ASTM A270 Sanitary Tube (3-A) & Fitting
- International Standard
- Material Grades
- Outer Diameter
- Wall Thickness
- Surface
- Tube Type
- Mill Test Certificate(MTC)
- Certificate
- ASTM A270 / ASME SA270 , 3-A Sanitary Standard
- AISI 304/304L/316/316L
- 1/4″ - 12"
- 0.035″ - 0.12″
- Grit 180, 240, 320
- Welded , Seamless
- EN10204 3.1
- ISO 9001:2015 , PED 2014/68/EU , AD 2000-WO
-
- 6.35mm - 304.8mm
- 0.89mm - 3.05mm
- ≤20Ra (0.5 μm) ID
≤30Ra (0.8 μm) OD
Dimension of ASTM A270
| DN | Tube OD | Wall Thickness | OD Tolerance | WT Tolerance | Length Tolerance | Weight |
|---|---|---|---|---|---|---|
| inch(mm) | inch(mm) | inch(mm) | inch(mm) | (kg/m) | ||
| 8 | 1/4" (6.35) | 0.035" (0.89) | +/-0.005" (0.13) | +/-10.0% | +1/8" (3.18) -0 | 0.124 |
| 15 | 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 |
| 20 | 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 |
| 25 | 1" (25.4) | 0.065" (1.65) / 0.049"(1.25) | +/-0.005" (0.13) | +/-10.0% | +1/8" (3.18) -0 | 0.976 |
| 40 | 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 |
| 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 |
| 65 | 2-1/2" (63.5) | 0.065" (1.65) | +/-0.010" (0.25) | +/-10.0% | +1/8" (3.18) -0 | 2.54 |
| 80 | 3" (76.2) | 0.065" (1.65) | +/-0.010" (0.25) | +/-10.0% | +1/8" (3.18) -0 | 3.06 |
| 100 | 4" (101.6) | 0.083" (2.11) | +/-0.015" (0.38) | +/-10.0% | +1/8" (3.18) -0 | 5.23 |
| 150 | 6" (152.4) | 0.109" (2.77) | +/-0.030" (0.76) | +/-10.0% | +1/8" (3.18) -0 | 10.32 |
| 200 | 8" (203.2) | 0.109" (2.77) | +/-0.030" (0.76) | +/-10.0% | +1/8" (3.18) -0 | 13.86 |
| 250 | 10"(254) | 0.120"(3.05) | +/-0.040" (1.016) | +/-10.0% | +1/8" (3.18) -0 | - |
| 300 | 12"(304.8) | 0.120"(3.05) | +/-0.040" (1.016) | +/-10.0% | +1/8" (3.18) -0 | - |
Finish Specifications
The standard mandates that the interior surface must be smooth, non-toxic, non-absorbent, and corrosion-resistant. This is primarily achieved through a mechanical polishing and electropolishing process. The result is an ultra-smooth finish that minimizes the ability for microbes and product particles to adhere, and it allows for effective cleaning and sterilization.
The most common and accepted finish is defined by a maximum Ra (Roughness Average) value. A typical Ra specification for ASTM A270 tubing is ≤ 0.38 µm (15 microinches) or better, often referred to as a “sanitary finish” or “micro-finish.” Some applications, like high-purity pharmaceutical or biotech processes, may require an even smoother finish of ≤ 0.25 µm (10 microinches).
This smooth surface is created by first mechanically abrading the tube with progressively finer abrasives to remove imperfections and weld beads. This is often followed by electropolishing, an electrochemical process that removes a thin layer of surface material. Electropolishing further smooths the surface, removes embedded contaminants, and enhances the natural passive oxide layer, which significantly improves corrosion resistance.
The primary purpose of this meticulously controlled surface is to prevent contamination, facilitate easy and effective cleaning-in-place (CIP) and sterilization-in-place (SIP) procedures, and provide superior corrosion resistance against aggressive cleaning chemicals and process fluids.
Mirror Polished Surface
| 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 |
Tensile Properties
| Material | Heat Treatment | Yield Strength Ksi (MPa), Min. | Tensile Strength Ksi (MPa), Min. | Temperure Min. ℉(℃) | Elongation %, Min |
| ASME SA270 304 | Solution | 30(205) | 75(515) | 1900 (1040) | 35 |
| ASME SA270 304L | Solution | 25(170) | 70(485) | 1900 (1040) | 35 |
| ASME SA270 316 | Solution | 30(205) | 75(515) | 1900(1040) | 35 |
| ASME SA270 316L | Solution | 25(170) | 70(485) | 1900(1040) | 35 |
Sanitary Fittings in Process Piping (Food, Pharma, Dairy, etc.)
In industrial contexts, Sanitary Fittings (or Hygienic Fittings) refer to the specialized components used to connect pipes in systems where purity and cleanliness are critical. They are designed to prevent bacterial growth, allow for complete cleaning, and ensure product integrity.
Key Idea: These are the connectors and pipes themselves, used to build a system for processing sensitive products.
Key Characteristics:
Smooth, Polished Surfaces: Internally, they have a very smooth finish (often measured in Ra micro-inches) to prevent bacteria from clinging and to allow for easy cleaning.
No Crevices or Dead Spaces: They are designed to be flush with the pipe, creating a seamless flow path so that product or cleaning fluids don’t get trapped.
Easy to Disassemble and Clean (CIP/SIP): They are designed for frequent cleaning, often using methods like Clean-in-Place (CIP) or Sterilize-in-Place (SIP).
Material: Almost exclusively made from 304 or 316L Stainless Steel for its corrosion resistance and non-reactivity.
Common Types of Sanitary Fittings:
Clamp Fittings (Tri-Clamp): The most common type, using a three-piece clamp to seal a gasket between two ferrules.
Butt Weld Fittings: Permanently welded to create a perfectly smooth, crevice-free joint. Used where disassembly isn’t needed.
Bevel Seat Fittings: An older style, similar to clamp fittings but with a different gasket and connection system.
DIN/SMS Fittings: Standards more common in Europe, using a threaded nut to compress a gasket.
Common Components:
Elbows (90°, 45°)
Tees
Reducers
Caps
Ferrule (the stub end that gets connected)
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.
