High-Frequency Welded Pipe Mill — HF Welding Machine Line

This range is about the welding step itself: what high-frequency induction welding does to the strip edges, what the welder has to be matched to, and what that means when you are choosing a mill. It is the process behind the twelve model steps.

That single fact settles several things at once. There is no welding wire on this line and no consumable electrode; the consumables that matter are the impeder and the induction coil, which shape where the current goes.

High-Frequency Welded Pipe Mill — Range, Configuration and Output

The whole HFW series uses this process, across all twelve steps from HG32 to HG630.

Three units around the weld box decide the result:

The impeder and induction coil concentrate the current at the seam. As they wear, weld energy spreads, seam quality drifts and energy consumption rises — which is why they are treated as wear parts with continuous supply rather than as fixed parts.

The forming section ahead of the weld box sets whether the edges arrive aligned at all. If the forming passes or roll gaps are set wrong, the open seam is uneven, the pipe shape is off, and the weld goes off-centre no matter what the welder is doing.

The welder supplies the energy and therefore decides fusion quality and welding speed. Power is matched to the pipe range. If power or frequency is unstable the seam shows lack of fusion, cold welds or burn-through, and the pipe fails pressure and inspection testing.

Key Parameters: Size Range, Wall Thickness, Line Speed and Welder Power Band

• Process: high-frequency induction welding across the whole series.
• Welder type: solid-state or thyristor.
• Power band: 150 kW to 1500 kW, matched by pipe range.
• The two endpoints: HG32 = 150 kW and HG630 = 1500 kW.

Wall thickness across the series is 0.5–16 mm; per-step windows are available on request.

Forming on these lines uses the W, FFX and FF forming methods. The roll pass is designed in the German COPRA roll-forming design software, which serves both as the design guide for the roll means and as the final verification before the rolls are cut.

Where a real decision remains is automation and inspection. Automation is a grade of the same series — semi-automatic or full PLC — not a different mill. In-line NDT is not: ultrasonic and eddy-current inspection belong to the API line, which adds intermediate annealing, straightening, end facing and hydrostatic testing on top of the tube mill.

The welder arrives as part of the line, matched to the step, with impeders and induction coils available as ongoing supply. Cooling water or emulsion is a process medium: we give the specification, the plant sources it locally.

Where responsibility sits is explicitly. Weld fusion quality is on the equipment side through power matching, seam alignment and squeeze control; strip quality and operating practice are on the buyer’s side. Impeder and coil service lives are available on request.

Misadjusted forming passes or roll gaps leave the open seam uneven, so the pipe shape is off and the weld goes off-centre before the welder is even involved. Mismatched power, welding speed or squeeze produces the same fusion defects from the process side rather than the equipment side.

That ordering matters when a plant is diagnosing: two of the four causes sit upstream of the weld box, so a seam problem is not automatically a welder problem.

What the strip brings with it

Incoming strip is the buyer’s responsibility, with the line offering levelling and incoming checks rather than correction of grade or flatness. The quality factors on the raw-material side are strip grade, thickness tolerance and shape.

Automation, and what it does and does not change

Automation is a grade of the same series — semi-automatic or full PLC — with the full-automatic tube mill sitting as the high-automation grade rather than as a different machine. What PLC and variable-frequency control change is repeatability: line speed and cut length stop being operator-dependent. What they do not change is the physics at the seam.

Power still has to match diameter, edges still have to arrive aligned, and squeeze still has to be right.

Who asks about the welder specifically

The profile that asks about welding rather than about the mill is the auto-parts and new-energy manufacturer, judging on dimensional accuracy, stability and technical response time. The concern behind the question is standards compliance — whether the equipment reaches the standard an order is gated on.

Certification, and what each certificate actually covers

ISO 9001 is held under certificate number 18524Q11269R2S, issued by National Standard Integration (Beijing) Certification Co., Ltd. under IAF MLA and CNAS accreditation.

CE certificates are held from UDEM under three separate numbers, and each covers a different line type: welded pipe equipment under M.2022.206.C72171, cold roll forming equipment under M.2022.206.C72172, and slitting lines under M.2022.206.C72173. A fourth CE certificate for cold forming is held from Ente Certificazione Macchine in Italy under 0P250616.HTWTT37.

Each number can be checked at the issuing body rather than taken on trust, which is why we publish numbers and verification routes instead of certificate images.

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An enterprise standard, Q/GYLTT01-2023 for HGF150 high-frequency welded pipe equipment, is published on the national enterprise-standard platform. High-Tech Enterprise certificate GR202413001148 is held. The Madrid international trademark for TENGTIAN is registered under number 1 707 606. The patent portfolio is 30 granted utility model patents, with 7 invention patents applied for.

Delivery, payment and after-sales

Lines are dismantled into units and shipped in containers: heavy frames braced bare on cradles with designated lifting points and rust protection, precision and wear items in moisture-protected wooden cases with a spare-parts pack. Delivery takes 50 to 90 days.

Installation and commissioning are part of the supply rather than a separate quotation, backed by on-site dispatch and round-the-clock online support. There is a single point of contact, with a response time of under one hour. Payment is staged — 30 per cent deposit, 70 per cent before shipment — with third-party escrow and multiple trade terms available.

Anonymised reference deliveries

Our lines are running in more than a dozen countries — mostly on construction tube, and also on fire-extinguisher tube, furniture tube and other sections. Delivery cards show region and model or size; commissioning dates are available on request.

The five operating steps where the welder is involved

The line has five operating steps, and three of them touch the weld directly.

Loading and threading: the coil car feeds, the uncoiler tensions, and the operator guides the strip head through levelling into the mill. Training is required. Shear-weld coil joining: before a coil runs out, head and tail are cut and joined, coordinated with the accumulator so the mill does not stop.

Training required, because the failure mode is a broken strip and scrap at the joint. Setting specification and changing tooling: set to the target diameter — a conventional line changes rolls, direct forming adjusts servos without changing rolls. Training required for the tooling-change crew, because the failure mode is shape drift and scrap while setting up.

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Setting and running weld parameters: set welder power and welding speed, start the continuous forming, welding and sizing sequence and monitor it. Professional operating and process training as required, because the failure modes are lack of fusion, burn-through and dimensional drift.

Cutting and collecting: the flying saw cuts to the set length and the run-out table collects. Routine operation.

Post-weld cooling, and why it belongs here

Post-weld cooling is its own quality factor: it stabilises the seam structure and has to be matched to welding speed. When it is not, the outcome is poor seam structure and distortion. The cooling medium — water or emulsion — is a process medium: we give the specification, the plant sources it locally.

That pairing is worth spelling out because it is where a plant most often looks last: a seam problem that survives power and alignment checks is often a cooling-versus-speed mismatch rather than a welder fault.

What the API line adds, and what it does not change

The API configuration adds medium-frequency annealing, straightening, end facing, hydrostatic testing, ultrasonic and eddy-current inspection on top of the tube mill. What it does not change is the welding process itself — it is the same high-frequency weld, with post-weld treatment and inspection added around it.

What to send when you enquire about the welder

The step, the wall thickness, the steel grade and the welding speed you expect to run. Power is matched to the pipe range, but power, frequency and welding speed together are what set fusion, so a power number on its own does not answer the question.

Export packing is specified per item — control cabinets, impeders and induction coils, rolls and cutting tools in moisture-protected wooden cases with a spare-parts pack; heavy frames braced bare on cradles with designated lifting points and rust protection.