EN 10305 seamless precision steel tube

EN 10305 Standard specification

EN 10305 european standard specifies the technical delivery conditions for seamless cold drawn steel pipe of circular cross section used in hydraulic and pneumatic power systems.

Standard and Steel grade:

  • EN10305-1 E215
  • EN10305-1 E235
  • EN10305-1 E355

The allowed pressure rates and temperatures are the responsibility of the customer in accordance with the state of the art and in the application of the safety coefficients specified in the applicable regulations, codes or standards.

Tubes according to this EN 10305 European standard are characterised by having precisely defined tolerances on dimensions and a specified surface roughness.

EN 10305 seamless precision steel tube shall be manufactured from hot finished seamless tubes by cold drawing. Other suitable methods of cold working are permitted. The tubes shall be delivered in the delivery condition +N which means that after the final cold drawing operation the tubes are normalized in a controlled atmosphere.

NBK means protective heat-treating under the non-oxidation environment to get a bright and smooth surface for the tubes.

BS EN 10305 Steel tubes for precision applications. Technical delivery conditions, consists of the following parts:

  • Part 1: Seamless cold drawn tubes
  • Part 2: Welded cold drawn tubes
  • Part 3: Welded cold sized tubes
  • Part 4: Seamless cold drawn tubes for hydraulic and pneumatic power systems
  • Part 5: Welded cold sized square and rectangular tubes
  • Part 6: Welded cold drawn tubes for hydraulic and pneumatic power system

Chemical composition(%) of EN 10305-1

Steel grade Steel Number 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

Mechanical and technological properties of EN 10305-1

 Yield strength
(min Mpa)
 Tensile strength
(min Mpa)
(min %)
 215 290-430 30
 235 340-480 25
 355 490-630 22

Inspection and test list

Inspection and test typeInspection and test frequency
Internal testsAcceptance tests
Chemical analysisMM
Tensile testingMOne pipe per every tested batch
Flattening test or expansion testM2 per every tested batch
Dimension verificationMM
Visual inspectionMM
The yield point for the annealed (GBK)condition on delivery is at least 50% of the (ultimate) tensile strength. Depending upon the degree of deformation in the drawing operation, the yield point of tubes delivered in the cold-finished/hard (BK)and cold-finished/soft(BKW) conditions, may be increased to a level close to the tensile strength.
In calculating the yield point, the following values are recommended : cold-finished/hard condition on delivery ≥ 80% of the tensile strength, cold-finished/soft condition on delivery ≥ 70% of the tensile strength.

Quality grade of EN 10305-1

The tubes are supplied in the following quality grades :

  1. Precision steel tubes intended primarily for mechanical stressing, without any particular quality requirement and without acceptance test certificate.
  2. Precision steel tubes intended primarily for mechanical stressing, with special quirement and exclusively with acceptance test certificate.
  3. Precision steel tubes with special requirement according to section 12. Theses requirements and corresponding tests must be agreed, with the customer having to specify his requirements at the time of enquiry and on ordering.

Seamless steel pipe conditions on delivery

Cold-finished/hard (cold-finished as-drawn)BKNo heat treatment after the last cold-forming process. The tubes therefore have only low deformability.
(lightly cold-worked)
BKWAfter 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.
AnnealedGBKAfter the final cold-forming process the tubes are annealed in a controlled atmosphere or under vacuum.
NormalizedNBKThe tubes are annealed above the upper transformation point in a controlled atmosphere or under vacuum.