ASME PTC 19.3 TW 2016
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ASME PTC 19.3 TW – 2016: Thermowells
| Published By | Publication Date | Number of Pages |
| ASME | 2016 | 62 |
This Standard applies to thermowells machined from bar stock and includes those welded to or threaded into a flange as well as those welded into a process vessel or pipe with or without a weld adaptor. Thermowells manufactured from pipe are outside the scope of this Standard. Thermowells with specially designed surface structures (e.g., a knurled surface or a surface with spiral ridges) are beyond the scope of this Standard, due to the difficulty of providing design rules with broad applicability for these types of thermowells. Thermowell attachment methods, standard dimensions, parasitic vibration of a sensor mounted inside the thermowell, and thermal equilibrium of the sensor relative to the process stream are beyond the scope of this Standard. In addition, thermowells fabricated by welding, including flame spray or weld overlays, at any place along the length of the shank or at the tip are outside the scope of this Standard. Table of Contents
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 4 | CONTENTS |
| 6 | FOREWORD |
| 7 | ASME PTC COMMITTEE ROSTER |
| 8 | CORRESPONDENCE WITH THE PTC COMMITTEE |
| 10 | Section 1 Object and Scope 1-1 OBJECT 1-2 SCOPE |
| 11 | Section 2 Nomenclature |
| 13 | Section 3 Jurisdiction of Codes 3-1 REFERENCE STANDARDS AND GOVERNING CODES 3-2 SPECIFICATION OF THERMOWELLS |
| 14 | Section 4 Dimensions 4-1 CONFIGURATIONS 4-2 DIMENSIONAL LIMITS |
| 19 | Section 5 Materials 5-1 GENERAL CONSIDERATIONS |
| 20 | Section 6 Stress Equations 6-1 GENERAL CONSIDERATIONS 6-1.1 Overview of Design Criteria 6-1.2 Optimization of Thermowell Design 6-1.2.1 Factors Improving Mechanical Strength. 6-1.2.2 Factors Improving Thermal Performance. 6-2 CORROSION AND EROSION |
| 22 | 6-3.3 Choice of Maximum Velocity Value 6-3.4 Flow-Induced Vibration of Thermowell Arrays 6-3.5 Turbulence-Induced Vibration of Thermowells 6-3.6 Low Fluid Velocities |
| 23 | 6-3.7 Pulsed Flow 6-4 STROUHAL NUMBER, DRAG COEFFICIENTS, AND LIFT COEFFICIENT 6-4.1 Strouhal Number 6-4.1.1 Example. |
| 24 | 6-4.2 Drag and Lift Coefficients 6-5 NATURAL FREQUENCY OF THERMOWELLS 6-5.1 Transverse Vibrations 6-5.2 Finite Element Methods |
| 25 | 6-5.3 Calculations and Correction Factors Table 6-5.3-1 Parameters for Natural Frequency Calculation for Step-Shank Thermowells |
| 26 | 6-6 MOUNTING COMPLIANCE FACTOR |
| 28 | 6-7 UNSUPPORTED LENGTH, DIAMETER, AND FILLET RADIUS |
| 31 | 6-8.3 Frequency Limit for the General Case 6-8.4 Frequency Limit When the In-Line Resonance Does Not Limit Operation |
| 32 | 6-8.5 Passing Through In-Line Resonance Where the Design Does Not Meet the Cyclic Stress Requirements for Continuous Operation at Resonance 6-9 MAGNIFICATION FACTOR 6-9.1 Magnification Factor Away From Resonance |
| 33 | 6-9.2 Magnification Factor Near Resonance 6-10 BENDING STRESSES 6-10.1 Point of Maximum Stress |
