DIN 30670 Fusion Bonded Epoxy Coated Steel Pipe With Guaranteed Coating Properties

Product Name :DIN30670, DIN30671, Polyethylene coating Steel Pipe ,Fitting and Flanges Guaranteed coating properties DIN 30 670 - N 

Polyethylene coating  ø 159 - 820 mm

The installed line makes possible to coat pipes in the O.D. range 159 - 820 mm with the three-layer coating pursuant to the DIN 30 670 Standard in normal design (maximum operating temperature 50°C)
or in special design (operating temperature 80/90°C, increased surface hardness). Thus, it covers the entire assortment of the spiral welded pipes, part of the seamless tube assortment, and leaves the space for coating of pipes, supplied by other manufacturers

Grit-blasting machine

The grit blasting takes a course in the mechanical grit-blasting machine, equipped with two throwing wheels, operating with metal crushed material. The surface quality after grit-blasting corresponds to the SA 21/2 degree according to ISO 8501-1.

Induction heating

The mid-frequency induction heating has 750 kW output, which is sufficient for heating of 10 t of pipes per hour. By passing the pipe through the inducting coil, it is heated to the application temperature,
which is usually the temperature between 170 and 200 °C. The pipe temperature is continually measured by the infra-red sensor, and displayed on the control desk.

Pipe pre-heating

The whole line starts with the intake bed, from which the tubes are conveyed to the grit-blasting machine. Before the blasting itself, the tubes are heated by the natural gas burners to the temperature of 50-80 °C, that is sufficiently above the dew point temperature.

Visual inspection

After the grit blasting, the pipes undergo the visual inspection, during which possible surface defects are removed by grinding. The surface roughness is measured

Epoxy coating

The pipe enters the spraying booth, where the powdered epoxy is sprayed in the electrostatic field with 60 - 100 μm thickness, which melts down immediately, and cures during 30 - 60 seconds, whereby
a high adherence to the steel surface is reached. 

Polyethylene application

Directly behind the spraying booth, there follows the application of the second layer - the so-called adhesive intermediate layer. This is the question of 250 μm thick adhesive layer, the function of which is
to create the chemical bond between the epoxy and upper polyethylene layer. Coating itself is done by forcing-out the adhesive substance through the extruder flat nozzle into the thin strip, which is wrapped
on the tube in semi-liquid condition.

Coating thickness measuring

Further, the coating thickness measuring is performed on the whole pipe length and surface, at 12 points at least. At the spiral-welded pipe, there are performed the additional 4 insulation measurements above the weld. The measurement is performed by the magnetic or ultrasonic apparatus. The Table shows the required values according to DIN 30 670 Standard.

Types and Features of Corrosion-resistant Steel Pipe