Piping orthographics are the other half of your drawing set. By now you can produce isometrics from your model, a clean drawing of every line, ready to build. But an isometric only ever shows you one line at a time, lifted out of its surroundings and drawn not to scale. There are plenty of moments […]
Piping orthographics are the other half of your drawing set. By now you can produce isometrics from your model, a clean drawing of every line, ready to build. But an isometric only ever shows you one line at a time, lifted out of its surroundings and drawn not to scale. There are plenty of moments when that is not what you need, when the question is not how do I build this line, but where is everything, and how does it all fit together.
That is the piping orthographic.
An isometric and an orthographic answer two different questions, and a complete drawing set needs both. The isometric is the build drawing: one line, in detail, for the fabricator. The orthographic is the context drawing: the whole area, to scale, showing equipment, pipe and steel where they actually sit in relation to each other. It is, in plain terms, your general arrangement.
And like the isometric, you do not draw it. It is a live snapshot of the 3D model. When the model changes, you request an update and the drawing refreshes to match. That is the whole difference between this and a hand drawn GA that drifts out of date the moment site moves on.
Because they show the plant in context and to scale, piping orthographics earn their place in ways an isometric cannot. It is your general arrangement, a top down view of the model that can be built up with civil and site detail for a fuller picture. It is the natural way to show new work, where an addition sits among the existing plant, which makes it the drawing you put in front of managers and stakeholders who need to see and approve what is changing without navigating a 3D model. Pair one with an isometric and you have a complete fabrication pack, the line to build and the context it sits in. And it supports inspection too: an orthographic can show which line sits where across an area, and some clients take piping orthographics in place of isometrics, drawn per service for each area.
There is one caveat worth knowing. You can generate the view top down, from the side, or in an isometric style, but only the top down and side views are to scale, so those are the ones you dimension from. The isometric style view is for showing the layout, not for measuring off.
Where an isometric is written out through a .pcf file and Isogen, an orthographic is made more directly. You drop a clipping box around the part of the model you want, set the scale, and make a couple of choices such as whether to show hidden pipework. Autodesk Plant 3D generates the view, you place it on your border, and you add your dimensions and annotations. You control the borders, the scale, the views and the layers, so you display only what is needed and colour the output by line status, new against existing, the setup for which we covered back in the project layout article. You can hold several views on one sheet, and once one is set up, asking for another side brings it straight out.
This is our work. We produce orthographics and general arrangements straight from the model, and for an existing site that model is built from your laser scan, so the drawing shows the plant as it genuinely stands. Whether you need a GA for planning, a drawing to show stakeholders what is being added, piping orthographics to pair with isometrics for a full fabrication pack, or inspection drawings by area, they come off the model and refresh when it changes. No redrawing, no drifting out of date.
The real beauty of piping orthographics is simple. A 3D model is a powerful thing, but it lives on a screen, and not everyone wants to drive one. An orthographic turns that model into something a person can hold, print, and carry out onto the plant to check the drawing against the steel in front of them. It is the model made readable, the context drawing that pairs with the isometric, and the one anyone on the project can pick up and understand.
Next in this series: Exports, Lists and Schedules.
