Short answer: how do you choose an ERW tube mill?
You can specify an ERW tube mill in ten steps: (1) maximum OD, maximum wall thickness and square/rectangular sizes decide the mill model; (2) OD and wall thickness decide the strip width; (3) coil weight and coil ID/OD decide the uncoiler; (4) thickness, material strength and strip shape decide whether you need a separate leveler and which shear & butt welder grade; (5) the spiral accumulator is chosen in this order: type, then diameter from the maximum strip thickness and material strength, then a check against strip width, and finally a check of storage and refill against line speed and coil-change time; (6) OD, wall thickness and line speed decide the HF welder; (7) accuracy, cut quality and budget decide the saw; (8) cut length and line speed decide the run-out table and bundling; (9) voltage, frequency and brand requirements decide motors and controls; (10) workshop size and cranes decide the layout and foundations.
The core rule: choose the smallest model that covers your maximum OD and maximum wall thickness. If your size range is wider than one model, plan two lines.
Before you start: write a product list
List every tube you plan to make: round tube OD × wall, square or rectangular size × wall, material grade and strength. Mark which sizes you will run every day and which are occasional sizes near the limits. The maximum OD, maximum wall thickness and maximum speed in a model table cannot all be reached at the same time, so checking each size on your list is far more reliable than comparing a few maximum values.
Step 1: tube sizes → mill model
Input: maximum round tube OD, maximum wall thickness, square and rectangular sizes and their wall thickness. Decision: the mill model. Choose the smallest model that covers your maximum OD and maximum wall thickness. The InGen MillTek YJ range goes up to YJ273. The large-diameter YJ219, YJ254 and YJ273 mills are designed and built to order: our engineers design each one for the tube sizes in that order, and the size range and configuration are set in the technical proposal, so they are not listed below. The six standard models, YJ32 to YJ165 (catalogue standard series), cover:
- YJ32: round Φ12.7–38.1 mm; square 10×10–30×30 mm; rectangular 12×8–40×20 mm; wall 0.4–2.0 mm
- YJ50: round Φ19.1–63.5 mm; square 15×15–50×50 mm; rectangular 20×10–60×40 mm; wall 0.6–3.0 mm
- YJ76: round Φ38.1–89 mm; square 30×30–70×70 mm; rectangular 40×20–80×60 mm; wall 0.8–3.5 mm
- YJ89: round Φ50–102 mm; square 40×40–80×80 mm; rectangular 50×30–90×70 mm; wall 1.0–4.0 mm
- YJ114: round Φ63.5–127 mm; square 50×50–100×100 mm; rectangular 60×40–120×80 mm; wall 1.5–5.0 mm
- YJ165: round Φ76–165 mm; square 60×60–130×130 mm; rectangular 70×50–150×110 mm; wall 1.5–6.0 mm
- Note: OD, wall thickness and speed are not combinations that can all be reached at once; the wall thickness limit for square and rectangular tube is usually lower than for round tube; the maximum line speed of each model is shown on its model page, and actual speed depends on pipe size and wall thickness; parameters vary with configuration and are confirmed in the technical proposal.
Step 1 examples: which model fits common requests?
These examples are read from the table above. The final choice is confirmed in the technical proposal.
- Square and rectangular tube from 20×20 to 60×40 mm: YJ50 covers square 15×15–50×50 mm and rectangular 20×10–60×40 mm. Also check that your thickest size is within the wall limit for square tube.
- Square tube from 20×20 to 60×60 mm: YJ50 square tube stops at 50×50, and YJ76 square tube starts at 30×30, so no single standard model covers the whole range. Plan two lines, or send the full size list for our engineers to review.
- Square and rectangular tube 40×40 and 40×80 mm: 40×80 is outside the YJ50 rectangular range and inside YJ76 (square 30×30–70×70 mm, rectangular 40×20–80×60 mm).
- Round pipe from 1/2 inch to 2 inch: 1/2-inch pipe is about 21 mm OD and 2-inch pipe about 60 mm OD, both within the YJ50 OD range. If the larger sizes need a wall over 3.0 mm, they are outside the YJ50 wall range, and the next model, YJ76, starts at Φ38.1 and cannot make 1/2-inch pipe. In that case you normally need two lines or a narrower size range.
- Round pipe from 1/2 inch to 4 inch: 4-inch pipe is about 114 mm OD, which is not in the same model range as 1/2-inch pipe, so this normally means two lines.
Step 2: OD and wall thickness → strip width
Input: OD (or square/rectangular side lengths) and wall thickness for each size. Decision: strip width. The widest strip sets the width class of the entry section (uncoiler, leveler, shear & butt welder and spiral accumulator). For a quick rough idea, convert from the outside perimeter of the tube (D = OD, in mm). This is a theoretical value only; the actual strip width is set by the roller design, is usually slightly less, and is confirmed by a trial run on the first coil of a new size.
