DIN 11850 is the German standard for welded stainless steel tubes for the food and chemical industries — dairy, brewery, beverage and chemical process lines. It defines tube dimensions and tolerances, steel grades, surface finish and marking. The last edition is DIN 11850:2009-06; it has since been superseded by the European standard EN 10357 (2014), but “DIN 11850” sizes are still the everyday language of hygienic piping in Europe and on many drawings worldwide.
1. Scope
- Dimensions, materials, inside and outside surface condition and marking of welded stainless steel tubes for piping in the food and chemical industries.
- Testing follows EN 10217-7, test category 1 (TC1) or, for special requirements, test category 2 (TC2), together with AD 2000-Merkblatt W 2.
- Materials are taken from EN 10088-1 / EN 10088-2.
2. Sizes, tolerances and weights (Table 1)
The 2009 edition has two series: Series 1 with a 1.0 mm wall (DN 10–50) and Series 2 with a 1.5 mm wall up to DN 50 and 2.0 mm from DN 65 to DN 200. Series 2 is the size range most hygienic fittings are made for. All dimensions in mm.
| DN | Series 1 (Reihe 1) | Series 2 (Reihe 2) | |||||
|---|---|---|---|---|---|---|---|
| OD × WT | OD tol. | kg/m | OD × WT | OD tol. | WT tol. | kg/m | |
| DN 10 | 12 × 1.0 | ±0.1 | 0.27 | 13 × 1.5 | ±0.1 | ±0.15 | 0.43 |
| DN 15 | 18 × 1.0 | ±0.1 | 0.42 | 19 × 1.5 | ±0.1 | ±0.15 | 0.66 |
| DN 20 | 22 × 1.0 | ±0.11 | 0.51 | 23 × 1.5 | ±0.12 | ±0.15 | 0.81 |
| DN 25 | 28 × 1.0 | ±0.14 | 0.66 | 29 × 1.5 | ±0.15 | ±0.15 | 1.03 |
| DN 32 | 34 × 1.0 | ±0.17 | 0.82 | 35 × 1.5 | ±0.18 | ±0.15 | 1.26 |
| DN 40 | 40 × 1.0 | ±0.2 | 0.97 | 41 × 1.5 | ±0.21 | ±0.15 | 1.5 |
| DN 50 | 52 × 1.0 | ±0.26 | 1.26 | 53 × 1.5 | ±0.27 | ±0.15 | 1.9 |
| DN 65 | – | – | – | 70 × 2.0 | ±0.35 | ±0.2 | 3.43 |
| DN 80 | – | – | – | 85 × 2.0 | ±0.43 | ±0.2 | 4.16 |
| DN 100 | – | – | – | 104 × 2.0 | ±0.78 | ±0.2 | 5.03 |
| DN 125 | – | – | – | 129 × 2.0 | ±0.97 | ±0.2 | 6.36 |
| DN 150 | – | – | – | 154 × 2.0 | ±1.16 | ±0.2 | 7.49 |
| DN 200 | – | – | – | 204 × 2.0 | ±1.53 | ±0.2 | 10.12 |
Source: DIN 11850:2009-06, Table 1. Series 1 wall tolerance is ±0.1 mm. The OD tolerance includes out-of-roundness; tube ends are smooth and deburred. Weights are as tabulated in the standard (density 7.97 kg/dm³). Straightness: deviation no more than 0.005 × tube length and 2 mm per metre.
Earlier editions of DIN 11850 included a third series with 2.0 mm walls for small sizes; it is not part of the 2009 edition. If a drawing calls for “DIN 11850 Series 3”, confirm the exact OD and wall with the designer.
3. Steel grades (Table 3)
| Steel name | Number | Closest ASTM type |
|---|---|---|
| X5CrNi18-10 | 1.4301 | 304 |
| X2CrNi18-9 | 1.4307 | 304L |
| X2CrNiMo17-12-2 | 1.4404 | 316L |
| X2CrNiMo17-12-3 | 1.4432 | 316L (higher Mo) |
Annex A of the standard compares these with ASTM A269/A270 grades and notes the differences — for example EN grades limit sulphur to 0.015% where ASTM A269/A270 allow 0.030%, and 1.4404 has Mo 2.0–2.5% against 2.0–3.0% for ASTM 316L. They are comparable, not identical.
