Temperature Controls Pty Ltd ACN: ABN:

Transcription

1 Temperature Controls Pty Ltd ACN: ABN: Sydney (Head Office): 7 Yamma St, Sefton, NSW 2162 Australia Ph: Fax: Melbourne: 8/280 Whitehall St, Yarraville VIC 3013 Australia Ph: Fax: Brisbane: 28a Kerry Rd, Archerfield, QLD 4108 Australi Ph: Fax: W: E: sales@temperature.com.au 1661 ALL THERMOWELL CALCULATIONS TO THE NEW ASME PTC 19.3 TW 2016 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-2016 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 2016 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 2016 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.

2 THERMOWELL CALCULATIONS TO ASME PTC 19.3 TW 2016 Scope of ASME PTC 19.3 TW-2016 Tapered and Straight Design Stepped Tip Design Design Input Minimum Maximum Minimum Maximum Unsupported Length U 63.5 mm mm 127 mm mm Bore Diameter d 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 N/A N/A Minimum Wall Thickness 3.0 mm 3.0 mm Sample Certificate 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 Process Data Required for a calculation Process Medium : Gas or Liquid Type Velocity Viscosity Density Maximum Temperature Maximum Pressure Shielded Length Pipe Size / Schedule 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 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-2016 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.

3 Temperature Controls Pty Ltd ACN: ABN: Sydney (Head Office): 7 Yamma St, Sefton, NSW 2162 Australia Ph: Fax: Melbourne: 8/280 Whitehall St, Yarraville VIC 3013 Australia Ph: Fax: Brisbane: 28a Kerry Rd, Archerfield, QLD 4108 Australia Ph: Fax: W: E: sales@temperature.com.au ASME PTC 19.3 TW 2016 Process Data required for a calculation #1661/A Before we can prepare your calculation we need you to complete the table below. Customer # Tag # Reference # Material Thermowell type Flange size / process fitting Flange penetration weld Standard Partial (standard) Full penetration (recommended) Fillet (Root) R3 Standard (Option R5) Bore (d) = to 20.9mm 6.5mm Process medium gas or liquid Velocity m/s Viscosity cp Density kg/mᶾ Maximum design temperature Maximum design pressure Kpa 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 Note: Calculating pipe immersion = (L) (Lo) (F) = pipe immersion (L) OVERALL LENGTH REQUIRED FOR CALCULATION LAGGING EXTENSION (F) U (UNSUPPORTED LENGTH) Answer MINIMUM 25mm INSTRUMENT CONNECTION FILLET RADIUS STD R3 OPTION R5 FULL PENETRATION WELD PARTIAL PENETRATION WELD BORE (d) TIP THICKNESS (t) STD B STEM MINOR

4 (L) OVERALL LENGTH REQUIRED FOR CALCULATION LAGGING EXTENSION (F) U (UNSUPPORTED LENGTH) MINIMUM 25mm FILLET RADIUS STD R3 OPTION R5 FULL PENETRATION WELD PARTIAL PENETRATION WELD BORE (d) SPECIFY SHIELDED LENGTH (Lo) (INCLUDES STAND OFF AND PIPE THICKNESS) (PIPE SIZE REQUIRED FOR CALCULATION) STD A (Q) STEM MAJOR TIP THICKNESS (t) B MATERIAL Flange Size 150# 300# 600# 900 / 1,500# 2,500# mm 19.1mm 23.9mm 35.4mm 41.4mm 1 ½ 19.1mm 22.6mm 28.9mm 38.4mm 50.9mm mm 24.1mm 31.9mm 44.9mm 57.4mm Flange (F) 57mm 57mm 80mm 80mm 90mm FLANGED TAPER DESIGN BARSTOCK THERMOWELL TEMPERATURE CONTROLS PTY LTD CONDITIONS THIS DRAWING IS OUR EXCLUSIVE PROPERTY AND MUST NOT BE COPIED OR HANDED TO ANY OTHER PARTIES WITH OUT WRITTEN PERMISSION. IT SHALL BE RETURNED UPON REQUEST Certificate No:QEC AS/NZS 9001:2000 SYDNEY : 7 YAMMA ST SEFTON, NSW 2162 PHONE : (02) FAX : (02) MELBOURNE : 8/280 Whitehall St YARRAVILLE VIC 3013 PHONE : (03) FAX : (03) sales@temperature.com.au TITLE SIZE : A4 DATE : 13/04/12 SCALE : NTS DRAWING BY R.B Quality System Quality Endorsed Company ASME-PTC-19.3-TW-2016

