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DIN 2391 precision tubes
DIN 2391-1 cold Drawn or cold rolled steel tube is used in hydraulic & pneumatic cylinder, mechanical and automotive engineering.
Please send your inquiry by sales@sunnysteel.com
Description
DIN 2391-1 cold Drawn or cold rolled steel tube is used in hydraulic & pneumatic cylinder, mechanical and automotive engineering.
DIN 2391 standard specifies the seamless steel tubes used for mechanical and automobile.
Application:
- for Atuo usd
- for machinery use
- Oil cylinder tube
- Motorcycle shock reducer steel tubes
- Auto shock reducer inner cylinder
- 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
Size:
- O.D.: 6mm-350mm.
- W.T.: 0.8mm-50mm.
- Length: Single random length/ Double random length or as customer’s actual request max length is 10m.
- Shape: Round.
Production type: Cold drawn or cold rolled.
Grade: St30 Si, St30 Al, St35, St45, St52.
Chemical composition(%) of DIN2391
| Grade | C max | Si max | Mn | P max | S max |
|---|---|---|---|---|---|
| St 35 | 0.17 | 0.35 | ≥0.40 | 0.025 | 0.025 |
| St 45 | 0.21 | 0.35 | ≥0.40 | 0.025 | 0.025 |
| St 52 | 0.22 | 0.55 | ≤1.60 | 0.025 | 0.025 |
| Steel name | Steel number | C max | Si max | Mn | P max | S max | Al min |
|---|---|---|---|---|---|---|---|
| E215 | 1.0212 | 0.1 | 0.05 | 0.7 | 0.025 | 0.025 | 0.025 |
| E235 | 1.0308 | 0.17 | 0.35 | 1.2 | 0.025 | 0.025 | - |
| E355 | 1.058 | 0.22 | 0.55 | 1.6 | 0.025 | 0.025 | - |
Mechanical properties(Mpa) of DIN2391
| 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 | 1.058 | 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 |
Marking:
- Pipes are supplied with marking according to standard and customer request.
- Marking is paint on the ends of pipes.
- The same data, as well as additional information per customer’s request, is indicated on the bundle’s tags.
- 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.
Delivery:
- Pipes are supplied in hexagonal bundles or round bundles tied with steel strip.
- Weight of bundle – up to 5000 kg upon request of customer.
- Each bundle is furnished with three tags.
Note:
- 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.
Standard
The production of our seamless pipes is tightly regulated and all of the pipes we stock have been fully tested to international standards to ensure we only supply the highest quality products.
ASTM / ASME
American Society for Testing and Materials(ASTM), American Society of Mechanical Engineers (ASME)| Product name | Executive standard | Dimension (mm) | Steel code/ Steel grade |
|---|---|---|---|
| Black and Hot-dipped Zinc-coated Steel Pipes Seamless | ASTM A53 | 0.3-1200 x 1.0-150 | GR.A, GR.B, GR.C |
| Seamless Carbon Steel for High Temperature Service | ASTM A106 | 10.3-1200 x 1.0-150 | GR.B, GR.C |
| Seamless Cold-drawn Low-Carbon Steel Heat-Exchanger and Condenser Tubes | ASTM A179 | 10.3-426 x 1.0-36 | Low Carbon Steel |
| Seamless Carbon Steel Boiler Tubes for High Pressure | ASTM A192 | 10.3-426 x 1.0-36 | Low Carbon Steel |
| Seamless Cold-drawn Intermediate Alloy Steel Heat-exchanger and Condenser Tubes | ASTM A199 | 10.3-426 x 1.0-36 | T5, T22 |
| Seamless Medium-carbon Steel Boiler and Superheater Tubes | ASTM A210 | 10.3-426 x 1.0-36 | A1, C |
| Seamless Ferritic and Austenitic Alloy Steel Boiler, Superheater and Heat-exchanger Tubes | ASTM A213 | 10.3-426 x 1.0-36 | T5, T5b, T9 , T11, T22 ,T91 |
| Seamless Carbon and Alloy Steel for Mechanical Tubing | ASTM A333 | 1/4"-42" x SCH20-XXS | Grade1 Gr. 3,Gr..6, Gr.8 , Gr. 9 |
| Seamless Cold-drawn Carbon Steel Feedwater Heater Tubes | ASTM A556 | 10.3-426 x 1.0-36 | A2, B2 |
| Round and shaped steel cold formed welded and seamless carbon steel structural pipe. | ASTM A500 | OD :10.3-820 x 0.8- 75 | Grade A, B, C, D |
| Carbon and alloy steel mechanical tubing, either hot-finished or cold-finished | ASTM A519 | 10.3-426 x 1.0-36 | 1020, 1025, 4130, 4140 |
| For seamless ferritic alloy-steel pipe for high-temperature service | ASTM A335 | 1/4"-42" x SCH20-XXS | A/SA 335 P1, P2, P11, P12, P15, P22, P91, P92, P122 |
Process
Cold drawn seamless steel tube deformed process
Cold Drawn Seamless Mechanical Tubing (CDS) is a cold drawn 1018/1026 steel tube which offers uniform tolerances, enhanced machinability and increased strength and tolerances compared to hot-rolled products. 