- Round tube: B ≈ 3.14 × D. Examples: Φ76 → 76 × 3.14 ≈ 239 mm; Φ219 → 219 × 3.14 ≈ 688 mm.
- Square and rectangular tube: B ≈ sum of the four sides. Examples: 40×40 → 160 mm; 60×40 → 200 mm.
Step 3: coil weight and coil size → uncoiler
Input: coil weight, coil inside diameter (ID) and outside diameter (OD), strip width. Decision: uncoiler capacity and type.
A double-head uncoiler has two mandrels back to back: it turns 180°, and one side pays off while the other is loaded. It suits narrow-strip tube lines. A single-head uncoiler works with a hydraulic coil car and suits wider, heavier coils. The rated capacity is what the mandrel can carry; narrow strip often cannot reach the rated weight at a normal coil OD. Whichever limit is reached first, coil OD or coil weight, applies, so please state your actual coil weight. The standard coil ID is 508 mm; if your coils are 500 mm or 610 mm ID, tell us so the mandrel expansion range can be set.
Step 4: thickness, strength and strip shape → leveler and shear & butt welder
Input: maximum thickness, material grade with yield and tensile strength, and the shape of the incoming strip. Decision: whether to add a separate leveler, and the grade and size of the shear & butt welder. Each step up in thickness or strength usually means a stronger leveler and larger welder cylinders and clamps.
The tube mill has a set of non-driven flattening rolls at its entry, so a small mill running ordinary strip usually does not need a separate leveler. Our engineers assess this from the material strength, thickness and strip shape.
Shear & butt welders come in three grades. Integrated Shear & Manual Welder: hydraulic shear and clamps, with manual alignment and welding. Semi-automatic Shear & Welder: hydraulic shear and clamps, with a welding torch that travels automatically along a linear guide. Fully Automatic Shear & Welder: a PLC controls the whole cycle of shearing, aligning, clamping, welding and reset. Besides strip width, thickness and strength, consider how fast the joint must be made and how flat the weld must be. State the feed direction (left-hand or right-hand line) in the contract.
Step 5: strip thickness, line speed and coil-change time → spiral accumulator
Input: maximum strip width and thickness, material strength, mill line speed, and the time needed for one coil change and joint. Decision: accumulator type (horizontal or floor type) and diameter. The usual order is: choose the type, set the diameter from the thickest strip and the material strength (thicker strip needs a larger diameter, and high-strength steel usually one size larger again; grades of 980 MPa and above are assessed separately from ordinary high-strength steel), check the strip width, then check storage length and refill against line speed and coil-change time.
Size the storage by length, not by tons: storage length ≥ mill line speed × coil change and joining time × 1.2 to 1.5. Count the full cycle, from the moment the uncoiler stops feeding until strip feeding restarts (with a single-head uncoiler, loading the new coil falls inside this time). Example (assumed figures, only to show the method): at 80 m/min and a 5-minute coil change and joint, you need 400 m, or about 520 m with a safety factor of 1.3. Also check that the feeder runs fast enough above mill speed to refill the accumulator in time after each joint.
In general, narrower and thinner strip uses a horizontal spiral accumulator, while wider, thicker strip or larger storage calls for a floor type accumulator. The catalogue range is 2–6.5 m diameter for horizontal accumulators and 4–20 m for floor type. Our engineers choose the type and diameter from strip width, thickness, strength and storage length.
Step 6: OD, wall thickness and line speed → HF welder
Input: maximum OD, maximum wall thickness, target line speed and material. Decision: HF welder power class and configuration. Larger OD, thicker wall and higher speed all need more HF power. The HF welder is configured for each project, and its power is set size by size in the technical proposal.
Step 7: accuracy, cut quality and budget → saw
Input: cut length, length accuracy, cut-end and burr requirements, budget. Decision: hot friction flying saw or servo cold saw. A hot friction flying saw travels with the tube and cuts by friction; it suits general cut-length requirements. A servo cold saw cuts with a slow-turning blade for a flat cut with little burr and higher accuracy, but its speed depends on cut length, tube size and wall thickness. Typical cutting accuracy is about ±3 mm for a hot friction flying saw and about ±1.5–2 mm for a servo cold saw; the figure for your line is confirmed in the technical proposal. The two options are listed and quoted separately in the technical proposal so you can compare them.
Step 8: cut length and line speed → run-out table and bundling
Input: cut length, line speed and packing method. Decision: run-out table length and type, and whether to add stacking and bundling. The run-out table length depends on the cut length and line speed and is set on the project layout. Types include two-side tipping, push-off, kick-off, and a plain type used with a stacker. Stacking and bundling equipment can be configured per project.
