DIN 2391 and EN 10305 are the most widely used international standards for cold-drawn precision steel tubes. This guide compares both standards and explains which to choose for your application.
DIN 2391 is the German standard defining cold-drawn precision steel tubes. It has been used as an industry reference since the 1970s, covering steel grades St 37-4, St 45, and St 52 with NBK, BK, and GBK delivery conditions. It is widely known as 'DIN tube' in Turkish and European markets.
EN 10305 is the European Union standards framework equivalent of DIN 2391. It consists of four sub-sections:
Standard selection according to your application requirements can be made using the following table:
| Application | Recommended Standard | Delivery Condition |
|---|---|---|
| General mechanical and machine elements | DIN 2391 / EN 10305-1 | NBK or BK |
| Hydraulic cylinder and line | EN 10305-4 | NBK (H8 bore) |
| Pneumatic circuit | EN 10305-4 | NBK |
| Defence / barrel | EN 10216-3 | QT (42CrMo4) |
Under DIN 2391 and EN 10305, the most commonly used tolerance classes are D4 (±0.1 mm or ±0.4%) for outside diameter and T3 (±10%) for wall thickness. For hydraulic applications, H8 bore tolerance and Ra ≤ 0.4 µm surface roughness are additionally specified.
Are DIN 2391 and EN 10305-1 the same tube?
Largely yes. EN 10305-1 is the updated version of DIN 2391 within the European standardisation framework. Steel grade names have changed (e.g. St 52 → E355) but mechanical properties and dimensional requirements largely overlap.
What information do I need to provide when ordering?
Standard name, steel grade (e.g. E355), outside diameter, wall thickness, tolerance class (e.g. D4/T3), delivery condition (NBK, BK, etc.), and inspection certificate type (e.g. EN 10204 3.1) should be specified.
Is an inspection certificate mandatory?
In many sectors, an EN 10204 2.2 or 3.1 test report is required. In automotive and defence sectors, a 3.1 certificate is typically requested. Telatar Boru provides a batch inspection certificate with every shipment.