Cold drawn steel tube is with hot-rolled steel coil as raw material, and tandem cold rolling pickled to remove oxide scale, its finished rolling hard roll, rolling hard volumes due to the continuous cold deformation caused by cold hardening strength, hardness increased indicators declined tough plastic, stamping performance will deteriorate, which can only be used for simple deformation of the parts. Rolling hard roll can be used as the raw material of the hot-dip galvanizing plant, hot dip galvanizing line set annealing line. Rolling hard roll weight is generally 6 to 13.5 tons, the coil diameter of 610mm.
Hot rolled seamless steel pipe deformed process
Hot-rolled seamless steel pipe production base deformation process can be summarized as three stages: perforation, extension and finishing. 
The main purpose of the perforation process is to become a solid round billet piercing hollow shell. Capillary in the specifications, accuracy and surface quality can not meet the requirements of the finished product, further improvements are needed to deform the metal through. The main purpose of the stretching machine is further reduced sectional view (main compression wall) for a larger axial extension, so that the capillary improved dimensional accuracy, surface quality and organizational performance. After stretching machine rolled steel pipe shortage collectively need further molding mill in order to achieve the requirements of the finished pipe. Rolled steel due to pass in the method widely used in the production of seamless steel tubes. So far, due to the method pass rolling steel can be divided into two categories: core pension without rolling rolling (hollow body rolling), and with the mandrel. Sizing machines, reducing mill and stretch reducing mill belonging to the hole without mandrel type continuous rolling mills are generally coffin. Its main purpose is to reduce the diameter of the deformation process or sizing get finished steel, the wall thickness of process control, can make thinning, thickening or nearly unchanged. All the traditional hole-type rolling machine with mandrel belong to extend machine. The main purpose is to reduce the deformation process perforated capillary wall thickness and outer diameter roll passes in the deformation zone and the mandrel posed, for a larger axial extension. At the same time a certain improvement in the organization, performance, accuracy, surface quality.
Cut to Length
Before cutting pipe and tubing No matter the material, measure the diameter of the pipe or tube to be cut to ensure that you use the right-size tube cutter for the job. When determining how to make a straight cut, use a tape measure and a pencil or other writing instrument to mark on the surface where you want to cut. If possible, mark around the circumference of a pipe, especially when cutting with a handsaw. Ensure that a cut is as straight as possible by securing the pipe with a vise, clamp, miter box or even duct tape to keep the length from shifting out of place while cutting. After cutting pipe and tubing
- Unless a cut is perfectly clean, you should expect to remove burrs from around the edge, especially after sawing.
- Use a deburring tool to clean the edge after tube cutting.
- You may opt to use a metal file on the cut of a metal pipe.
Inspection
Size inspection
Geometrical inspection of steel pipes The outer diameter, wall thickness, bending and length of the steel pipe can be inspected on the inspection table with an outer caliper, a micrometer and a bending ruler, and a length tape measure.
Tolerances of pipes you should notice
Take seamless steel pipe as an example, there are some tolerances that affect quality. Noting this, and you will get a better pipe.
