The standard equipment sequence
Following the strip, a standard InGen MillTek ERW (high-frequency welded) tube mill line is arranged as: uncoiler (with coil car where needed) → leveling machine → shear & butt welder → flat support stand → adjustable twist stands → feeder → spiral accumulator → high turnover stand → tube mill (forming, HF welding, cooling, sizing and straightening) → flying saw or cold saw → run-out table → optional stacking and bundling → finished goods area. This order has stayed essentially the same in InGen MillTek layout drawings for many years; individual projects add or omit items depending on strip width, accumulator type and workshop conditions.
What each station does:
- Coil preparation area: space beside the uncoiler for crane lifting and coil storage.
- Uncoiler: holds the coil, expands to grip it, pays off strip and applies back tension through a brake. A coil car, hold-down arm and outboard support arm can be added.
- Leveling machine: flattens the strip head during threading before it enters the welder. Small mills running ordinary strip often do without a separate leveler.
- Shear & butt welder: trims the tail of the old coil and the head of the new one and welds them into one strip.
- Flat support stand and adjustable twist stands: support the strip and gradually turn it from flat to on-edge before it enters the feeder and the accumulator.
- Feeder: vertical pinch rolls drive the strip into the accumulator.
- Spiral accumulator (horizontal or floor type): stores strip and keeps feeding the mill during coil change and welding.
- High turnover stand: turns the on-edge strip back to flat and guides it to the mill entry.
- Tube mill: entry guide and leveling rolls → forming → HF welding (squeeze rollers close the seam and the outside weld bead is scarfed in line) → cooling → sizing → straightening. The HF welder is configured to suit tube size and wall thickness.
- Cutting: a hot friction flying saw or a servo cold saw cuts the moving tube to length; a cold saw can be configured on request.
- Run-out table: receives and discharges the cut tubes. Stacking and bundling equipment can be supplied to suit the project.
- Finished goods area: storage for finished tubes, which can be shared with the warehouse.
Why the line is arranged in this order
The order follows the logic of the process:
- Leveling comes before joining: the welder needs flat, straight strip ends to butt them accurately, so the strip head is straightened first.
- Joining comes before the accumulator: during a coil change the strip at the uncoiler and welder stands still. Only with the accumulator downstream can the mill keep running on stored strip. If the welder were placed after the accumulator, the mill would stop at every coil change.
- The accumulator sits just before the mill: its job is to separate the stop-and-go entry from the continuously running mill, so it follows every entry machine that has to pause.
- Cutting comes after sizing and straightening: the tube is brought to final size and straightened, then cut to length and carried away on the run-out table.
Around the accumulator: strip goes on edge, then back to flat
Inside a spiral accumulator the strip is stored standing on edge, wound in a spiral. At the entry, the flat support stand and adjustable twist stands turn the flat strip gradually to vertical, and the feeder's pinch rolls are mounted vertically. At the exit, the high turnover stand turns the strip back to flat before it enters the mill. Floor type accumulators handling wider strip or running at higher speeds often need several twist stands at the entry.
Strip enters the accumulator tangentially at the outer ring and leaves near the center. As a result, the exit line is not in line with the entry line: the mill center line is offset sideways from the entry-section center line. The size of this lateral offset depends on the accumulator type, diameter and exit direction. When you check workshop width, include this offset instead of looking only at the length along the line.
Because the accumulator can deliver strip near its center in the direction needed, it is also the key to L-shaped, U-shaped or angled layouts when a workshop is too short for a straight line.
Line direction and strip center height
- Direction: on InGen MillTek layout drawings, stand on the operator side facing the line. If the uncoiler (entry end) is on your right, the line is right-hand; if it is on your left, the line is left-hand. The same layout is often prepared in mirror-image left and right versions, and the left-hand or right-hand version of the shear & butt welder follows the layout direction. Please tell us your feed direction and operator side early.
- Strip center height: the entry-section machines are designed to one strip center height, while the pass line height of the tube mill is set by the mill. The difference is bridged by the high turnover stand, with a two-roll pinch unit added after it where needed. When adding an entry section to an existing mill, please send the mill center height or pass line height first.
Estimating line length: add up the sections
The length of a line has to be calculated section by section for the actual configuration. The effective workshop length is roughly the sum of the following sections; the figures for each project come from its layout drawing:
- Coil preparation area and crane lifting distance outside the uncoiler
- Entry-section length, measured from the uncoiler center to the high turnover stand. It depends mainly on the accumulator type and diameter, and grows if a leveling machine is added or a single-head hydraulic uncoiler with coil car is used
- Transition from the high turnover stand to the mill entry
- Mill section: forming, welding, cooling, sizing and straightening
- Saw section
- Run-out table, whose length depends on cut length and line speed
- Finished goods area
Two things to watch when reading a layout drawing
First, check the start and end points before you quote a length. Most entry-section lengths end at the high turnover stand, but some drawings measure to the accumulator center or to a pinch unit. For a double-head uncoiler, check whether the length starts from the working mandrel center or from the turret's center of rotation.
Second, the footprint on a layout drawing is the equipment footprint, not the building requirement. The building also needs a suitable span, crane capacity and rail height, room for the HF welder and control cabinets, and maintenance access. Add the accumulator's lateral offset when you plan the workshop width.
Information we need to plan your layout
At the proposal stage we can prepare layout options for your workshop so that you can compare them. The final equipment layout and foundation drawings are issued as agreed in the contract, so that civil work and building preparation can start.
- Finished tube sizes (outside diameter or side length × wall thickness), material grade and strength
- Strip width and thickness range, coil weight, coil inside and outside diameter
- Target line speed and cut lengths
- Workshop length, width and column spacing; crane capacity and rail height
- Whether pits can be dug in the floor, which affects how the uncoiler and coil car are installed
- Feed direction and operator side
- For upgrades: existing mill model, center height or pass line height, and available floor space
- Local supply voltage and frequency
Frequently asked questions
- Q: Is a separate leveling machine always needed? A: No. The tube mill entry has its own non-driven leveling rolls, so small mills running ordinary strip usually do without one. Our engineers decide based on material strength, thickness and strip flatness.
- Q: Why is the shear & butt welder placed before the accumulator? A: While the ends are joined, the strip at the uncoiler and welder stops and the accumulator keeps feeding the mill. With the welder after the accumulator, the mill would have to stop at every coil change.
- Q: Does the accumulator make the line wider? A: It affects the width. Strip enters at the outer ring and leaves near the center, so the mill center line is offset sideways from the entry line; include this offset in the workshop width.
- Q: What is the standard length of a complete line? A: There is no single figure. Length varies with the mill model, accumulator type, saw, run-out table and finishing equipment. We prepare a layout drawing for your products and workshop, and that drawing governs.
- Q: My workshop is too short. What can I do? A: L-shaped, U-shaped or angled layouts are possible, with the accumulator changing the strip direction. They need to be checked on a drawing against your building.
About this article
Prepared by the InGen Engineering Team. This guide describes the layout sequence and method only; it is not a specification or performance guarantee for any project. Equipment spacing, section lengths and installation heights are set by each project's layout drawing, foundation drawing and technical agreement.