Engineering Drawings and Symbols

Engineering drawings, such as the cellular phone schematics here, are important in conveying usefui information to other engineers or machinists in a standard manner that ailows for visuaiization of the proposed product. Important information, such as the shape of the product, its size, type of material used, and the assembly steps required, are provided by these drawings. 

Source From Pto/ENGINEEFF 2000by Louis Gary Lamit, pp. LlO-19 and LlO-20, Brooks/Cole, 2001. Reprinted with permission of Brooks/Cole, an imprint of the Wadsworth Group, a division of Thomson Learning. 

---

Some of the features of GO (EPRI NP-3123) are given in Table 3.4.6-2. A GO model is networks GO operators to represent a system. It can be constructed from engineering drawings by replacing system elements (valves, switches, etc.) with one or more GO symbols. The GO computer code quantifies the GO model for system reliability, availability, identification of system fault sequences, and relative importance in rank of the constituent elements. 

The second system is based on the IEC60255 and its references. The symbols used are comprehensive but tend to suffer from poor clarity when photoreduced, as is often required with engineering drawings. The first method is regularly used in the oil industry and is preferred herein. 

Electrical drawings include symbols and diagrams that depict an electrical process system. Electrical drawings show unit electricians where power transmission lines run and places where it is stepped down or up for operational purposes. A complex P ID is designed to be used by a variety of crafts. The primary users of the document after plant start-up are process technicians, instrument and electrical, mechanical, safety, and engineering. 

Detailing plant and utilities with lines and symbols from which engineering drawings are developed. 

Rather less freedom is allowed in the construction of mechanical flowsheets. The relative elevations and sizes of equipment are preserved as much as possible, but all pumps usually arc shown at the same level near the bottom of the drawing. Tabulations of instrumentation symbols or of control valve sizes or of relief valve sizes also often appear on P I diagrams. Engineering offices have elaborate checklists of information that should be included on the flowsheet, but such information is beyond the scope here. 

---