Weight tolerance
For pipe NPS 12 (DN300, 323.8mm) and under, the weight shall vary within -3.5% / +10%.
For pipe over NPS 12 (DN300, 323.8mm), the weight shall vary within -5% / +10%.
Pipe of NPS 4 (DN100, 114.3mm) and smaller may be weighed in convenient lots; pipe in sizes larger than NPS 4 shall be weighed separately.
Quantity tolerance
Normally mills take -10% to +10% tolerance, but TPMCSTEEL keeps ±3% variation.
Length tolerance
For Seamless pipe& tube, if definite cut lengths are ordered, the length shall vary within -0mm / +6mm.
Dimension tolerances of seamless steel pipe
| Pipe types | Pipe Szie(mm) | Tolerances | |
|---|---|---|---|
| Hot rolled | OD | <50 | ±0.50mm |
| ≥50 | ±1% | ||
| WT | <4 | ±12.5% | |
| ≥4-20 | +15%, -12.5% | ||
| >20 | ±12.5% | ||
| Cold drawn | OD | 6-10 | ±0.20mm |
| 10-30 | ±0.40mm | ||
| 30-50 | ±0.45 | ||
| >50 | ±1% | ||
| WT | <1 | ±0.15mm | |
| >1-3 | + 15%, – 10% | ||
| >3 | + 12.5%, – 10% | ||
| Standard | Hot finished seamless tube | Cold flnished seamless tube | ||
|---|---|---|---|---|
| Out diameter (mm) | Tolerance | Out diameter (mm) | Tolerance | |
| EN10216-1 | ≤100 | +/-0.75% (min.+/-0.5mm) | All | +/-0.5% |
| EN10216-2 | (min. +/-0.30mm) | |||
| DIN17175 | >100 | +/-0.90% | ||
| GB/T 3087 | ≤460 | +/-0.75% (min.+/-0.5mm) | 10-30 | +/-0.40mm |
| >30-50 | +/-0.45mm | |||
| >50 | +/-1.0% | |||
| GB/T 5310 GB/T 9948 GB/T 6479 | <57 | +/-0.40mm | ≤30 | +/-0.20mm |
| 57-325 | +/-0.75% | >30-50 | +/-0.30mm | |
| >325-460 | +1%,-2mm | >50 | +/-0.8% | |
| ASME SA-179M ASME SA-192M ASME SA-209M ASME SA-210M ASME SA-213M JIS G 3461 JIS G 3461 | ≤101.6 | +0.4, -0.8mm | <25.4 | +/-0.10mm |
| >25.4-38.1 | +/-0.15mm | |||
| >38.1-50.8 | +/-0.20mm | |||
| 101.6-190.5 | +0.4, -1.2mm | >50.8-63.5 | +/-0.25mm | |
| >63.5-76.2 | +/-0.30mm | |||
| >76.2 | +/-0.38mm | |||
| ASME SA106 ASME SA335 | ≤48.3 | +/-0.40mm | ≤48.3 | +/-0.40mm |
| 48.3-114.3 | +/-0.79mm | |||
| 114.4-219.1 | +1.59, -0.79mm | |||
| 219.2-323.9 | +2.38, -0.79mm | >48.3 | +/-0.79mm | |
| >324 | +/-1.0% | |||
Tolerances on wall thickness
The wall thickness at any point shall be within the below tolerance table.| Standard | Hot finished seamless tube | Cold flnished seamless tube | ||||
|---|---|---|---|---|---|---|
| DIN17175 | Out diameter OD(mm) | Wall thickness T(mm) | Tolerance | Out diameter (mm) | Wall Thickness T(mm) | Tolerance |
| ≤130 | S≤2Sn | +15%, -10% | -- | All | +/-10% (min. +/-0.2mm) |
|
2Sn| +12.5%, -10% |
| |||||
| S>4Sn | +-/9% | |||||
| >130 | S≤0.05da | +17.5%, -12.5% | ||||
0.05da| +/-12.5% |
| |||||
| S>0.11da | +/-10% | |||||
| EN 10216-1 EN 10216-2 | ≤219.1 | - | +/-12.5% (min.+/-0.4mm) |
|||
| -- | T/D≤0.025 | +/-20% | ||||
0.025| +/-15% |
| |||||
0.05| +/-12.5% |
| |||||
0.1| +/-10% |
| |||||
| GB/T 3087 | -- | ≤20 | +15%,-12.5% (min.+0.45, -0.35mm) | -- | 1.0-3.0 | +15%, -10% |
| >20 | +/-12.5% | -- | >3 | +12.5%, -10% | ||
| GB/T 5310 GB/T 9948 GB/T 6479 | -- | <4.0 | +15%,-10% (min.+0.48, -0.32mm) | -- | 2-3 | +12%,-10% |
| 4-20 | +12.5%,-10% | >3 | +/-10% | |||
| >20 | +/-10% | |||||
| ASME SA-179M ASME SA-192M ASME SA-209M ASME SA-210M ASME SA-231M JIS G 3461 JIS G 3462 | -- | 2.41-3.8 | +35%, -0% | ≤38.1 | -- | +20%,-0% |
| 3.8-4.6 | +33%,-0% | >38.1 | -- | 22%,-0% | ||
| >4.6 | +28%,-0% | -- | -- | -- | ||
| ASME SA-106 ASME SA-335 | -- | All | +/12.5% | All | +/-10% | |
