3D CAD Piping Questions'' Answers - Followup

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Q1: Do 3D jobs still need to follow the normal route of producing general arrangements, and then 2D details and isometrics?

Tom Greer [Intergraph]: All of the standard deliverables and construction documents come from 3D systems, and in many cases much more efficiently. The primary difference is in the mindset: attention to detail is put into the modeling phase and the intelligence that each of each 3D object (e.g., pipelines, equipment, structural systems, etc). Deliverables are simply a by-product of the 3D model. The adage "garbage in, garbage out" is especially true in the world of 3D plant design.

Rene Dalmeijer: Yes, in general. Use 3D to define the design and GA [general arrangement or layouts]. You could displace the necessity of a 2D GA, though. The 3D pictures -- either shaded solid models or hidden-line removals -- tend to be much more insightful to most parties than the old 2D GA. It does require some additional annotation though. What I prefer is to create medium-specific views, with one overall view showing all systems together. Everybody gets the overall 3D GAs

Q2: Do companies using the 3D concept produce 2Ds from the model, or do they use AutoCAD (or similar) for the drafts?

Tom Greer: Companies using 3D effectively generate most, if not all, of the 2D deliverables from the model. The purpose of the model is for pre-validation for constructability -- by revealing clashes and other construction-related issues before construction begins, as well as to obtain accurate material quantities and automated piping isos [isometric views]. Over our 20+ years in the business, we have seen our clients' field rework costs drop from 3%-7% of project budget to less than 1% through the effective use of 3D CAD. Our experience is that when 2D drawings are done apart from the 3D modeling effort, the old problems of field rework reappear.

Rene Dalmeijer: It depends very much on the package. The last team I worked with used MicroStation with the then-current Bentley piping add-on (whose name I can now not recollect). This meant we could do everything in one package, which does help avoiding an early associativity cutoff between 3D and 2D. Depending on the drafting convention requirements a cutoff is nearly always necessary, though. I do strongly suggest that you adjust drafting conventions to the package's capabilities -- and not try to force the 3D package to model conventional 2D drafting requirements.

When you do you create overly detailed 3D models, this causes tremendous hardware requirements. This means, for instance, that equipment and fittings have as low a detail as possible. All you need are blocks or cylinders showing the volume they occupy with three orientation points. If you need a very detailed 2D drawings, just replace the cylinders and blocks with the required 2D symbols.

Q3: Has anyone ever produced a good PDMS 2D general arrangement comparable to, say, an AutoCAD drawing?

Tom Greer: People have been relying on our PDS software to produce project GAs for over 20 years. Depending upon client preferences and corporate graphics standards, it is possible that some drawings are manually embellished after the fact, but this is often the result of preferences and not so much inadequacies of 3D systems.

Rene Dalmeijer: I have no direct experience, but have seen quite capable 2D drafts coming out of PDMS.

Q4: Do 3D modelers have to be multidisciplinary, or does a piper only do piping, and a structural guy only structures? I always wonder if the best 3D guys are IT specialists with a bit of drafting knowledge, or
"drafties" with a bit of IT knowledge.

Tom Greer: Many engineering companies have so-called "flex engineers" who have knowledge and capabilities across more than one discipline. If this is the case, then these engineers and designers certainly can function productively in more than one 3D design application.

There are no hard and fast rules about 3D modelers having to be multi-discipline or single-discipline in their abilities any more than there are in the world of linen, vellum, mylar, and 2D CAD. Some people are specialists while others are versatile -- this is true with or without 3D.

The best 3D designers are those professionals who take the time to get trained on their tools of choice and who routinely hone their skills. A little bit of computer aptitude might help in a jump-start situation but that is not an advantage over the long term. There is no substitute for skill and knowledge in a discipline such as piping design or structural design and neither the best computer software nor the deepest IT background can supplant engineering domain expertise.

A non-degreed designer with good engineering knowledge and good 3D CAD skills will find himself or herself on a level playing field with a degreed engineer doing the same tasks with the same tool. By the same token, degreed engineers with a reluctance to master a 3D design application can often find themselves significantly behind the curve when compared to highly motivated and skilled "technicians" and
"drafties" [drafters] with good 3D CAD plant design skills.

Rene Dalmeijer: Preferably you are able to do both, but at the same time you will always be more of a specialist in one or the other. It also depends on team and project size. Received on Tue Oct 12 23:00:00 2004