Data Sheet 73: Steel Tubing – Pressure and Flow Ratings for Hydraulic Plumbing
Pressure ratings are for annealed steel tubing “hydraulic grade” having a tensile strength of 55,000 PSI (the kind most often used for plumbing hydraulic systems). See notes on back for adjustment to other steels. Pressure ratings are shown for S.F. (safety factors) from 2 to 6. A factor of 4 is recommended for general service. On shockless systems a smaller factor is sometimes used.
GPM ratings are shown for flow velocities from 10 through 30 f/s (feet per second). A general guideline is to use 10 f/s on systems operating at a maximum pressure of 1,000 PSI; 15 f/s on systems having maximum pressures from 1,000 to 2,000 PSI; 20 f/s if system pressure is in the range of 2,000 to 3,500 PSI; and a velocity of 30 f/s on systems designed for pressures higher than 3,500 PSI.
| Wall, Inches | 0.025 | 0.032 | 0.035 | 0.042 | 0.049 | 0.058 | 0.065 | 0.072 | 0.083 | 0.095 | 0.109 | |
| 3/8˝ O.D. TUBING55,000 PSI Tensile | Inside Area | 0.0830 | 0.0760 | 0.0731 | 0.0665 | 0.0603 | 0.0527 | 0.0471 | 0.0419 | 0.0343 | 0.0269 | 0.0194 |
| PSI @ S.F. = 6 | 1,220 | 1,560 | 1,710 | 2,050 | 2,400 | 2,840 | 3,180 | 3,520 | 4,060 | 4,640 | 5,330 | |
| PSI @ S.F. = 5 | 1,470 | 1,880 | 2,050 | 2,460 | 2,880 | 3,400 | 3,800 | 4,220 | 4,870 | 5,570 | 6,390 | |
| PSI @ S.F. = 4 | 1,830 | 2,350 | 2,570 | 3,080 | 3,590 | 4,250 | 4,770 | 5,280 | 7,300 | 6,970 | 7,990 | |
| PSI @ S.F. = 3 | 2,440 | 3,150 | 3,420 | 4,100 | 4,790 | 5,670 | 6,350 | 7,040 | 8,120 | 9,290 | 10,650 | |
| PSI @ S.F. = 2 | 3,670 | 4,690 | 5,130 | 6,160 | 7,190 | 8,500 | 9,530 | 10,550 | 12,150 | 13,900 | 16,000 | |
| GPM @ 10 f/s | 2.59 | 2.37 | 2.28 | 2.07 | 1.88 | 1.64 | 1.47 | 1.31 | 1.07 | 0.84 | 0.61 | |
| GPM @ 15 f/s | 3.88 | 3.55 | 3.42 | 3.11 | 2.82 | 2.46 | 2.20 | 1.96 | 1.60 | 1.26 | 0.91 | |
| GPM @ 20 f/s | 5.17 | 4.74 | 4.56 | 4.15 | 3.76 | 3.29 | 2.94 | 2.61 | 2.14 | 1.68 | 1.21 | |
| GPM @ 30 f/s | 7.76 | 7.11 | 6.84 | 6.22 | 5.64 | 4.93 | 4.40 | 3.92 | 3.21 | 2.52 | 1.81 | |
| 1/2˝ O.D. TUBING55,000 PSI Tensile | Inside Area | 0.1590 | 0.1493 | 0.1452 | 0.1359 | 0.1269 | 0.1158 | 0.1075 | 0.0995 | 0.0876 | 0.0754 | 0.0625 |
