Pre-engineering

Pre-engineering is the stage that comes before detailed design. Its purpose is to check whether the planned solution is feasible and what exactly will need to be done, before the company commits significant funds to design and procurement.

At this stage, engineers, among other things:

• clarify the requirements: what product, what capacity, which standards must be met,
• check the on-site conditions: available space, floor load capacity, transport routes, existing installations,
• assess utility demand and whether the existing sources will be sufficient,
• prepare preliminary process flow diagrams and equipment layouts,
• estimate costs and the schedule,
• identify risks and items that are easy to overlook.

Pre-engineering costs a small fraction of the total investment, yet it makes it possible to detect problems when solving them means changing a drawing rather than rebuilding a finished installation. In large projects, a similar stage is called FEED (Front-End Engineering Design).

Carrying out pre-engineering requires cooperation with the plant. The investor provides the available documentation, such as hall layouts, diagrams of existing installations and utility data, and gives access to the site for a site survey. It often turns out at this stage that the plant’s documentation is out of date, so some measurements have to be taken on site. This is also valuable information, because without it the design would be based on incorrect data.

Example: A household chemicals manufacturer wants to install a new 10,000-litre reactor to produce dishwashing liquid. According to the hall layout, there is enough space. However, the engineer carrying out the pre-engineering finds that:

• the floor slab on which the reactor is to stand will not bear its weight when full,
• the reactor will not fit through the hall door, so part of a wall will have to be removed or the reactor lifted in through the roof,
• the existing boiler house will not supply enough steam to heat the new reactor.

All three problems came to light on paper, before anyone ordered the reactor. Had they only emerged during installation, they would have meant downtime, redesign and significant extra costs. That is why it is worth commissioning pre-engineering before decisions on technology and suppliers are made. The earlier it is carried out, the more options can still be considered calmly, without additional costs or delays.