kakaie, the query is short, and general. A considered answer would take pages. I'll try to give a short answer, not the overall picture; it would, by its nature, suffer from incompleteness.
An accepted definition of design is: the act of conceiving and planning the structure and parameter values of a system, device, process or even works of art. Normally, defining the scope (aka definition) of the project is a subject that the relevant authorities of a company must initiate.
Concerned with chemical process engineering as we are in this forum, basic design would mainly include gathering of sufficient information, and is a preliminary time-limited step in a project that generally ends with an economic feasibility analysis to show its relative advantage or disadvantage, be it research work for a new chemical, a new process, the study of erecting a new plant, a plant expansion, equipment replacement, etc. The amount of process engineering involved depends on the scope of the project.
Basic and detail design are separated by the important step of taking a decision (mainly by the board of directors, BOD) on whether to continue, expand, momentarily shelve, or altogether abandon a project.
The BOD may wish to consult with marketing and financial experts before reaching a decision. When discussing a multi-million dollar (preliminary) project they might have to consider the impact it will have on future company long-range policy and ask for a (present and future) market analysis for the products and raw materials. They may then decide to give it a temporary approval and ask for more basic work to be done as in a pilot plant. Or they may finally approve it. That's the moment detail engineering design starts.
The parameters involved in basic design are so many and varied, I'd recommend you read books on the subject. One that comes to mind is Preliminary Chemical Engineering Design by William D. Baasel (Van Nostrand Reinhold).
How I understand it is: Basic engineering - a pipeline with diameter x should be installed between A and B (done by the process engineer) Detail engineering design - where the pipeline will be installed, how the pipeline will be fitted at A and B, the configuration of the pipeline, schedule of pipe, supports, etc (done by the mechanical engineer)
to daniellouw, what authority determines that a pipeline should at all be installed ?
The process engineer in his/her basic design job determines the optimum diameter, the pipeline material of construction, corrosion problems, flow controls, flow regimes, operating conditions, alarms, pipe schedule, thermal insulation, instrumentation, traps, etc.
What are the parameters that guide him, economic, safety or environmental considerations, or what? He/she may need the help of a mechanical engineer to assess the costs of the as-finished work. So, the mechanical engineer's work doesn't just cover the detail design stage.
Having gathered the necessary information and made the relevant process flow sheets and techno-economic calculations, as the case may be, somebody has to decide on whether this preliminary job is sufficient to proceed or that it may require a further study.
Only upon this authority's decision the detail design engineering follows or not.
Detail engineering -on the other hand- may need the help of the process engineer, for example, in cases where a HAZOP review may be carried out. So, the process engineer is not only in charge of the basic design after all, her/his reponsibilities are spread over both stages, the basic and the detail design. Both stages may be coordinated by a project manager himself/herself answering to the job-commissioning authority.
This is the picture that, as I understood, kakaie is seeking.
Basic engineering = basic study to allow everyone involved to agree on the exact scope of work to be done to solve the problem involved in the project and put a groos figure on how much it will cost , before going ahead with the detail engineering.
Detail engineering = get the thing designed in detail by the relevant personel , so that you can put it into construction , installation , commissioning and handover to maintenance.
I think the exact definition of the outcome of each design stage may vary, depending on company and industry, but here's a rough definition as we (almost) use in the company I work for:
1. Conceptual Design (CD) (=feasability study)
Preliminary study performed to define:
Purpose of plant/project
Location of plant
Overall cost of plant (+/- 30%)
Design deliverables will typically include a design basis with main process parameters defined (=overall plant production requirements etc.), some overall block flow diagrams, a preliminary space study to define overall space requirements and finally an overall cost estimate.
The CD will be presented for the BOD who may decide to proceed with a Basic design.
2. Basic design (BD)
Development of a well defined design package to in order to prove the feasibility and the cost estimate from the CD. Cost estimate may typically be refined to +/- 10%, and will be used as the final Go Ahead from the BOD.
Furthermore this is the start up package for Detailed Design (DD). In many cases this package may also be used as a tender package for a Design/Construction Contract.
Typical deliverables will include:
Process Flow Diagrams
P&ID's
Process simulations/calculations as required to complete the above.
Equipment Lists
Line Lists
Instrument lists
Site Plans
Plot Plan's (The overall layout approved - this is also required for)
Preliminary Equipment specifications (datasheets)
Other overall layouts which may impact process design (e.g. Hazardous area classification drawings, Fire zone layouts which may dictate shut down valve requirements etc.)
All of these drawings should preferably be finalised to status AFD (Approved For Design) which means that they are completed in all aspects except for what will be decided in the Detailed Design phase (vents/drains, vendor data etc.)
When I say preferably, this is because depending on project/company strategy, it may well be decided to issue the BD package with a level of completion lower than AFD.
For piping layout design, the BD phase will include mainly piping studies which are conducted in order to:
-prove the overall layout
-define space requirements for main pipe racks
-define basic routing of distribution headers so these can be sized.
3. Detailed Design
All further design is developed until it reaches AFC status (Approved for Construction).
For process design (assuming the BD outcome was status AFD) remaining work will be limited to verifying that the actual piping layout, the equipment purchased etc is in line with the present process design and incorporate any updates required. Typically procurement of main equipment takes place during the detailed design stage and this requires interaction from the process engineer as well as other disciplines.
In addition to the above comes all the electrical/instrumentation/structural/building/ architectural works etc.
I think Mogens covered the definitions well. Basic design is about 50% process engineering, with about 50% of the process engineering effort being done there. Detail design involves much more work from the other disciplines.
My summary is: Basic design goes up to process design (you understand process design'): Flows, operating conditions, size of equipments, budget costematings, etc. Detailled Dsgn covers all details of piping and all works,
NOROS
Basic engineering ,sometimes refered to as FEED, primarily provides preliminary estimates of the facility in other to give the EPCI (Detail engineering,procurement,construction and installation)contractor a basis for bidding. As a matter of fact, the basic engineering phase can entail evaluating the EPCI contractors. So there can be quite a few loose ends in the design at the end of the Basic which has to be knotted up at the Detailed engineering.
like 25362 said, it is a long story, but over time you will appreciate the difference as you get into either/both of them.
I think mgp was accurate in his detail. I would add some documents which should be included in a complete basic design :
- The Instrument Process Data
- The piping classes
![[pipe]](/data/assets/smilies/pipe.gif "[pipe] [pipe]")