ASTM A312 Pipes Dimensions
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ASTM A312 is a standard established by the American Society for Testing and Materials (ASTM) that governs the manufacturing requirements and mechanical properties of seamless and welded austenitic stainless steel pipes. This standard covers a range of Nominal Pipe Sizes (NPS) from 1/8 inch (6.4 mm) to 30 inches (760 mm), with wall thickness schedules ranging from SCH 5S to XXS, and is widely utilized in sectors such as the petroleum, natural gas, chemical, and food industries.
Dimensions of ASTM A312 Welded and Seamless Stainless Steel Pipe(Table 1.1)
The standardized dimensions for welded and seamless stainless steel pipe, as specified in ANSI B36.19, are listed herein. These dimensions also apply to heavily cold-worked pipe. Pipe of other dimensions may also be furnished, provided that it complies with all other requirements of this specification.
| NPS Designator | Outside Diameter | Nominal Wall Thickness | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| in. | mm | Schedule 5Sᴬ | Schedule 10Sᴬ | Schedule 40S | Schedule 80S | |||||
| in. | mm | in. | mm | in. | mm | in. | mm | |||
| ⅛ | 0.405 | 10.29 | ... | ... | 0.049 | 1.24 | 0.068 | 1.73 | 0.095 | 2.41 |
| ¼ | 0.540 | 13.72 | ... | ... | 0.065 | 1.65 | 0.088 | 2.24 | 0.119 | 3.02 |
| ⅜ | 0.675 | 17.15 | ... | ... | 0.065 | 1.65 | 0.091 | 2.31 | 0.126 | 3.20 |
| ½ | 0.840 | 21.34 | 0.065 | 1.65 | 0.083 | 2.11 | 0.109 | 2.77 | 0.147 | 3.73 |
| ¾ | 1.050 | 26.67 | 0.065 | 1.65 | 0.083 | 2.11 | 0.113 | 2.87 | 0.154 | 3.91 |
| 1.0 | 1.315 | 33.40 | 0.065 | 1.65 | 0.109 | 2.77 | 0.133 | 3.38 | 0.179 | 4.55 |
| 1¼ | 1.660 | 42.16 | 0.065 | 1.65 | 0.109 | 2.77 | 0.140 | 3.56 | 0.191 | 4.85 |
| 1½ | 1.900 | 48.26 | 0.065 | 1.65 | 0.109 | 2.77 | 0.145 | 3.68 | 0.200 | 5.08 |
| 2 | 2.375 | 60.33 | 0.065 | 1.65 | 0.109 | 2.77 | 0.154 | 3.91 | 0.218 | 5.54 |
| 2½ | 2.875 | 73.03 | 0.083 | 2.11 | 0.120 | 3.05 | 0.203 | 5.16 | 0.276 | 7.01 |
| 3 | 3.500 | 88.90 | 0.083 | 2.11 | 0.120 | 3.05 | 0.216 | 5.49 | 0.300 | 7.62 |
| 3½ | 4.000 | 101.60 | 0.083 | 2.11 | 0.120 | 3.05 | 0.226 | 5.74 | 0.318 | 8.08 |
| 4 | 4.500 | 114.30 | 0.083 | 2.11 | 0.120 | 3.05 | 0.237 | 6.02 | 0.337 | 8.56 |
| 5 | 5.563 | 141.30 | 0.109 | 2.77 | 0.134 | 3.40 | 0.258 | 6.55 | 0.375 | 9.52 |
| 6 | 6.625 | 168.28 | 0.109 | 2.77 | 0.134 | 3.40 | 0.280 | 7.11 | 0.432 | 10.97 |
| 8 | 8.625 | 219.08 | 0.109 | 2.77 | 0.148 | 3.76 | 0.322 | 8.18 | 0.500 | 12.70 |
| 10 | 10.750 | 273.05 | 0.134 | 3.40 | 0.165 | 4.19 | 0.365 | 9.27 | 0.500ᴮ | 12.70ᴮ |
| 12 | 12.750 | 323.85 | 0.156 | 3.96 | 0.180 | 4.57 | 0.375ᴮ | 9.52ᴮ | 0.500ᴮ | 12.70ᴮ |
| 14 | 14.000 | 355.60 | 0.156 | 3.96 | 0.188ᴮ | 4.78ᴮ | ... | ... | ... | ... |
| 16 | 16.000 | 406.40 | 0.165 | 4.19 | 0.188ᴮ | 4.78ᴮ | ... | ... | ... | ... |
| 18 | 18.000 | 457.20 | 0.165 | 4.19 | 0.188ᴮ | 4.78ᴮ | ... | ... | ... | ... |
| 20 | 20.000 | 508.00 | 0.188 | 4.78 | 0.218ᴮ | 5.54ᴮ | ... | ... | ... | ... |