| PSI @ S.F. = 6 | 920 | 1,170 | 1,280 | 1,540 | 1,800 | 2,130 | 2,380 | 2,640 | 3,040 | 3,480 | 4,000 | |
| PSI @ S.F. = 5 | 1,100 | 1,400 | 1,540 | 1,850 | 2,150 | 2,550 | 2,860 | 3,170 | 3,650 | 4,180 | 4,800 | |
| PSI @ S.F. = 4 | 1,380 | 1,760 | 1,920 | 2,310 | 2,700 | 3,190 | 3,580 | 3,960 | 4,560 | 5,220 | 6,000 | |
| PSI @ S.F. = 3 | 1,830 | 2,350 | 2,570 | 3,080 | 3,590 | 4,250 | 4,770 | 5,280 | 6,090 | 6,970 | 8,000 | |
| PSI @ S.F. = 2 | 2,750 | 3,520 | 3,850 | 4,620 | 5,390 | 6,380 | 7,150 | 7,920 | 9,130 | 10,450 | 12,000 | |
| GPM @ 10 f/s | 4.96 | 4.65 | 4.53 | 4.24 | 3.96 | 3.61 | 3.35 | 3.10 | 2.73 | 2.35 | 1.95 | |
| GPM @ 15 f/s | 7.43 | 6.98 | 6.79 | 6.35 | 5.93 | 5.41 | 5.03 | 4.65 | 4.10 | 3.53 | 2.92 | |
| GPM @ 20 f/s | 9.91 | 9.31 | 9.05 | 8.47 | 7.91 | 7.22 | 6.70 | 6.20 | 5.46 | 4.70 | 3.90 | |
| GPM @ 30 f/s | 14.9 | 14.0 | 13.6 | 12.7 | 11.9 | 10.8 | 10.1 | 9.30 | 8.19 | 7.05 | 5.84 | |
| 5/8˝ O.D. TUBING55,000 PSI Tensile | Inside Area | 0.2597 | 0.2472 | 0.2419 | 0.2299 | 0.2181 | 0.2035 | 0.1924 | 0.1817 | 0.1655 | 0.1486 | 0.1301 |
| PSI @ S.F. = 6 | 730 | 940 | 1,030 | 1,230 | 1,440 | 1,700 | 1,910 | 2,110 | 2,430 | 2,790 | 3,200 | |
| PSI @ S.F. = 5 | 880 | 1,130 | 1,230 | 1,480 | 1,720 | 2,040 | 2,290 | 2,530 | 2,920 | 3,340 | 3,840 | |
| PSI @ S.F. = 4 | 1,100 | 1,400 | 1,540 | 1,850 | 2,160 | 2,550 | 2,860 | 3,170 | 3,650 | 4,180 | 4,800 | |
| PSI @ S.F. = 3 | 1,470 | 1,880 | 2,050 | 2,460 | 2,870 | 3,400 | 3,810 | 4,220 | 4,870 | 5,570 | 6,390 | |
| PSI @ S.F. = 2 | 2,200 | 2,800 | 3,080 | 3,700 | 4,320 | 5,100 | 5,720 | 6,340 | 7,300 | 4,360 | 9,600 | |
| GPM @ 10 f/s | 8.10 | 7.71 | 7.54 | 7.17 | 6.80 | 6.34 | 6.00 | 5.66 | 5.16 | 4.63 | 4.06 | |
| GPM @ 15 f/s | 12.1 | 11.6 | 11.3 | 10.7 | 10.2 | 9.52 | 9.00 | 8.50 | 7.38 | 6.95 | 6.08 | |
| GPM @ 20 f/s | 16.2 | 15.4 | 15.1 | 14.3 | 13.6 | 12.7 | 12.0 | 11.3 | 10.3 | 9.26 | 8.11 | |
| GPM @ 30 f/s | 24.3 | 23.1 | 22.6 | 21.5 | 20.4 | 19.0 | 18.0 | 17.0 | 15.5 | 13.9 | 12.2 | |
| 3/4˝ O.D. TUBING55,000 PSI Tensile | Inside Area | 0.3848 | 0.3632 | 0.3632 | 0.3484 | 0.3339 | 0.3157 | 0.3019 | 0.2884 | 0.2679 | 0.2463 | 0.2223 |
