DIN 2391 Part I Seamless Precision Steel Tubes
DIN 2391 Part I Seamless Precision Steel Tubes
Scope and field of application
This standard specifies dimensions for cold finished,seamless precision steel tubes and is to be used in conjunction with DIN 2391 Part2 which states the relevant technical delivery conditions.The preferred sizes listed in table 2 are mainly used In mechanical and automotive engineering.
Where steel tubes of dimensions specified in this standard are to comply with the technical delivery conditions listedIn subclause 1.2 of DIN 2391 Part 2, they Shan be orderedin quality grade C.
Dimensions
The tube diameter is subject to the limit deviations specified in table 2.
if one of the limit deviations is to be zero, this shall be stated in the order, e.g. instead of (55 ±0,25) mm, either (55±0.5 ) mm
Table 1:Limit deviations for the diameter of heat treated tubes
| wall thickness. T, | Limit deviations tor diameters,D |
| 0.05*D and above | As specified in table 2 |
| Above 0.05*D up to0.025*D | 1.5 times the values in table 2. |
| Above 0.025*D | Twice the values in table 2. |
Table 2：Dimensions
| Wall thicn-esss | Nominal dim-ension | 0.5 | 0.8 | 1 | 1.2 | 1.5 | 1.8 | 2 | 2.2 | 2.5 | 2.8 | 3 | 4.5 | 5 | 5.5 | 6 | 7 | 8 | 9 | 10 | 12 | 14 | 16 | 18 | 20 | 22 | 25 |
| Permissible deviation | |||||||||||||||||||||||||||
| Outside diameter da | |||||||||||||||||||||||||||
| Nominal dimension | Permissible deviation | ||||||||||||||||||||||||||
| 4 | ±0.1 |
|
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| 5 | |||||||||||||||||||||||||||
| 6 | |||||||||||||||||||||||||||
| 7 | |||||||||||||||||||||||||||
| 8 | |||||||||||||||||||||||||||
| 9 | |||||||||||||||||||||||||||
| 10 | |||||||||||||||||||||||||||
| 12 | ±0.08 | ||||||||||||||||||||||||||
| 14 | |||||||||||||||||||||||||||
| 15 | |||||||||||||||||||||||||||
| 16 | |||||||||||||||||||||||||||
| 18 | |||||||||||||||||||||||||||
| 20 | |||||||||||||||||||||||||||
| 22 | |||||||||||||||||||||||||||
| 25 | |||||||||||||||||||||||||||
| 26 | |||||||||||||||||||||||||||
| 28 | |||||||||||||||||||||||||||
| 30 | |||||||||||||||||||||||||||
| 32 | ±0.15 | ||||||||||||||||||||||||||
| 35 | |||||||||||||||||||||||||||
| 38 | |||||||||||||||||||||||||||
| 40 | |||||||||||||||||||||||||||
| 42 | ±0.20 | ||||||||||||||||||||||||||
| 45 | |||||||||||||||||||||||||||
| 48 | |||||||||||||||||||||||||||
| 50 | |||||||||||||||||||||||||||
| 55 | ±0.25 | ||||||||||||||||||||||||||
| 60 | |||||||||||||||||||||||||||
| 65 | ±0.30 | ||||||||||||||||||||||||||
| 70 | |||||||||||||||||||||||||||
| 75 | ±0.35 | ||||||||||||||||||||||||||
| 80 | |||||||||||||||||||||||||||
| 85 | ±0.40 | ||||||||||||||||||||||||||
| 90 | |||||||||||||||||||||||||||
| 95 | ±0.45 | ||||||||||||||||||||||||||
| 100 | |||||||||||||||||||||||||||
| 110 | ±0.50 | ||||||||||||||||||||||||||
| 120 | |||||||||||||||||||||||||||
| 130 | ±0.70 | ||||||||||||||||||||||||||
| 140 | |||||||||||||||||||||||||||
| 150 | ±0.80 | ||||||||||||||||||||||||||
| 160 | |||||||||||||||||||||||||||
| 170 | ±0.90 | ||||||||||||||||||||||||||
| 180 | |||||||||||||||||||||||||||
| 190 | ±1.0 | ||||||||||||||||||||||||||
| 200 | |||||||||||||||||||||||||||
| 220 | ±1.20 | ||||||||||||||||||||||||||
| 240 | |||||||||||||||||||||||||||
| 260 | ±1.30 | ||||||||||||||||||||||||||
|
|
s/D
=1/60 |
s/D
=1/40 |
s/D
=1/20 |
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The limit deviations tor diameters given in table 2 allow for ovality and apply for the cold finished (hard) (BK) and cold finished (soft) (BKW) conditions.
For heat treated tubes, l.e. cold finished and stress-relief annealed (BKS). annealed (GBK) or normalized (N8K) tubes, the limit deviations for the diameter increase as a function of the wall thickness/diameter ratio (see table 1).
The dimensions given in table 1 also apply to the inside diameter of steel tubes.
In the case of intermediate sizes, the deviations for the next largest size shall apply.
