DIN 11850 Sanitary Stainless Steel Tube
- International Standard
- Material Grades
- Outer Diameter
- Wall Thickness
- Surface
- Tube Type
- Mill Test Certificate(MTC)
- Certificate
- DIN 11850
- 1.4301/1.4401/1.4404
- DN10 - DN250
- 1.0mm , 1.5mm , 2.0mm , 2.5mm
- Grit 180, 240, 320
- Welded , Seamless
- EN10204 3.1
- ISO 9001:2015 , PED 2014/68/EU , AD 2000-WO
- AISI 304/304L/316/316L
- 12mm - 254mm
- ≤20Ra (0.5 μm) ID ,
≤30Ra (0.8 μm) OD
DIN 11850 Sanitary Stainless Steel Tube
- International Standard
- Material Grades
- Outer Diameter
- Wall Thickness
- Surface
- Tube Type
- Certificate
- DIN 11850
- AISI 304/304L/316/316L
- DN10 - DN250
12mm - 254mm - 1.0mm , 1.5mm , 2.0mm , 2.5mm
- Grit 180, 240, 320
≤20Ra (0.5 μm) ID ,
≤30Ra (0.8 μm) OD - Welded , Seamless
- ISO 9001:2015 , PED 2014/68/EU , AD 2000-WO
DIN 11850 is the German industrial standard defining the specifications for seamless and welded stainless steel tubes intended for use in food, chemical, and pharmaceutical processing installations. Its full title translates to “Tubes of stainless steel for the food, chemical and pharmaceutical industries – Dimensions, technical conditions for delivery.” This standard is a cornerstone of sanitary engineering across Europe and in many international markets, renowned for its precision and focus on hygienic design.
The standard covers a range of austenitic stainless steel grades suitable for corrosive environments, with 1.4301 (equivalent to AISI 304) and 1.4401/1.4404 (equivalent to AISI 316/316L) being the most prevalent. A key characteristic of DIN 11850 tubes is their dimensional system based on nominal diameters (DN), such as DN 15, DN 25, DN 51, and DN 76. Unlike other standards, these diameters correspond specifically to the *outside diameter* of the tube in millimeters, providing a clear and consistent reference for system design. This facilitates compatibility with a wide range of standardized DIN-sanitary fittings, valves, and pumps.
The standard outlines strict technical delivery conditions. This includes requirements for the tubes to be supplied clean and free of scale, and it mandates non-destructive testing, such as eddy current testing, to ensure material integrity without defects. While DIN 11850 remains widely used, it is important to note its historical context. For new projects, many European fabricators are transitioning to the more modern ISO 2037 standard, which offers a more globally harmonized approach while still accommodating the dimensional legacy of DIN 11850. Nevertheless, DIN 11850 tubes represent a benchmark for quality and reliability in sanitary process systems, ensuring systems are durable, cleanable, and compatible with a vast ecosystem of European-manufactured sanitary components.
Dimension of DIN 11850 Sanitary Tubing
The wall thickness is relatively thin, making it suitable for low-pressure or normal-temperature applications (such as low-pressure conveying in the food and pharmaceutical industries).
Typical applications: Non-corrosive media or low-pressure scenarios
| Nominal Diameter | Tube OD | Tolerances, OD | Wall Thickness | Telerances, WT | Telerances, Length | Weight |
|---|---|---|---|---|---|---|
| mm | mm | mm | mm | Kg/m | ||
| DN10 | 12 | ±0.12 | 1.0 | ±10% | ＋3.0 | 0.27 |
| DN15 | 18 | ±0.12 | 1.0 | ±10% | ＋3.0 | 0.42 |
| DN20 | 22 | ±0.12 | 1.0 | ±10% | ＋3.0 | 0.51 |
| DN25 | 28 | ±0.12 | 1.0 | ±10% | ＋3.0 | 0.66 |
| DN32 | 34 | ±0.12 | 1.0 | ±10% | ＋3.0 | 0.82 |
| DN40 | 40 | ±0.12 | 1.0 | ±10% | ＋3.0 | 0.97 |
| DN50 | 52 | ±0.2 | 1.0 | ±10% | ＋3.0 | 1.27 |
Medium wall thickness, combining strength and lightweight, suitable for medium pressure or general industrial applications.
