MATERIALS AND FABRICATION
Due to the complex chemical processes involved, the materials to construct these tanks required careful consideration and was ultimately sourced from Sweden as a special mill run.
Once the steelwork was manufactured, a stringent regime of testing was conducted to ensure that the supplied material met the chemical and mechanical standards required. To fabricate the storage tanks, LGM produced a series of welding procedures and deployed specialised fabrication and welding personnel to complete the tanks construction. Specialised welding equipment, including wire fed TIG welders with preheated oscillating filler wire, was also deployed to guarantee high deposition rates with superior quality.
LGM fabricated the tanks roof and floor in sections at its Bunbury fabrication facility to minimise the works on site (more cost effective, shorter fabrication duration, lower risk due to dedicated hotworks environment). Due to the size of the tank, the roof sections were transported in halves via road freight to Karratha, requiring main roads permits and police escorts. The trip by road took three days, and had to be booked three months in advance, to allow the necessary traffic management associated with the 7m wide (two lanes) to be implemented.
LGM constructed the tanks on site, strake by strake on purpose built concrete construction pads, in a construction area adjacent to the operating plant. This zone allowed construction to persist without the restrictions that would have been imposed from within the major hazard facility.
Once each strake was completed at ground level, it was lifted onto the previous strake (or floor in the case of the first strake). At each stage, the erected scaffold was extended to allow the circumferential weld to be completed. Once the final strake was welded in position, the roof structure was lifted into position and welded. The scaffold structure, which had been built to the tanks full height at this stage, was used to encapsulate the tank, allowing surface treatment to be completed.
The first of two stainless steel storage tanks at Yara Pilbara Nitrates Karratha were lifted into place in late April, despite impact from extreme weather (heat), cyclone events and covid impacts. LGM engaged Mammoet to complete a tandem lift using 250 and 160 tonne cranes, lifting the tank from within the scaffold structure onto the seven-row drake trailer and transport frame.
The transport frame was engineered and fabricated to support the tank during transportation to its final destination. The 70 tonne tank was carefully transported from the construction zone, across the site before a Liebherr 500 tonne crane then lifted the tank into its final position within the operating plant.