Piping and Instrumentation Diagrams 357

actuator

A device that activates linear or rotary movement. Actuators control the position of a valve in automatic valves.

American National Standards Institute

ANSI. An organization that administers and coordinates voluntary standards for products, services, and systems in the United States. The American National Standards Institute and the International Society of Automation established much of the symbology in standard ANSI S5.1-1984 (R1992).

ANSI S5.1-1984 (R1992)

The standard that is used in the United States for P&IDs. ANSI S5.1-1984 (R1992) determines the various symbols and notations used in fluid systems documents.

automatic shut-off valves

A valve that stops the flow of fluid without user intervention when certain conditions occur. Automatic shut-off valves are controlled by Safety Instrumented Functions.

ball valve

A valve that uses a rotating spherical obstruction to control the flow of fluid. Ball valves can be adjusted to a range of positions between fully closed and fully open.

binary

A numbering system that uses two digits, 0 and 1, to represent data. Binary data in a fluid system represents the presence or lack of fluid, pressure, or electric current.

boilers

A closed vessel in which water or another liquid is heated. Boilers are used to produce steam for a variety of applications.

British Standards Institute

BSI. An organization based in the United Kingdom (UK) that administers and coordinates voluntary industrial standards. The British Standards Institute is the standards organization for companies in the UK and for many European companies.

capillary tubes

A tube that runs between some sensors and hydraulic signal lines. Capillary tubes contain pressure-sensitive liquid that is affected by the fluid in the signal line.

casing volute

A curved channel within a centrifugal compressor. Casing volutes carry fluid that is pushed from the impeller to the diffuser and out of the compressor.

centrifugal compressors

A type of dynamic compressor that pressurizes air and expels it with a centrifugal force created by a rotating wheel with radial vanes. Centrifugal compressors are often used for fans and cooling units.

codes

A group of two to four letters that is used to identify instrument functions on P&IDs. The first part of a code indicates the variable the instrument measures or manages, and the following letters indicate what the instrument does with that variable, such as recording or transmitting.

compressors

A component that pressurizes gas and directs it through a pneumatic system. Compressors come in many types, such as reciprocating compressors and centrifugal compressors.

computer function

A step in a process that is controlled by a computing device. Computer functions appear in P&IDs as hexagons.

computerized data links

A wire or other pathway through which digitized information is transmitted. Computerized data links are depicted as empty or solid black circles on P&IDs, depending on whether the signal is transmitted within a system or between systems.

continuous

A type of signal that constantly transmits information about a variable. Continuous signals carry more information than binary signals.

control panel

A device that allows a user to interface with a machine. The location of display relative to a control panel is depicted on a P&ID as a solid line for a display on the control panel, or as a double line for a control panel without a local display.

conveyors

A machine that moves parts or other objects from one area of a manufacturing facility to another. Conveyors come in different forms, such as conveyor belts, vibrating conveyors, and conveyor chains.

cooling towers

A type of vessel in which water or another liquid is cooled. Cooling towers use air to cool liquid to be reused in water-cooled systems.

electric motor

A device that converts electricity into mechanical energy or motion. An electric motor is a common power source for devices in a fluid system.

electromagnetic signals

Information that is transmitted via electromagnetic waves. Electromagnetic signals may be transmitted by a signal line or be broadcast wirelessly.

Equipment and Instrument Specifications

A document that details the materials each piece of equipment in a system is made from, how it is inspected, and the definitions of each part of the device. The Equipment and Instrument Specifications is an important supporting document for a P&ID.

fiber-optic cable

A cable made of thin, flexible glass or plastic fibers that are bundled together. A fiber-optic cable transmits data as particles of light.

fittings

A fluid system component used to connect, redirect, extend, or terminate a pipe run. Pipe fittings come in a variety of shapes and are often named after the letters they resemble.

fluid system

A power transmission system that uses the force of flowing liquids and gases to transmit power. Fluid systems include hydraulic systems and pneumatic systems.

Functional Requirement Specifications

FRS. A document that describes in detail how a fluid system works, what it is intended to do, who is qualified to use it, and other details. The Functional Requirement Specifications is an important supporting document for a P&ID.

gas cylinder

A metal container used to store gases. Gas cylinders are built specifically for each gas and have different properties depending on the gas.

gaskets

A part that seals the junction between two surfaces in a device. Gaskets in piping are often circular or oval-shaped rings made of rubber, metal, or a composite material.

heat exchangers

A device that changes the heat of the fluid by either pulling heat away from a fluid or by supplying heat to it. Heat exchangers separate fluids with a heat-conductive surface.

hydraulic signals

Information that is transmitted via liquids. Hydraulic signals are transmitted via pipes.

impeller

A rotating wheel with radial blades that is used to increase fluid pressure. An impeller spins to create the centrifugal force that pushes fluid through a centrifugal compressor.

instruments

A device that measures, controls, or indicates variables in a fluid system. Instruments include sensors, indicators, and alarms, among others.

instruments

A part of a process or system that measures or controls an aspect of the system. Instruments include switches, sensors, and alarms.

insulation

A material that does not conduct heat. Insulation is used on pipes to maintain the temperature of fluids flowing through them.