| 22 | 22.000 | 558.80 | 0.188 | 4.78 | 0.218ᴮ | 5.54ᴮ | ... | ... | ... | ... |
| 24 | 24.000 | 609.60 | 0.218 | 5.54 | 0.250 | 6.35 | ... | ... | ... | ... |
| 30 | 30.000 | 762.00 | 0.250 | 6.35 | 0.312 | 7.92 | ... | ... | ... | ... |
ᴬ Schedules 5S and 10S wall thicknesses do not permit threading in accordance with the American National Standard for Pipe Threads (ANSI B1.20.1).
ᴮ These do not conform to the American National Standard for Welded and Seamless Wrought Steel Pipe (ANSI B36.10-1979).
Except for the implicit limitations on seamless pipe wall thickness imposed by the weight restrictions specified in Specification A 999/A 999M, the wall thickness of both seamless and welded pipes at any point shall comply with the tolerance requirements specified in Table 1.2; however, for welded pipes, the weld area is exempt from the "over tolerance" limitation. For pipe materials ordered by Nominal Pipe Size (NPS) and Schedule Number, the wall thickness and outside diameter values to be measured for the purpose of verifying compliance with this requirement are listed in Table 1.1.
TABLE 1.2 Permitted Variations in Wall Thickness
| NPS Designator | Tolerance, % from Nominal | |
|---|---|---|
| Over | Under | |
| ⅛ to 2½ incl., all t/D ratios | 20.0 | 12.5 |
| 3 to 18 incl., t/D up to 5 % incl. | 22.5 | 12.5 |
| 3 to 18 incl., t/D > 5 % | 15.0 | 12.5 |
| 20 and larger, welded, all t/D ratios | 17.5 | 12.5 |
| 20 and larger, seamless, t/D up to 5 % incl. | 22.5 | 12.5 |
| 20 and larger, seamless, t/D > 5 % | 15.0 | 12.5 |
t = Nominal Wall Thickness
D = Ordered Outside Diameter
t/D ratio = Wall thickness-to-outside diameter ratio, used to distinguish between thin-walled and thick-walled pipes
NPS = Nominal Pipe Size (U.S. standard nominal pipe diameter, in inches)
Over/Under = Permissible deviation (as a percentage) relative to the nominal wall thickness
3.1 For welded pipe having a diameter equal to or greater than NPS 6 and a nominal wall thickness equal to or greater than 0.200 inches, weld repairs may be performed by the addition of compatible filler metal; such repairs shall be carried out using the same procedures as those specified for the repair of plate defects in the "Weld Repair" section of Specification A 999/A 999M.
3.2 The length of weld repair shall not exceed 20% of the total weld length.
3.3 Weld repairs shall be performed using the Gas Tungsten Arc Welding (GTAW) process; the bare filler wire used shall be of the same classification as the grade of stainless steel pipe being repaired and shall comply with the requirements of the latest edition of AWS Specification A5.9 (specific classifications are shown in Table 5). Alternatively, subject to purchaser approval-and where necessitated by requirements for corrosion resistance or other performance characteristics-weld repairs may be performed using the GTAW process with a filler metal having an alloy content higher than that of the base metal.
