```html ROM shop size & machine cost – Duplex stainless float (pressure tank) + corrugated panels

Rough-order-of-magnitude (ROM) building size & machine cost

Scope: in-house fabrication of duplex stainless cylindrical floats (pressure-tank-like) plus corrugated duplex stainless panels. Costs shown are typical USD machine-only ranges (mix of new/used market), excluding land, building construction, installation, tooling design/qualification, permits, consumables, and labor.

1) Inputs / assumptions used for the ROM

Heads dominate capital cost if you truly want to form them in-house.
Forming a 48" diameter, 1/2" thick duplex dished head typically requires a very large dishing/flanging capability (often 800–1500+ ton class equipment, depending on head geometry and method). Many shops outsource heads even at moderate volumes. Below, the budgets include a head-forming option because you asked to make your own tanks, but a “buy heads” alternative is also shown because it can cut capex drastically.

2) Typical process flow (what the shop must support)

  1. Plate/sheet receiving & storage (racks, overhead crane/forklift).
  2. Cutting (shell plate rectangles, head blanks, nozzles, stiffeners; corrugated blanks if not coil-fed).
  3. Edge prep (beveling for full-penetration welds).
  4. Rolling (form shell cylinder).
  5. Welding shell seam (automated or semi-automated; duplex-friendly procedure).
  6. Head forming (if in-house) + trimming.
  7. Fit-up & welding heads to shell (rotators/positioners, internal purge where needed).
  8. NDT / QA (visual, PT, UT; RT often outsourced unless you invest in radiography).
  9. Hydrotest / pressure test setup and documentation.
  10. Pickling/passivation & final finish (critical for corrosion performance).
  11. Corrugated panel forming (roll-forming line or press-brake method).

3) Case A – Capacity ~1 float/week

Building footprint (typ.) ~10,000–15,000 ft²
Clear height (typ.) ~24–28 ft
Key bay length ~80–100 ft
Overhead crane 5–10 ton

Footprint rationale: you need a straight-line bay long enough for 20 ft vessels plus fixtures, turning rolls, and staging, plus separate cutting/forming and finishing areas (especially for pickling/passivation containment).

3.1 Machine list & ROM costs (Case A)

Area Equipment (typical) ROM cost (USD) Notes
Material handling Overhead bridge crane (5–10 ton), forks/pallet jacks, plate racks $90k–$300k Crane capacity depends on plate bundles, fixtures, and handling approach.
Cutting CNC plasma (high-def) table (e.g., 6'×12' or 8'×20') or fiber laser (if thin work dominates) $180k–$550k For 1/2" duplex plate, HD plasma is common; laser becomes costly at thickness. Waterjet is possible but slower/more expensive per cut.
Edge prep Plate beveling machine (portable or stand-alone), grinders, fit-up tools $25k–$140k Bevel quality matters for consistent automated welding.
Rolling 4-roll plate roll (≈60" working width, 8–10 mm capacity) $140k–$380k Duplex springback is higher; sizing passes and stronger roll are helpful.
Tank welding (core) Turning rolls/rotators (10–20 ton class), welding power sources (GTAW/GMAW/SAW), purge equipment, fixturing $180k–$650k This range assumes “semi-automated” (good fixtures + rotators + skilled welders). SAW is often used on thicker sections; duplex procedures must be qualified.
Optional automation Longitudinal seam welder (column & boom + seam tracker) for shell seam $250k–$900k If you add this, you reduce welding time variability and improve repeatability.
Head forming (in-house) Dishing press + tooling and flanging machine/press + trimming $1.5M–$6.0M The largest single capex driver. Exact tonnage depends on head shape (2:1 elliptical vs torispherical), depth, and forming method. Duplex increases forming loads.
NDT / QA PT kit, UT flaw detector, weld gauges; (RT typically outsourced) $15k–$80k In-house UT is common. Full radiography systems add significant cost and compliance burden.
