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EN 10305-1 is the technical delivery condition for cold-drawn seamless precision tube with a circular cross-section, an outer diameter ≤380mm, and precisely defined tolerances and specified maximum surface roughness. Typical applications of EN 10305-1 include the automotive, furniture, and general engineering industries.
EN 10305-1 seamless precision tubes are high-quality cold-drawn tubes with a circular cross-section, designed for applications requiring tight dimensional tolerances and superior surface quality.
EN 10305 seamless precision tubes shall be manufactured using a cold-drawing process from hot-rolled seamless steel tubes. Other suitable cold-working methods may also be used. The tubes shall be delivered in +N condition, meaning that after the final cold-drawing process, the tubes shall be normalized in a controlled atmosphere.
EN 10305-1 standard covers pipes made of both non-alloy and alloy steels, each including the following grades:
1. Non-alloy steels: E215 (1.0212), E235 (1.0308), E355 (1.0580), E255 (1.0408), E410 (1.0509), 26Mn5 (1.1161), 10S10 (1.0711), 15S10 (1.0710), 18S10 (1.0712), and 37S10 (1.0713);
2. Non-alloy special steels: C35E (1.1181) and C45E (1.1191);
3. Alloy steels: 26Mo2 (1.5417), 25CrMo4 (1.7218), and 42CrMo4 (1.7225);
Note: BS EN 10305-1 and DIN EN 10305-1 are equivalent to EN 10305-1, but are used in different countries/regions.
|
BS |
DIN |
DIN |
GB |
ASTM |
|
BS EN 10305-1 |
DIN EN 10305-1 |
GB/T 3639 |
ASTM A519 |
EN 10305-1 dimensions cover seamless precision tubes with an outer diameter of 380 mm or less, with precise dimensional tolerances and specified surface roughness requirements.
When ordering tubes based on outer and inner diameters, the dimensional tolerances should be selected according to the delivery condition and meet the following requirements:
Applicable to +C and +LC delivery conditions;
Applicable to +SR, +A, and +N delivery conditions.
When ordering pipes by outer diameter and wall thickness or by inner diameter and wall thickness, the wall thickness tolerance shall be ±10% or ±0.1 mm, whichever is greater.
DIN 10305-1 allows for lengths to be supplied in three ways: random length, approximate length, and exact length.
Random Length: The minimum length is 3 meters. The length difference between pipes in each order shall not exceed 2 meters.
Approximate Length: Specified length, with a tolerance of ±500 mm; a maximum of 10% of the order quantity may be supplied in shorter lengths ≥2 meters. Shorter lengths should be bundled separately.
Exact Length:
|
Length L, mm |
Tolerance, mm |
|
≤ 500 |
0 – + by agreement |
|
500 ＜ L ≤ 2000 |
0 – + 3 |
|
2000 ＜ L ≤ 5000 |
0 – + 5 |
|
5000 ＜ L ≤ 8000 |
0 – + 10 |
|
＞ 8000 |
0 – + by agreement |
|
Steel grade |
Steel |
C(% max) |
Si(% max) |
Mn(% max) |
P(% max) |
S(% max) |
|
E215 |
1.0212 |
0.10 |
0.05 |
0.70 |
0.025 |
0.015 |
|
E235 |
1.0308 |
0.17 |
0.35 |
1.20 |
0.025 |
0.015 |
|
E355 |
1.0580 |
0.22 |
0.55 |
1.60 |
0.025 |
0.015 |
|
Yield strength |
Tensile strength |
Elongation |
|
E215 |
290-430 |
30 |
|
E235 |
340-480 |
25 |
|
E355 |
490-630 |
22 |
The flattening test is applicable to precision tubes conforming to EN 10305-1 with a wall thickness less than 15% of the outer diameter.
The tube is flattened between two parallel plates. When the distance H between the plates meets the specified requirement, the tube is inspected for cracks.
H = (1 + C) × T / (C + T/D)
H is the distance between the plates measured under load, in millimeters;
D is the specified outer diameter, in millimeters;
T is the specified wall thickness, in millimeters;
C is a factor: 0.09 for E215 and E235, and 0.07 for E355.
The test shall be conducted according to EN ISO 8493, using a 60° tapered mandrel, provided the outer diameter is less than 150 mm and the wall thickness is less than 10 mm.
EN 10305-1 requires three tests for mechanical properties, of which the tensile test is mandatory, while the flattening test and drift expansion test are optional.
Non-destructive testing for longitudinal defects may be performed using one or more of the following methods:
1. Eddy current testing: EN ISO 10893-2, acceptance level E3;
2. Magnetic sensor/magnetic flux leakage test: EN ISO 10893-3, acceptance level F3;
3. Ultrasonic testing: EN ISO 10893-10, acceptance level U3B;
Non-destructive testing shall be performed according to EN ISO 10893-1 to verify sealing.
The surface finish of the inner and outer surfaces of the pipe shall conform to the typical characteristics of the manufacturing process, and, where applicable, also to the typical characteristics of the heat treatment process employed.
Generally, the surface finish and condition should be sufficient to identify any surface defects requiring correction.
EN 10305 specifies the following requirements for the maximum surface roughness of steel pipes:
For steel pipes with an outer diameter D ≤ 260 mm:
Under delivery conditions +SR, +A, and +N, the outer surface roughness ≤ 4 μm;
Under delivery conditions +C and +LC, the thickness of both the outer and inner surfaces of the pipe ≤ 4 μm, where the inner surface thickness requirement applies to specified or calculated inner diameters ≤ 15 mm;
For steel pipes with an outer diameter D > 260 mm:
The outer and inner surfaces ≤ 6 μm.
|
Yield strength |
Tensile strength |
Elongation |
|
Cold-finished/hard |
BK |
No heat treatment after the last cold-forming process. The tubes therefore have only low deformability. |
|
Cold-finished/soft |
BKW |
After the last heat treatment there is a light finishing pass (cold drawing) With proper subsequent processing, the tube can be cold-formed (e.g. bent, expanded) within certain limits. |
|
Annealed |
GBK |
After the final cold-forming process the tubes are annealed in a controlled atmosphere or under vacuum. |
|
Normalized |
NBK |
The tubes are annealed above the upper transformation point in a controlled atmosphere or under vacuum. |
Note：
1. The yield point of annealed (GBK) tubing must be at least 50% of its ultimate tensile strength. Depending on the degree of deformation during drawing, the yield point of cold-rolled hard (BK) and cold-rolled soft (BKW) tubing can be increased to near the tensile strength level.
2. When calculating the yield point, the following values are recommended:
tensile strength ≥ 80% for cold-worked/hard-state delivery,
and tensile strength ≥ 70% for cold-worked/soft-state delivery.
EN 10305-1 seamless precision tubes are used in the following applications: heat exchangers, elevator ducts, gas cylinders, maintenance station supports, HPL tubes (with phosphated or galvanized surfaces), cable conduits, motorcycle/bicycle frames, rivets, pump tubes, textile machinery structures, cylindrical tubes, piston tubes, telescopic tubes, and stabilizing tubes.
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