Mechanical designers work with engineers using computer design software to create from sketches and even field work, technical drawings for equipment, foundations, and facilities.

Design Engineering Glossary

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A

• Angle  -  Two rays sharing a common point.

B

• Base point  -  The point on a parametric sketch that remains fixed to the coordinate system.

• Block diagram  -  A schematic drawing that shows the relationahip in a systen using simple shapes.

C

• Center line  -  A linetype used to indicate the axis of symmetry of a hole or part.

• Circumscribed (outside)  -  A circle that touches every vertex.

• Coordinate  -  Any point on a plane.

• Coordinate plane  -  A plane having a horizontal and vertical axis number line intersecting at the origin.

D

• Datum plane  -  A geometric reference point for parametric dimensions.

• Dimension line  -  A type of line used when applying dimension to a drawing.

• Design constraint  - A line on the range of options that is acceptable.

• Drawing revision  -  Drawings are typically released and revised as the design process progresses.  Depending on the companies engineering and construction requirements depends on how the drawings are releases.

• Dynamic assembly  -  An assembly model in which parts are linked to their individual part files so the software can update the assembly when individual part files are modified.

E

• Electrical one line diagram  -  A simplified drawing used to represent the power system in a plant.

• Electrical schedule  -  Tabulation of conduit, conductors and/ or cable quantities that are routed through various raceways for the purpose of connecting components of an electrical system.

• Equipment location plan  -  A drawing created to show the location of equipment relative to other pieces of equipment.

• Exploded  -  An assembly in which parts are moved out of position along a axis so that each individual part is visible.

• Export  -  To save data from one application in a file format that can be read by another software application.

F

• Face  - A planar surface on an object bounded by edges when it intersects other surfaces.

• Flange  -  A flattened collor or rim around a cylindrical part to allow for attachment.

G

• General Arrangement Drawing  -  See equipment location plan

• Global parameters  - Parameters that are common to more than one part in an assembly.

H

• Hard copy  -  Printed or plotted materials.

• Hatch line  -  A series of parallel lines drawn on a diagonal to indicate a surface created by a cut.

• Hazardous area classification drawing  -  Outlines the classifications of areas where flammable liquids, gasses or vapors are handed, processed or stored.  It is created based on input from the Process Flow Diagrams, Piping & Instrumentation Diagrams and the Equipment Location Plan.

• Hidden line  -  A type of line that represents an edge that is not directly visible because it is behind or beneath another surface.

I

• Inscribed (inside)  -  A sphere that touches the center of every faces.

• Interface  -  The portion of a system or device used to interact with or control it.

• Intersection  -  The point at which two points or surfaces meet, or the area shared bt overlapping surfaces.

J

K

L

• Limit tolerance  -  A tolerance that states the maximum and minimum allowable dimension, not the basic dimension value.

• Line designation  -  Flow lines should be labeled to show pipe size, line service identification, line number, line material, piping class and the line pressure rating.

M

• Match line  -  A match line is used to denote a cut line between two or more drawings where the area is to large for one drawing.

• Machining scale  -  A steel ruler with its smallest divisions 0.01 inch apart.

N

O

• Offset  -  The distance from an existing object at which a new object will be created.

• On plot  -  Large and/or complex facilities require demarcation between hazardous and nonhazardous areas.

• Over dimensioning  -  Showing the same dimension more than one way in the drawing.

P

• Part drawings  -  Individual drawings prepared for each part that will be manufactured or modified for the project.

• Parting line  -  A line on a molded part where the two mold halves come togeather.

• Paper size  -  A plot size, drawing size or paper size is the size that the drawing is plotted on.

• Pipe design management system  -  Was developed by AVEVA formerly CAD Center in UK.  PDMS as it is known in the 3D CAD industry, is a customizable, multi-user and multi-discipline, engineer controlled design software package for engineering, design and construction projects in, but not limited to, offshore and onshore oil & gas industry, chemical & process plants, mining, pharmaceutical & food industry, power generation and paper industries.

• Piping and instrumentation diagram  -  In the design process, a piping and instrumentation diagram, abbreviated as P&ID, is created following the Block Flow Diagram and Process Flow Diagram.

• Piping and Instrumentation Diagram/How To  -  It is important that the Piping and Instrumentation Diagram contains all the information for the process because this is the basis for the Piping Design and HazOP.

• Process flow diagram  -  Shows the relationships between the major components of a system or process plant. The PFD is more detailed than a Block Flow Diagram but does not contain as much detail as Piping and Instrumentation Diagram P&IDs.

Q

R

S

• Schematic diagram  -  A schematic diagram or elementary diagram shows every wire and device involved in the control of an electrical load.

• Service classification  -  Service class is a one to three letter designation that shows what service the line is in.  It is typically shown on a Piping and Instrumentation Diagram as part of the line numbering system.

• Solid modeling  -  A type of 3D modeling that represents the volume of an object, not just its lines and surfaces.

• Static assembly  -  An assembly that does not update when individual part files change.

• Storyboard  -  Pictures that dipict the sequence and composition of key events in an animation.

• Subassembly  -  A group of parts that fit togeather to create one functional unit.

• Surface modeling  -  A three-dimensional modeling that defines only surfaces and edges.

• System variables  -  Settings that control the default operation of a CAD package.

T

• Template  -  A drawing with certain settins that can be used repeatedly as the basis for starting a new drawing.

U

• Update  -  To regenerate the model or drawing using any new dimension values or changed perameters.

• User coordinate system  -  A coordinate system defined by the user to assist in creating CAD geometry.

V

• Vanishing point  -  A location where the projections converge in a perspective drawing.

• Vertex  -  A point where two or more curves, edges, or lines meet.

W

• Wiring diagram  -  The purpose of wiring diagrams are to provide the installer with the information required for terminating the individual conductors at various points.

• Working drawing  -  Drawings that convey all the information needed to manufacture and assemble a design.

X

Y

Z

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