1、PFI Technical Bulletin TB-1 (Revised December 2013) PRESSURE-TEMPERATURE RATINGS USED IN POWER PLANT PIPING SYSTEMS Prepared by Pipe Fabrication Institute Engineering Committee All PFI Standards are advisory only. There is no agreement to adhere to any PFI Standard and their use by anyone is entirel
2、y voluntary. Copyright by PIPE FABRICATION INSTITUTE Dedicated to Technical Advancements and Standardization in the Pipe Fabrication Industry Since 1913 USA 666 Fifth Ave., #325 New York, NY 10103 CANADA 655, 32ndAve., suite 201 Lachine, QC H8T 3G6 WEB SITE www.pfi-institute.orgPFI Technical Bulleti
3、n TB-1 (Revised December 2013) PRESSURE-TEMPERATURE RATINGS USED IN POWER PLANT PIPING SYSTEMS METRIC CONVERSIONS The conversion of quantities between systems of units involves a determination of the number of significant digits to be retained. All conversions depend upon the intended precision of t
4、he original quantity and are rounded to the appropriate accuracy. Pipe sizes together with applicable wall thicknesses are not shown with metric equivalents. The SI (metric) values where included with the customary U.S. values in this Standard are the rounded equivalents of the U.S. values and are f
5、or reference only. Metric units were derived utilizing the following conversion factor: Conversion Factor inches to 25.4 millimeter The worksheets in TB-1 present both Imperial and SI calculation 1. Scope 1.1 This bulletin provides pressure ratings, in Imperial and SI units, for each pipe size and a
6、pplicable schedule, 1/8 NPS through 48 NPS. Selection of a suitable material must consider such items as service, temperature, safety, thermal shock, corrosion allowance, exposure to fire, system life and economy, using sound engineering judgment, and is not within the scope of this bulletin. 1.2 Re
7、ferencing the applicable fabrication code will provide allowable stress values, “S”, for a given material and temperature, weld joint efficiency “E”, and temperature coefficient “y”. TB-1 will also provide a minimum design thickness, when a design pressure is provided. 1.3 The following formula and
8、nomenclature are in accordance with ASME B31.1, Power Piping code, 2004 edition. The pressure ratings provided in this technical bulletin may be used for other codes that utilize the same pressure formula as shown below, however, the nomenclature may be different. It is the users responsibility to d
9、etermine if this bulletin is applicable. 2. Formulas 2.1 The following formula, as given in Paragraph 104.1.2 formula (4) of ASME B31.1, is used to calculate the pressure ratings (PSIG/kPa) provided in columns “C” through “R” of the TB-1 “Imperial Units” worksheet, (sheet 1), and “SI Units” workshee
10、t, (sheet 2). )(2)(2AtyDAtSEPmom 2.2 The following formula, as given in Paragraph 104.1.2 formula (3) of ASME B31.1 is used to calculate the minimum wall thickness required, as provided in column “S” of the TB-1 “Imperial Units” worksheet, (sheet 1), and “SI Units” worksheet, (sheet 2): APySEPDotm )
11、(2PFI Technical Bulletin TB-1 (Revised December 2013) 2.3 The formulas above use the following nomenclature: P = Internal design pressure, pounds per sq. inch gage (PSIG)/ kilopascals (kPa) S = Allowable stress in pound per sq inch (PSI/MPa) for the respective material and design temperature, not to
12、 exceed that given in ASME B31.1, Appendix A E = Weld joint efficiency. A value of 1.00 shall be used. The allowable stress values in the Power Piping Code B31.1, Appendix A, include the weld joint efficiency. tm= Minimum required wall per thickness. The pressure rating equation multiplies the nomin
13、al wall thickness, as defined in TB-1 “Wall Thicknesses” Table (Sheet 3), by 0.875, to account for a 12.5% manufacturing tolerance. The far right columns of “Imperial Units” worksheet, (sheet 1), and “SI Units” worksheet, (sheet 2), displays tmbased on a user supplied pressure. This minimum thicknes
14、s shall be increased by an amount sufficient to provide manufacturing tolerance allowed in the applicable pipe specification or required by the process. A = Additional thickness, in decimal inches/millimeters, required for corrosion, erosion, threading, grooving, and/or additional mechanical strengt
15、h. y = Temperature Coefficient. See Power Piping Code B31.1, Table 104.1.2 (A) Do= Pipe outside diameter. The chart provides the outside diameter for 1/8 NPS through 48 NPS pipe. 3. Consideration 3.1 Most codes caution that consideration should be given to the possibility of graphite formation under
16、 prolonged exposure of carbon steel to temperatures above 800 Deg F. (427 Deg C.). 3.2 When referencing any of the code stress tables, careful examination of any referenced notes may restrict or limit the use of the material under consideration for a particular code. 3.3 The calculations in this bul
17、letin provide ratings based on pressure alone, and give no consideration to expansion, cyclic, upset conditions or external loads. 3.4 All schedules and corresponding wall thicknesses listed in TB-1 are in accordance with ASME B36.10 and B36.19.The worksheets in TB-1 require Microsoft Excel version
18、2000 or later. Click here to access the electronic version CURRENT INDEX OF 2014-2015 PFI STANDARDS A complete list of PFI members and available membership CHARTER MEMBERS CONTRACTOR MEMBERS ASSOCIATE MEMBERS AFFILIATE MEMBERS HONORARY MEMBERS Associate and Affiliate member contributors Walter Sperk
19、o Sperko Engineering Services, Inc. Greensboro, NC Thomas Warrelmann Victaulic Company of America Easton, PA Sheryl Michalak Welding Outlets, Inc. Houston, TX PFI Standards and Technical Bulletins are published to serve proven needs of the pipe fabricating industry at the design level and in actual
20、shop operations. Hence, such needs are continually considered and reviewed by the Engineering Committee of the Pipe Fabrication Institute to provide recommended procedures, which have been demonstrated by collective experiences to fulfill requirements in a manner for Code compliance. However, as the PFI Standards are for minimum requirements the designer or fabricator always has the option of specifying supplementary conditions in the form of requirements beyond the scope of the PFI publications.