The limit devations for wall thickness shall be ±10% of the nominal size and include the concentricity tolerance, which is calculated as a percentage using the following formula:
Tmax -Tmin
—————— * 100
Tmax+Tmin
where
Tmax is the largest wall thickness measured of a tube cross section’.
Tmin the smallest wall thickness measured of a tube cross section
Tubes are generally ordered In terms of outside diameter and inside diameter.
Where the wail thickness is of significance, the tubes may also be ordered in terms of outside diameter and wall thickness or inside diameter and wall thickness. In this case, the limit deviations specified here refer only to two of three possible parameters, the deviations for the third being subject to agreement. Such tubes shall be ordered in quality grade C
Steel grades and chemical composition of DIN 2391 Seamless Precision Steel Tubes
Table 3. Steel grades and chemical composition of the steels (ladle analysis)
| Steel grade | Chemical composition, % | |||||
|
Symbol |
Material number |
C max |
Si max |
Mn |
P max |
S max |
| St 30 Si | 1.0211 | 0.10 | 0.30 | ≤ 0.55 | 0.040 | 0.040 |
| St 30 Al 9) | 1.0212 | 0.20 | 0.05 | ≤ 0.55 | 0.040 | 0.040 |
| St 35 | 1.0308 | 0.17 | 0.35 | ≥ 0.40 | 0.050 | 0.050 |
| St 45 | 1.0408 | 0.21 2) | 0.35 | ≥ 0.40 | 0.050 | 0.050 |
| St 52 | 1.0580 | 0.22 | 0.55 | ≤ 1.60 | 0.050 | 0.050 |
|
1) This steel is deoxidized using aluminum. 2) In subsequent testing on the individual tube, the C-content must not exceed 0.25%. |
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Mechanical properties of DIN 2391 Seamless Precision Steel Tubes
Table 4. Mechanical properties
| Grade | Material number | Tensile Test MPa or N/mm2 |
Remaks (Similar to JIS) |
|
| Min Yield point | Tensile Strength | |||
|
St30Si
|
1.0211
|
-
|
400Min
|
(STKM11)
|
|
-
|
355Min
|
|||
|
-
|
285Min
|
|||
|
215
|
295~420
|
|||
|
St30Al
|
1.0212
|
-
|
400Min
|
(STKM11)
|
|
-
|
355Min
|
|||
|
-
|
285Min
|
|||
|
215
|
295~420
|
|||
|
St35
|
1.0308
|
-
|
440Min
|
(STC38)
|
|
-
|
370Min
|
|||
|
-
|
315Min
|
|||
|
235
|
340~470
|
|||
|
St45
|
1.0408
|
-
|
540Min
|
(STKM13)
|
|
-
|
470Min
|
|||
|
-
|
390Min
|
|||
|
255
|
440~570
|
|||
|
St52
|
1.0580
|
-
|
590Min
|
(STKM19)
|
|
-
|
540Min
|
|||
|
-
|
490Min
|
|||
|
350
|
490~630
|
|||
Designation
Designation of a seamless precision steel tube, made of St 35 steel, with an outside diameter, D, of 100 mm and an inside diameter. D, of 94 mm (ID 94), normalized (NBK):
Tube DIN 2391 - St 35 NBK 100 x ID 94
Designation of seamless precision steel tube, made of St 35 steel, with an outside diameter. D, of 100 mm and a wall thickness. T, of 3 mm, normalized (NBK):
Tube DIN 2391 - St 35 NBK 100 x 3
Designation of seamless precision steel tube, made of St 35 steel, with an inside diameter, D,, of 94 mm (ID 94) and a wall thickness, T, of 3 mm, normalized (NBK):
Tube DIN 2391 - St 35 NBK ID 94 x 3
Designation of seamless precision steel tube, made of St 35.8 steel, quality grade C, with an outside diameter. D, of 25 mm and a wait thickness. T, of 1.5 mm, normalized (NBK), complying with the technical delivery conditions specified in
DIN 17175:
Tube DIN 2391 - C-25 x 1,5- DIN 17175 - St 35.8
Standards referred to
DIN 2391 Part 2 Seamless precision steel tubes; technical delivery conditions
DIN 17175 Seamless tubes with elevated temperature properties; technical delivery conditions
Previous editions
DIN 2385:1993-12 ； DIN 2385-1 ： 1940-06. 1943-12, 1957-07; DIN 2391 ： 1932-04 ； DIN 2391-1:1940-06. 1957-11,1981-07.
Amendments
In comparisoa with the July 1981 edition, this standard has b««n restructured and the following amendments made:
a) The limtt deviations (or wall thickness have been amended (±10%). They now include the tolerance on concentricity.
b) The specified limit deviations only refer to two of three possible parameters, limit deviations for the third parameter
being subject to agreement (cf. clause 2 ).
c) In table 2, limit deviations of ± 0.08 mm for the outside diameter have been specified for sizos up to 30 mm, the limit
deviations for the inside diameter havin 〇 be«n reduced for smaller nomnal sizes.
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