Stainless Steel Sanitary Seamless Pipes
A seamless stainless steel sanitary tube to ASTM A270/A270M, cold-drawn and bright-annealed with polished surfaces, for food, dairy, and pharma service.
Product Introduction
ASTM A270 / A270M Sanitary Grade Seamless Stainless Steel Round Tubing
Full Standard Name: ASTM A270/A270M
Scope: Seamless stainless steel sanitary tubing for food, dairy, beverage, pharmaceutical, biotech & high-purity fluid service.
1. Fundamental Manufacturing Requirements for Seamless Tubing
- All seamless tubes shall be cold drawn / cold rolled, fully solution annealed (bright annealed) before delivery.
- Strict internal & external surface finishing to avoid crevices, pits and bacterial adhesion.
- Standard delivery end: plain ends, deburred.
- Mandatory testing per tube lot: tensile test, reverse flattening test.
- Each tube shall undergo hydrostatic test OR eddy current test (ET) 100%.
2. Common Material Grades & UNS Designations
| Grade | UNS No. | Key Features | Typical Applications |
|---|---|---|---|
| TP304 | S30400 | General sanitary austenitic stainless steel | Food processing, drinking water, beverage pipelines |
| TP304L | S30403 | Low carbon, improved resistance to intergranular corrosion after welding | Welded sanitary installations, dairy lines |
| TP316 | S31600 | Molybdenum-alloyed, better chloride corrosion resistance | Brine, fermenting medium, mild acidic fluid |
| TP316L | S31603 | Low-carbon molybdenum grade, most popular pharmaceutical & sanitary grade | Pharmacy, biotech, seawater sanitary piping, ultra-pure water |
| TP321 | S32100 | Titanium stabilized, anti-sensitization at moderate high temperature | Hot food medium, sterilization circulation piping |
Note: Duplex grades (2205 / 2507) are also permitted by A270 for special corrosion service.
3. Minimum Room-Temperature Mechanical Properties
| Test Item | TP304 / 304L / 316 / 316L |
|---|---|
| Minimum Tensile Strength | 485 MPa |
| Minimum Yield Strength | 170 MPa |
| Minimum Elongation | 40 % |
| Maximum Hardness | HB 192 / HRB 90 |
4. Dimensional System – Sanitary Standard Outside Diameter (Imperial Sanitary OD Series)
Sanitary tubing follows industry standard sanitary outer diameters (not ASME B36.19 pipe schedule).
Common commercial seamless A270 sizes:
| Nominal Size | Outside Diameter OD (inch) | Outside Diameter OD (mm) | Common Standard Wall Thickness WT (inch / mm) |
|---|---|---|---|
| 1/2" Sanitary | 0.500" | 12.70 | 0.049" (1.24mm), 0.065" (1.65mm) |
| 3/4" Sanitary | 0.750" | 19.05 | 0.049" (1.24mm), 0.065" (1.65mm) |
| 1" Sanitary | 1.000" | 25.40 | 0.049" (1.24mm), 0.065" (1.65mm), 0.083" (2.11mm) |
| 1.5" Sanitary | 1.500" | 38.10 | 0.065" (1.65mm), 0.083" (2.11mm) |
| 2" Sanitary | 2.000" | 50.80 | 0.065" (1.65mm), 0.083" (2.11mm), 0.109" (2.77mm) |
| 2.5" Sanitary | 2.500" | 63.50 | 0.065" (1.65mm), 0.083" (2.11mm) |
| 3" Sanitary | 3.000" | 76.20 | 0.065" (1.65mm), 0.083" (2.11mm), 0.109" (2.77mm) |
| 4" Sanitary | 4.000" | 101.60 | 0.083" (2.11mm), 0.109" (2.77mm) |
| 6" Sanitary | 6.000" | 152.40 | 0.109" (2.77mm) |
- Standard length: 6000mm fixed length; random lengths negotiable.
- Maximum OD covered in A270 standard: 12 inch (304.8 mm).
5. Dimensional Tolerances (Seamless Tubing)
- Outside Diameter Tolerance
OD ≤ 3 inch (76.2 mm): ±0.010 inch (±0.25 mm)
OD ＞ 3 inch up to 6 inch: ±0.015 inch (±0.38 mm)
- Wall Thickness Tolerance: ±10% of nominal wall thickness
- Straightness: Max 1.5 mm per meter
- End squareness: Tube ends shall be cut square, burr-free.
6. Surface Finish Options (Critical for Sanitary Service)
All surfaces can be specified in purchase order:
- Bright Annealed (BA): Smooth metallic surface, unpolished
- Mechanically polished ID & OD: 180#, 240#, 320#, 400# grit
- Electropolished (EP): Ultra-smooth, low Ra, preferred for pharma / pure water
Typical requirement: Internal surface roughness Ra ≤ 0.8 μm for hygienic service.