The manufacturing process for steel tubes consists of the following stages:

Α. Quality control and treatment of raw material
The raw material (steel strip) is submitted to quality controls before it enters the manufacturing process. Next, the steel strip is slit to the required width so as to enable tube making and welding in accordance with the stringent production specifications of the factory. The steel strip is submitted to further quality controls on the production line.

Β. Tube making
The steel strip is formed into a tube with the use of suitable forming rolls until the two edges of the strip are in contact. The process of tube making takes place at ambient temperature.

C. Welding
The next stage of manufacturing involves the welding of the strip edges that are in contact. Welding is achieved as the two edges are heated up to the ideal temperature to ensure proper welding of steel with the use of high frequency currents. Welding is performed autogenously (High Frequency Electric Resistance Welding, HF ERW) by compression and without the use of an electrode.

Compression of the appropriately heated edges of the steel strip results in the autogenous welding of the edges. A mixture of the heated steel, together with the oxides that arise from the heating of the edges, is driven outside the welding zone, which remains free of inclusions. The mixture is cooled to ambient temperature and forms the welding bead.

The external welding bead is removed with the use of suitable cutting equipment.

D. Removal of the internal welding bead
In the case of SD TUBE IBS - TUBO TYPE steel tubes, the internal welding bead is removed with the use of special equipment. The internal welding bead is not removed from SIDENOR IBS steel tubes.

Ε. Welding inspection
Welding is submitted to continuous inspections with the non-destructive quality control method of Eddy Current Testing.

F. Hot rolling
At the next stage of manufacturing, the steel strip is heated to 850^οC – 1,100^οC and is fully normalized.

G. Other stages
The final stage of steel tube manufacturing is hot-dip galvanization or surface dying, edge treatment and finished product quality control.

Advantages of the manufacturing process used for SD TUBE IBS - TUBO TYPE & SIDENOR IBS steel tubes

1. During the stage of autogenous welding, the crystal lattice and subsequently the mechanical behaviour of steel at the welding spot (heat-affected zone) differ from those of the rest of the tube. To achieve a uniform crystal structure, the tube after shaping is submitted to full normalizing at 850^οC - 1,100^οC. Additional heat treatment offers a high level of safety, as it strengthens the area of longitudinal welding.

2. Moreover, during the stage of gradual tube making at ambient temperature, unevenly distributed residual stresses set up into the tube, making it less workable and safe. Full normalizing of steel at  850^οC - 1,100^οC offers optimal ductility, resilience, workability and fire-resistance.

Removal of the internal welding bead from SD TUBE IBS - TUBO TYPE steel tubes

The removal of the internal welding bead from SD TUBE IBS – TYBO TYPE steel tubes enables a more regular flow in the tube with lower pressure drop during the design of heat and fluid flow systems compared to common steel tubes. Moreover, the removal of the internal welding bead provides a high level of protection against potential corrosion that may begin from the welded area, due to inclusions or overlaying water residues.

CHARACTERISTICS, DIMENSIONS & WEIGHTS

SD TUBE IBS - TUBO TYPE & SIDENOR IBS steel tubes are available as follows:

• Hot-dip galvanized in accordance with ELOT Standard ΕΝ 10240
• Black
• Self-coloured

 In addition, with regard to tube ends, the following steel tubes are available:

• With threaded ends and one couple
• With grooved ends (only for SD TUBE ΙΒS - TUBO TYPE Steel Tubes)
• With thread without couple or with free ends, upon request

Steel tubes with grooved ends are used in fire extinguishing systems as well as in other systems with fast connection fittings. Ribbed SD TUBE IBS - TUBO TYPE steel tubes enable faster connection. At the same time, there is less wastage, because due to factory grooving, there is no need to groove the tubes at the construction site, which may result in the galvanisation breaking, and the tube being rejected. In any case, with the use of grooved SD TUBE IBS - TUBO TYPE steel tubes, the total cost of fitting is reduced by up to 30% due to savings and by up to 10% due to lower rejection rates.

C - Carbon, P - Phosphorus, S - Sulphur, Mn - Manganese

* In these dimensions, pipes are available either black-painted or self-coloured. They are produced with plain ends or can be ordered with grooves.

MARKING

 

Tensile Test

Bending Test

Compression Test

Continuous Welding Test

 

QUALITY CERTIFICATES

 

Certificate ISO 9002:2000
Certificate 2.1 according to ELOT EN 10204
Other certificates can be provided, according to customer's request
Guarantee of good opertaion for 25 years for pipes SD TUBE ΙΒΣ - TUBO TYPE