October 29 - Johnson Crane Hire has played its part in the removal of three pressure vessels for the GHHER (gas heated heat exchanger reformer) project at the Sasol gas reforming plant in Secunda, South Africa.

The removal had to be conducted during the shutdown of the plant, which Johnson explained meant that the project had strict time constraints.

All three items of equipment were housed within the plant structure, which was also fitted with cabling, racking, pipework and ancillary equipment.

The equipment consisted of two identical waste heat boilers, each measuring 17 m long by 2 m in diameter and weighing 60 tonnes, while the third vessel - a steam drum - had a length of 8 m and diameter of 2.5 m.

The smaller unit was mounted on 3.5 m high concrete plinths. Johnson designed, engineered and manufactured a steel bracing system, which would allow the steam drum and its concrete plinths to be removed in one piece.

Once the bracing system was assembled around the unit, a demolition contractor was deployed to cut the plinths at their bases. At this point the base was jacked up to provide sufficient clearance for the steam drum and plinths to pass the existing concrete structure on the plant floor. 

"The weight was transferred onto the sliding rails using jacks and then the combined unit of vessel and concrete plinth was slid out of the plant to a position where crane access was possible," explained heavy lift manager for crawler cranes and projects at Johnson, James Robinson.

The vessel and concrete plinths were then lifted out of the plant using a Johnson 550-tonne mobile crane with a luffing boom.

The remaining two units were removed from the steel plinths on which they were mounted, and removed from the plant using the same sliding system. Once overhead clearance was available, the two boilers were lifting using the mobile crane.