ASTM A270 Sanitary Tube (3A)
- International Standard : ASTM A270 / ASME SA270 , 3-A Sanitary Standard
- Material Grades : AISI 304/304L/316/316L
- Outer Diameter : 1/4″ - 12" , 6.35mm - 304.8mm
- Wall Thickness : 0.035″ - 0.12″ , 0.89mm - 3.05mm
- Surface : Grit 180, 240, 320 ≤20Ra (0.5 μm) ID , ≤30Ra (0.8 μm) OD
- Tube Type : Welded , Seamless
- Mill Test Certificate(MTC) : EN10204 3.1
- Certificate : ISO 9001:2015 , PED 2014/68/EU , AD 2000-WO
Description
ASTM A270 is the definitive standard established by ASTM International that specifies the requirements for seamless and welded austenitic stainless steel tubing intended specifically for sanitary service. This standard is critical in industries where absolute cleanliness, corrosion resistance, and smooth, cleanable surfaces are non-negotiable. Unlike more general tubing standards like A269, A270 is meticulously designed for applications involving the processing, conveyance, and handling of consumable products where contamination and bacterial growth pose significant risks. Its specifications are tailored to meet the stringent hygienic demands of the food, beverage, dairy, pharmaceutical, and bioprocessing industries.
A270 covers common austenitic stainless steel grades, primarily S30400 (304) and S31600 (316), and their low-carbon variants S30403 (304L) and S31603 (316L). The low-carbon “L” grades are highly preferred as they resist sensitization (the formation of chromium carbides at grain boundaries) during welding, thereby maintaining their maximum corrosion resistance and making them ideal for the welded constructions typical in sanitary systems. The tubing is produced as either seamless or welded (automatic TIG welded). A mandatory solution annealing heat treatment is required after welding to restore the alloy’s microstructure and corrosion resistance. Following heat treatment, the tubes must be pickled and passivated to remove any scale or iron contamination and to reform the protective chromium oxide layer on the surface.
Dimension of ASTM A270
| Tube OD | Wall Thickness | OD Tolerance | WT Tolerance | Length Tolerance | Weight |
|---|---|---|---|---|---|
| inch(mm) | inch(mm) | inch(mm) | inch(mm) | (kg/m) | |
| 1/4" (6.35) | 0.035" (0.89) | +/-0.005" (0.13) | +/-10.0% | +1/8" (3.18) -0 | 0.124 |
| 1/2" (12.7) | 0.065" (1.65) / 0.049"(1.25) | +/-0.005" (0.13) | +/-10.0% | +1/8" (3.18) -0 | 0.454 |
| 3/4" (19.1) | 0.065" (1.65) / 0.049"(1.25) | +/-0.005" (0.13) | +/-10.0% | +1/8" (3.18) -0 | 0.717 |
| 1" (25.4) | 0.065" (1.65) / 0.049"(1.25) | +/-0.005" (0.13) | +/-10.0% | +1/8" (3.18) -0 | 0.976 |
| 1-1/2" (38.1) | 0.065" (1.65) / 0.049"(1.25) | +/-0.008" (0.20) | +/-10.0% | +1/8" (3.18) -0 | 1.50 |
| 2" (50.8) | 0.065" (1.65) / 0.049"(1.25) | +/-0.008" (0.20) | +/-10.0% | +1/8" (3.18) -0 | 2.02 |
| 2-1/2" (63.5) | 0.065" (1.65) | +/-0.010" (0.25) | +/-10.0% | +1/8" (3.18) -0 | 2.54 |
| 3" (76.2) | 0.065" (1.65) | +/-0.010" (0.25) | +/-10.0% | +1/8" (3.18) -0 | 3.06 |
| 4" (101.6) | 0.083" (2.11) | +/-0.015" (0.38) | +/-10.0% | +1/8" (3.18) -0 | 5.23 |
| 6" (152.4) | 0.109" (2.77) | +/-0.030" (0.76) | +/-10.0% | +1/8" (3.18) -0 | 10.32 |
| 8" (203.2) | 0.109" (2.77) | +/-0.030" (0.76) | +/-10.0% | +1/8" (3.18) -0 | 13.86 |
| 10"(254) | 0.120"(3.05) | +/-0.040" (1.016) | +/-10.0% | +1/8" (3.18) -0 | - |
| 12"(304.8) | 0.120"(3.05) | +/-0.040" (1.016) | +/-10.0% | +1/8" (3.18) -0 | - |
Finish Specifications
| Process | RA Micro Inch | RA Micron | ISO Designation |
|---|---|---|---|
| 150 grit | 30-35 | 0.75-0.875 | N6 |
| 150 grit + Electropolish | 12-20 | 0.3-.05 | |
| 180 grit | 20-25 | 0.5-.0625 | |
| 180 grit + Electropolish | 10-16 | 0.25-0.4 | |
| 240 grit | 15-20 | 0.375-0.5 | N5 |
| 240 grit + Electropolish | 8-12 | 0.2-0.3 | |
| 320 grit | 8-12 | 0.2-0.3 | N4 |
| 320 grit + Electropolish | 6-12 | 0.15-0.3 |
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