The letters in EPC describe three different workforces. Engineering needs designers and discipline engineers, mostly in an office. Procurement needs buyers, expeditors and inspectors, often at vendor shops around the world. Construction needs trades and supervisors on site, in far larger numbers. Commissioning then needs a small, specialized team at the end. Manpower requirements across EPC project phases change in type, location and volume as the project moves forward. The map below follows those changes for EPC project managers, HR leads and workforce planners.
How do manpower requirements change across an EPC project?
They shift from office-based engineering roles, through procurement and inspection roles, to large site-based construction workforces, and finally to specialist commissioning teams, with project management and controls staff present throughout.
Manpower by phase
| Phase | Main roles | Where they work | What drives the peak |
|---|---|---|---|
| Engineering | Discipline engineers, designers, checkers, document controllers | Home office | Detailed design deliverables |
| Procurement | Buyers, expeditors, vendor inspectors, logistics coordinators | Home office and vendor shops | Order placement and vendor manufacturing |
| Construction | Trades, foremen, superintendents, QA/QC, HSE, materials staff | Site | Installation quantities and schedule |
| Commissioning | Commissioning engineers, technicians, vendor representatives, operators | Site | System turnover and startup |
| Throughout | Project management, planning, cost control, document control | Office and site | Project size and reporting demands |
Engineering manpower
Engineering demand peaks during detailed design, then shifts toward site support as construction begins. Discipline balance matters: piping and instrumentation often need larger teams than civil. Staffing engineering peaks is covered in engineering staffing services for EPC projects.
Procurement manpower
Procurement manpower is often underestimated. Buyers and expeditors track hundreds of orders, while vendor inspectors witness tests at manufacturers’ facilities. Late vendor deliveries frequently trace back to too few expeditors chasing too many orders. Logistics coordinators handle shipping, customs and delivery to site. On large projects, a vendor inspection plan that matches the procurement schedule tells you how many inspectors are needed in which countries and when.
Construction manpower
Construction carries by far the largest headcount. Within it, the trade mix moves from civil to steel and mechanical, to piping, then to electrical, instrumentation and finishing trades. How to forecast that mix is explained in forecasting skilled labor requirements by project phase. Indirect staff, including supervisors, QA/QC, HSE, planners and materials controllers, scale with the direct workforce.
Commissioning manpower
Commissioning teams are small but specialized and arrive as systems approach completion. Their size and timing are covered in how to build a commissioning workforce plan. Because the team is small, each specialist is hard to replace at short notice.
Overlaps and transfers between phases
The phases overlap, especially on fast-track projects. Some people move between them: engineers who designed a system can support construction queries on site, and construction technicians can join commissioning. Planned transfers retain knowledge and reduce recruitment, but they need to be agreed early, before people are released or committed elsewhere.
A common mistake: planning only for construction
Many workforce plans cover construction in detail and treat engineering, procurement and commissioning staff as fixed overheads. Those groups have peaks of their own, and shortages there delay construction indirectly through late drawings, late materials and late system turnover. Planning all four phases together shows those knock-on effects before they happen.
What this means for planning
- Different sourcing channels: engineering staff through technical staffing, inspectors through inspection firms or staffing, trades through suppliers and recruitment
- Different lead times: experienced engineers often have notice periods; trades from abroad need visas and travel
- Different locations: home office staffing, international vendor inspection and site mobilization each need their own plans
- Different approvals: clients may approve engineering leads, key site personnel and inspectors individually
The roles themselves are described in technical roles needed for oil and gas projects, and the overall approach for contractors in EPC workforce solutions for contractors.
Apex Core Engineering supports EPC manpower across phases, from engineering and technical staffing to trades supply and commissioning personnel, coordinated through its workforce planning service.
Frequently asked questions
Which EPC phase needs the most people?
Construction, by a wide margin, with the peak usually during piping and mechanical installation.
Why is procurement manpower often underestimated?
Because expediting and vendor inspection workloads grow with the number of orders and vendors, and late deliveries are not always traced back to too few procurement staff.
Can engineers move from the home office to site?
Yes, and it often helps, because they bring design knowledge to site queries. Transfers should be planned before the design team is released.
Plan manpower across your EPC project with Apex Core Engineering.