1、PFI Standard ES-1 (Revised September 2010) INTERNAL MACHINING AND SOLID MACHINED BACKING RINGS FOR 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 their use by anyone
2、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.pfi-institute.org PFI
3、 Standard ES-1 (Revised September 2010) INTERNAL MACHINING AND SOLID MACHINED BACKING RINGS FOR CIRCUMFERENTIAL BUTT WELDS 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
4、 the intended precision of the 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
5、of the U.S. values and are for reference only. Metric units were derived utilizing the following conversion factor: Conversion Factor inches to 25.4 millimeter 1. Scope 1.1 This Standard covers the dimensioning of solid machined backing rings and the internal machining of seamless and welded piping
6、components for use with these rings. 1.2 Piping components must be internally machined to a close tolerance to accept solid machined backing rings. For this reason, solid machined backing rings are not recommended for use with piping components with wall thickness less than 0.562“ (14mm). 2. Backing
7、 Rings 2.1 Solid machined backing rings may be of either flat or tapered design. Refer to Figures l, 2, 3, and 4 for backing ring dimensions and design. 2.2 The nominal diameter of a tapered solid machined backing ring shall be 0.010“ (0.3mm) larger than the corresponding nominal internal counterbor
8、e of the piping component. The nominal diameter of a flat solid machined backing ring shall be equal to the corresponding nominal internal counterbore of the piping component. The diametrical tolerance on either a flat or tapered solid machined backing ring shall be +.000“ .010“ (+0.0mm 0.3mm). 3. E
9、nd Preparation 3.1 Typical end preparations for different wall thicknesses are shown in Figures 1 through 4. Those dimensions which are marked with an asterisk (*) may be modified as appropriate for the applicable welding process and variables associated with that process. These specific dimensions
10、shall be defined in the Welding Procedure Specification. 4. Internal Machining 4.1 The following terms define the various dimensions and tolerances required to compute the internal machining dimensions (“C“ dimension) for different types of piping components. A = specified outside pipe diameter B =
11、nominal inside 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 wal
12、l thickness t = nominal wall thickness tm= minimum wall required by design 4.2 To assure proper fit-up of adjoining components, and to assure proper fit-up of the backing ring it is recommended that “Mo“ be set at +.010“ (0.3mm) and “Mu“ at .000“ ( .000mm). NOTE: It must be recognized that large dia
13、meter pipe with a relatively thin wall, has a tendency to spring back after removal from the machining fixture, so the PFI Standard ES-1 (Revised September 2010) tolerance (Mu or Mo) on the internal machining dimension “C“ is therefore applicable to pipe ends measured in the restrained condition. Th
14、is should be considered when checking the “C“ dimension after removal from the machining fixture. 4.3 Pipe and companion components specified by outside diameter. 4.3.1 For pipe and companion components specified by outside diameter and minimum wall, the I. D. machining dimension is determined as: C
15、 = A Ru Mo 2tm , +Mo Mu 4.3.2 For seamless and hollow forged pipe to ASTM A106, A3121, A335, A376, or A405, “Ru = 0.031 in. Using the recommended values of “Mo“ and “Mu“ in paragraph 4.2 Formula 4.3.1 becomes: C = A 0.041 2tm+.010“ .000“ 4.3.3 For pipe specified by outside diameter and nominal wall
16、(or schedule) where the ASTM 12 1/2% nominal to minimum wall thickness tolerance applies, Formula 4.3.1 becomes C = A 0.041 1.75 t +.010“ .000“ “C“ dimensions and corresponding backing ring dimensions for standard ANSI B36.10 pipe sizes, 24“ and under with wall thickness 0.562“ (14mm) and heavier, a
17、re published in Table 1 : “Pipe specified by outside diameter and nominal wall “. These dimensions have been calculated in accordance with Formula 4.3.3. 4.4 Pipe and companion components specified by inside diameter. 4.4.1 The formulas below may be used as a guide to determine the internal machinin
18、g dimension for pipe and companion components specified by inside diameter: a) for use of flat solid backing rings. C = d+So+Su Mo +Mo Mu b) for use of tapered solid backing rings where the possibility of weld buildup is to be minimized or eliminated. 1under tolereance for A312 varies with pipe size
19、. Refer to ASTM specification. C = d+So+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 plate pipe, permissible variations in out-of-roundness and diameter may make procurement of pipe with sized ends des
20、irable. In this case “So“ should be set equal to the plus sizing tolerance and “Su“ the minus sizing tolerance. 4.5 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 accordance wi
