Definition
On industrial plant sites, erection engineering plans and controls how process modules, vessels, tanks and pipe racks are sequenced into a site that is frequently congested, partially operational, or constrained by a fixed shutdown window in which the tie-in work must be completed.
Brownfield access, not a clear site
Many industrial erection projects take place on live or partially operational plants, where existing structures, pipe racks and equipment restrict crane positions and access routes that a greenfield site would not constrain.
Shutdown windows are fixed and non-negotiable
Tie-ins to existing process equipment frequently require the plant, or a section of it, to be shut down. That shutdown window is typically fixed well in advance and shared with other maintenance and construction work, so erection sequencing has to fit the available window rather than the other way around.
Sequence risk compounds in confined space
Where structures and equipment are packed closely together, an error or delay in one erection step restricts access for the next one, in a way that open sites rarely experience to the same degree.
Temporary works — falsework, bracing, lifting frames — are frequently required to stabilise modules and equipment through the construction-stage loading a congested industrial site imposes, which the permanent design does not need to consider.
SPMTs deliver pre-assembled modules directly to their installation position where crane access from the surrounding site is limited, reducing the number of separate lifts required inside a constrained plot.
Erection sequence risk is managed explicitly rather than left to site judgement, because the cost of resequencing inside a live plant is materially higher than on an open site.