1、AN AMERICAN NATIONAL STANDARDThermowellsASME PTC 19.3 TW-2010Performance Test CodesCopyright ASME International Provided by IHS under license with ASME Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-INTENTIONALLY LEFT BLANKCopyright ASME International Provided by
2、IHS under license with ASME Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ASME PTC 19.3 TW-2010ThermowellsPerformance Test CodesAN AMERICAN NATIONAL STANDARDThree Park Avenue New York, NY 10016 USACopyright ASME International Provided by IHS under license with AS
3、ME Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Date of Issuance: July 12, 2010This Code will be revised when the Society approves the issuance of a new edition. There will be no addenda issued to PTC 19.3 TW-2010.ASME issues written replies to inquiries concern
4、ing interpretations of technical aspects of this document. Periodically certain actions of the ASME PTC Committee may be published as Code Cases. Code Cases and interpretations are published on the ASME Web site under the Committee Pages at http:/cstools.asme.org as they are issued.ASME is the regis
5、tered trademark of The American Society of Mechanical Engineers.This code or standard was developed under procedures accredited as meeting the criteria for American National Standards. The Standards Committee that approved the code or standard was balanced to assure that individuals from competent a
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7、” or “endorse” any item, construction, proprietary device, or activity.ASME does not take any position with respect to the validity of any patent rights asserted in connection with any items mentioned in this document, and does not undertake to insure anyone utilizing a standard against liability fo
8、r infringement of any applicable letters patent, nor assumes any such liability. Users of a code or standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, is entirely their own responsibility.Participation by federal
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10、hich precludes the issuance of interpretations by individuals.No part of this document may be reproduced in any form,in an electronic retrieval system or otherwise,without the prior written permission of the publisher.The American Society of Mechanical EngineersThree Park Avenue, New York, NY 10016-
11、5990Copyright 2010 byTHE AMERICAN SOCIETY OF MECHANICAL ENGINEERSAll rights reservedPrinted in U.S.A.Copyright ASME International Provided by IHS under license with ASME Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-iiiCONTENTSForeword vAcknowledgments vCommittee
12、 Roster viCorrespondence With the PTC Committee . viiSection 1 Object and Scope 11-1 Object . 11-2 Scope 1Section 2 Nomenclature 2Section 3 Jurisdiction of Codes . 43-1 Reference Standards and Governing Codes 43-2 Specification of Thermowells . 4Section 4 Dimensions . 54-1 Configurations . 54-2 Dime
13、nsional Limits . 5Section 5 Materials . 105-1 General Considerations 10Section 6 Stress Equations . 116-1 General Considerations 116-2 Corrosion and Erosion 116-3 Flow-Induced Thermowell Stresses 126-4 Strouhal Number, Drag Coefficients, and Lift Coefficient 136-5 Natural Frequency of Thermowells 14
14、6-6 Mounting Compliance Factor 156-7 Unsupported Length, Diameter, and Fillet Radius 166-8 Frequency Limit . 186-9 Magnification Factor . 216-10 Bending Stresses 216-11 Pressure and Shear Stresses . 246-12 Steady-State Static and Dynamic Stress Limits . 246-13 Pressure Limit 27Section 7 Overview of
15、Calculations . 287-1 Quantitative Criteria . 287-2 Fluid Properties 287-3 Fluid Velocity . 287-4 Material Properties and Dimensions 287-5 Reynolds and Strouhal Numbers 297-6 Natural Frequency at Operation Temperature 297-7 Natural Frequency at Expected Mode of Operation 297-8 Steady-State and Dynami
16、c Stresses 297-9 Allowable Fatigue Limits . 297-10 Pressure Rating 29Section 8 Examples . 308-1 Tapered, Welded Thermowell for a Steam-Header Application (U.S. Customary Units) 308-2 Step-Shank, Threaded Thermowell for a Hot Water Application (SI Units) . 33Copyright ASME International Provided by I
17、HS under license with ASME Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ivSection 9 Statement of Compliance 399-1 Specification of a Thermowell . 399-2 Velocity and Pressure Ratings 39 Section 10 References 4010-1 Referenced Documents . 4010-2 Referenced ASME Do
18、cuments . 40Figures4-1-1 Schematic Diagram of a Thermowell 64-1-2 Examples of Straight-Shank Thermowells . 74-1-3 Examples of Step-Shank Thermowells . 84-1-4 Examples of Tapered Thermowells . 96-3.1-1 Fluid-Induced Forces and Assignment of Axes for Calculation of Thermowell Stresses . 126-6-1 Unsupp