21、th ANSI B16.25, Figure l. 5. Material Ordering 5.1 In some cases selection of internal machining dimensions may affect ordered wall thicknesses of pipe and mating components. 5.2 Seamless pipe ordered by outside diameter: Formulas 4.3.1, 4.3.2 and 4.3.3 are intended to permit minimum wall to be main
22、tained 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“ but within the permitted O.D. tolerance, or when internal machining for solid machined b
23、acking rings is performed, 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 satisfactory contact between the internal machined surface of the piping component and the backing ring and to maintain t
24、m. Industry experience indicates that use of Formulas 4.3.1, 4.3.2 and 4.3.3 to determine the internal machining dimension will result in a satisfactory seat contact 7/32“ (6mm) minimum (approximately 75% minimum length of contact) between pipe and 10 tapered backing rings. Occasionally it will be n
25、ecessary to perform a weld buildup to provide sufficient material for machining for satisfactory seating. 5.3 Pipe ordered to inside diameter: PFI Standard ES-1 (Revised September 2010) When the formulas listed in 4.4.1 are used for computing internal machining dimensions, and pipe is received with
26、the I.D. at the minimum of the permitted tolerance range, the possibility exists that machining will encroach “tm” To minimize this problem, one of the following options may be utilized: a) The ordered pipe wall thickness must be increased to provide additional stock for machining by use of the foll
27、owing 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 pipe: Due to the greater tolerances permitted for this material regarding out of roundnes
28、s and variation in diameter, use of the options listed in 5.3 above may not necessarily eliminate the need for weld buildups in these materials. FLAT BACKING RINGS FOR NOMINAL WALLTHICKNESS (t) 9/16“ TO 1“ (14-25mm) INCLUSIVEFIG. 23/4“ (19mm)DFC(RING O.D.)(BORE)tBBREAK CORNERS3/16“* (5mm)1/2“(13mm)1
29、/8“ R. MIN(3mm)1/16“* (2mm)3/16“(5mm)30*30 MAX.A3/16“* (5mm)30*7/32“ MIN.(6mm)103/4“ (19mm)3/16“1/16“* (2mm)(5mm)DTC(RING O.D.)(BORE)ABtBREAK CORNERSTAPERED BACKING RING FOR NOMINAL WALLTHICKNESS (t) 9/16“ TO 1“ (14-25mm) INCLUSIVEFIG. 1PFI Standard ES-1 (Revised September 2010) BREAK CORNERSROUNDED
30、TAPERED RINGS FOR NOMINAL WALLTHICKNESS (t) GREATER THAN 1“ (25mm)FIG. 33/4“ (19mm)7/32“ MIN(6mm)3/4“*(19mm)DTC(RING O.D.)(BORE)tB3/16“* (5mm)1/16“* (2mm)3/16“(5mm)30*10*10A1/2“(13mm)DS(RING O.D.)(BORE)1/16“* (2mm)3/16“(5mm)30 MAX.FLAT BACKING RINGS FOR NOMINAL WALLTHICKNESS (t) GREATER THAN 1“ (25m
31、m)FIG. 43/4“ (19mm)3/4“(19mm)CBBREAK CORNERS1/8“ R. MIN(3mm)AROUNDED3/16“* (5mm)30*10*tPFI Standard ES-1 (Revised September 2010) TABLE 1 PIPE SPECIFIED BY OUTSIDE DIAMETER AND NOMINAL WALL Nominal Pipe Size Schedule Number or Wall Nominal O. D. Nominal I. D. Nominal Wall Thickness Machined I. D. of
32、 Pipe “C“ O.D. of Backing Ring “A“ “B“ “t“Tapered Ring “DT” Straight Ring “DS” Tolerance+ 0.010“ - 0.000“ Tolerance + 0.000“ - 0.010“ Tolerance+ 0.000“ - 0.010“ 3 XXS 3.500 2.300 .600 2.409 2.419 2.409 4 XXS 4.500 3.152 .674 3.279 3.289 3.279 5 160 XXS 5.563 “ 4.313 4.063 .625 .750 4.428 4.209 4.438
33、 4.219 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 5.610 5.337 5.082 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 7.556 7.337 7.173 7.063 7.008 7.546 7.327 7.163 7
34、.053 6.998 10 80 100 120 140 160 10.750 “ “ “ “ 9.562 9.312 9.062 8.750 8.500 .594 .719 .844 1.000 1.125 9.671 9.452 9.234 8.959 8.740 9.681 9.462 9.244 8.969 8.750 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
35、1.125 1.312 11.725 11.507 11.234 10.959 10.740 10.413 11.735 11.517 11.244 10.969 10.750 10.423 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 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 11.4
36、98 12.931 12.656 12.329 12.056 11.781 11.508 12.921 12.646 12.319 12.046 11.771 11.498 All dimensions are in inches. PFI Standard ES-1 (Revised September 2010) TABLE 1 PIPE SPECIFIED BY OUTSIDE DIAMETER AND NOMINAL WALL (continued) Nominal Pipe Size Schedule Number or Wall Nominal O. D. Nominal I. D
37、. Nominal Wall Thickness Machined I. D. of Pipe “C“ O.D. of Backing Ring “A“ “B“ “t“Tapered Ring “DT” Straight Ring “DS” Tolerance+ 0.010“ - 0.000“ Tolerance + 0.000“ - 0.010“ Tolerance+ 0.000“ - 0.010“ 16 O. D. 60 80 100 120 140 160 16.000 “ “ “ “ “ 14.688 14.312 13.938 13.562 13.124 12.812 .656 .8
38、44 1.031 1.219 1.438 1.594 14.811 14.484 14.155 13.827 13.442 13.171 14.821 14.494 14.165 13.837 13.452 13.181 14.811 14.484 14.155 13.827 13.442 13.171 18 O. 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
39、 16.646 16.319 15.936 15.553 15.225 14.842 16.985 16.656 16.329 15.946 15.563 15.235 14.852 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 1.031 1.281 1.500 1.750 1.969 18.921 18.538 18.
