A312 TP321 Pipe MAWP Calculator ASTM A312 TP321 SS Pipe Smls 18Cr-10Ni-Ti, <=3/8" thk.
Size Variant Wall thickness <= 3/8 in. Wall thickness > 3/8 in.
Material Properties Description
ASTM A312 TP321 SS Pipe Smls 18Cr-10Ni-Ti, <=3/8" thk.
Min Design Temperature
-425 °F
Y Coefficient
Ref 4 — Austenitic steels
Maximum Allowable Working Pressure (psig) Sch STD Sch XS Sch 160
NPS OD (in) 100 °F 200 °F 300 °F 400 °F 500 °F 600 °F 700 °F 800 °F 1/8 0.405 6,659 6,659 6,659 6,659 6,426 6,093 5,827 5,627 1/4 0.54 6,438 6,438 6,438 6,438 6,213 5,891 5,633 5,440 3/8 0.675 5,210 5,210 5,210 5,210 5,028 4,767 4,559 4,403 1/2 0.84 4,995 4,995 4,995 4,995 4,821 4,571 4,371 4,221 3/4 1.05 4,074 4,074 4,074 4,074 3,931 3,727 3,564 3,442 1 1.315 3,810 3,810 3,810 3,810 3,676 3,486 3,333 3,219 1 1/4 1.66 3,137 3,137 3,137 3,137 3,027 2,870 2,745 2,651 1 1/2 1.9 2,822 2,822 2,822 2,822 2,723 2,582 2,469 2,384 2 2.375 2,377 2,377 2,377 2,377 2,294 2,175 2,080 2,009 2 1/2 2.875 2,600 2,600 2,600 2,600 2,509 2,379 2,275 2,197 3 3.5 2,258 2,258 2,258 2,258 2,179 2,066 1,975 1,908 3.5 4 2,059 2,059 2,059 2,059 1,987 1,884 1,802 1,740 4 4.5 1,914 1,914 1,914 1,914 1,847 1,751 1,675 1,617 5 5.563 1,678 1,678 1,678 1,678 1,619 1,535 1,468 1,418 6 6.625 1,524 1,524 1,524 1,524 1,471 1,395 1,334 1,288 7 7.625 1,421 1,421 1,421 1,421 1,371 1,300 1,243 1,201 8 8.625 1,342 1,342 1,342 1,342 1,295 1,228 1,174 1,134 9 9.625 1,275 1,275 1,275 1,275 1,231 1,167 1,116 1,078 10 10.75 1,217 1,217 1,217 1,217 1,175 1,114 1,065 1,029 12 12.75 1,051 1,051 1,051 1,051 1,014 962 920 888 14 14 955 955 955 955 922 874 836 807 16 16 834 834 834 834 805 763 730 705 18 18 740 740 740 740 714 677 647 625 20 20 665 665 665 665 642 608 582 562 22 22 604 604 604 604 583 552 528 510 24 24 553 553 553 553 534 506 484 467 26 26 510 510 510 510 492 467 446 431 28 28 473 473 473 473 457 433 414 400 30 30 441 441 441 441 426 404 386 373 36 36 367 367 367 367 354 336 321 310 42 42 314 314 314 314 303 288 275 266 44 44 300 300 300 300 290 275 263 254 46 46 287 287 287 287 277 263 251 242 48 48 275 275 275 275 265 252 241 232
Allowable Stress vs Temperature 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 Temperature (°F) 0 5 10 15 20 Allowable Stress (ksi) Disclaimer: This calculator is for guidance only. Results are based on ASME B31.3-2024 allowable stresses for seamless pipe (Ej=1.0, W=1.0). Always verify against the current edition of the standard. The engineer of record is responsible for all design decisions.
References ASME B31.3-2024 — Process Piping, Table A-1 ASME B36.10M — Welded and Seamless Wrought Steel Pipe ASME B16.5-2020 — Pipe Flanges and Flanged Fittings 
