Tube & Pipe Welding Induction Heating

Induction Heating for Tube & Pipe Manufacturing

SMC impeders for energy-efficient, high-speed HF tube and pipe welding.

Tube and pipe mills use high-frequency induction to heat the strip edges before pressure rolls forge the seam. An impeder inside the tube steers current to the seam. Fluxtrol soft magnetic composite impeders offer higher saturation flux density than ferrite, which suits small, thick-walled tubing and demanding mills.

Tube and pipe manufacturing is where Fluxtrol’s soft magnetic composites have the most published production evidence. In high-frequency induction welding, a flat strip is formed into a tube, an induction coil heats the edges, and rolls press them together to form a longitudinal weld seam. Induction heats directly in the metal, giving localized heat at high line speeds.

The impeder problem

If too much induced current runs along the tube’s inside diameter instead of the seam edges, energy is wasted and weld quality can suffer. The impeder, a magnetic core inside the tube near the coil, steers that current. Traditional impeders are ferrite. Ferrite struggles with small diameters and thick walls, where it can saturate, and it wears out quickly.

What SMC impeders add

Fluxtrol SMCs have higher saturation flux density than ferrite. Published benefits include reduced energy use, higher production speeds, longer impeder life, fewer replacements and less unintended heating of machine components. The trade-off is that SMC losses are higher, so good water cooling is required, and the cores cost more per unit. Fluxtrol’s cooling research addresses this directly.

Mill results

At the same line speed, Prinz & Co. Stahlrohre saw 40% energy savings and five times the impeder life with a Fluxtrol 10 impeder on 15 mm tubing. Sartid Fahop in Serbia reported 30-50% energy savings with Fluxtrol A on larger, thicker tube. These are individual mill results.

Research behind it

Simulation work showed upwards of 25% system power savings in modeled comparisons of SMC and ferrite impeders. Test-stand papers cover cooling requirements , impeder geometry and off-line validation .

Explore further

See the SMC impeder cores page and the tube and seam welding application. To evaluate an impeder for your mill, contact Fluxtrol .

Published tube mill results

Prinz & Co. Stahlrohre (Germany)

On 15 mm steel tubing at the same line speed, Fluxtrol 10 SMC impeders were compared with ferrite.

40% energy savings
5x greater impeder life
4-5x reduction in changeover time and scrap costs

Read the full study →

Sartid Fahop (Serbia)

On 21-27 mm OD steel tube with a 2.6 mm wall, Fluxtrol A impeders were tested against ferrite and local impeders.

30-50% energy savings across line speeds
About 5x longer impeder life

Read the full study →

Frequently asked questions

What does an impeder do in induction tube welding?

An impeder is a magnetic core placed inside the tube near the induction coil. It limits current flowing on the tube’s inside diameter and directs it toward the strip edges where the weld forms, so more of the power heats the seam and less is wasted.

Why use SMC impeders instead of ferrite?

Ferrite has a low saturation flux density and can saturate in small-diameter or thick-wall applications, which raises ID current and hurts weld quality. SMCs offer higher saturation flux density. They have higher losses than ferrite, so cooling must be designed carefully.

Where do SMC impeders fit best?

Fluxtrol identifies small diameter, heavy-walled steel tube; small-tube lines where the welder is the bottleneck and the impeder is saturated; lines where impeders break from mechanical impact; impeders with metallic components inside; and applications with very short impeder life.

What industries use induction seam welding?

Induction seam welding serves tube and pipe manufacturers supplying industries including automotive, construction, energy and HVAC, working in steel, stainless steel, aluminum and other conductive materials in high-volume production.