“Space on site was very constrained, providing only enough room for both cold boxes to approach the plinth at one point. It was also necessary to position the column cold box and heat exchanger cold box directly next to each other. Coupled with this, no crane was available in Namibia that could perform this type of lift, and transporting the required crane through to site would prove too costly,” says Roland Cumings, project engineer at Vanguard.

To perform the lift, Vanguard used two strandjacks, each configured to 50 tons, which were placed on a header beam secured to 30m lattice tower sections. A travelling framework was developed by Vanguard for the header beam to enable the strandjacks to move horizontally to position the cold boxes.

A top and tailing method was utilised to lift each cold box. The strandjack reeled in cables connected to the top end of the boxes to provide vertical lift, while a standard 170t crane was used to secure and manoeuvre the bottom end. Once vertical, the boxes were moved horizontally – with the help of the unique travelling system, turned 90°, and then lowered onto their final locations.

“Strandjacking provides a very controlled and engineered lift, offering precision and safety. This was necessary for placing the second cold box and heat exchanger directly next to each other. We were able to design the unique solution that was within budget and prescribed timelines,” says Cumings. Vanguard was also responsible for the transport to the site of all additional items for the oxygen plant that were shipped to Walvis Bay. Vanguard further lifted and installed five additional items on site, including a storage vessel, water wash tower, two mulsive vessels and a chill tower.