PIPING Isometric Drawings. Why Isometric Drawings are required?: Generally in the development of a project, a conceptual 2. D drawing is first created. In this all pipelines are drawn at zero z co- ordinate. This is then converted into a 3. D scale model, to check interference of pipe lines. D General Arrangement (GA) drawings are used for fabrication on site. A GA drawing is generally on A0 or A1 size paper and contains a lot of lines, and may not be easy to understand pipe routine. A0 or A1 size drawing is to big to handle. A pipe fabricator can understand GA drawing better only with the help of 3. D scale model. But 3. D scale model can not be put on a paper, and 3. D scale model does not indicate dimensions. To aid pipe fabricator on site, isometric drawings are prepared. An isometric drawing is generally on a A3 size paper. A pipe fabricator can read it and understand pipe routine easily. Also pipe fabricator can pick up material required for fabrication of pipe line from stores, with the help of Bill of Material given in isometric drawing. ISO vs ORTHOGRAPHIC. You would have a double break line. Any good architectural drafting/design book would have an example of what you are looking for. Simplicity (Only one pipe line is drawn in one A3 size paper). In a orthographic view it is not a problem if the pipe runs in one plane, but when a pipe runs in two or three planes (north to south, then down and then to the west, etc.) an orthographic view can be unclear. More number of drawings needed in orthographic views than ISO to represent the same piping system. Find out what AutoCAD 2013 can do and what the new features are. Commands, bugs and fixes, resources, help, tutorials, guides, tips and trix and updates. 4 TIPS AND TRICKS TIPS AND TRICKS Part 1: General The Future of AutoLISP? Should I learn it or VB instead? What changed with AutoCAD 2000? We cannot create ARX anymore? Where can I find AutoLISP. Random Tutorials and Tips & Tricks about using the AutoCAD software. Sectional views are required for clarity of pipe routing. Unlike orthographic drawings, piping isometric drawings allow the pipe line to be drawn in a manner by which the length, width and depth are shown in a single view. Directly opens PDF drawings in AutoCAD; Tightly integrated with AutoCAD; Operates via AutoCAD command line (pdfin), menus and ribbon toolbar. Home: Benefits: Free CADclips: Revit CADclips: Purchase: About Us: Contact Us: Comments: Sign In. Question: Where can I find a list of the latest Autodesk Knowledge Network support solutions that were created and/or updated for AutoCAD Plant 3D? A tutorial demonstrating various methods to debug AutoLISP code using the Visual LISP IDE (VLIDE). StrucPLUS for Full AutoCAD. If you already have full AutoCAD Isometrics are usually drawn from information found on a plan and sectional elevation views. The symbols that represent fittings, Valves and flanges are modified to adapt to the isometric grid. The Iso, as isometric is commonly referred, is oriented on the grid relative to the north arrow found on plan drawings. Because isos are not drawn to scale, accurate dimensions are required to specify exact lengths of piping runs. Pipe lengths are determined through calculations using coordinates and elevations. Vertical lengths of pipe are calculated using center line elevations of pipe lines, while horizontal lengths are calculated using north- south and east- west coordinates. Piping isometrics are generally produced from orthographic drawings and are important pieces of information to engineers. In very complex or large piping systems, piping isometrics are essential to the design and manufacturing phases of a project. Piping isometrics are often used by designers prior to a stress analysis and are also used by draftsmen to produce shop fabrication spool drawings. Isometrics are the most important drawings for installation contractors during the field portion of the project. What is an Isometric Drawing? A piping isometric drawing is a 2. D drawing in which piping is represented like a 3. D drawing. In CAD drawing, only x and y co- ordinates are used to draw entire drawing. Isometric Layout: Isometric lines can be in vertical direction and two other directions at 3. All directions of the pipe may match the three isometric axis lines. It is popular within the process piping industry because it can be drawn and read with ease and shows the piping in a realistic view. It is used along with plans and sectional elevations but typically it is used to supplement the plan drawings. Isometrics are used as fabrication & shop drawings for fabrication of run of a pipe. Isometrics also provide a drafter with the ability to calculate angular offsets in the pipe run. Isometrics are drawn on b- size paper (1. A3 size paper (2. Drawing number and revision number is indicated in box on top left corner. It is also shown in title box. The table at bottom indicates the numbers of relevant P& ID drawing and General Arrangement (GA) drawing. The bill of material appears in top right corner. A table is also provided for indicating revisions made. The rectangular area on left is reserved for Isometric drawing. The line number is shown in space in right column. General notes appear below line number. Every company has its own template, showing company's name, address, logo etc.,Arrow showing north direction is shown in top left corner. A north arrow shows North direction with respect to North direction in GA