1、Denotes Revision | PFI Standard ES-21 (Revised 1992) (Reaffirmed 1998) INTERNAL MACHINING AND FIT-UP OF GTAW ROOT PASS CIRCUMFERENTIAL BUTT WELDS Prepared by Pipe Fabrication Institute Engineering Committee All PFI Standards are advisory only. There is no agreement to adhere to any PFI Standard and
2、their use by anyone is entirely voluntary. Copyright by PIPE FABRICATION INSTITUTE Dedicated to Technical Advancements and Standardization in the Pipe Fabrication Industry Since 1913 USA 511 Avenue of Americas, # 601 New York, NY 10011 CANADA 655, 32ndAvenue, # 201 Lachine, QC H8T 3G6 WEB SITE www.p
3、fi-institute.org PFI Standard ES-21 |Denotes Revision (Revised September 2010) 2 INTERNAL MACHINING AND FIT-UP OF GTAW ROOT PASS CIRCUMFERENTIAL BUTT WELDS METRIC CONVERSIONS The conversion of quantities between systems of units involves a determination of the number of significant digits to be reta
4、ined. All conversions depend upon the intended precision of the original quantity and are rounded to the appropriate accuracy. Pipe sizes together with applicable wall thickness are not shown with metric equivalents. The SI (metric) values where included with the customary U.S. values in this Standa
5、rd are the rounded equivalents of the U.S. values and are for reference only. Metric units were derived utilizing the following conversion factor: Conversion Factor inches to millimeter 25.4 1. Scope 1.1 This Standard covers the internal machining and fit-up tolerances for seamless and welded piping
6、 components when the gas tungsten-arc welding process is used for the root pass of circumferential butt welds. 2. End Preparation and Fit-up Tolerances 2.1 Typical end preparations for different wall thicknesses are shown in Figures 1 through 4. Those dimensions which are marked with an asterisk (*)
7、 may be modified as appropriate for the applicable welding process and variables associated with that process. These specific dimensions shall be defined in the Welding Procedure Specification. 2.2 Refer to Table 1 for fit-up tolerances that are applicable to gas tungsten-arc root pass welding with
8、or without consumable insert rings. 3. Internal Machining 3.1 To determine I.D. dimensions that must be maintained (usually by machining) to limit internal mismatch to that required for gas tungsten-arc root pass welding, the following terms apply: A = specified outside pipe diameter B = nominal ins
9、ide pipe diameter C = I.D. machining dimension d = specified minimum inside diameter Mo = over tolerance on C-bore Mu = under tolerance on C-bore Ru = under tolerance on outside diameter So = over tolerance on inside diameter Su = under tolerance on inside diameter T = minimum ordered wall thickness
10、 t = nominal wall thickness tm = minimum wall required by design 3.2 To assure proper fit-up of adjoining components, and to assure proper fit-up of consumable inserts (where used), it is recommended that “Mo“ be set at +.010“ (0.3mm) and “Mu“ at .040“ (1.0mm). NOTE : It must be recognized that larg
11、e diameter pipe with a relatively thin wall has a tendency to spring back after removal from the machining fixture. The tolerance (Mu or Mo) on the internal machining dimension “C“ is therefore applicable to the ends measured in the restrained condition. This should be considered when checking the “
12、C“ dimension after removal from the machining fixture. 3.3 Pipe and companion components specified by outside diameter PFI Standard ES-21 |Denotes Revision (Revised September 2010) 3 3.3.1 For pipe and companion components specified by outside diameter and minimum wall the I.D. machining dimension i