| PSI @ S.F. = 6 | 610 | 860 | 860 | 1,030 | 1,200 | 1,420 | 1,590 | 1,760 | 2,030 | 2,320 | 2,660 | |
| PSI @ S.F. = 5 | 730 | 1,030 | 1,030 | 1,230 | 1,440 | 1,700 | 1,900 | 2,110 | 2,430 | 2,790 | 3,200 | |
| PSI @ S.F. = 4 | 920 | 1,280 | 1,280 | 1,540 | 1,800 | 2,130 | 2,380 | 2,640 | 3,040 | 3,480 | 4,000 | |
| PSI @ S.F. = 3 | 1,220 | 1,710 | 1,710 | 2,050 | 2,400 | 2,840 | 3,180 | 3,520 | 4,060 | 4,640 | 5,330 | |
| PSI @ S.F. = 2 | 1,840 | 2,560 | 2,560 | 3,080 | 3,600 | 4,260 | 4,760 | 5,280 | 6,080 | 6,960 | 8,000 | |
| GPM @ 10 f/s | 12.0 | 11.3 | 11.3 | 10.9 | 10.4 | 9.84 | 9.41 | 8.99 | 8.35 | 7.68 | 6.93 | |
| GPM @ 15 f/s | 18.0 | 17.0 | 17.0 | 16.3 | 15.6 | 14.8 | 14.1 | 13.5 | 12.5 | 11.5 | 10.4 | |
| GPM @ 20 f/s | 24.0 | 22.6 | 22.6 | 21.7 | 20.8 | 19.7 | 18.8 | 18.0 | 16.7 | 15.4 | 13.9 | |
| GPM @ 30 f/s | 36.0 | 34.0 | 34.0 | 32.6 | 31.6 | 29.5 | 28.2 | 27.0 | 25.1 | 23.0 | 20.8 | |
| 7/8˝ O.D. TUBING55,000 PSI Tensile | Inside Area | 0.5346 | 0.5166 | 0.5090 | 0.4914 | 0.4742 | 0.4525 | 0.4359 | 0.4197 | 0.3948 | 0.3685 | 0.3390 |
| PSI @ S.F. = 6 | 520 | 670 | 730 | 880 | 1,030 | 1,210 | 1,360 | 1,500 | 1,740 | 1,990 | 2,280 | |
| PSI @ S.F. = 5 | 630 | 800 | 880 | 1,060 | 1,230 | 1,460 | 1,630 | 1,810 | 2,090 | 2,390 | 2,740 | |
| PSI @ S.F. = 4 | 790 | 1,000 | 1,100 | 1,320 | 1,540 | 1,820 | 2,040 | 2,260 | 2,600 | 2,990 | 3,420 | |
| PSI @ S.F. = 3 | 1,050 | 1,340 | 1,470 | 1,760 | 2,050 | 2,430 | 2,720 | 3,020 | 3,480 | 3,980 | 4,570 | |
| PSI @ S.F. = 2 | 1,580 | 2,000 | 2,200 | 2,640 | 3,080 | 3,640 | 4,080 | 4,520 | 5,200 | 5,980 | 6,840 | |
| GPM @ 10 f/s | 16.7 | 16.1 | 15.9 | 15.3 | 14.8 | 14.1 | 13.6 | 13.1 | 12.3 | 11.5 | 10.6 | |
| GPM @ 15 f/s | 25.0 | 24.2 | 23.8 | 23.0 | 22.2 | 21.2 | 20.4 | 19.6 | 18.5 | 17.2 | 15.9 | |
| GPM @ 20 f/s | 33.3 | 32.2 | 31.7 | 30.6 | 29.6 | 28.2 | 27.2 | 26.2 | 24.6 | 23.0 | 21.1 | |
| GPM @ 30 f/s | 50.0 | 48.3 | 47.6 | 46.0 | 44.3 | 42.3 | 40.8 | 39.2 | 36.9 | 34.5 | 31.7 | |
| 1˝ O.D. TUBING55,000 PSI Tensile | Inside Area | 0.7088 | 0.6881 | 0.6793 | 0.6590 | 0.6390 | 0.6138 | 0.5945 | 0.5755 | 0.5463 | 0.5153 | 0.4803 |
| PSI @ S.F. = 6 | 460 | 590 | 640 | 770 | 900 | 1,060 | 1,190 | 1,320 | 1,520 | 1,740 | 2,000 | |
