Execution standards

STAS 7656 Longitudinally welded steel tubes for water, gas and steam installation
Dimensions and linear weights According to STAS 7656, see table 4.1
Steel OL 32, OL 34, OL 37

DIN 1626 Welded circular tubes of non-alloy steel with special quality requirements
Dimensions and linear weights According to DIN 2458
Steel St 37.0

DIN 2440 Medium weight steel tubes suitable for threading
Dimensions and linear weights According to DIN 2458
Steel St 37.2

DIN 2441 Heavy weight steel tubes suitable for threading
Dimensions and linear weights Conform DIN 2458
Steel St 37.2

ISO 65 Carbon steel tubes suitable for threading according to ISO 7/1
Dimensions and linear weights According to ISO 65
Steel TW.0

BS 1387/85 Steel tubes and tubular profiles with threads and couplings and with plain edns, suitable for welding and screwing
Dimensions and linear weights According to BS 1387/85
Steel Non-alloy steel for general purpose with the tensile strenght between 320 si 460 N/mm2

GOST 10704 Electrically welded steel line - weld tubes
Dimensions and linear weights According to GOST 10704
Steel St 1, St 2, St 3, 10

GOST 10705 Electrically welded steel line - weld tubes
Dimensions and linear weights According to GOST 10705
Steel St 1, St 2, St 3, 10

DIN 2444 Hot dipping galvanized tubes
UNI 5745 Hot dipping galvanized tubes
ASTM A 53 Hot dipping galvanized tubes

Note: By agreement between parties, tubes of other typified steel grades can be manufactured, with the maximum tensile strenght of 490 N/mm2.

QUALITY TECHNICAL CONDITIONS ACCORDING TO STAS 7656

1. Pipe category
M medium series
G heavy series
U light series

2. Dimensions and linear weights according to STAS 7656 (Tabel 4.1)

Nominal diameter
Outside diameter
Light series
mm
Symbol
Calculation (mm)
max. (mm)
min. (mm)
Wall thickness (mm)
Linear weight (kg/ml)
Black tube
Galvanized tube
15
1/2
21,3
21,7
21,0
2,3
1,08
1,15
20
3/4
26,9
27,1
26,4
2,3
1,39
1,49
25
1
33,7
34,0
33,2
2,9
2,20
2,32
32
1 1/4
42,4
42,7
41,9
2,9
2,82
2,97
40
1 1/2
48,3
48,6
47,8
2,9
3,24
3,42
50
2
60,3
60,7
59,6
3,2
4,49
4,72
65
2 1/2
76,1
76,3
75,2
3,2
5,73
6,02
80
3
88,9
89,4
87,9
3,6
7,55
7,89
100
4
114,3
114,9
113,0
4,0
10,8
11,30
Nominal diameter
Outside diameter
Medium series
mm
Symbol
Calculation (mm)
max. (mm)
min. (mm)
Wall thickness (mm)
Linear weight (kg/ml)
Black tube
Galvanized tube
15
1/2
21,3
21,8
21,0
2,6
1,21
1,27
20
3/4
26,9
27,3
26,5
2,6
1,56
1,65
25
1
33,7
34,2
33,3
3,2
2,41
2,53
32
1 1/4
42,4
42,9
42,0
3,2
3,10
3,24
40
1 1/2
48,3
48,8
47,9
3,2
3,56
3,73
50
2
60,3
60,8
59,7
3,6
5,03
5,24
65
2 1/2
76,1
76,6
75,3
3,6
6,42
6,71
80
3
88,9
89,5
88,0
4,0
8,36
8,70
100
4
114,3
115,0
113,1
4,5
12,2
12,60
Nominal diameter
Outside diameter
Heavy series
mm
Symbol
Calculation (mm)
max. (mm)
min. (mm)
Wall thickness (mm)
Linear weight (kg/ml)
Black tube
Galvanized tube
15
1/2
21,3
21,8
21,0
3,2
1,44
1,50
20
3/4
26,9
27,3
26,5
3,2
1,87
1,96
25
1
33,7
34,2
33,3
4,0
2,93
3,05
32
1 1/4
42,4
42,9
42,0
4,0
3,79
3,94
40
1 1/2
48,3
48,8
47,9
4,0
4,37
4,54
50
2
60,3
60,8
59,7
4,5
6,19
6,40
65
2 1/2
76,1
76,6
75,3
4,5
7,93
8,22
80
3
88,9
89,5
88,0
---
---
---
100
4
114,3
115,0
113,1
---
---
---

3. Tolerances

3.1 Permissible variantions in outside diameter According to table 4.1
3.2 Permissible variantions in wall thickness
+/- 12,5%
In isolated places and on lenghts not exceeding twice the outside diameter deviations of - 15% are allowed.
3.3 Permissible variantions in weight on each pipe +/- 10%
per waggonable lot of min. 10mt weight +/- 7,5%

4. Lenghts

- random lenghts
4 - 6 m
- fixed lenghts within the manufacture lenghts of 6000 +/- 100 mm

5. Chemical requirements - %

Steel grade Quality class Composition, %, max. Disoxidation degree
C
Mn
P
S
OL 32
1, 1a, 1b
0,15
0,60
0,055
0,055
---
OL 34
1, 1a, 1b
0,17
0,60
0,055
0,055
---
OL 37
1, 1a, 1b
0,25
0,85
0,065
0,065
---
2
0,22
0,85
0,055
0,055
---

6. Mechanical requirements

Steel grade
Quality class
Yield limit Rp 0,2, N/mm2, (Kgf/mm2)
Tensile strenght Rm, N/mm2, min. (kgf/mm2)
Elongation, min %
OL 32
1, 1a, 1b
180 (18)
310...390 (32...40)
33
OL 34
1, 1a, 1b
210 (21)
330...410 (34...42)
31
OL 37
1, 1a, 1b
240 (24)
360...440 (37...45)
25
2
240 (24)
360...440 (37...45)
25

7. Hydrostatic test pressure (bar)

- max 50 bar or eddy currents check according to SEP 1925

8. Other quality checks

- bend testing (at customer's choice);
- flattening test (at customer's choice);
- electromagnetic testing;
- checking of chemical analysis on pipe (at customer's choice).

DELIVERY, MARKING, PACKING, DOCUMENTS

- the pipes are delivered unprotected or hot-dipping galvanized;
- the pipes are delivered with bevelled unthread ends and not internally debbured, in bundles with fixed number of pieces, packed in hexagonal shape, tied in minimum five places with steel strips;
- a tag will be attached to each bundle;
- each lot of pipes will be accompanied by the mill test certificate according to EN 10204/DIN 50049;
- the delivery will be made by railway, truck or ship.

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