Three-Layer Coating of Steel Tubes
Technical Data
Steel tubes coated with three-layers of plastic insulation are specified particularly for gas and liquid distribution. In the gas industry, they are used for natural gas distribution up to an operating pressure of 6,3 Mpa, and for propane-butane gas distribution. In addition, they can be broadly used in the furniture, engineering and building industries.
Coated pipe dimensions
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inside diameter
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steel tube
outer diameter
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|
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Inches
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mm
|
|
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3/4"
|
20
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27,0
|
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1"
|
25
|
33,7
|
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1 1/4"
|
32
|
42,4
|
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1 1/2"
|
40
|
48,3
|
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2"
|
50
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60,3
|
|
2 1/2"
|
65
|
76,1
|
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3"
|
80
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89,0
|
|
4"
|
100
|
108
|
|
4"
|
100
|
114
|
|
5"
|
125
|
133
|
The composition of the three-layer coating
- epoxy-based primer
- plastic-copolymer-based adhesive
- polyethylene used in the production of the coating (BRALEN, LITEN or BOREALIS)
The testing of the tube´s polyethylene coating is conducted by
Checking with a maximum voltage of 25 kV - 100 % of the surface. The quality of the three-layer coating is ensured to meet the requirements of all standard testing philosophies (DIN 30 670 and Czech testing methods).
The surface appearance and coating thickness
The surface of the polyethylene coating is smooth, and the holes and scratches do not exceed the permissible critical tolerance of the coating thickness.
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Permissible critical tolerances of the coating thickness:
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|
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PE coating thickness
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critical tolerance
|
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1 mm
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0,15 mm
|
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1,5 mm
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0,2 mm
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2 mm
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0,3 mm
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The basic colour of the polyethylene coating is black; other colours are also possible by request. The coating of tubes for the gas industry is black, and yellow or grey is specified for protectors.
The finishing of the tube endings
a) the polyethylene coating is removed to within 150 mm of the end, the approach angle of the PE coating is 30o; the steel tube end is then coated with temporary protection coating.
b) untreated tube ends where the plastic coating can exceed the tube end by 15 mm or it can be left without coating up to 30 mm from the tube end..
Tube markings
Each tube is marked with a yellow description with the characteristic height, according to the appropriate standard.
Example of marking:
SIGNUM EN 10208-1 L360 GA W 80 3LPE DIN 30670-N-v A1 12/02 00001
SIGNUM - Manufacturer
EN 10208-1 - Standard No.
L360 GA - Steel mark
W - Tube type
80 - Tube dimension in mm
3LPE DIN 30670-N-v - Coating standard and insulation type, meets standard requirements
A1 - Inspection authority identification
12/02 - Production month
00001 - Tube serial number
Tube packing
Tubes are supplied in bundles up to 3000 kg in weight, and tied with a cyklotape with a fabric wrapping against tube surface damage. On request, it is possible to supply tubes in layers on profiled wooden crossers, which make the handling of stocks easier.
Prior to dispatch, each bundle of tubes is marked with labels with the following information:
- dimension
- tube material quality
- coating type
- number of tubes
- number of meters
- weight in kg
- tube length
- bundle No.
- order No.
- checkout
- buyer
- production date
Each completed production comes with a certificate containing details of the results of tests and inspectionse.
