Pressure Temperature Chart - DOT Tubes

The pressure temperature chart below can be used to find maximum allowable working pressure (MAWP) of compressed gases at different temperatures. The MAWP values of DOT Tubes (stamped pressure on the tube or 10% overfill if permitted) is at 70 degrees F. As temperature changes, the MAWP value needs to be corrected which can be found from the chart below. The technical details and an example calculation is provided below the chart and also at the end of the document. The chart can be viewed in full screen or downloaded using the tools below.

Technical details:

Gay-Lussac's Law or Combined Gas Law when volume is constant:
P1/T1 = P2/T2

Temperature Conversions
C = (F - 32) x 5/9
K = C + 273.15
where C, F and K are temperatures in Centigrade, Fahrenheit and Kelvin respectively.

For DOT tubes, pressure is known at 70° F. Pressure at any desired temperature can be calculated using Gay-Lussac's Law.

Example:
P1 = 2850 psi
T1 = 70 ° F = 294.261 ° K
T2 = 110 ° F = 316.483 ° K
P2 = ?
P2 = (P1 x T2) / T1 = (2850 x 316.48) / 294.26 = 3065 psi

For calculating volume and weight of gases at certain temperature and pressure, please go to the Gas Calculator page under Technical section of this site.

The materials on this site are provided for information purpose only. The materials appearing on this site could include technical, typographical, or photographic errors. CMW does not warrant that any of the materials on its site are accurate, complete, or current. CMW may make changes to the materials contained on its site at any time without notice. CMW does not, however, make any commitment to update the materials. CMW assumes no liability whatsoever for results obtained or loss or damage incurred as a result of application of any data or information presented herein. Use of contents on this website is subject to our Terms of Use.