13、s determined as: C = A - Ru - Mo - 2tm+Mo Mu 3.3.2 For seamless and hollow forged pipe to ASTM A106, A3121, A335, A376, or A405 “Ru“ = 0.031“ (0.8mm) Using the recommended values of “Mo“ and “Mu“ in Paragraph 3.2, Formula 3.3.1 becomes: C = A - 0.041 - 2tm+.0l0“ (0.3mm) .040“ (1.0mm) 3.3.3 For pipe
14、specified by outside diameter and nominal wall (or schedule) where the ASTM 12% nominal to minimum wall thickness tolerance applies, Formula 3.3.1 becomes: C = A - 0.041 - 1.75t +.0l0“ (0.3mm) .040“ (1.0mm) “C“ dimensions for standard ANSI B36.10 pipe sizes, 24“ and under with wall thickness 0.562“
15、(14mm) and heavier are published in Table 2. These dimensions have been calculated in accordance with Formula 3.3.3. 3.4 Pipe and companion components specified by inside diameter. 3.4.1 The formulas below may be used as a guide to determine the internal machining dimension for pipe and companion co
16、mponents specified by inside diameter. C = d + So + Su - Mo +Mo Mu NOTES : 1. Where “d“ is specified as nominal instead of minimum I.D., “Su“ should be dropped from the expression. 2. When using welded pipe, permissible variations in out-of-roundness and diameter may make procurement of pipe with si
17、zed ends desirable. In this case “So“ should be set equal to the plus sizing tolerance and “Su“ the minus sizing tolerance. 3.5 Where the outside and/or inside diameters of the adjacent components differ from each other by more than the nominal tolerances, the heavier component shall be tapered in a
18、ccordance with ANSI B16.25, Figure 1. 1Under tolerance for A312 varies with pipe size. Refer to ASTM specifications. 4. Material Ordering 4.1 In some cases selection of I.D. machining dimensions may affect ordered wall thicknesses of pipe and companion components. 4.2 Seamless pipe ordered by outsid
19、e diameter: Formulas 3.3.1, 3.3.2 and 3.3.3 are intended to permit minimum wall to be maintained without purchase of material having wall thickness in excess of that required to satisfy “tm“ or T as applicable. When pipe and adjoining components are received with the O.D. larger than dimension “A“ b
20、ut within the permitted O.D. tolerance, it may be necessary to perform an additional operation of depositing weld metal on the I.D. or O.D. surface at the welding end (weld buildup) to assure full circumferential boring and tm. 4.3 Pipe ordered to inside diameter: When the formula listed in 3.4.1 is
21、 used for computing internal machining dimensions, and pipe is received with the I.D. at the minimum of the permitted tolerance range, the possibility exists that machining will encroach on “tm“. To minimize this problem, one of the following options may be utilized. a) The ordered pipe wall thickne
22、ss must be increased to provide additional stock for machining by use of the following formula: T = So + Su + tm+ Mo b) The “C“ dimension and the minimum wall (tm) that must be maintained at the “C“ dimension should be specified on the purchase order for the pipe. Note regarding rolled and welded pi
23、pe: Due to the greater tolerances permitted for this material regarding out of roundness and variation in diameter, use of the options listed in 4.3 above may not necessarily eliminate the need for weld buildups in these materials.PFI Standard ES-21 |Denotes Revision (Revised September 2010) 4 PFI S
24、tandard ES-21 |Denotes Revision (Revised September 2010) 5 TABLE 1 PIPE SPECIFIED BY OUTSIDE DIAMETER AND NOMINAL WALL Dimensional joint & fit-up tolerances applicable to welding with and without consumable insert rings. LEGEND FIG. WITH INSERT WITHOUT TYPE A TYPE B TYPE C INSERT G 1 TT + 1/32“ Max.
