What is a HFW steel pipe?

High frequency welded pipe is based on solid resistance heat energy. Resistor thermal welding, using high-frequency current is generated in the workpiece so that the surface of the workpiece weld zone is heated to the melting or close to the plastic state, then applied (or not applied) upsetting force is achieved for such a steel pipe of the metal combination. HFW steel pipe production rate, welding speed of up to 30m/min. It is mainly used for the manufacture of pipes welded longitudinal seam or spiral seam. The welded pipe used high-frequency welding process of welding is mainly used for water, oil, natural gas, such as pressurized fluid delivery.

What is DSAW steel pipe?

DSAW steel pipe can be specified in very large diameter and to exact inside or outside dimensions.
Double Submerged Arc Welded (DSAW) steel pipe is available in straight and spiral welded formats and used in a variety of applications. The submerged welding process protects the steel from contamination of impurities in the air. Both inside and outside welds are performed.

Difference between HFW and DSAW

The difference between DSAW and HFW is mainly manifested in the appearance of the weld appearance, Double submerged arc welding steel pipe in appearance is with a slight indentation strip, mainly in steel interior. Straight seam submerged arc weld pipe is higher than the base material for the neat 1-3mm weld. In appearance frequency steel tube smooth, non-oxide adhesion. In the weld, high-frequency straight seam steel pipe weld high measure to squeeze flow resistance, the jagged serrate irregular weld, this weld is "scratch" before they go out, leaving a flat weld removal of trace.

In addition, two-sided submerged arc welding and high frequency difference is also reflected in the production process, the use of different raw materials, different molding process, the welding process is different from different production units, production of different scope. Sided submerged arc welding straight seam steel production process only with JCOE molding process molding process complex, forming efficiency relative to the low-frequency welded pipe, so the manufacturing cost is higher than the high-frequency straight seam welded steel pipe. High-frequency straight seam welded steel pipe (ERW) production process is simple, a single specification. Double-sided submerged arc straight seam steel pipe forming process is JCOE cold forming, features that make the steel at 50mm gradually forming, J, C, O, E represents the image of straight seam steel submerged arc forming process. Frequency straight seam steel pipe forming process for the multi-pass rolls, squeeze both ends of the strip, and finally justified the strip cold molding process, the molding process is characterized by uninterrupted, continuous welding. Submerged arc welding process is characterized by using steel wire electric effect and melt together, as filler welding. Frequency straight seam steel pipe welding process is characterized by the use of high frequency current skin effect rapid warming strip ends in a short time under the action of external forces strip from melting together.

Frequency straight pipe production unit for the same lines of uninterrupted production line efficiency, and submerged arc welding straight seam steel pipe has up to 15 intermittent production processes complete unit. Frequency straight seam steel pipe production specifications fewer production thinner.