| PSI @ S.F. = 5 | 550 | 700 | 770 | 920 | 1,080 | 1,280 | 1,430 | 1,580 | 1,830 | 2,090 | 2,400 | |
| PSI @ S.F. = 4 | 690 | 880 | 960 | 1,150 | 1,350 | 1,590 | 1,790 | 4,980 | 2,280 | 2,610 | 3,000 | |
| PSI @ S.F. = 3 | 920 | 1,170 | 1,280 | 1,540 | 1,800 | 2,130 | 2,380 | 2,640 | 3,040 | 3,480 | 4,000 | |
| PSI @ S.F. = 2 | 1,380 | 1,760 | 1,920 | 2,300 | 2,700 | 3,180 | 3,580 | 3,960 | 4,560 | 5,220 | 6,000 | |
| GPM @ 10 f/s | 22.1 | 21.4 | 21.2 | 20.5 | 19.9 | 19.1 | 18.5 | 17.9 | 17.0 | 16.1 | 15.0 | |
| GPM @ 15 f/s | 33.1 | 32.2 | 31.8 | 30.8 | 29.9 | 28.7 | 27.8 | 26.9 | 25.5 | 24.1 | 22.5 | |
| GPM @ 20 f/s | 44.2 | 42.9 | 42.4 | 41.1 | 39.8 | 38.3 | 37.1 | 35.9 | 34.1 | 32.1 | 29.9 | |
| GPM @ 30 f/s | 66.3 | 64.3 | 63.5 | 61.6 | 59.8 | 57.4 | 55.6 | 53.8 | 51.1 | 48.2 | 44.9 | |
| 1¼˝ O.D. TUBING55,000 PSI Tensile | Inside Area | 1.131 | 1.105 | 1.094 | 1.068 | 1.042 | 1.010 | 0.9852 | 0.9607 | 0.9229 | 0.8825 | 0.8365 |
| PSI @ S.F. = 6 | 365 | 470 | 515 | 615 | 720 | 850 | 950 | 1,060 | 1,220 | 1,390 | 1,600 | |
| PSI @ S.F. = 5 | 440 | 560 | 610 | 740 | 860 | 1,020 | 1,140 | 1,270 | 1,460 | 1,670 | 1,920 | |
| PSI @ S.F. = 4 | 550 | 700 | 770 | 920 | 1,080 | 1,280 | 1,430 | 1,580 | 1,820 | 2,090 | 2,400 | |
| PSI @ S.F. = 3 | 730 | 940 | 1,030 | 1,230 | 1,440 | 1,700 | 1,900 | 2,110 | 2,430 | 2,790 | 3,200 | |
| PSI @ S.F. = 2 | 1,100 | 1,400 | 1,540 | 1,840 | 2,160 | 2,560 | 2,860 | 3,160 | 3,640 | 4,180 | 4,800 | |
| GPM @ 10 f/s | 35.3 | 34.4 | 34.1 | 33.3 | 32.5 | 31.5 | 30.7 | 29.9 | 28.8 | 27.5 | 26.1 | |
| GPM @ 15 f/s | 52.9 | 51.7 | 51.2 | 49.9 | 48.7 | 47.2 | 46.1 | 44.9 | 43.2 | 41.3 | 39.1 | |
| GPM @ 20 f/s | 70.5 | 68.9 | 68.2 | 66.6 | 65.0 | 63.0 | 61.4 | 59.9 | 57.5 | 55.0 | 52.2 | |
| GPM @ 30 f/s | 106 | 103 | 102 | 100 | 97.4 | 94.5 | 92.1 | 89.8 | 86.3 | 85.5 | 78.1 | |
| 1½˝ O.D. TUBING55,000 PSI Tensile | Inside Area | 1.651 | 1.612 | 1.606 | 1.575 | 1.544 | 1.504 | 1.474 | 1.444 | 1.398 | 1.348 | 1.291 |
| PSI @ S.F. = 6 | 305 | 390 | 430 | 515 | 600 | 710 | 795 | 880 | 1,014 | 1,161 | 1,332 | |
| PSI @ S.F. = 5 | 370 | 470 | 510 | 610 | 720 | 850 | 950 | 1,050 | 1,210 | 1,390 | 1,600 | |
| PSI @ S.F. = 4 | 460 | 590 | 640 | 770 | 900 | 1,060 | 1,190 | 1,320 | 1,520 | 1,740 | 2,000 | |
