TABLE OF CONTENTS A vast amount of documentation is required for the design and construction of a process facility, which are front-end and detailed engineering drawings. The main engineering documents used on a regular basis by the engineering staff for smooth and efficient running, maintenance, and upgrading of the facility are Alarm and Trip Systems, PLC documentation, and Pipe and Instrumentation Diagrams (P&ID). As in all engineering disciplines, the initial accuracy of these documents, and the regular updating of them when changes are made, is critical, and one of the most important aspects of engineering. For this reason, documentation is discussed in this chapter. Documentation standards and symbols for all aspects of process control have been set up and standardized by the ISA, in conjunction with the ANSI [1].
[1]Mulley, R. M., Control System Documentation, Research Triangle Park, NC: ISA, 1998.
The purpose of an alarm system is to bring a malfunction to the attention of operators and maintenance personnel, whereas the purpose of a trip system is to shut down a system in an orderly fashion when a malfunction occurs, or to switch failed units over to standby units. The elements used in the process control system are the first warnings of a failure. This could show up as an inconsistency in a process parameter, or as a parameter going out of its set limits. The sensors and instruments used in the alarm and trip system are the second line of defense,...