25、 TT + 1/32“ Max. TT + 1/32“ Max. 0 to 1/32“ Max. G 2&3 TT + 1/32“ Max. TT + 1/32“ Max. TT + 1/32“ Max. 0 to 3/32“ Max. G 4 TT + 1/32“ Max. TT + 1/32“ Max. TT + 1/32“ Max. 0 to 1/16“ Max. Y 1 0 to 1/32“ Max. 0 to 1/32“ Max. 0 to 1/32“ Max. 0 to 1/32“ Max. Y 2&3 0 to 3/32“ Max. 0 to 1/32“ Max. 0 to 1/
26、16“ Max. 0 to 1/16“ Max. Y 4 0 to 3/32“ Max. 0 to 1/32“ Max. 0 to 1/16“ Max. 0 to 1/16“ Max. With or Without Insert R 4A Slightly Rounded R 4B 3/16“ (5mm) Z 4A 1/8“ (3mm) Minimum Z 4B 0 to Approx. 1/8“ (3mm) L 2&3 1/16“ 1/32“ (1.5mm 0.8mm) M 4 5/64“ 1/64“ (2mm 0.4mm) X 4 3/16“ (5mm) Minimum PFI Stan
27、dard ES-21 |Denotes Revision (Revised September 2010) 6 TABLE 2 MACHINING DIMENSIONS Nominal Pipe Size Schedule Number or Nominal O. D. “A“ Nominal I. D. “B“ Nominal Wall Thickness Machined I. D. of Pipe “C“2Wall “t“ Tolerance+ 0.010 - 0.040 3 XXS 3.500 2.300 .600 2.409 4 XXS 4.500 3.152 .674 3.279
28、5 160 XXS 5.563 “ 4.313 4.063 .625 .750 4.428 4.209 6 120 160 XXS 6.625 “ “ 5.501 5.187 4.897 .562 .719 .864 5.600 5.327 5.072 8 100 120 140 XXS 160 8.625 “ “ “ “ 7.437 7.187 7.001 6.875 6.813 .594 .719 .812 .875 .906 7.546 7.327 7.163 7.053 6.998 10 80 100 120 140 160 10.750 “ “ “ “ 9.562 9.312 9.0
29、62 8.750 8.500 .594 .719 .844 1.000 1.125 9.671 9.452 9.234 8.959 8.740 12 60 80 100 120 140 160 12.750 “ “ “ “ “ 11.626 11.374 11.062 10.750 10.500 10.126 .562 .688 .844 1.000 1.125 1.312 11.725 11.507 11.234 10.959 10.740 10.413 14 O. D. 60 80 100 120 140 160 14.000 “ “ “ “ “ 12.812 12.500 12.124
30、11.812 11.500 11.188 .594 .750 .938 1.094 1.250 1.406 12.921 12.646 12.319 12.046 11.771 11.498 All dimensions are in inches. 2“C“ dimension are identical to B16.25 PFI Standard ES-21 |Denotes Revision (Revised September 2010) 7 TABLE 2 : MACHINING DIMENSIONS (Continued) Nominal Pipe Size Schedule N
31、umber or Nominal O. D. “A“ Nominal I. D. “B“ Nominal Wall Thickness Machined I. D. of Pipe “C“3Wall “t“ Tolerance+ 0.010 - 0.040 16 O. D. 60 80 100 120 140 160 16.000 “ “ “ “ “ 14.688 14.312 13.938 13.562 13.124 12.812 .656 .844 1.031 1.219 1.438 1.594 14.811 14.484 14.155 13.827 13.442 13.171 18 O.
32、 D. 40 60 80 100 120 140 160 18.000 “ “ “ “ “ “ 16.876 16.500 16.124 15.688 15.250 14.876 14.438 .562 .750 .938 1.156 1.375 1.562 1.781 16.975 16.646 16.319 15.936 15.553 15.225 14.842 20 O. D. 40 60 80 100 120 140 160 20.000 “ “ “ “ “ “ 18.812 18.376 17.938 17.438 17.000 16.500 16.062 .594 .812 1.0
33、31 1.281 1.500 1.750 1.969 18.921 18.538 18.155 17.717 17.334 16.896 16.515 22 O. D. - 60 80 100 120 140 160 22.000 “ “ “ “ “ “ 20.750 20.250 19.750 19.250 18.750 18.250 17.750 .625 .875 1.125 1.375 1.625 1.875 2.125 20.865 20.428 19.990 19.553 19.115 18.678 18.240 24 O. D. 30 40 60 80 100 120 140 1