5 Report Information Customer: Temperature Controls (Sample copy) Date / Time: Tag Numbers: 0 Reference #: 28/09/ :45: 0 Process Operating Conditions Process Fluids: Pipe Size / Schedule: Max Temperature (T) / Pressure (P): Fluid Flow Rate: Fluid Velocity (v): Fluid Density: Fluid Viscosity: Thermowell Material Properties Density (Pm): Elastic Modulus, E(T): Allowable Stress (S) / Fatigue Limit (Sf): Gas 6" STD 60 C / 1960 KPa in^3/s 30 m/s 7.12 Kg/m^ centipoise 0.29 lb/in^ psi psi/9100 psi In-Line Reson. Velocity(VIR): m/s Von Mises Stress (Root): psi Bending Stress at VIR (So.max) psi Dynamic Stress at V (So.max) psi Vibration Thermowell Configuration Frequency Limit: 0.40 Reynolds # (Re): Process Connection: Flanged Frequency must be below: [Hz] Strouhal # (Ns): Stem Style: Tapered Installed Natural Freq (fnc): [Hz] Scruton # (Nsc): 5.24 Thermowell Material: 316/316L Strouhal Frequency (fs): [Hz] Freq Ratio (fs/fnc): 0.35 Flange Size l Rating: Flange Facing: Flange Material: Bore Size: Overall Length (L): Unsupported Length (U): Shielded Length (Lo): Lag Extension: Root Diameter (Q): Tip Diameter (B): Tip Thickness (t): Fillet (Root): 2" 150# Raised Face 316/316L Allowable Stem Pressure(Pc): psi 6.5mm Allowable Tip Pressure(Pt): psi 245mm 188mm 109mm 57mm 31mm 27mm 6mm 3mm Stresses Pressure Thermowell Rating Status Value Oscillating Stress (psi) PASS Steady-State Stress (psi) PASS Pressure (psi) PASS Frequency (Hz) PASS The thermowell design has PASSED the wake frequency calculation These well design calculations are based on the ASME power test code PTC 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 SAI Global ISO 9001 LIC 14412

6 PIPE SIZE / SCH FOR ASME PTC 19.3 TW 2016 Nominal Pipe Size Inches Nominal Pipe Size mm OD mm Schedule ANSI / ASME Wall thickness mm Internal Diameter mm STD/40/40S XS/80/80S / STD/40/40S / XS/80/80S STD/40/40S XS/80/80S / STD/40/40S / XS/80/80S STD/40/40S XS/80/80S / STD/40/40S / XS/80/80S STD/40/40S XS/80/80S STD/40/40S XS/80/80S STD/40/40S XS/80/80S STD/40/40S XS/80/80S STD/40/40S XS/60/80S STD/40S XS/80S STD/30/40S XS/80S STD/30/40S XS/40/80S STD/40S XS/80S STD/20/40S XS/30/80S STD/20/40S XS/80S STD/40S XS/20/80S STD/40S XS/80S For calculation purposes When calculating sheilded length use 100mm for the Stand off plus pipe thickness Line size 50mm = 2" STD, 100mm = 4" STD, 150mm = 6" STD, 200mm = 8" STD, 250mm = 10" STD & 300mm = 12" STD