40、155 17.717 17.334 16.896 16.515 18.931 18.548 18.165 17.727 17.344 16.906 16.525 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 1
41、9.115 18.678 18.240 20.875 20.438 20.000 19.563 19.125 18.688 18.250 20.865 20.428 19.990 19.553 19.115 18.678 18.240 24 O. D. 30 40 60 80 100 120 140 160 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
42、.827 21.280 20.788 20.350 19.859 22.985 22.767 22.275 21.837 21.290 20.798 20.360 19.869 22.975 22.757 22.265 21.827 21.280 20.788 20.350 19.859 All dimensions are in inches. PFI Standard ES-1 (Revised September 2010) TABLE 1 PIPE SPECIFIED BY OUTSIDE DIAMETER AND NOMINAL WALL (Metric) Nominal Pipe
43、Size (mm) Schedule Number or Wall Nominal O. D. Nominal I. D. Nominal Wall Thickness Machined I. D. of Pipe “C“ O.D. of Backing Ring “A“ “B“ “t“ Tapered Ring “DT” Straight Ring “DS” Tolerance0.25Tolerance 0.000 Tolerance0.000-0.00 -0.030 -0.0303 (76) XXS 88.90 58.42 15.24 61.19 61.44 61.194 (102) XX
44、S 114.30 80.06 17.12 83.29 83.54 83.295 (127) 160 141.30 109.55 15.88 112.47 112.73 112.47XXS “ 103.20 19.05 106.91 107.16 106.91120 168.28 139.73 14.27 142.24 142.49 142.246 (152) 160 “ 131.75 18.26 135.31 135.56 135.31XXS “ 124.38 21.95 128.83 129.08 128.83100 219.08 188.90 15.09 191.67 191.92 191
45、.67120 “ 182.55 18.26 186.11 186.36 186.118 (203) 140 “ 177.83 20.62 181.94 182.19 181.94XXS “ 174.63 22.23 179.15 179.40 179.15160 “ 173.05 23.01 177.75 178.00 177.7580 273.05 242.87 15.09 245.64 245.90 245.64100 “ 236.52 18.26 240.08 240.33 240.0810 (254) 120 “ 230.17 21.44 234.54 234.80 234.54140
46、 “ 222.25 25.40 227.56 227.81 227.56160 “ 215.90 28.58 222.00 222.25 222.0012 (305) 60 323.85 295.30 14.27 297.82 298.07 297.8280 “ 288.90 17.48 292.28 292.53 292.28100 “ 280.97 21.44 285.34 285.60 285.34120 “ 273.05 25.40 278.36 278.61 278.36140 “ 266.70 28.58 272.80 273.05 272.80160 “ 257.20 33.32
47、 264.49 264.74 264.4914 O. D. (356) 60 355.60 325.42 15.09 328.19 328.45 328.1980 “ 317.50 19.05 321.21 321.46 321.21100 “ 307.95 23.83 312.90 313.16 312.90120 “ 300.02 27.79 305.97 306.22 305.97140 “ 292.10 31.75 298.98 299.24 298.98160 “ 284.18 35.71 292.05 292.30 292.05All dimensions are in milli
48、meters. PFI Standard ES-1 (Revised September 2010) TABLE 1 PIPE SPECIFIED BY OUTSIDE DIAMETER AND NOMINAL WALL (Metric) (continued) Nominal Pipe Size (mm) Schedule Number or Wall Nominal O. D. Nominal I. D. Nominal Wall Thickness Machined I. D. of Pipe “C“ O.D. of Backing Ring “A“ “B“ “t“ Tapered Ri
49、ng “DT” Straight Ring “DS” Tolerance0.25Tolerance0.000 Tolerance0.000-0.00 -0.030 -0.03016 O. D. (406) 60 406.40 373.08 16.66 376.20 376.45 376.2080 “ 363.52 21.44 367.89 368.15 367.89100 “ 354.03 26.19 359.54 359.79 359.54120 “ 344.47 30.96 351.21 351.46 351.21140 “ 333.35 36.53 341.43 341.68 341.43160 “ 325.42 40.49 334.54 334.80 334.5440 457.20 428.65 14.27 431.17 431.42 431.1760 “ 419.10 19.05 422.81 423.06 422.8180 “ 409.55 23.83 414.50 414.76 414.5018 O. D. 100 “ 398.48 29.36 404.77 405.03 404.77(457) 120 “ 387.35 34.93 395.05 395.30