4. Execution and surface finish (Table 4)
| Code | Condition | Inside surface | Inside weld area | Outside |
|---|---|---|---|---|
| CC | Not heat treated | Ra < 0.80 µm, pickled & passivated | Ra < 1.60 µm | Pickled & passivated |
| CD | Not heat treated | Ra < 0.80 µm, pickled & passivated | Ra < 1.60 µm | Ground, Ra < 1.00 µm |
| BC | Heat treated | Ra < 0.80 µm, pickled & passivated or bright annealed | Ra < 1.60 µm | Pickled & passivated or bright annealed |
| BD | Heat treated | Ra < 0.80 µm, pickled & passivated or bright annealed | Ra < 1.60 µm | Ground, Ra < 1.00 µm |
Source: DIN 11850:2009-06, Table 4. All types are welded with the inside weld bead smoothed, made from cold-rolled strip (2B or 2R). Tubes that are not bright annealed and not heat treated must be pickled inside and outside in a full bath and then passivated, with no acidic water residue left after rinsing.
5. Permissible pressures (Annex B, informative)
| DN | Series 1, bar (20 °C / 150 °C) | Series 2, bar (20 °C / 150 °C) |
|---|---|---|
| DN 10 | 256 / 158 | 355 / 219 |
| DN 15 | 170 / 105 | 242 / 150 |
| DN 20 | 139 / 86 | 200 / 124 |
| DN 25 | 109 / 67 | 159 / 98 |
| DN 32 | 90 / 55 | 131 / 81 |
| DN 40 | 76 / 47 | 112 / 69 |
| DN 50 | 59 / 36 | 87 / 53 |
| DN 65 | – | 87 / 54 |
| DN 80 | – | 72 / 44 |
| DN 100 | – | 59 / 36 |
| DN 125 | – | 47 / 29 |
| DN 150 | – | 39 / 24 |
| DN 200 | – | 30 / 18 |
Source: DIN 11850:2009-06, Tables B.1 and B.2. Calculated for welded 1.4301 tube (EN 10088-2, product form C, cold strip) at 100% weld utilisation under static load; at 150 °C to AD-Merkblatt B1/B9. These are guidance values — the governing pressure equipment code applies.
6. Matching fittings
The standard lists DIN 11851 unions (for rolling-in and butt welding), DIN 11853-1/-2/-3 hygienic unions, flanges and clamps, and DIN 32676 clamps (butt welding) as the preferred connections for these tubes.
7. DIN 11850 vs EN 10357, ASME BPE and ISO 2037
- EN 10357 replaced DIN 11850 in 2014 as the European standard for welded stainless tubes for the food and chemical industry. For new projects, ask whether the specification should read EN 10357 and which of its series matches your DIN 11850 sizes.
- ASME BPE uses inch OD tubes (for example 2.000 in = 50.80 mm), which do not fit DIN 11850 metric fittings — see our ASME BPE tubing guide.
- ISO 2037 is another metric series with different ODs — see our ISO 2037 guide.
How TeCarve supplies DIN 11850 tubes
TeCarve is the sole export arm of two stainless steel tube factories in Foshan and Wenzhou, China. We supply sanitary stainless steel tube in DIN 11850 Series 1 and 2 sizes, in 1.4301, 1.4307, 1.4404 and 1.4432, with pickled and passivated, bright annealed or polished finishes and Ra reports, plus an EN 10204 3.1 certificate. Trial orders start from 100–300 kg; in-stock sizes ship in 7–10 days and custom production in 10–25 days. Contact sales@tecarve.com.
Frequently asked questions
Is DIN 11850 still valid?
DIN 11850:2009-06 has been superseded by EN 10357 (2014), but DIN 11850 sizes remain in wide use. State on the order which standard and edition apply.
What is DN 50 in DIN 11850?
Series 2 DN 50 is 53 × 1.5 mm (OD tolerance ±0.27 mm); Series 1 DN 50 is 52 × 1.0 mm.
How many series does DIN 11850 have?
The 2009 edition has two: Series 1 (DN 10–50, 1.0 mm wall) and Series 2 (DN 10–200, 1.5 or 2.0 mm wall).
What surface roughness does DIN 11850 specify inside the tube?
Ra < 0.80 µm on the inside surface and Ra < 1.60 µm in the inside weld area for all execution types (CC, CD, BC, BD).
What pressure can DIN 11850 Series 2 DN 50 tube take?
Annex B gives 87 bar at about 20 °C and 53 bar at 150 °C for welded 1.4301, as guidance values.
Related reading: How to specify sanitary tubing · ASME BPE tubing guide · ISO 2037 guide · EN 10216-5 guide
