In Secunda, South Africa, Sasol was in the process of replacing the tar separator tanks at its coal-to-liquids facility. During this replacement operation, the facility had to remain in production. The heavily congested plant proved such a challenge, that the conventional way of cutting up the tanks on site and removing them in parts would take one month per tank. With 30 tanks to replace, Sasol was keen to find a faster approach. Mammoet provided the solution, by lifting the tanks out in one piece, reducing removal time per tank to just two days.
A one month tank replacement job completed in two days
Once the decision was made to lift out the tanks completely, instead of cutting them up in their existing location, the logistic operation began. The facility itself presented the biggest challenge: space was very tight and, to raise the stakes even further, the plant had to remain live during the entire tank replacement operation. The limited space called for very precise maneuvering. As soon as the tanks were lifted out of their position, they had to be moved over a pipe rack and onto a trailer for transport to a nearby scrap yard for further demolition.
Mammoet mobilized a 400-ton crawler crane to lift out the tanks to a temporary staging position. From there, the tank was moved onto the trailer. Because of the limited available space this had to be done in two lifts, performed by a 350-ton crawler crane: one to carry the tank over the pipe rack and one to lift it onto the trailer. To keep up the pace, Mammoet brought two identical sets of crawler cranes to the site, so two sets of lifts could be carried out simultaneously. The replacement tanks were transported 11 kilometers over public roads from their construction site to the refinery, where Mammoet installed them into their final position – this was done in an operation which was an exact copy of the removal process, only completely reversed, adding further to operational efficiency.
All in all, Mammoet’s deep expertise in working in congested areas and close working relationship with its clients brought Sasol peace of mind and saved them roughly two and a half years of tank replacement time.