Nine metres across, already standing in La Negra
In fabrication · 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 it is standing. The four shell courses are closed and the external welding is 100% complete, with nozzles, drains and the bottom brackets installed. What comes next is the fine print of a tank this size: non-destructive testing on every joint, blasting and painting, the yoke load test and the move to 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
- 42 t load test before leaving for site
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
Real status · August 2026
Standing, welded and waiting for the truck
Nine metres of steel that six months ago were flat plates. The shell is closed, the external welding 100% complete and the bottom brackets installed; the access stairway and perimeter handrails have been finished and painted for weeks.
Now quality runs the schedule: every joint goes through non-destructive testing — radiography where the code requires it, 100% visual and dye penetrant inspection on the roof, per API 650 — before blasting and painting. In parallel, the yoke load test and the oversize transport permits are being arranged.
- Engineering 100% · fabrication 93% · quality 93%
- External shell welding closed at 100%
- Move to Spence projected for August 2026
"The tank is assembled and welded. What is left is the part you don't see: testing, painting, the yoke load test and the trip to Spence."
Progress status · weekly report No. 29 · 5 August 2026
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