Nine metres across, painted and in the air
Final stretch · Minera SpenceNine metres across and some 26 tonnes of steel: that is the pressure-break tank CGK is building complete — floor, four shell courses, roof with nozzles and drains, helical stairway and removable handrails — at its La Negra plant in Antofagasta, for Minera Spence.
It started in February 2026 with the fabrication engineering settled up front: shop drawings, WPS and qualified welders, and the calculation reports for the lifting yoke and the transport frame, both CGK designs and both validated by the client before anyone touched a crane.
The challenge was not just the size: it was the journey. The route to the mine allows 9.5 metres of height at most, so the tank is built in sections, with a bolted flange joint in the shell, travels as an oversize load and is closed by welding on site.
Today the fine print is behind us. With non-destructive testing approved, the tank was shot-blasted and received its complete paint system: shell, roof, stairway and handrails now wear the final red. And it has already hung from the lifting yoke — this time the whole body — in the manoeuvres that leave it ready for dispatch. Only the last leg remains: the oversize trip to Spence and the closing weld on site.
Lifting yoke · CGK design
A six-arm yoke that started in CAD
Lifting a 9-metre, 7-tonne roof without deforming it means spreading the load around its whole circumference. For that CGK designed a six-arm lifting yoke in HEA sections, with slings at 45° and lifting lugs calculated point by point.
The calculation report — along with the one for the transport frame — was validated by the client before the lift. The steel star now hanging from the crane in the La Negra yard is exactly the one from the model.
- 6-arm yoke in HEA sections · in-house calculation
- Lifting and transport reports validated by the client
- Slings at 45° and lugs calculated point by point
Load test · 42 t
42 tonnes hung to be certain
A calculation is not signed off on paper alone: before the yoke ever touched the tank roof, it carried a 42-tonne test load. Seven tonnes on each of the six lugs, spread symmetrically, exactly as it works in the real lift.
The test does not validate one part, it validates the whole assembly: the yoke, the lifting lugs and also the slings and shackles that will hold the load. All passed; only then was the lift authorised.
- 42 t total · 7 t per lug, symmetrical loading
- Yoke, lugs, slings and shackles validated together
- Certified before the lifting operation
Platform on the roof
A helical stairway wrapped around the tank
Roof access is solved with a helical stairway curving along the shell, plus grating platforms and removable perimeter handrails for maintenance.
All that structure was built and painted alongside the tank, and the top platforms were fitted onto the roof before it was lifted — which is why the yellow structure already crowns the shell while the rest of the tank is still being assembled.
- Helical stairway and handrails finished and painted
- Platforms fitted to the roof before the lift
- Removable handrails for the oversize move
Assembly in La Negra
A tank cut to fit the route it has to travel
Nine metres across does not fit whole on the highway: the route to site allows a maximum of 9.5 metres in height. The engineering answer was to split the shell with a bolted flange joint, move the tank in parts and close the weld on site.
For the journey, CGK also designed a dedicated transport frame, with its calculation report validated and load certificates for the body, the roof and the yoke.
- Shell split with a bolted flange joint
- Transport frame designed and calculated by CGK
- Closing weld and finishing on site
Seven tonnes in the air
The moment that sums up the project: the crane picks up the whole roof — platforms, handrails and nozzles included — and sets it on the scaffolded shell in a single manoeuvre.
The six-arm yoke keeps the roof perfectly level while the La Negra crew guides it with tag lines from the ground. Minutes later, the tank has the silhouette it will travel to the mine with.
- Lift planned with a validated lifting report
- High-tonnage crane + tag lines in the yard
- Real site footage · no digital retouching
Painted head to toe
Shot blasting first, then the full system on top: inorganic zinc, epoxy and polyurethane, the three coats that will defend the steel from the desert sun and dust. The whole tank — shell, roof, stairway and handrails — wears the final red.
The video shows it fresh out of painting: the tank body hanging from the yoke, immaculate, while the La Negra crew positions it in the yard.
- 3-coat system: inorganic zinc + epoxy + polyurethane
- Shot blasting and painting after passing NDT
- Roof, stairway and handrails painted in parallel
The finished tank, ready for the road
The last manoeuvre at home: the crane takes the tank body — already painted, nozzles and drains installed — using the same six-arm yoke that lifted the roof in July. The crew positions it for dispatch while the roof, also painted, waits its turn in the yard.
That takes progress to 95 %. What remains no longer goes through the shop: the oversize load-out, the route to Spence and the closing weld on site.
- Overall progress 95% · August 2026
- Body and roof painted, in loading manoeuvres
- Next milestone: oversize transport to the mine
“The tank is painted and has hung from the yoke again, whole this time. What remains is the journey: load it, take it to Spence and weld the closure on site.”
Progress status · site record · 14 August 2026
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