34、60 24.000 “ “ “ “ “ “ “ 22.876 22.624 22.062 21.562 20.938 20.376 19.876 19.312 .562 .688 .969 1.219 1.531 1.812 2.062 2.344 22.975 22.757 22.265 21.827 21.280 20.788 20.350 19.859 All dimensions are in inches. 3“C“ dimension are identical to B16.25 PFI Standard ES-21 |Denotes Revision (Revised Sept
35、ember 2010) 8 TABLE 2 MACHINING DIMENSIONS (Metric) Nominal Pipe Size Schedule Number or Nominal O. D. “A“ Nominal I. D. “B“ Nominal Wall Thickness Machined I. D. of Pipe “C“4(mm) Wall “t“ Tolerance0.25-1.003 (76) XXS 88.90 58.42 15.24 61.19 4 (102) XXS 114.30 80.06 17.12 83.29 5 (127) 160 141.30 10
36、9.55 15.88 112.47 XXS “ 103.20 19.05 106.91 120 168.28 139.73 14.27 142.24 6 (152) 160 “ 131.75 18.26 135.31 XXS “ 124.38 21.95 128.83 100 219.08 188.90 15.09 191.67 120 “ 182.55 18.26 186.11 8 (203) 140 “ 177.83 20.62 181.94 XXS “ 174.63 22.23 179.15 160 “ 173.05 23.01 177.75 80 273.05 242.87 15.09
37、 245.64 100 “ 236.52 18.26 240.08 10 (254) 120 “ 230.17 21.44 234.54 140 “ 222.25 25.40 227.56 160 “ 215.90 28.58 222.00 12 (305) 60 323.85 295.30 14.27 297.82 80 “ 288.90 17.48 292.28100 280.97 21.44 285.34 120 “ 273.05 25.40 278.36140 266.70 28.58 272.80 160 “ 257.20 33.32 264.4914 O. D. (356) 60
38、355.60 325.42 15.09 328.19 80 “ 317.50 19.05 321.21100 “ 307.95 23.83 312.90 120 “ 300.02 27.79 305.97140 “ 292.10 31.75 298.98 160 “ 284.18 35.71 292.05All dimensions are in millimeters. 4“C“ dimension are identical to B16.25 PFI Standard ES-21 |Denotes Revision (Revised September 2010) 9 TABLE 2 :
39、 MACHINING DIMENSIONS (Metric) (Continued) Nominal Pipe Size Schedule Number or Nominal O. D. “A“ Nominal I. D. “B“ Nominal Wall Thickness Machined I. D. of Pipe “C“5Wall “t“ Tolerance 0.25-1.0016 O. D. (406) 60 406.40 373.08 16.66 376.20 80 “ 363.52 21.44 367.89100 “ 354.03 26.19 359.54 120 “ 344.4
40、7 30.96 351.21140 “ 333.35 36.53 341.43 160 “ 325.42 40.49 334.5440 457.20 428.65 14.27 431.17 60 “ 419.10 19.05 422.81 80 “ 409.55 23.83 414.50 18 O. D. 100 “ 398.48 29.36 404.77 (457) 120 “ 387.35 34.93 395.05140 “ 377.85 39.67 386.72 160 “ 366.73 45.24 376.99 40 508.00 477.82 15.09 480.59 60 “ 46
41、6.75 20.62 470.87 80 “ 455.63 26.19 461.14 20 O. D. 100 “ 442.93 32.54 450.01 (508) 120 “ 431.80 38.10 440.28140 “ 419.10 44.45 429.16 160 “ 407.97 50.01 419.48 - 558.80 527.05 15.88 529.97 60 “ 514.35 22.23 518.87 80 “ 501.65 28.58 507.75 22 O. D. 100 “ 488.95 34.93 496.65 (559) 120 “ 476.25 41.28
42、485.52140 “ 463.55 47.63 474.42 160 “ 450.85 53.98 463.30 24 O. D. (610) 30 609.60 581.05 14.27 583.5740 “ 574.65 17.48 578.03 60 “ 560.37 24.61 565.5380 “ 547.67 30.96 554.41 100 “ 531.83 38.89 540.51120 “ 517.55 46.02 528.02 140 “ 504.85 52.37 516.89160 “ 490.52 59.54 504.42 All dimensions are in millimeters. 5“C“ dimension are identical to B16.25
