Piping isometrics are the drawings that leave the office and get built from. A piping isometric is the working drawing of a single pipe run, drawn in a three dimensional style on a flat sheet, not to scale but fully dimensioned, and it shows everything needed to build and install that one line: the route […]
Piping isometrics are the drawings that leave the office and get built from. A piping isometric is the working drawing of a single pipe run, drawn in a three dimensional style on a flat sheet, not to scale but fully dimensioned, and it shows everything needed to build and install that one line: the route it takes, its sizes and lengths, the fittings, valves and instruments on it, the welds, the support points, the elevations and slopes, and the materials, with a bill of materials listed alongside. It is the one the fabrication shop builds from, the field crew installs from, and the inspector works to.
For most of the history of pipework, someone drew each of those piping isometrics by hand, line by line. That is the part worth rethinking.
If you have built a proper model, you do not draw piping isometrics at all. The model produces them. Every one comes out carrying the data you built into the model, the tags, the service, the dimensions, the materials, and when the model changes you regenerate the drawing and it is current again. This is the moment the whole model pays off. All the accuracy from the equipment and piping articles, all the data from the specs article, the isometric is where it stops being a model on a screen and becomes something a fabricator can hold in their hands.
Drawn by hand, piping isometrics are slow, they are expensive because someone is drafting each one, and they are inconsistent because every drafter does it slightly differently. Worse, the bill of materials and the dimensions are transcribed by hand, so errors creep in, and the day the design moves, the drawing is wrong and gets redrawn from scratch. You are paying, repeatedly, for drawings that do not quite match the model or the plant.
If you own the site, that is real money spent on drafting and redrafting, and procurement working from hand counted quantities that may not be right. If you engineer the site, it is you drawing the same isometrics again after every change, and you carrying the blame when a transcribed dimension turns out wrong on site.
It is worth knowing that the drawing does not come straight out of the 3D model. When you run the export, Autodesk Plant 3D first writes a .pcf file, a plain text file holding the coordinates and dimensions of every line and component. That file is then put through a system called Isogen, originally built by Hexagon, which turns it into the 2D drawing. We met the .pcf in the supports article, where the same file feeds stress analysis, so this completes the picture: one file, two jobs.
How that drawing looks is yours to control, and the control is vast. All of it sits in a file called isoconfig.xml, which runs to over three and a half thousand lines, with a sixty nine page reference for anyone who wants to master it. You set your symbols, your dimensioning style, your annotations, your themes, your title blocks and borders. We covered setting these up in the project layout article, so the short version is that once your template is built, every isometric comes off it in your house style. And because the same model can drive more than one template, it produces a full fabrication isometric for the shop, a clean line numbered drawing for inspection, or individual spool drawings, each for its own audience, which we went into in the purpose article.
To export a line it first needs a line number tag, which is what lets you select it in the first place, the same tagging that runs through the whole model. From there a few controls matter. You can export the bill of materials and the weld list out to CSV, which is exactly what you want for quantifying and pricing a build. You can offset a line that sits too far from the drawing origin, which otherwise causes export errors. And there is a congestion setting that by default splits a line across several sheets, though for a clean line it is usually better to switch that off and keep it on one. The drawing exports as a dwg, with its CSV files for welds and bill of materials, and the pcf, alongside it.
One practical worth having: get your template set up perfectly, saved and closed in layout space, with the page setup pointed at a dwg to pdf printer, so you can batch plot all your isometric dwgs to pdf in one go afterwards.
This is our work, and it is where the model earns its keep. We produce your piping isometrics straight from the model, in your borders and to your standards, fully tagged and line numbered, with accurate bills of materials and weld lists drawn from the model rather than counted by hand. For an existing site, those piping isometrics come off a model we built from your laser scan, so they reflect the plant as it actually stands, not a drawing from years ago. Whether you need fabrication isometrics for the shop, spool drawings, or clean tagged piping isometrics for inspection, they come off the same model, and when the model changes they regenerate to match. No hand drafting, no transcription errors, no drawings that quietly fall out of step with the plant.
If your piping isometrics are still being drawn by hand, you are paying to redraw them every time something changes, and trusting that nothing was mistyped along the way. A model produces them in a fraction of the time, and gets them right.
Set your templates up once, properly, and every line that comes off the model comes off correct. That is the whole point of an isometric export: the model stops being a model, and becomes the thing that gets built.
Next in this series: Exports and Piping Orthographics.
