The moment a seam stops being flat, a rigid track stops being useful. A flexible magnetic track bends with the shell and still gives the carriage a straight, controlled path — which is why curved shells are where flexible-track carriages earn their keep.
On a cylindrical shell, gravity changes as the torch travels, and any rigid track either cannot be laid or holds the carriage off the surface. A flexible stainless-steel belt is held to the plate by strong magnets, follows the curvature, and gives the carriage a controlled path. The torch then travels at a constant speed relative to the joint — which is what keeps penetration even around the shell.
| Requirement | Practical answer |
|---|---|
| Minimum plate thickness for magnetic adsorption | 3 mm carbon steel; thinner plate needs clamping or a conventional rail |
| Materials | Carbon and low-alloy steel directly; stainless and aluminium with clamped track |
| Travelling outside diameter | From Ø1800 mm upward (RG series) |
| Travelling inside diameter | From Ø2900–3000 mm minimum travelling inner diameter on curved work |
| Welding speed | 0–990 mm/min, adjustable, held constant for the run |
| Surface condition | Bare, dry steel along the travel path — remove paint, rust scale, water and heavy oil |
Magnets need bare metal. Clean a band along the seam where the belt and wheels will sit, and dry it if the shell has been outside.
Bend the flexible track around the shell and let the magnets hold it, aligned to the seam. Check the line over the full length before welding.
Contact-to-work distance, torch angle and oscillation set once. On vertical seams, hold the same parameters the welder would use — the carriage just repeats them.
Weld the seam, peel the belt off, reposition for the next one. No scaffold, no turning roll and no waiting for a crane to re-orient the vessel.
Tell us your shell diameter, plate thickness and seam type — we will confirm the right carriage and track length, and quote within 24 hours.