TABLE 5 Pipe and Filler Metal Specification
| Pipe Grade | Pipe UNS Designation | Filler Metal AWS A5.9 Class | Filler Metal UNS Designation |
|---|---|---|---|
| TP304 | S30400 | ER308 | S30800, W30840 |
| TP304L | S30403 | ER308L | S30883, W30843 |
| TP304N | S30451 | ER308 | S30880, W30840 |
| TP304LN | S30453 | ER308L | S30883, W30843 |
| TP304H | S30409 | ER308 | S30880, W30840 |
| TP309Cb | S30940 | … | … … |
| TP309S | S30908 | … | … … |
| TP310Cb | S31040 | … | … … |
| TP310S | S31008 | … | … … |
| S31272 | S31272 | … | … … |
| TP316 | S31600 | ER316 | S31680, W31640 |
| TP316L | S31603 | ER316L | S31683, W31643 |
| TP316N | S31651 | ER316 | S31680, W31640 |
| TP316LN | S31653 | ER316L | S31683, W31643 |
| TP316H | S31609 | ER316H | S31680, W31640 |
| TP321 | S32100 | ER321ER347 | S32180, W32140S34780, W34740 |
| TP347 | S34700 | ER347 | S34780, W34740 |
| TP348 | S34800 | ER347 | S34780, W34740 |
| TPXM-19 | S22100 | ER209 | S20980, W32240 |
| TPXM-29 | S28300 | ER240 | S23980, W32440 |
| … | N08367 | … | N06625 |
| … | S20400 | ER209 | S20980, W32240 |
| … | N08926 | … | N06625 |
Referenced Documents
ASTM Standard: A 999/A 999M Standard Specification for General Requirements for Alloy and Stainless Steel Pipe
ANSI Standard: B1.20.1 Pipe Threads (General)
B36.10 Welded and Seamless Wrought Steel Pipe
B36.19 Stainless Steel Pipe
ASME Standard: ASME Boiler and Pressure Vessel Code: Section VIII
AWS Standard: A5.9 Corrosion-Resisting Chromium and Chromium-Nickel Steel Welding Rods and Bare Electrodes
Gnee maintains long-term strategic partnerships with major Chinese steel mills (such as TISCO, BAOSTEEL, and TSINGSHAN), ensuring that our raw materials are authentic and competitively priced. We provide complete Material Test Certificates (MTCs) that comply with EN 10204 3.1 or 3.2 standards. Third-party inspections (by SGS, BV, TUV, Lloyd's) can be arranged, including non-destructive testing (UT/ET), hydrostatic testing, intergranular corrosion testing, and more.
Custom Processing: We offer value-added processing services such as cutting, beveling, drilling, pipe bending, and other deep processing operations.
In addition to pipes, we can also supply a full range of matching pipe fittings-including flanges, elbows, and tees-to help customers streamline their procurement process and avoid the complexities of sourcing individual components.
| Standard | ASTM A312 |
| Process Classification | - Seamless (SMLS): - Welded (ERW/EFW): |
| Material Grades | - Most Common: TP304, TP304L, TP316, TP316L. - High Performance/Heat-Resistant: TP321, TP347, TP310S, TP904L. |
| Specifications | - Outer Diameter (OD): From 1/8" (10.3mm) to 30" (762mm). - Wall Thickness (WT): SCH 5S, 10S, 40S, 80S (per ANSI B36.19). |
| Surface Treatments | - Pickled & Annealed: Industrial standard. - Bright Annealed. - Polished: 180#, 320#, 400#, etc. (as per customer requirements). |
Click to Customize ASTM A312 Stainless Steel Pipe
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Packaging Methods
End Protection: Both ends of the pipe are fitted with plastic caps to prevent the ingress of dust and foreign objects, as well as to protect the pipe ends from impact damage.
Surface Protection: Individual pipes can be enclosed in plastic sleeves.
Outer Packaging: Industrial-grade packaging involves wrapping the entire bundle in woven bags.
Premium/Small-Dimension Packaging: For high-value or smaller-sized products, we utilize export-specific wooden crates to prevent deformation caused by compression during transit.
Marking: Each pipe typically features clear stenciled markings indicating the grade, standard, dimensions, and heat number.
