Gas carriers  LNG RIVERS  & LNG SOKOTO  in dry dock in Brest.
Cargo tanks :      

The spherical cargo tanks are made of aluminum and are more than 40 meters in diameter. The opportunity to visit them is quite rare. Between two dry docks they are normally never empty in order to keep them cold. The cargo is carried at a temperature of -162° Celsius, maintained only by the tanks insulation.
This small brown structure is a sort of airlock, installed by the yard for the duration of the works. Afterwards the tank is closed by a stainless steel plate.

From top to bottom of the sphere this tube contains stairs and pipes.
Mid way an observation balcony.
 
Welding inspection shows no defect. Whiter marks are grinding traces.
The superintendent leaning
on a cargo pump.
Here we are outside the tank, between the aluminum sphere and its steel envelop.
It is coated with insulating material and rest at its equator by aluminum/steel blocks welded on the ship structure.
One can see here some blocks through an inspection opening.
The insulating material is held in place by a sort of basket made of steel strips hooked at large springs all around.