Design and Drafting

We will begin by considering some of the more narrow discipline issues, in order to build a base from which an overview is possible. The details are addressed mainly to promote an understanding of the methodology of design system development. 

As stated in the previous chapter, it is preferable to design all elevated equipment supports, plant enclosures, access platforms, piperacks, and pipe and cablerack supports as steel structures. Exceptions typically include  

For the rest, even where reinforced concrete construction may at first appear to be a more economical option, it is usually avoided because of the relative difficulty of modifications and the increased quantity of site work steelwork fabrication can proceed in the shop while foundations are constructed. 

Sometimes the workshop detailing is carried out by the project steelwork design team or a separate sub-contractor, either because such a work breakdown is preferred or because the steelwork fabricator does 

Detailed steelwork design, and its effect on access and relationship to connected items, can be some of the most challenging aspects of plant design, in particular for solids handling plants, which sometimes need complex and non-perpendicular coimections between conveyors, chutes, and supports. Information flow is often problematic steelwork connects to, and supports, most other discipline items. Especially on a fast-track project there may be a need for many site modifications, and still there may remain some unsatisfactory compromises. 

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Some plants have engineering departments with design and drafting capabilities and are quite capable of doing equipment layouts and piping design as well as electrical and instrumentation schematics and loop drawings. 

Computer-aided design and drafting software (Alibre, AutoCad 2000 and LT 2000, Microstation, SmartSketch) ... 

BR butadiene rubber CADD computer-aided design and drafting... 

The further development and application of integrated computer-assisted design and drafting is the way ahead, but the choices of methodology to be made for a real, present-day project have to be carefully considered, in particular the need and availability of suitably qualified staff to handle the project s peak load requirement. 

As an aid in determining the severity of vapor cloud explosions, overpressure radius circles are normally plotted on a plot plan from the source of leakage or ignition. Computer applications are available that can easily calculate and plot these on electronic plant design and drafting applications. These overpressure circles can be determined at the levels at which destructive damage may occur to the facility from the worst case credible event (WCCE). 

In preparing his design and drafting the Specification the Engineer must have a proper appreciation not only of the adequacy of the works when completed, but also of a practical method (not necessarily the only method) by which they can be constructed. 

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