Typical applications: Chemical industry, water treatment and other conventional working conditions.
| Nominal Diameter | Tube OD | Tolerances, OD | Wall Thickness | Tolerances, WT | Tolerances, Length | Length |
|---|---|---|---|---|---|---|
| mm | mm | mm | mm | (m) | ||
| DN10 | 13 | ±0.3 | 1.5 | ±10% | ＋3.00 | 0.43 |
| DN15 | 19 | ±0.3 | 1.5 | ±10% | ＋3.00 | 0.66 |
| DN20 | 23 | ±0.3 | 1.5 | ±10% | ＋3.00 | 0.81 |
| DN25 | 29 | ±0.3 | 1.5 | ±10% | ＋3.00 | 1.03 |
| DN32 | 35 | ±0.3 | 1.5 | ±10% | ＋3.00 | 1.26 |
| DN40 | 41 | ±0.3 | 1.5 | ±10% | ＋3.00 | 1.50 |
| DN50 | 53 | ±0.3 | 1.5 | ±10% | ＋3.00 | 1.944 |
| DN65 | 70 | ±0.3 | 2.0 | ±10% | ＋3.00 | 3.43 |
| DN80 | 85 | ±0.3 | 2.0 | ±10% | ＋3.00 | 4.16 |
| DN100 | 104 | ±0.3 | 2.0 | ±10% | ＋3.00 | 5.03 |
| DN125 | 129 | ±0.4 | 2.0 | ±10% | ＋10.00 | 6.36 |
| DN150 | 154 | ±0.4 | 2.0 | ±10% | ＋10.00 | 7.612 |
| DN200 | 204 | ±0.4 | 2.0 | ±10% | ＋10.00 | 10.116 |
| DN250 | 254 | ±0.4 | 2.0 | ±10% | ＋20.00 | 12.555 |
| DN300 | 304 | ±0.4 | 2.0 | ±10% | ＋20.00 | 15.045 |
The wall thickness is relatively thick, with a higher pressure-bearing capacity, making it suitable for high-pressure, high-temperature or highly corrosive media.
Typical applications: High-pressure steam, strong acids, strong alkalis and other harsh environments.
| Nominal Diameter | Tube OD | Tolerances, OD | Wall Thickness | Tolerances, WT | Tolerances, Length | Weight |
|---|---|---|---|---|---|---|
| mm | mm | mm | mm | Kg/m | ||
| 10 | 14 | ±0.3 | 2.0 | ±10% | +3.00 | 0.60 |
| 15 | 20 | ±0.3 | 2.0 | ±10% | +3.00 | 0.90 |
| 20 | 24 | ±0.3 | 2.0 | ±10% | +3.00 | 1.10 |
| 25 | 30 | ±0.3 | 2.0 | ±10% | +3.00 | 1.40 |
| 32 | 36 | ±0.3 | 2.0 | ±10% | +3.00 | 1.70 |
| 40 | 42 | ±0.3 | 2.0 | ±10% | +3.00 | 2.00 |
| 50 | 54 | ±0.3 | 2.0 | ±10% | +3.00 | 2.60 |
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.
| 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 |
Chemical Composition of Stainless Steel Tubing
| TUBE GRADES | UNS | Cr | Ni | Mo | C | P | S | Mn | Si |
| TP304 | S30400 | 18.0-20.0 | 8.0-11.0 | – | 0.08 | 0.045 | 0.03 | 2 | 1 |
| TP304L | S30403 | 18.0-20.0 | 8.0-13.0 | – | 0.035 | 0.045 | 0.03 | 2 | 1 |
| TP316 | S3160 | 16.0-18.0 | 11.0-14.0 | 2.0-3.0 | 0.08 | 0.045 | 0.03 | 2 | 1 |
| TP316L | S31603 | 16.0-18.0 | 10.0-14.0 | 2.0-3.0 | 0.035 | 0.045 | 0.03 | 2 | 1 |
Tensile Properties of Stainless Steel Tubing
| Material | Heat Treatment | Yield Strength | Tensile Strength | Temperure | Elongation %, Min |
| Ksi (MPa), Min. | Ksi (MPa), Min. | Min. º F(º C) | |||
| 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 |
DIN 11850 DIN 11850 DIN 11850 DIN 11850 DIN 11850 DIN 11850 DIN 11850 DIN 11850 DIN 11850
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)
DIN 11850 DIN 11850 DIN 11850 DIN 11850 DIN 11850 DIN 11850
