Electric Resistance/ Fusion Welded (ERW and EFW)

Petrosadid: Electric Resistance/ Fusion Welded (ERW and EFW)

Spiral welded pipe is an alternative process, spiral weld construction allows large diameter pipe to be produced from narrower plates or skelp. The defects that occur in spiral welded pipe are mainly those associated with the SAW weld, and are similar in nature to those for longitudinally welded SAW pipe.

Spiral welded steel pipes are widely used in Oil, Natural Gas, Water and other flammable & nonflammable liquid conveyance and distribution pipelines, steel structures for construction and other general purposes by means of their wide size range.

Widely preferred longer lengths up to 18,5 m. considerably decreases the cost of pipeline construction resulting in less number of girth welds compared to shorter pipe lengths.

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ERW

ERW steel pipe is manufactured through low or high frequency resistances Electric Resistance. Welding seam is in longitudinal. During the ERW pipe welding processes, the electric current will make the heat when flow through the contact surface of the welding area. It will heat the 2 edges of the steel to a point that the edges can form a bond. Meanwhile with the combined pressure, the edge of the pipe billet steel melted and extruded together.

ERW steel pipe used for transporting gas and liquid objects such as oil and gas, could meet the low and high pressure requirement. In recent years, with the development of ERW technology, more and more ERW steel pipe used in the oil and gas fields, automobile industry and so on.

Petrosadid: Electric Resistance/ Fusion Welded (ERW and EFW)

ERW pipe manufacturing process includes HFW. ERW have low, medium, high frequency welding processes, and HFW is especially for high-frequency electric resistance welding. The differences between ERW and HFW steel pipe, is EFW is a type of ERW process for ordinary and thin-wall thickness steel pipes.

HFW

High frequency welding (HFW) steel pipe is that ERW pipe produced with a welding current frequency equal to or greater than 70 kHZ. Through high-frequency current welding resistance, the heat generated in the contact objects, so the objected surface are heated to the plastic state, then with or without forging to achieve a combination of steels. HFW is a solid resistance heat energy. The high frequency current pass through the metal conductor, will produce two peculiar effects, skin effect and proximity effect. And HFW process is to use the skin effect to concentrated on steel object surface, use proximity effects to control the position and the power of the high-frequency electric current flow path. Since the speed is very high, the contacted plate edge could be heated and melted in shore time, then extruded through docking process.

Petrosadid: Electric Resistance/ Fusion Welded (ERW and EFW)

EFW

Electric Fusion Welding (EFW) steel pipe refers to an electron beam welding, the use of high-speed movement of the electron beam directed impact kinetic energy is converted to heat the workpiece so that the workpiece leaving the melt, the formation of the weld. It is mainly used for welding dissimilar steel welding sheet or which high power density, metal weldment can rapidly heated to high temperatures, which can melt any refractory metals and alloys. Deep penetration welding fast, heat-affected zone is extremely small, so small performance impact on the joints, the joint almost no distortion. But it has a requirement on a special welding room because welding using X-rays.

Petrosadid: Electric Resistance/ Fusion Welded (ERW and EFW)

Highlights of the ERW/ EFW Pipe

Materials

• ASTM A53 (Gr. A, B)

• API 5L Welded -Grades (B, X42, X46, X52, X56, X60, X65 and X70) PSL 1, PSL 2 (PSL2 shall be in HFW process)

• ASTM A252

• ASTM A134

• ASTM A135

• EN 10219 (S275, S355)

• A671 (CC60, CC65)

• A672 (CC60, CC65)

• ASTM A691

• API 5L Grades X80

• ASTM A312 (TP304/304L, TP316/316L, TP321, TP321H, TP347, TP347H)

• ASTM A790

• ASTM A358 (TP304/304L, TP316/316L, TP321, TP321H, TP347, TP347H)

• ASTM A928 (UNS S31803, UNS S32750, UNS S32760)

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