| PSI @ S.F. = 3 | 610 | 780 | 850 | 1,030 | 1,200 | 1,420 | 1,590 | 1,760 | 2,030 | 2,320 | 2,660 | |
| PSI @ S.F. = 2 | 920 | 1,180 | 1,280 | 1,540 | 1,800 | 2,120 | 2,380 | 2,640 | 3,040 | 3,480 | 4,000 | |
| GPM @ 10 f/s | 51.5 | 50.2 | 50.1 | 49.1 | 48.1 | 46.9 | 45.9 | 45.0 | 43.6 | 42.0 | 40.2 | |
| GPM @ 15 f/s | 77.2 | 75.4 | 75.1 | 73.6 | 72.2 | 70.3 | 68.9 | 67.5 | 65.4 | 63.0 | 60.4 | |
| GPM @ 20 f/s | 103 | 101 | 100 | 98.2 | 96.3 | 93.8 | 91.9 | 90.0 | 87.2 | 84.0 | 80.5 | |
| GPM @ 30 f/s | 154 | 151 | 150 | 147 | 144 | 141 | 138 | 135 | 131 | 126 | 121 | |
| 2˝ O.D. TUBING55,000 PSI Tensile | Inside Area | 2.986 | 2.944 | 2.926 | 2.883 | 2.841 | 2.788 | 2.746 | 2.705 | 2.642 | 2.573 | 2.490 |
| PSI @ S.F. = 6 | 230 | 295 | 320 | 385 | 450 | 530 | 595 | 660 | 760 | 870 | 1,000 | |
| PSI @ S.F. = 5 | 270 | 350 | 390 | 460 | 540 | 640 | 710 | 790 | 910 | 1,040 | 1,200 | |
| PSI @ S.F. = 4 | 340 | 440 | 480 | 580 | 670 | 800 | 890 | 990 | 1,140 | 1,300 | 1,500 | |
| PSI @ S.F. = 3 | 460 | 590 | 640 | 770 | 900 | 1,060 | 1,190 | 1,320 | 1,520 | 1,740 | 2,000 | |
| PSI @ S.F. = 2 | 680 | 880 | 960 | 1,160 | 1,340 | 1,600 | 1,780 | 1,980 | 2,280 | 2,600 | 3,000 | |
| GPM @ 10 f/s | 93.1 | 91.8 | 91.2 | 89.4 | 88.6 | 86.9 | 85.6 | 84.3 | 82.4 | 80.2 | 77.6 | |
| GPM @ 15 f/s | 139 | 138 | 137 | 135 | 133 | 130 | 128 | 126 | 123 | 120 | 116 | |
| GPM @ 20 f/s | 186 | 184 | 182 | 180 | 177 | 174 | 171 | 169 | 165 | 160 | 233 | |
| GPM @ 30 f/s | 279 | 275 | 274 | 270 | 266 | 261 | 257 | 253 | 247 | 241 | 233 |
For steels with tensile strength other than 55,000 PSI, pressure ratings are proportional to tensile strength. Barlow’s Formula was used for pressure calculations.
P = 2t × S ÷ 0
P = burst pressure, PSI;
t = wall thickness in inches;
S = tensile strength in PSI;
0 = outside diameter in inches.
The following formula was used for calculating flow capacity.
GPM = V × A ÷ 0.3208
V = velocity in feet per second;
A = inside area in square inches.
© 1990 by Womack Machine Supply Co. This company assumes no liability for errors in data nor in safe and/or satisfactory operation of equipment designed from this information.