Hydrotest Hydrostatic test pump/skid, test bay fixtures, gauges, safety barriers $25k–$120k Also consider a water management plan (filtration, containment).
Pickle/passivate Local contained wash-down/pickling area, ventilation, rinse/neutralization, wastewater handling $60k–$300k Often underestimated; critical for seawater corrosion performance.
Corrugated panels Option 1: heavy-duty roll-forming line (decoiler + straightener + roll former + shear)
Option 2 (lower capex): large CNC press brake + custom corrugation tooling 		Roll-former: $350k–$1.2M
Press brake: $120k–$450k 		For 2–3 mm stainless, roll-forming is best for repeatability/throughput. Press-brake corrugation works for short runs but is slower.

3.2 Case A – Total machine cost (ROM)

Scenario ROM total machine capex What drives the difference
A1: Make heads in-house $3.0M–$10.0M Head dishing/flanging equipment + tooling dominates.
A2: Buy heads (outsource forming), weld/finish in-house $1.2M–$4.0M Removes the big press/spinner; you still need cutting, rolling, welding, QA, finishing, corrugation.

4) Case B – Capacity ~1 float/day

Building footprint (typ.) ~30,000–50,000 ft²
Clear height (typ.) ~28–35 ft
Overhead cranes 2+ cranes, 10 ton typical
Flow concept Parallel stations / takt-time

At ~1/day, you generally need parallelism (multiple fit-up/weld stations), more automated seam welding, and a real finishing/QC pipeline so one constraint (welding, NDT, pickling) doesn’t stop the line.

4.1 Machine list & ROM costs (Case B)

Area Equipment (typical) ROM cost (USD) Notes
Material handling Multiple cranes (10 ton), forklifts, powered transfer carts, racks $250k–$900k Material flow becomes a primary design driver at this rate.
Cutting Higher-duty CNC plasma (possibly 2 tables) or plasma + laser combo $400k–$1.5M Often 2 cutting stations to avoid queueing.
Edge prep Automated beveling line + dedicated stations $120k–$450k Automated beveling supports consistent automated weld quality.
Rolling Two plate rolls (or one very fast roll + staging fixtures) $350k–$900k Parallel rolling reduces bottleneck risk.
Automated welding Dedicated longitudinal seam welding system (column/boom + seam tracking), plus circumferential head-to-shell welding stations with rotators; possible robotic GMAW cell for attachments $1.5M–$5.5M This is where “1/day” becomes feasible without extreme labor. Duplex welding procedure control is non-negotiable.
Head forming (in-house) Higher throughput dishing/flanging setup (larger press class, faster handling), automated blank handling, trimming $3.0M–$10.0M You may need redundancy or faster cycles to keep up. Tooling wear/maintenance becomes real.
NDT / QA UT + PT plus (optionally) in-house digital RT bay $150k–$900k In-house RT adds compliance, shielding, training, and schedule benefits.
Hydrotest Dedicated hydrotest cell (fast connect), data logging $120k–$450k Higher throughput benefits from quick-connect fixtures and repeatable instrumentation.
Pickle/passivate Larger contained finishing line (ventilation + neutralization system) $250k–$1.2M Often needs environmental engineering; don’t treat as “just a wash bay.”
Corrugated panels Dedicated heavy roll-forming line (coil fed), possibly 2 lines if panels are a major product $700k–$2.5M At 1/day vessel rate, panel demand may justify a dedicated line and automated stacking.

4.2 Case B – Total machine cost (ROM)

Scenario ROM total machine capex What drives the difference
B1: Make heads in-house $8M–$25M Head forming + higher automation + multiple stations to hold takt-time.
B2: Buy heads (outsource forming), weld/finish in-house $5M–$15M Still significant due to automation/parallel lines, but avoids large press/spinner capex.

5) Practical notes (duplex + marine use)

6) If you want, I can tighten the numbers

If you answer the items below, I can produce a more specific layout (bay-by-bay), equipment sizing (tonnage, roll capacity), and a narrower cost range:

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