DIN 2391-1 cold Drawn or cold rolled steel tube

DIN 2391-1 cold Drawn or cold rolled steel tube is used in hydraulic & pneumatic cylinder, mechanical and Automotive engineering.

Related information for DIN 2391

DIN 2391 standard specifies the Seamless steel tubes used forMechanical and Automobile.

DIN2391 ST52 Seamless Honed Tube

DIN2391 ST52 Seamless Honed Tube

GB/T 3639 Cold drawn or cold rolled precision seamless steel tubes

GB/T 8713 inside precision seamless tubes for hydraulic pressure and pneumatic services



Features Specifications
OD(mm)  Wall Thickness Unit(mm)
2 2.5 3 3.5 4 4.5 5 6 6.5-7 7.5-8 8.5-9 9.5-10 11 12

Mechanical Properties(Mpa)
Steel Grade Minimum values for the delivery condition
Steel Name Steel Number BK BKW BKS GBK NBK
Rm A % Rm A % Rm ReH A % Rm A % Rm ReH A %
Mpa Mpa Mpa Mpa Mpa Mpa Mpa
St 30 Si 1.0211 430 8 380 12 380 280 16 280 30 290 to 420 215 30
St 30 Al 1.0212 430 8 380 12 380 280 16 280 30 290 to 420 215 30
St 35 1.0308 480 6 420 10 420 315 14 315 25 340 to 470 235 25
St 45 1.0408 580 5 520 8 520 375 12 390 21 440 to 570 255 21
St 52 1.0580 640 4 580 7 580 420 10 490 22 490 to 630 355 22
Inspection and test list for the DIN 2391 Standard.
Inspection or test types Test frequency
Internal test Acceptance test
Chemical analysis M M
Tensile testing M One per tested batch
Flattening test or extension test M Two per tested batch
Dimension verification M M
Visual inspection M M
NDT in order to identify leaks Individual Individual
DIN 2391 NBK Seamless Precision Steel Tubes

DIN 2391 NBK Seamless Precision Steel Tubes

Description Name:
DIN 2391 Seamless cold drawn tubes, DIN 2391 Seamless precision steel tubes, ST35 Precision tubes, ST45 Precision tubes, ST52 Precision tubes, Seamless precision tubes, DIN 2391 ST35 Seamless precision steel tubes, DIN 2391 ST45 Seamless precision steel tubes, DIN 2391 ST52 Seamless precision steel tubes, ST 52 Honed tubes, ST52 cylinder tubes.

  • Size: 6mm-350mm.
  • W.T.: 0.8mm-50mm.
  • Shape: Round.

Production type: Cold drawn or cold rolled.

Length: Single random length/ Double random length or as customer’s actual request max length is 10m.

Grade: St30 Si, St30 Al, St35, St45, St52.


The following marking shall be shown on a label attached to the bundle:

  • the manufacturer’s name or trade mark;
  • the specified dimensions;
  • the number of this European Standard;
  • the steel name or number;
  • the cast number;
  • the delivery condition;

in the case of specific inspection, an identification number (e. g. order or item number) which permits the correlation of the product or delivery unit to the related document.


  • Mill test certificates will be issued according to EN10204.3
  • The tubes Shall be Seamless cold drawn or cold rolled.
  • The manufacture should have TS16949 certificate.

Protection and Packing:

  • Packed in wooden box or bundles protected with plastic paper, and suitably protected for sea-worthily delivery or as requested.
  • The tubes shall be delivered with a temporary corrosion protection.
  • The type of protection shall be at the discretion of the manufacturer.

Tech & Service of Seamless pipe

Seamless pipes are extensively applied for the nuclear device, gas, petrochemical, ship building and boiler industries. Seamless pipes dominates 65% of market share in Chinese boiler industry.

How to make seamless pipe(seamless pipe process)?
Hot Piercing Workshop
Piercing process
The cross roll piercing and pilger rolling process in the size range from approx. 250 to 660 mm outside diameter.
Precision cold drawn steel tube production process
Pipe weld cracks
often follow different mechanisms can be divided into two types of thermal cracking and cold cracking.
How to calculate a steel pipe and tube theoretic weight
Calculate a steel pipe?
Pipe fittings are necessary to join together pipes, or to change the direction of an existing pipe.
Pipe beveling
Pipe beveling is the process where an angle is formed between the edge of the end of a pipe or tube and a plane perpendicular to the surface.
Steel pipe cutting machine
Pipe cutting
Cutting tools have a grinding wheel piece cutting machine (also known as toothless saw), hand saw, cutter and other hand tools.
How to calculate a steel pipe and tube theoretic weight
Packing the steel pipes
There are probably hundreds of different methods for packing a pipe, and most of them have merit, but there are two principles that are vital for any method.
Condition on delivery:

It refers to the state of final plastic deformation or final heat treatment of the delivered product. The hot-rolled or cold drawn (rolled) state or manufacturing state generally delivered without heat treatment; the heat-treated state after heat treatment delivery, or the normalizing, tempering, solid solution, annealing according to the type of heat treatment status.

Delivery status Abbreviation Description

(cold-finished as-drawn)

BK No heat treatment after the last cold-forming process. The tubes therefore have only low deformability.
(lightly cold-worked)
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.

Delivery according to actual weight or delivery according to theoretical weight

  • Actual weight - at the time of delivery, the weight of its product is delivered according to the weighing (weighing) weight;
  • Theoretical weight - The weight of the product at the time of delivery is calculated from the nominal size of the steel.


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