Step 9: voltage, frequency and brand requirements → motors and controls
Input: local grid voltage and frequency, whether a neutral is available, PLC and electrical brand requirements, and the HMI language. Decision: motor and control specifications. In China the supply is 380 V/50 Hz; common export supplies are 415 V/50 Hz, 440 V/60 Hz, 460 V/60 Hz and 480 V/60 Hz. Power circuits are built for your local grid. On a 415–440 V supply, the entry-section equipment normally has a control transformer that steps the control circuit down to 220 V AC (for other voltages this is decided in the project's electrical design), and its push buttons, relays and solenoid valves run on 24 V DC.
The tube mill main drive is DC by default; AC variable-frequency drives are available on request. Electrical brands can follow your specification, and the controls can be built to your electrical standard; please send the specification with your inquiry.
Step 10: workshop and cranes → layout and foundations
Input: workshop length and width, crane capacity, whether pits can be dug, and the feed direction. Decision: layout form, left or right hand, and foundations. The line length is roughly the sum of the coil storage area, entry section, run-in to the mill, the mill itself, the saw, the run-out table and the finished-goods area. Equipment footprint is not the same as the building you need. The accumulator exit line is offset sideways from the entry line, so include that offset in the workshop width. If the workshop is too short, the accumulator can change the strip direction to make an L-shaped, U-shaped or angled layout.
Left and right are defined like this: stand on the operator side facing the line; if the uncoiler is on your right, it is a right-hand line, and if it is on your left, a left-hand line. The shear & butt welder follows the same hand. Foundations are built to the layout and foundation drawings supplied by InGen MillTek. The customer usually provides the building and cranes, equipment foundations, air compressor, cooling pool or cooling tower, cooling water pumps, HF cooling water, and power cables with grounding.
Common mistakes when specifying a tube mill
- Looking only at maximum OD: maximum OD, maximum wall thickness and maximum speed usually cannot be reached at the same time.
- Expecting one model to cover every size: if your range is wider than one model, plan two lines.
- Sizing the accumulator in tons: storage tonnage is not a valid check; use storage length and the full coil-change cycle.
- Asking for one price for “flying saw or cold saw”: the two options differ in accuracy, cut quality and investment, so compare them separately.
- Using the theoretical strip width as the cutting width: it is only a rough figure; the real width comes from the roller design and a trial run, and is usually slightly less.
- Treating equipment footprint as building size: the building also needs space for coil storage, finished goods, cranes and walkways.
What to send with your inquiry
Following the ten steps, please send as much of the following as you can; mark anything not yet decided as “to be confirmed.” Tube mills and entry equipment are configured to order and quoted per configuration: each machine is listed separately, shear & butt welders and saws are offered in different configurations, rollers are priced per size, and sea freight and installation are quoted separately.
- Finished sizes: round tube OD × wall, square or rectangular size × wall, and the sizes you make most often
- Material grade with yield and tensile strength
- Strip width and thickness range; coil weight, coil ID and OD
- Target line speed; cut length and length accuracy
- Local voltage and frequency, and whether a neutral is available; electrical brand, PLC and HMI language requirements
- Workshop size, crane capacity, and whether pits can be dug
- Project type (new line or upgrade), trade term and port of destination
Frequently asked questions
- Q: Can one tube mill line make every size? A: No line covers everything. Each model has an OD and wall thickness range; choose the smallest model that covers your maximum OD and maximum wall thickness, and split very wide ranges into two lines.
- Q: Does a small ERW line need a spiral accumulator? A: The accumulator lets the mill keep running during coil changes and strip joining. Whether you need one, and how large, depends on line speed, coil-change time and output targets; our engineers size it by storage length.
- Q: Do I need a separate leveler? A: The mill has non-driven flattening rolls at its entry, so small mills running ordinary strip usually do not. For high-strength, thicker or poorly shaped strip, our engineers will assess it.
- Q: Can I ask for a quotation before choosing a model? A: Yes. Send your product list (sizes, material, coil weight, line speed, power supply and workshop conditions), and our engineers will recommend a model and configuration.
- Q: How fast can the mill run? A: Each model has a maximum line speed, but actual speed depends on pipe size and wall thickness. It is confirmed size by size in the technical proposal.
- Q: What if my tube sizes are larger than the YJ165 range? A: Consider the large-diameter YJ219, YJ254 and YJ273 mills. They are designed and built to order: our engineers design each one from your full size list, and the range and configuration are set in the technical proposal.
About this article
Prepared by the InGen Engineering Team. This article explains a selection method; it is not a specification or performance guarantee for any project. Model ranges are the catalogue standard series, and formulas and examples are estimates. Final parameters are set in the technical proposal and technical agreement.