During a hydrotreater expansion the overall contractor was convinced 3D modeling would solve all problems with our layout. Unfortunately, some people consider isometrics an anachronism. Stick figures and familiar symbols can easily represent construction details sufficient for a welder to build a process, a contractor to bid a project, and an engineer to evaluate process feasibility. Isometric drawings can be the most valuable construction aid available besides Process and Instrumentation Diagrams (P&IDs). Over the next few months our efforts to upgrade its desalter were stalled several times because of incomplete, conflicting and often dead-wrong isometrics. Pipe size – Given pipe size is 2″ and 1″.The refinery's documentation was organized and generally pretty good but its isometrics were terrible.Refering to the above Iso drawing, lets go through the item one by one: Let’s use the isometric below as an example An example of a pipe fabrication isometric drawing

There are a few information that can be derived from an isometric drawing. Isometrics drawing is also the most important drawings for installation contractors during the field portion of the project. It is often used by designers prior to a stress analysis and used by draftsmen to produce shop fabrication spool drawings. Piping isometrics are generally produced from orthographic drawings and essential to design and manufacturing phase of a very complex or large piping systems. Vertical pipe lengths are calculated using elevations, while horizontal lengths are calculated using north-south and east-west coordinates. Pipe lengths are measured using coordinates and elevations. Therefore, dimensions are required to specify exact lengths of piping runs. The isometric drawing is oriented on the grid relative to the north arrow found on plan drawings and not drawn to scale. Piping isometrics are usually drawn on a pre-printed paper, with lines of equilateral triangles form of 60°. Symbols like fittings, Valves and flanges are modified to adapt to the isometric grid. The Isometrics drawing are created from information found on a plan and elevation views. In a piping isometrics drawing, pipe is drawn according to it’s length, width and depth, and often shown in a single view.

How to draw piping isometrics