Material Grades
The ASTM specifications you will meet on a piping line list — pipe, flange forgings, buttweld fittings and bolting — with minimum strengths, temperature ranges and what each one is actually for.
- Specifications listed
- 34
- Categories
- 6
- Strength units
- ksi (1 ksi = 6.895 MPa)
- Bolting standard
- ASTM A193 / A194 / A320
Strengths are the specified minimums, not typical mill values. Temperature ranges are the usual service limits in ordinary practice, not code limits — the governing design code, normally ASME B31.3 or B31.1, sets the allowable stress at temperature and has the final word.
Matching pipe, fittings and flanges
Components in a line should be metallurgically compatible so the weld and the post-weld heat treatment behave predictably. The usual sets are A106 Gr B pipe with A234 WPB fittings and A105 flanges; A333 Gr 6 pipe with A420 WPL6 fittings and A350 LF2 flanges; A312 TP316L pipe with A403 WP316L fittings and A182 F316L flanges.
Carbon steel pipe
| Specification | Form | Tensile, min | Yield, min | Usual temperature range | Notes |
|---|---|---|---|---|---|
| ASTM A53 Gr B | Pipe | 60 ksi | 35 ksi | -20 to 750 °F | Seamless or ERW. Ordinary utility service — air, water, steam, gas. Not impact-tested. |
| ASTM A106 Gr A | Pipe | 48 ksi | 30 ksi | -20 to 800 °F | Seamless. Softer than Gr B; used where cold bending is needed. |
| ASTM A106 Gr B | Pipe | 60 ksi | 35 ksi | -20 to 800 °F | The workhorse seamless carbon steel pipe for high-temperature process service. |
| ASTM A106 Gr C | Pipe | 70 ksi | 40 ksi | -20 to 800 °F | Higher carbon than Gr B; more strength, harder to weld. |
| API 5L Gr B | Pipe | 60 ksi | 35 ksi | -20 to 400 °F | Line pipe for oil and gas transmission. Cross-certified with A53 Gr B in many mills. |
| API 5L X42-X70 | Pipe | 60-82 ksi | 42-70 ksi | -20 to 250 °F | High-strength transmission line pipe; the number is the yield in ksi. |
| ASTM A333 Gr 6 | Pipe | 60 ksi | 35 ksi | -50 to 650 °F | Impact-tested carbon steel for low-temperature service. The standard cryo-adjacent carbon pipe. |
Alloy steel pipe
| Specification | Form | Tensile, min | Yield, min | Usual temperature range | Notes |
|---|---|---|---|---|---|
| ASTM A335 P11 | Pipe | 60 ksi | 30 ksi | up to 1100 °F | 1¼Cr-½Mo. Steam and hydrocarbon service in the creep range. |
| ASTM A335 P22 | Pipe | 60 ksi | 30 ksi | up to 1100 °F | 2¼Cr-1Mo. Refinery heater and high-temperature hydrogen service. |
| ASTM A335 P5 | Pipe | 60 ksi | 30 ksi | up to 1200 °F | 5Cr-½Mo. Sulphidation resistance in crude and vacuum units. |
| ASTM A335 P91 | Pipe | 85 ksi | 60 ksi | up to 1200 °F | 9Cr-1Mo-V. Modern high-energy steam. Requires strict PWHT control. |
Stainless steel pipe
| Specification | Form | Tensile, min | Yield, min | Usual temperature range | Notes |
|---|---|---|---|---|---|
| ASTM A312 TP304 | Pipe | 75 ksi | 30 ksi | -425 to 1500 °F | General-purpose austenitic stainless. Sensitises if welded and held at 800-1500 °F. |
| ASTM A312 TP304L | Pipe | 70 ksi | 25 ksi | -425 to 800 °F | Low-carbon 304 for welded assemblies; resists weld decay. |
| ASTM A312 TP316 | Pipe | 75 ksi | 30 ksi | -425 to 1500 °F | Adds 2-3% molybdenum for chloride pitting resistance. |
| ASTM A312 TP316L | Pipe | 70 ksi | 25 ksi | -425 to 850 °F | Low-carbon 316. The default stainless for welded chemical process piping. |
| ASTM A790 S31803 | Pipe | 90 ksi | 65 ksi | -60 to 600 °F | Duplex, commonly sold as 2205 (strictly, 2205 is UNS S32205, at 95/65 ksi). Roughly twice the yield of 316L with far better chloride SCC resistance. |
Flange forgings
| Specification | Form | Tensile, min | Yield, min | Usual temperature range | Notes |
|---|---|---|---|---|---|
| ASTM A105 | Flange | 70 ksi | 36 ksi | -20 to 800 °F | The default carbon steel flange forging. B16.5 material Group 1.1. |