Note:
- The size in the table above is for the hot-rolled tubes.
- The size of the green area is the regular specification, we can accept orders directly, but the yellow area shall be subject to a technical evaluation.
- The Out side diameter (O.D) and wall thickness (W.T.) of the tube should be complied.
PMI test
Positive material identification (PMI) testing is the examination of a material, usually a metallic alloy, to confirm the material is consistent with the user’s request.
Delivery
Steel pipe delivery status(condition)
Steel pipe delivery status(condition): cold / hard (BK), cold / soft (BKW), after cold stress relief annealing (BKS), annealing (GBK), normalized (NBK).
Condition on delivery of steel pipe
| Term | Symbol | Explanation |
|---|---|---|
| Cold-finished/hard (cold-finished as-drawn) | BK | No heat treatment after the last cold-forming process. The tubes therefore have only low deformability. |
| Cold-finished/soft (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. |
Cold rolled steel coil substrate products deep processing of high value-added products. Such as electro-galvanized, hot dip galvanized, electro-galvanized fingerprint resistant, painted steel roll damping composite steel, PVC laminating steel plates, etc., so that the excellent quality of these products has a beautiful, high resistance to corrosion, has been widely used.
Cold rolled steel coil finishing after annealing, cut the head, tail, trimming, flattening, smooth, heavy volume, or longitudinal clipboard. Cold-rolled products are widely used in automobile manufacturing, household electrical appliances, instruments, switches, buildings, office furniture and other industries. Steel plate strapping package weight of 3 to 5 tons. Flat sub-volume typically 3 to 10 tons / volume. Coil diameter 6m.
Packing
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 to work prevent rusting and Sea transportation security. 
- Plastic caps plugged at the two sides of pipe ends
- Should be avoided by the steel strapping and transport damage
- Bundled signs should be uniform and consistent
- The same bundle(batch) of steel pipe should be came from the same furnace.
- The steel pipe has the same furnace number, the same steel grade, the same specifications.
Our packing can meet any needs of the customers.
Inquiry
Need to inquire about our products? Fill out the form below and our staff will be in touch!
FAQ
Q: How long is your delivery time? A: The delivery time of customized products is generally 25 35 days, and non customized products are generally shipped within 24 hours after payment. Q: Do you provide samples? Is it free? A: If the value of the sample is low, we will provide it for free, but the freight needs to be paid by the customer. But for some high value samples, we need to charge a fee. Q: What are your payment terms? A: T/T 30% as the deposit,The balance payment is paid in full before shipment Q: What is the packaging and transportation form? A: Non steaming wooden box and iron frame packaging. Special packaging is available according to customer needs. The transportation is mainly by sea. Q: What is your minimum order quantity? A: There is no minimum order quantity requirement. Customized products are tailor made according to the drawings provided by the customer.
