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Put that in your pipe!

From CAD User AEC Magazine Vol 22 No 9 - SEPTEMBER/OCTOBER 2009

David Chadwick looks at the creation of piping isometrics in piping models in Autodesk's Plant 3D 2010

Ihave a striking photograph of some refineries in the North east of England, taken on a dark evening with grey steam emanating from the complex of cylindrical tanks, piping and gangways, as seen across a weed strewn wasteland. Looking like Dante's Inferno revisited in the twentieth century, it was both aweinspiring and beautiful - in its own way!

The beauty and the awe stemmed from the utter complexity of the vast site, a bewildering mass of interweaving pipework. It’s almost a shame then that modern process plant designers have had the magic taken away from their work, and are now left with a mere topological problem - how to fit a mass of pipework into a finite space in the correct order!

The typical process plant is exactly what the name suggests; a number of chemical processes being conducted on a gigantic scale, with boilers, reservoirs, pressure vessels, valves and ducting to support the labrynthine pipework, interspersed with the walkways, ladders and access platforms needed by their human keepers.

Essentially a 3D puzzle, I am amazed that the earlier plants even came to fruition in such complexity. For much of that we have to thank design technology like P&ID, which eschewed any attempt at verisimilitude and relied instead on creating detailed schematics of the plant in construction, relying on the expertise of process plant design engineers to convert them into workable 2D construction drawings.

The introduction of 3D parametric modelling technology is a godsend to such processes. Engineers can now build a complete 3D plant model with piping, equipment and all other structures, and from that create piping isometrics, plans, sections and other construction drawings completely automatically. You can either start modelling and produce your P&ID afterwards, to give your maintenance teams a somewhat easier to understand view of the plant - or you can start at P&ID level and develop it into a full 3D model.

AUTODESK PLANT 3D

That's because AutoCAD P&ID, (Plant and Installation Diagrams) is part of the latest version of Autodesk's Plant 3D 2010. Currently in the process of being released, Plant 3D 2010 comes with numerous enhancements to the software's modelling capabilities, and, most importantly, the ability to create isometrics, the most convenient way to view the plant models.

Plant 3D is laid out around the standard Autodesk 2010 user interface, using ribbons and workspaces. No, I am not getting carried away with my analogies. Ribbons are the new toolbars (or the tool palettes of P&ID 2009), a more convenient way of presenting the various tools available for each design mode available to the architect or design engineer Workspaces allow users to switch between 3D Piping, 3D modelling, P&ID (including PIP, ISA and ISO standards), classic AutoCAD 2010 and standard AutoCAD 2D draughting and annotation. There is also access to a couple of management tools for handling the Project and Project Data, the latter being a good way of describing the benefits of the ribbon system.

Each new 3D drawing needs to be designated as a project and stored as such. Once plant objects have been added to a drawing in a project, they can be viewed using the Data Manager in a dedicated ribbon, which shows a small thumbnail of the object, its properties, and a selection of tools that can be used to modify its properties or placement. The Data Manager files can also be exported to Excel, to provide lists of plant objects used in a design. It’s bi-directional as well, so that clicking on a section of pipe in Excel and modifying its contents, will cause the 3D model object properties to be updated as well.

STRUCTURAL MODELLING

What then are the main features of Plant 3D? How easy is it to model a complete plant, including steel structures, plant equipment and piping?

The steel structure is the first part of the plant that needs to be modelled. That involves selecting steel members from a library of types and sizes, accessed by selecting Structure and Parts from the appropriate ribbon. Having also created a grid to place the structure, you can select the shape and size of the steel member, click on Member, and insert it in the drawing, replacing the line that previously indicated its position. There are other ways to place a member and different levels of detail that can be displayed with the member. Equipment is placed in exactly the same way, selecting, under Equipment, from the library of Plant 3D equipment, or using further tools to select and convert AutoCAD graphics to Plant 3D equipment. On the Equipment ribbon, you will also find a Modify button to modify the properties of the plant objects. Piping is the fun bit. Here you can bring in Part Insertion, Compass and Slope in the Home ribbon, allowing you to route the piping around the structure and equipment that you have already installed. A couple of things help you here. The pipes are numbered automatically if you haven't bothered to do so, and whilst creating the route, you can use a pull-down menu to modify pipe specifications and size at any time, and continue routing. You can also create your own pipe specifications if you so wish.

Pipes are routed in three dimensions. That's where Compass comes in. The routing of pipework is handled using grips - already familiar to 3D modellers - one of which, however, instructs the length of pipe to 'Continue'. Selecting this shows the options available for the pipe selected, either at an angle, straight ahead, or changing its plane (selected using 'P' for Plane) and toggling through the available planes. Alternatively, some pipe options will include 'snap-to-point' capabilities - to equipment or nozzles, even to those that might be out of plane or in Xrefs!

And, if you need to insert a couple of valves somewhere along the piping route, you can go to the Spec Viewer and select the type and performance of the valve you need from the list and 'Insert in Model'.

ISOMETRIC GENERATION

Now we come to the meat of the system - creating piping isometrics from piping models. There are a couple of ways you can do this. The simplest is to open a drawing and then open up the Isos tab in the ribbon, which gives you an option to select a quick Iso or a production Iso, amongst other functions. Selecting production, you then tell it which line numbers to run from the list shown and then click Create.

It takes a couple of seconds to create a full isometric, after which you are presented with a link to see the Iso details, and subsequently bring up the completed isometric as a DWF drawing. A pretty basic or 'default' result, which you can brighten up by customising the output using the Project Setup tools. You can also create Orthographic drawings (plans and elevations) from 3D models in Plant 3D, clicking on the appropriate command in the Project Manager and following the commands in the Orthos ribbon view. (I really like the Ribbon user interface, as it gets rid of extraneous options or incorrect alternatives. It’s a bit like the multiple choice answers in current school exams - it doesn't take much nous to select the right one!) You select the 3D model you want to create the Ortho view from, displaying them in the drawing area, and set drawing extents and clipping planes. You can also change scales, dimensions, zoom or pan during this phase. After confirming the setup, you are asked to set the drawing viewpoint. Once set up, you are then in a position to annotate and dimension it.

PLANT 3D AND P&ID

As mentioned earlier, AutoCAD Plant 3D 2010 contains both 3D modelling and P&ID programs, and the Plant 3D project can contain both P&ID drawings and 3D models, allowing users to use some data from P&IDs in 3D models. You can also check the model against a P&ID and run reports across both sets of data. You can view the P&ID line list by clicking the P&ID Line List button on the Home tab on the ribbon, and locate valves and nozzles on the lines, along with other inline items from the P&ID, which can be placed directly into the model. www.autodesk.com

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