19、orted Length of Thermowells 176-8.1-1 Schematic Indicating Excitation of Resonances When Excitation Frequency Coincides With the Thermowell Natural Frequency 196-8.1-2 Schematic Showing the Amplitude Response of a Thermowell Subjected to Fluid-Induced Forces as Solid Lines, for In-Line and Transvers
20、e Excitation Modes . 196-10.1-1 Bending Moment, Stress at the Support Plane, and Locations of Maximum Steady-State or Oscillating In-Line Stress 226-10.7-1 Mounting of a Thermowell in an Elbow, With the Tip Facing Downstream 246-10.7-2 Geometry to Be Used in Calculation of Thermowell Ratings . 256-1
21、0.7-3 Mounting of a Thermowell in an Elbow, With the Tip Facing Upstream . 25Tables4-1-1 Dimensional Limits for Straight and Tapered Thermowells Within the Scope of This Standard 74-2-1 Dimensional Limits for Step-Shank Thermowells Within the Scope of This Standard . 86-5.3-1 Parameters for Natural
22、Frequency Calculation for Step-Shank Thermowells . 156-12.3-1 Allowable Fatigue-Stress Amplitude Limits for Material Class A and Class B 26Nonmandatory AppendixA Conversion Factors 41Copyright ASME International Provided by IHS under license with ASME Not for ResaleNo reproduction or networking perm
23、itted without license from IHS-,-,-vFOREWORDIn 1957, the ASME Performance Test Codes Committee 19.3 determined that the 1930 edition of the Supplement on Temperature Measurement dealing with thermowells was unsatisfactory. Since the design of thermowells requires both thermal and stress consideratio
24、ns, the ASME Boiler and Pressure Vessel Committee was approached for assistance. However, the special needs for the design of intrusive pipe fittings were deemed beyond the scope of what could be properly included in the vessel codes.The PTC 19.3 Committee is charged with temperature measurement and
25、 thermowell design. The purpose of the ther-mowell is to facilitate temperature measurement while resisting fluid forces of the process. This committee undertook the task of providing guidance in this area, on the basis of a paper authored by J. W. Murdock 1, ultimately leading to the publication of
26、 PTC 19.3-1974, Supplement on Instruments and Apparatus, Part 3, Temperature Measurement. Prior to the acceptance of PTC 19.3-1974, the incidence of thermowell failures during the start-up testing of high-pressure steam turbines was unacceptable; its subsequent use in steam services has been highly
27、successful at preventing catastrophic thermowell failure.Since its publication, PTC 19.3 has received widespread acceptance and use in both steam and nonsteam applica-tions outside the scope of the performance test codes. In 1971 an ASME ad hoc committee, PB51, under the jurisdiction of the PTC Boar
28、d, was formed to assess the thermowell standard. This committee, designated PTC 19.3.1, produced a draft thermowell standard. In 1999, PTC 19.3 undertook the task of completing this draft. In the course of this effort, it was discovered that a number of thermowells designed to PTC 19.3-1974 but plac
29、ed in nonsteam services suffered catastrophic failure. Review of the literature revealed that the PTC 19.3.1 draft did not incorporate recent, significant advances in our knowledge of thermowell behavior, and the committee decided to thoroughly rewrite the standard. The goals of the new Standard are
30、 to provide a thermowell rating method that can be used in a myriad array of services, including processes involving corrosive fluids; offer advice where fatigue endurance is critical; and establish criteria for insuring sensor reliability. These factors result in a more reliable basis for thermowel
31、l design than the PTC 19.3-1974 Supplement. It is intended that this edition of this Standard not be retroactive.PTC 19.3 TW on thermowells was approved by the PTC Standards Committee on January 15, 2010, and approved and adopted as a Standard practice of the Society by action of the Board on Standa
32、rdization and Testing on February 18, 2010. It was also approved as an American National Standard by the ANSI Board of Standards Review on April 22, 2010.ACKNOWLEDGMENTSThe Committee gratefully acknowledges the special contributions of R. D. Blevins, D. R. Frikken, W. J. Koves, and A. Lbig.Copyright
33、 ASME International Provided by IHS under license with ASME Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-viASME PTC COMMITTEEPerformance Test Codes(The following is the roster of the Committee at the time of approval of this Code.)STANDARDS COMMITTEE OFFICERSM.
