Use this chart to find the allowable working pressure for fractional (inch) seamless stainless steel tubing by outside diameter and wall thickness. Find your tube OD in the left column, read across to your wall thickness, and that is the working pressure in psig at -20 to 100°F (-28 to 37°C). A blank cell means that wall isn't listed for that OD.
Fractional Seamless 304 / 316 Stainless Steel Tubing
| Tube OD (in.) | Tube Wall Thickness (in.) / Working Pressure (psig) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0.012 | 0.014 | 0.016 | 0.020 | 0.028 | 0.035 | 0.049 | 0.065 | 0.083 | 0.095 | 0.109 | 0.120 | 0.134 | 0.156 | 0.188 | |
| 1/16 | 6,800 | 8,100 | 9,400 | 12,000 | |||||||||||
| 1/8 | 8,500 | 10,900 | |||||||||||||
| 3/16 | 5,400 | 7,000 | 10,200 | ||||||||||||
| 1/4 | 4,000 | 5,100 | 7,500 | 10,200 | |||||||||||
| 5/16 | 4,000 | 5,800 | 8,000 | ||||||||||||
| 3/8 | 3,300 | 4,800 | 6,500 | 7,500 | |||||||||||
| 1/2 | 2,400 | 3,500 | 4,700 | 6,200 | |||||||||||
| 5/8 | 2,900 | 4,000 | 5,200 | 6,000 | |||||||||||
| 3/4 | 2,400 | 3,300 | 4,200 | 4,900 | 5,800 | ||||||||||
| 7/8 | 2,000 | 2,800 | 3,600 | 4,200 | 4,800 | ||||||||||
| 1 | 2,400 | 3,100 | 3,600 | 4,200 | 4,700 | ||||||||||
| 1 1/4 | 2,400 | 2,800 | 3,300 | 3,600 | 4,100 | 4,900 | |||||||||
| 1 1/2 | 2,300 | 2,700 | 3,000 | 3,400 | 4,000 | 4,900 | |||||||||
| 2 | 2,000 | 2,200 | 2,500 | 2,900 | 3,600 | ||||||||||
Notes
- Tubing: fully annealed Type 304 or 316 seamless stainless steel to ASTM A269 or A213 (or equivalent), free of scratches, draw marks and flat spots, suitable for bending. Recommended hardness: 90 HRB or less.
- Allowable working pressures are calculated per ASME B31.3 at -20 to 100°F (-28 to 37°C) using an allowable stress of 20,000 psi.
- Calculations use maximum OD and minimum wall thickness, with no allowance for corrosion or erosion.
- Safety factor is 3.75 to 1, based on an ultimate tensile strength of 75,000 psi.
- Welded tubing: multiply the working pressure by 0.80 for single-welded tubing or 0.85 for double-welded tubing. Example: 1/2" OD x 0.065" wall = 4,700 psig seamless; x 0.80 = 3,760 psig single-welded.
- Heavy-wall small sizes (wall thickness at or above 1/6 of the OD, such as 1/4" x 0.065" and 3/8" x 0.083") fall in the ASME B31.3 thick-wall range, where the code calls for special design consideration.
- Your system is only as strong as its lowest-rated part. Check the rating of the fittings, valves and other components, not just the tube.
Temperature Derating Factors
For service above 100°F, multiply the working pressure from the chart by the factor for your material and temperature. Example: 316 SS at 700°F, 1/2" OD x 0.065" wall: 4,700 psig x 0.82 = 3,854 psig.
| Temperature °F | Temperature °C | 304 SS | 316 SS |
|---|---|---|---|
| 100 | 38 | 1.00 | 1.00 |
| 200 | 93 | 1.00 | 1.00 |
| 300 | 149 | 1.00 | 1.00 |
| 400 | 204 | 0.94 | 0.97 |
| 500 | 260 | 0.88 | 0.90 |
| 600 | 316 | 0.82 | 0.85 |
| 700 | 371 | 0.80 | 0.82 |
| 800 | 427 | 0.76 | 0.80 |
| 900 | 482 | 0.73 | 0.78 |
| 1000 | 538 | 0.69 | 0.77 |
| 1200 | 649 | 0.30 | 0.37 |
Source: DK-Lok Tube Fittings catalog (Sep. 2020), tubing data tables. View the full DK-Lok tube fitting catalog. Always confirm ratings against the current manufacturer data for your exact tubing and fittings before you design or build a system.
Need Help Picking Tubing?
A-Best Industrial Inc. Fittings, Valves, and Tubing stocks 316/316L and 304/304L DFARS compliant stainless tubing, plus Inconel, electropolished, Teflon and nylon tubing. See our tubing page, or call 310-833-3353 or email sales@abesttube.com and we'll help you match the tube to your pressure and temperature.