As part of maintenance activity at ExxonMobil’s Fawley Refinery in the UK, Mammoet recently supported with the exchange of a reactor head in the fluid catalytic cracker (FCC) unit.
Mammoet utilised its self-erecting FOCUS30 pedestal crane, replacing the old 356t reactor head in less time than other cranes while taking up a footprint slightly larger than a five-a-side football pitch.
In 2006, Mammoet supported the exchange of a regenerator at the same site. The PT50 ring crane was used, which had a significantly higher load moment and smaller footprint than commercially available crawler cranes at the time.
Despite this, its boom had to be carefully assembled over live pipework as there was not enough free space to construct it at ground level.
18 years on, with less site space to carry out this project, Mammoet’s engineers suggested using the FOCUS30, which has been specifically designed to perform heavy lifting in facilities with complex infrastructure and limited space.
This high-capacity pedestal crane has a boom that is erected vertically in sections, instead of horizontally. Each boom section is inserted like a jacking cartridge before being lifted to make room for the next underneath.
This not only allows for faster assembly, but for the crane to be built in a footprint measuring just 34 by 42 m. It also means that the crane’s boom does not need to be laid flat before erection, potentially blocking access roads on site.
At the planning stage, Mammoet’s engineers conducted a full 3D scan of the refinery’s reactor and, using in-house planning software Move3D, created a visualisation of the project to show how the pedestal crane would be positioned and utilised on site.
By utilising this software in combination with 3D scan data, it was possible to identify any clashes in the highly congested site. The lift’s close proximity to an absorption column demanded a level of scrutiny and accuracy that could not be provided by a traditional 2D approach.
By carefully positioning the FOCUS30 crane around existing infrastructure, hardly any alterations were needed in the field. Only one large pipe was identified early in the engineering process, and this was able to be removed without delay.
Mammoet designed a specialist lifting beam that could be inserted through the top nozzle of the reactor head and clamped to its interior. The lifting beam had two large lifting pads that carried the reactor top from the inside of its plenum. This methodology provided a sure grip of the reactor head as it was lifted.
The FOCUS30 was configured with a divisible superlift tray of 900t and 400t sections, which made movement of the ballast fast and simple, while making sure that the crane did not need to slew over live pipe racks with the load.
The FOCUS30 is also much less susceptible to high winds. By storm anchoring itself to its own outriggers, it can withstand harsh conditions.