| 35 | 6-10.2 Maximum Stress for Tapered or Straight Thermowells, No Shielding From Flow 6-10.3 Maximum Stress for Tapered or Straight Thermowells, Shielded From Flow 6-10.4 Maximum Stress for Step-Shank Thermowells, No Shielding From Flow 6-10.5 Maximum Stress for Step-Shank Thermowells, Shielded From Flow |
| 38 | 6-12 STEADY-STATE STATIC AND DYNAMIC STRESS LIMITS 6-12.1 Overview 6-12.2 Steady-State Stress Limits 6-12.3 Dynamic Stress Limits |
| 39 | 6-12.4 Maximum-Stress Locations for Step-Shank Thermowells 6-12.5 Supercritical Operation Table 6-12.3-1 Allowable Fatigue-Stress Amplitude Limits for Material Class A and Class B |
| 40 | 6-13 PRESSURE LIMIT |
| 41 | Section 7 Overview of Calculations 7-1 QUANTITATIVE CRITERIA 7-2 FLUID PROPERTIES 7-3 FLUID VELOCITY 7-4 MATERIAL PROPERTIES AND DIMENSIONS 7-4.1 Necessary Dimensions |
| 42 | 7-4.2 Material Properties 7-4.3 Temperature Dependence of Properties 7-4.4 Installation Details 7-5 REYNOLDS AND STROUHAL NUMBERS 7-6 NATURAL FREQUENCY AT OPERATION TEMPERATURE 7-7 NATURAL FREQUENCY AT EXPECTED MODE OF OPERATION 7-8 STEADY-STATE AND DYNAMIC STRESSES 7-9 ALLOWABLE FATIGUE LIMITS 7-10 PRESSURE RATING |
| 43 | Section 8 Examples 8-1 TAPERED, WELDED THERMOWELL FOR A STEAM-HEADER APPLICATION U.S. CUSTOMARY UNITS 8-1.1 Application, Properties, Dimensions, and Installation 8-1.1.1 Steam Properties 8-1.1.2 Thermowell Dimensions. 8-1.1.3 Materials Properties. 8-1.1.4 Installation Details. 8-1.1.5 Reynolds and Strouhal Numbers. |
| 44 | 8-1.2 Natural Frequency Calculation |
| 45 | 8-1.3 Scruton Number Calculation 8-1.4 Frequency Limit Calculation 8-1.5 Cyclic Stress at the In-Line Resonance |
| 46 | 8-1.6 Steady-State Stress at the Design Velocity |
| 47 | 8-1.7 Dynamic Stress at the Design Velocity 8-1.8 Pressure Stress |
| 48 | 8-2 STEP-SHANK, THREADED THERMOWELL FOR A HOT WATER APPLICATION SI UNITS 8-2.1 Application, Properties, Dimensions, and Installation 8-2.1.1 Fluid Properties 8-2.1.2 Thermowell Dimensions. 8-2.1.3 Materials Properties. |
| 49 | 8-2.1.4 Installation Details. 8-2.2 Natural Frequency Calculation |
| 50 | 8-2.3 Scruton Number Calculation 8-2.4 Frequency Limit Calculation 8-2.5 Cyclic Stress at the In-Line Resonance 8-2.5.1 Evaluation at the Support Plane |
| 51 | 8-2.5.2 Evaluation at the Base of the Reduced-Diameter Shank |
| 52 | 8-2.6 Steady-State Stress at the Design Velocity 8-2.6.1 Evaluation at the Support Plane 8-2.6.2 Evaluation at the Base of the Reduced-Diameter Step Shank |
| 53 | 8-2.7 Dynamic Stress at the Design Velocity 8-2.7.1 Evaluation at the Support Plane |
| 54 | 8-2.7.2 Evaluation at the Base of the Reduced-Diameter Shank 8-2.8 Pressure Stress |
| 55 | Section 9 Statement of Compliance 9-1 SPECIFICATION OF A THERMOWELL 9-2 VELOCITY AND PRESSURE RATINGS |
| 56 | Section 10 References 10-1 REFERENCED DOCUMENTS 10-2 REFERENCED ASME DOCUMENTS |
| 58 | NONMANDATORY APPENDIX A CONVERSION FACTORS A-1 Conversion Factors Between SI and U.S. Customary Units A-2 Other Conversion Factors |
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