Most engineering disputes are scope disputes in disguise. The client expected a full set of piping isometrics; the designer priced general arrangement drawings. The client assumed the designer would survey the tie-in points; the designer assumed the client’s as-builts were accurate. The seven steps below are a way to scope engineering design for an industrial project so that both sides price and plan the same work.
What should an engineering design scope define?
An engineering design scope defines the purpose of the work, its physical and technical limits, the design stage, the deliverables, the standards to apply and the responsibilities of each party. If any of those are vague, the design schedule and cost are guesses.
Step 1: State the objective and design stage
Is this a feasibility study, FEED or detailed engineering for construction? One sentence naming the stage, and the decision or activity the output will support, removes a lot of ambiguity. “Detailed design to IFC for a new cooling water pump and its tie-ins” is a scope. “Engineering for the pump upgrade” is not.
Step 2: Fix the battery limits
Battery limits mark where design responsibility starts and stops. Define them physically, such as tie-in points, flange numbers, terminal boxes and foundations, and functionally, such as which utilities and which control system interfaces are included. Mark them on a plot plan or P&ID markup. Anything outside the line belongs to someone else, and the scope should say who.
Step 3: Write or confirm the basis of design
The basis of design records the inputs the engineers will use:
- Design capacities and operating conditions
- Site data: climate, seismic, soil and available utilities
- Applicable codes and standards
- Client specifications and preferred vendors
- Design life and any allowance for future expansion
If the client has its own engineering standards, list them by number and revision. A designer working without them will be caught out at the first review.
Step 4: Check the existing information
For brownfield work, ask how reliable the existing drawings really are. Where they are doubtful, include site surveys, laser scanning or field walk-downs in the scope. Tie-ins designed from unchecked as-builts are one of the most common causes of site rework, a theme picked up in how design coordination reduces rework.
Step 5: List the deliverables
Agree a deliverables register by discipline: document title, type and the revision status expected, whether for review, for approval or issued for construction. The usual pre-construction set is explained in engineering deliverables required before industrial construction.
Step 6: Define interfaces and review cycles
Who supplies vendor data, and by when? How many review cycles are included before extra reviews become a variation? How quickly will the client return comments? Late comments are a client-side delay, and the schedule should show them as one.
Step 7: Record assumptions and exclusions
Typical exclusions include permitting, HAZOP facilitation, procurement support and site supervision. There is nothing wrong with excluding any of them. The problem comes when an exclusion is assumed by one party and never written down.
Use the scope to compare design partners
A well-written scope also makes proposals comparable. When every bidder prices the same deliverables against the same basis of design, real differences in approach and price become visible. Other criteria worth weighing are covered in how to select an industrial engineering services partner.
Apex Core Engineering can help define or review a design scope as part of its design services. For a wider view of what design work covers, see industrial engineering design services.
Frequently asked questions
What are battery limits in engineering design?
The defined boundaries of a design scope, showing where one party’s design responsibility ends and another’s begins.
What is a basis of design?
A document that records the design inputs, operating conditions, codes and standards all engineering work must follow.
Who should write the engineering design scope?
The project owner should draft it, ideally with input from the designer before pricing so gaps are closed early.
Send your draft scope to Apex Core Engineering for review.