drawing. The direction orientation depends on North Direction of Plan drawing. This helps in reading the Plan and Isometric drawings together. Preparing a sketch to draft isometric drawing: View the model in the direction of north of model and start sketching pipe lines. The line may start from nozzle of an equipment, such as a vessel or a pump. Indicate nozzle number and equipment tag near nozzle. In some cases, it may originate from some other line. Indicate line number of that pipe line, its center line elevation, and isometric drawing number of that pipe line. Branches of the pipe run or continuations are placed on other drawings, typically shown as short portion of dashed line on main pipe run. Dashed lines show pipe continuation. Reference drawing information is given for continuation. One run of pipe is drawn in one isometric drawing. If one pipe run can not be accommodated in one drawing, it is continued in next drawing. Two identical pipe lines (Two similar suction lines of two pumps) are generally drawn in one isometric drawing. Isometrics are rarely drawn to scale. A longer pipe, (on left), may be shown shorter, if it does not have any fittings in it. However, a small length pipe may be shown with longer length, to show all the fittings in that portion of line. However, pipe lengths should be shown accurately. In this case, it is limited by space, so sometimes proportion may be sacrificed but it is important that the written dimensions are accurate. If the pipe is vertical, the lettering should be written vertically and at 3. Text in dimension in vertical lines, should always be parallel with dimension line. Direction & Location: Location and direction helps to orient the isometric drawing properly. Structural reference points that provide location of column along the grid can be shown on isometric. Dimensions must always be given to points of reference, such as structures, center line of existing equipment etc. Co- ordinates should also be shown on the isometric drawing. When orienting fittings or valves it is important to draw the fittings or valves, so that they are inclined to the last direction change or branch in the pipe. Fittings or valves are drawn the same shape as they appear on the plan & elevation drawings but they are drawn at an isometric angle. Looking at the orientation of model, go on sketching the line from one end to other. To get the length of each cut pipe, get distance between two ends of 3. D pipe. To get the length of pipe from center line of fitting to center line of anathor fitting get distance between insertion points of two fittings. If you are sketching with the help of plan drawings, use the difference in elevations of two adjacent lines as length of the vertical line. For horizontal lines, use the distance between two pipes, to get length of the pipe. Mark length of each pipeline on each line in the sketch of isometric drawing. Mark elbows on the drawing. Show location of valves, with type of flange. The location of the valve is shown by dimension of the center of valve. Show direction of flow, with pipe NB. If a horizontal pipe line has a slope, indicate it on that pipe line. Use branching table to select end connection of Elbows. Normally, Elbows with NB less than 5. Elbows with NB greater than 4. Elbows can be drawn in a couple of ways. Add any branch to the drawing, like, Tee, Reducing Tee, Weldolet, Socolet, elbolet etc. If the line is reduced in its path, add a reducer. Reducer can be concentric, eccentric with flat top or eccentric with flat bottom. Concentric reducer is generally used in a vertical line or line where flow pattern should not get disturbed, as in case of line of Control Valve. Eccentric reducer with flat top is generally used in suction line of a pump. Eccentric reducer with flat bottom is generally used in horizontal lines. It maintains the bottom level of pipe line after reduction in size. Swage is used to connect a pipe with butt weld end to a pipe with a socket weld end. If there is any Coupling, Union, Hose or trap in a pipe line, draw it on line. Spec change is generally implemented at isolating valve or at flange of different pressure rating. The spec of valve depends on Fluid in this and next pipe line or pressure ratings of this and next pipe line. Demarcation is shown between new and existing pipe spec and reference line number, drawing number and center line elevation is indicated for new drawing. Usually a note indicates the name or specification of the branch line. Offsets: To indicate an offset, hatches on isometric drawings are applied, to indicate that a pipe runs at a certain angle and in which direction the pipe runs. It is done with a fitting (typically a 4. But it would look like a vertical line. To avoid confusion, the offset is drawn 2. In this case, too, to avoid confusion, the offset is drawn 2. Best way to dimension a pipe line is between its center line at the intersection points. Try to keep all dimensions outside the piping view when possible. Dimensions should always be shown between points in the same plane. One of the extension lines of the dimension should be a center line of the run of pipe. In effect, this is an official master document that is always up to current revision level. Drawings for any purpose are based upon the model’s geometry. Three- dimensional geometry: The piping model is a true three- dimensional representation of the piping system.
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