| ASTM A350 LF2 | Flange | 70 ksi | 36 ksi | -50 to 650 °F | Impact-tested A105 equivalent for low-temperature service. B16.5 material Group 1.1, like A105. The -50 °F limit is for Class 1. |
| ASTM A182 F304/F316 | Flange | 75 ksi | 30 ksi | -425 to 1500 °F | Austenitic stainless flange forgings. F304 is B16.5 Group 2.1 and F316 is Group 2.2. Above 1000 °F only with carbon of 0.04% or more. |
| ASTM A182 F304L | Flange | 70 ksi | 25 ksi | -425 to 800 °F | Low-carbon 304 flange forgings. B16.5 Group 2.3, not to be used above 800 °F. |
| ASTM A182 F316L | Flange | 70 ksi | 25 ksi | -425 to 850 °F | Low-carbon 316 flange forgings. B16.5 Group 2.3. |
| ASTM A182 F11 Cl 2 | Flange | 70 ksi | 40 ksi | up to 1100 °F | 1¼Cr-½Mo flange forgings matched to A335 P11 pipe. B16.5 Group 1.9. |
| ASTM A182 F22 Cl 3 | Flange | 75 ksi | 45 ksi | up to 1100 °F | 2¼Cr-1Mo flange forgings matched to A335 P22 pipe. B16.5 Group 1.10. |
| ASTM A182 F91 | Flange | 90 ksi | 60 ksi | up to 1200 °F | 9Cr-1Mo-V flange forgings matched to A335 P91 pipe. The forging minimum is 90 ksi against 85 ksi for the pipe. B16.5 Group 1.15. |
Buttweld fittings
| Specification | Form | Tensile, min | Yield, min | Usual temperature range | Notes |
|---|---|---|---|---|---|
| ASTM A234 WPB | Fitting | 60 ksi | 35 ksi | -20 to 800 °F | Carbon steel buttweld fittings matched to A106 Gr B pipe. |
| ASTM A420 WPL6 | Fitting | 60 ksi | 35 ksi | -50 to 650 °F | Impact-tested fittings matched to A333 Gr 6 pipe. |
| ASTM A403 WP304/WP316 | Fitting | 75 ksi | 30 ksi | -425 to 1500 °F | Austenitic stainless buttweld fittings matched to A312 pipe. |
| ASTM A234 WP11 Cl 1 / WP22 Cl 1 | Fitting | 60 ksi | 30 ksi | up to 1100 °F | Chrome-moly buttweld fittings matched to A335 P11 and P22 pipe. |
| ASTM A234 WP91 | Fitting | 90 ksi | 60 ksi | up to 1200 °F | 9Cr-1Mo-V buttweld fittings matched to A335 P91 pipe. Minimum tensile is 90 ksi against 85 ksi for the pipe. |
Bolting
| Specification | Form | Tensile, min | Yield, min | Usual temperature range | Notes |
|---|---|---|---|---|---|
| ASTM A193 B7 | Stud bolt | 125 ksi | 105 ksi | -50 to 1000 °F | The standard flange stud. Paired with A194 2H heavy hex nuts. Strengths are for 2½ in diameter and under; 115/95 ksi over 2½ to 4 in. |
| ASTM A193 B7M | Stud bolt | 100 ksi | 80 ksi | -50 to 1000 °F | Hardness-controlled B7 for sour service per NACE MR0175. |
| ASTM A193 B8 Cl 2 | Stud bolt | 125 ksi | 100 ksi | -325 to 1000 °F | Strain-hardened 304 stainless studs for corrosive or cryogenic duty. Strengths are for ¾ in and under only: 115/80 ksi over ¾ to 1 in, 105/65 over 1 to 1¼ in, 100/50 over 1¼ to 1½ in. |
| ASTM A320 L7 | Stud bolt | 125 ksi | 105 ksi | -150 to 800 °F | Impact-tested B7 equivalent for low-temperature service. Strengths are for 2½ in diameter and under. |
| ASTM A194 Gr 2H | Nut | — | — | -50 to 1000 °F | Quenched and tempered heavy hex nut — the standard mate to A193 B7. |
Guides and comparisons for this page
Common questions
What is the difference between A53 and A106 pipe?
A106 is seamless only and is intended for high-temperature service; A53 may be seamless or ERW and is a general utility pipe. A106 Gr B and A53 Gr B share the same minimum strengths, but A106 has tighter chemistry and is the one specified for process service.
Which flange material goes with A106 Gr B pipe?
ASTM A105 forged carbon steel, which is B16.5 material Group 1.1. For low-temperature service, A333 Gr 6 pipe pairs with A350 LF2 flanges instead.
What does the L in 316L mean?
Low carbon — 0.03% maximum against 0.08% for standard 316. The lower carbon stops chromium carbides forming at grain boundaries during welding, which would otherwise leave the heat-affected zone vulnerable to intergranular corrosion. The cost is a slightly lower allowable stress.
What bolting goes with a standard carbon steel flange?
ASTM A193 Gr B7 stud bolts with ASTM A194 Gr 2H heavy hex nuts. For low-temperature service, A320 Gr L7 studs; for sour service, the hardness-controlled B7M.