Tower maintenance is usually limited to removal of exterior items (e.g. relief or control valves) and interior components (e.g. trays or packing rings). Handling of these items is achieved by fixed devices (e.g. davits or trolley beams) or by mobile equipment (e.g. cranes.)
When davits or beams are used, they are located at the top of the tower, accessible from a platform and designed to lower the heaviest removable item to a designated drop area at grade.
When mobile equipment is used, a clear space must be provided at the back of the tower that is accessible from the plant auxiliary road.
Following drawing depicts a typical davit arrangement.
Following drawing shows a typical trolley beam arrangement.
Following drawing shows a planned drop zone.
Drawing below shows a mobile equipment.
The dimensions, clerances and guidelines highlighted in this chapter are an example of those to be used for tower arrangements.
The plant layout designer, howerver must be familiar with company and client tower standards before proceeding with tower layout and should co-ordinate the effort with such supporting groups as vessel, systems, process and instrument engineering.