International Society of Automation

ISA. An organization that administers and coordinates voluntary standards for products, services, and systems around the world. The International Society of Automation and the American National Standards Institute established much of the symbology in standard ANSI S5.1-1984 (R1992).

joints

The point where two or more pipes are connected. Joints are formed by pipe fittings in a fluid system.

loops

A complete or closed path in a process system. A loop describes the path fluid takes through a part of a process, connecting it to instruments and equipment within that system.

mechanical links

A bar connected to two or more other bars by moving joints that is used to transmit signals. Mechanical links are depicted as circles with black dots on a P&ID.

needle valve

A valve that uses a retractable conical device to adjust the flow of fluid. Needle valves can be adjusted to a range of positions between fully closed and fully open.

notations

A series of numbers and letters that identifies a pipe, its location, its diameter, any insulation it may have, and what travels through it. Notations appear above or beside the pipe on a P&ID.

open tank

A vessel in a fluid system that is open on top. Open tanks are depicted on P&IDs as rectangles with an open top.

P&ID

Piping and Instrumentation Diagram. A type of process flow diagram that provides a detailed representation of a system or part of a system. P&IDs depict instruments, valves, and signal lines in addition to the main equipment and piping.

parallel

Equidistant at all points. Parallel lines never intersect with each other.

perpendicular

Intersecting or meeting at a 90° angle. Perpendicular lines on a P&ID indicate pipes crossing each other.

PFD

Process Flow Diagram. A visual representation of the steps in a process. PFDs, also known as process flow charts, depict the main equipment and pipelines to provide a high-level view of a large fluid system.

pipe fittings

A fluid system component used to connect, redirect, extend, or terminate a pipe run. Pipe fittings come in a variety of shapes and are often named for the letters they resemble.

Piping & Instrumentation Diagram

P&ID. A type of process flow diagram that provides a detailed representation of a system or part of a system. Piping and Instrumentation Diagrams depict instruments, valves, and signal lines in addition to the main equipment and piping.

Piping Material Specifications

PMS. A document that specifies pipe information such as the material grade, insulation, and other details. The Piping Material Specifications is an important supporting document for a P&ID.

pistons

A cylindrical component that moves up and down inside a hollow cylinder in response to a pressure change. Pistons may be used to transfer motion.

plug valve

A valve that uses a cylindrical, tapered obstruction with openings to control the flow of fluid. Plug valves are raised or lowered within a seat to maintain, restrict, or completely shut off flow.

pneumatic signals

Information that is transmitted via pressurized air. Pneumatic signals are transmitted via pipes or tubes.

process engineers

A person who designs, builds, and maintains manufacturing process systems, such as hydraulic or pneumatic systems. Process engineers use P&ID to lay out the processes they design.

process environments

The workplace in which a system operates. Process environments include chemical plants, oil refineries, cement plants, and many other types of factories.

process flow chart

A visual representation of the steps in a process. Process flow charts, also known as Process Flow Diagrams, depict the main equipment and pipelines to provide a high-level view of a large fluid system.

Process Flow Diagram

PFD. A visual representation of the steps in a process. Process Flow Diagrams, also known as process flow charts, depict the main equipment and pipelines to provide a high-level view of a large fluid system.

pumps

A mechanical device used to move liquids in a hydraulic system. Pumps use suction or pressure in order to operate.

reciprocating compressors

A compressor that uses a component that moves back and forth to pressurize gas. Reciprocating compressors commonly use pistons to pressurize gas.

run-off pipes

A pipe that carries excess liquid away from a fluid system. Run-off pipes are depicted on Piping and Instrumentation Diagrams but not on Process Flow Diagrams.

Safety Instrumented Function

SIF. A step in a process that is triggered when a hazard is detected. Safety Instrumented Functions appear on a P&ID as diamonds.

screw pumps

A type of displacement pump that moves fluid with a turning, screw-shaped cylinder. Screw pumps are used to move solids or viscous fluids.

sensor

A device that detects the presence or absence of a fluid in a fluid system, or certain properties of a fluid, and provides feedback. Sensors send feedback in the form of signals, which can be measured and recorded.

signal lines

A pipe or wire that carries a signal between two parts of a system. Signal lines may carry electronic, pneumatic, or hydraulic signals in a fluid system.

signals

Information that is sent from one device to another. Signals may be transferred electronically, electromagnetically, sonically, pneumatically, or hydraulically.

sine waves

A type of waveform that resembles the letter 'S.' Sine waves represent electromagnetic or sonic signals on a P&ID.

sonic signals

Information that is transmitted via sound waves. Sonic signals may be transmitted by a signal line or be broadcast wirelessly.

specifications

A description of the essential physical and technical properties of a part. Specifications include measurements, tolerances, and materials, among other attributes.

stirrers

An agitator that combines two or more fluids inside of a tank. Stirrers ensure that fluids are mixed evenly.

sump basin

A sunken area that contains liquid that is not needed. Sump basins are used with sump pumps.

sump pumps

A pump that draws liquid up from a sump basin. Sump pumps carry liquid away from where it is not needed.

tags

A group of two to four numbers that is used to identify instruments and their loops on P&IDs. The first part of a tag indicates the loop and the second part identifies the specific instrument.

tanks

A storage receptacle that contains materials in a manufacturing process. Tanks can hold a wide variety of materials.

threaded

Having a long spiraling groove. Threaded cylinders are used in screw pumps to guide liquids.

valves

A mechanical device that regulates the flow of liquid or gas in a fluid system. Valves contain movable parts that open, close, or obstruct one or more openings or passageways.

valves

A mechanical device used to regulate the flow of liquid, gas, or other objects. Valves have movable parts that open, close, or obstruct one or more openings or passageways.

vessels

A container that holds fluid in a system. Vessels in fluid systems are connected to other equipment by pipes.

waveguide

A type of path that directs sonic or electromagnetic signals in a desired direction. A waveguide is depicted on a P&ID as a solid line with a series of sine waves travelling along it.

wireless signals

Information that is broadcast via radio waves, sound waves, or electromagnetic waves. Wireless signals travel through the air to their source.