34、P. McHale, ChairJ. R. Friedman, Vice ChairJ. H. Karian, SecretarySTANDARDS COMMITTEE PERSONNELP. G. Albert, General Electric Co. M. P. McHale, McHale however, they should not contain proprietary names or information.Requests that are not in this format will be rewritten in the appropriate format by
35、the Committee prior to being answered, which may inadvertently change the intent of the original request.ASME procedures provide for reconsideration of any interpretation when or if additional information that might affect an interpretation is available. Further, persons aggrieved by an interpretati
36、on may appeal to the cognizant ASME Committee. ASME does not “approve,” “certify,” “rate,” or “endorse” any item, construction, proprietary device, or activity.Attending Committee Meetings. The PTC Standards Committee and its subcommittees, such as PTC 19.3, hold meetings or telephone conferences, w
37、hich are open to the public. Persons wishing to attend any meeting or telephone conference should contact the Secretary of the PTC Standards Committee.Copyright ASME International Provided by IHS under license with ASME Not for ResaleNo reproduction or networking permitted without license from IHS-,
38、-,-viiiINTENTIONALLY LEFT BLANKCopyright ASME International Provided by IHS under license with ASME Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ASME PTC 19.3 TW-20101THERMOWELLSSection 1Object and Scope1-1 OBJECTThe object of this Standard is to establish a mec
39、hani-cal design standard for reliable service of tapered, straight, and stepped-shank thermowells in a broad range of applications. This includes an evaluation of the forces caused by external pressure, and the combi-nation of static and dynamic forces resulting from fluid impingement.1-2 SCOPEThis
40、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 de
41、signed surface struc-tures (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 applica-bility for these types of thermowells. Thermowell attachment methods, standard dimen-sions, parasitic vibrati
42、on of a sensor mounted inside the thermowell, and thermal equilibrium of the sensor rela-tive to the process stream are beyond the scope of this Standard. In addition, thermowells fabricated by weld-ing, including flame spray or weld overlays, at any place along the length of the shank or at the tip
43、 are outside the scope of this Standard.Copyright ASME International Provided by IHS under license with ASME Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-ASME PTC 19.3 TW-20102Section 2NomenclatureFor U.S. Customary units, lb denotes pound as a unit of mass, lbf
44、 denotes pounds-force, kip denotes 103pounds-force, and ksi denotes 103pounds-force per square inch or kips per square inch. When parameters are specified in mixed units within the U.S. Customary unit system (e.g., diameter B in inches, velocity V in feet per second), conversion factors between feet
45、 and inches will be needed in the calculations. See para. 6-4.1 and subsection 8-1 for examples.A 5 outside diameter of thermowell at support plane or root, based on which point is closest to the thermowell tip, m (in.) Ap5 projected area of thermowell perpendicular to direction of flow and exposed
46、to the flow stream, m2(in.2)a 5 polynomial function used in eq. (6-8-4), dimensionlessB 5 outside diameter at tip of thermowell, m (in.)b 5 fillet radius at the root of the thermowell shank, m (in.)bS5 fillet radius at the base of the reduced-diameter length of a step-shank thermowell, m (in.) CD5 c
47、oefficient for steady-state drag pressure, dimensionlessCd5 coefficient for oscillating-drag (in-line with flow) pressure, dimensionlessCl5 coefficient for oscillating-lift (transverse to flow) pressure, dimensionlessc 5 corrosion allowance, m (in.)ci5 coefficients used in eq. (6-5-3), dimensionless
48、D 5 outside diameter at any cross section, m (in.)Da5 average diameter of the thermowell, as defined in para. 6-5.3, Step 1, m (in.)d 5 bore diameter of thermowell, m (in.)E 5 modulus of elasticity at service temperature, Pa psi or lb/(in.sec2) (Refer to Nonmandatory Appendix A and para. 6-5.3 for a discussion of units of E.)Eref5 reference value of modulus of elasticity, Pa (psi)FD5 in-line static drag force on thermowell, due to fluid impingement, N (lbf)Fd5 in-line dynamic drag force on thermowell, due to fluid impingement, N (lbf)Fl5 transverse dynamic d
