Typical Process Flow of an HF ERW Welded Pipe Mill

1. Process purpose

Map the continuous HF ERW route from coil to cut tube. Speed, OD, and installed-power bands stay on the round or push-square equipment pages — this flow page does not invent a merged rating table.

2. End-to-end sequence

1. Dual-station / dual-head decoil
2. Shear & end-weld (join coils for continuous run)
3. Accumulator (horizontal / spiral / cage) — buffer during coil change
4. Forming (breakdown + fin-pass)
5. Solid-state HF welding + squeeze
6. Scarf / cool
7. Sizing / straighten (round OD, or push-square / Turk-head when square/rect is selected)
8. Flying saw cut-to-length
9. Run-out → inspect / pack (project options)

3. Station notes

• Accumulator keeps forming/welding at constant speed while entry stops for end-weld
• HF + flying saw detail: dedicated station page
• Hydrostatic / UT / packing are often project options after the mill proper

4. Round vs push-square branch

Shared upstream stations do not authorize mixing downstream power or size tables.

5. Checkpoints

• End-weld quality before accumulator fill
• Weld V-angle and scarf after HF
• Diagonal / corner control when push-square is selected
• Cut-length accuracy at flying saw vs mill speed

6. Buyer FAQ

Is hydrostatic / UT part of every BOM?

Often project options after the mill proper. Confirm on the named proposal — not assumed on every structural mill.

Does this flow change for square?

Upstream is shared. Push-square adds Turk-head sizing; keep square ratings on the square page.

Where do speed numbers live?

On the round or square equipment pages — not re-locked here as a third “truth.”

Is the accumulator optional?

Continuous mills need a buffer for coil change. Exact type (horizontal / spiral / cage) follows the proposal.