton # (Nsc): 5.24
316/316L Strouhal Frequency (fs): 209.71 [Hz] Freq Ratio (fs/fnc): 0.35
2" 150#
Raised Face
316/316L Allowable Stem Pressure(Pc): 8147.09psi
6.5mm Allowable Tip Pressure(Pt): 109429.92psi
245mm
188mm
109mm Status57mm PASS31mm PASS27mm PASS6mm PASS3mm
LIC 14412
28/09/2011 10:45:07 AM
0
Process Operating Conditions
Stem Style:
Thermowell Material Properties
Stresses
Vibration
Process Connection:
Thermowell Material:
Flange Size l Rating:
PressureFlange Facing:
Flange Material:
Bore Size:
Overall Length (L):
Thermowell RatingUnsupported Length (U):
Shielded Length (Lo):
Oscillating Stress (psi) 86.68Lag Extension:
Value
284.259Tip Diameter (B):
Fillet (Root):
Frequency (Hz) 209.70Tip Thickness (t):
Steady-State Stress (psi) 369.916Root Diameter (Q):
Pressure (psi)
SAI Global
ISO 9001
The thermowell design has PASSED the wake frequency calculation“These well design calculations are based on the ASME power test code PTC 19.3- formulas. The results of these calculations
should only be used as a guide for thermowell design. Temperature Controls does not guarantee the performance of a specific
well design obtained from the use of these calculations”.
Printed using the V-MAC Wake Calc System
Nominal Pipe Size Inches
Nominal Pipe Size mm
OD mm Schedule ANSI / ASME
Wall thickness mm
Internal Diameter mm
1 25 33.4 STD/40/40S 3.38 26.641 25 33.4 XS/80/80S 4.55 24.30
1 1/2 40 48.3 STD/40/40S 3.68 40.941 1/2 40 48.3 XS/80/80S 5.08 38.142 50 60.3 STD/40/40S 3.91 52.482 50 60.3 XS/80/80S 5.54 49.22
2 1/2 65 73 STD/40/40S 5.16 62.682 1/2 65 73 XS/80/80S 7.01 58.983 80 88.9 STD/40/40S 5.49 77.923 80 88.9 XS/80/80S 7.62 73.66
3 1/2 90 101.6 STD/40/40S 5.74 90.123 1/2 90 101.6 XS/80/80S 8.08 85.444 100 114.3 STD/40/40S 6.02 102.264 100 114.3 XS/80/80S 8.56 97.185 125 141.3 STD/40/40S 6.55 128.205 125 141.3 XS/80/80S 9.53 122.246 150 168.3 STD/40/40S 7.11 154.086 150 168.3 XS/80/80S 10.97 146.368 200 219.1 STD/40/40S 8.18 202.748 200 219.1 XS/80/80S 12.7 193.7010 250 273.1 STD/40/40S 9.27 254.5610 250 273.1 XS/60/80S 12.70 247.7012 300 323.9 STD/40S 9.53 304.8412 300 323.9 XS/80S 12.70 298.5014 350 355.6 STD/30/40S 9.53 336.5414 350 355.6 XS/80S 12.70 330.2016 400 406.4 STD/30/40S 9.53 387.3416 400 406.4 XS/40/80S 12.70 381.0018 450 457.2 STD/40S 9.53 438.1418 450 457.2 XS/80S 12.70 431.8020 500 508 STD/20/40S 9.53 488.9420 500 508 XS/30/80S 12.70 482.6024 600 609.6 STD/20/40S 9.53 590.5424 600 609.6 XS/80S 12.70 584.2030 750 762 STD/40S 9.53 742.9430 750 762 XS/20/80S 12.70 736.6036 900 914.4 STD/40S 9.53 895.3436 900 914.4 XS/80S 12.70 889.00
PIPE SIZE / SCH FOR ASME PTC 19.3 TW 2010
For calculation purposes When calculating sheilded length use 100mm for the Stand off plus pipe thicknessLine size 50mm = 2" STD, 100mm = 4" STD, 150mm = 6" STD, 200mm = 8" STD,
250mm = 10" STD & 300mm = 12" STD
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