The trade-offs that decide where a job should be built.
Where a part is built — in the workshop or on site — depends on size, transport and access. The wrong choice adds cost and risk.
Workshop fabrication is faster, cleaner and cheaper for most parts. Power, lighting, fixtures and lifting gear are available, and fit-up can be checked before the part leaves. Use it for frames, benches, guards, hoppers and anything that fits through a doorway.
Build on site when the part is too large to transport, must fit around existing equipment, or cannot be measured accurately off site. On-site work also suits shutdowns where the line cannot be interrupted for long; spools are prefabricated and only the minimum hot work is done on site.
Most projects combine the two: prefabricate as much as possible in the workshop, then fit and weld on site. The split between bolted and welded connections is planned before cutting starts.
Where dimensions cannot be trusted remotely, we template the job on site, fabricate in sections, and return to weld and bolt everything together. Templating removes the risk of building to a drawing that does not match the existing structure.
On-site work carries lifting, isolation and hot-work risk, and costs more per hour than the workshop. It is only used where the geometry requires it. If a part can be built in the workshop and bolted on site, that is usually cheaper and safer.