Lecture 2Process DiagramInstrumentation

Process Diagram

Process DiagramCategoriesProcess Flow Diagram (PFD)Also called System Flow Diagram (SFD) or FlowsheetDescribes Primary flow path through operating unitProvides quick snapshot of operating unitsProcess and Instrumentation Diagram (P&ID)Also called Piping and Instrument DiagramIs a graphical representation ofEquipmentPipingInstrumentation

Process Diagram StandardsInternational/Regional/National StandardsInternational Organization for Standardization or Organisation Internationale de Normalisation widely known as (ISO)Deutsches Institut fr Normung e.V. or German Institute for Standardization (DIN)Government RegulationUS Occupational Safety and Health Administration (OSHA)Organization/AssociationAmerican Society of Mechanical Engineers (ASME)Instrumentation, Systems, and Automation Society (ISA), originally known as Instrument Society of AmericaTubular Exchanger Manufacturers Association, Inc. (TEMA)Process Industry Practices (PIP) by Construction Industry Institute (CII) at The University of Texas at Austin

Process Diagram StandardsIndustry Codes and StandardsAmerican National Standards Institute (ANSI)Standards Australia (SA) or formerly Standard Association of Australia (SAA)Proprietary StandardsStandard Process Design Criteria (Fluor)Design Engineering Practices (Shell) Snamprogetti (Italy)Mitsubishi Heavy Industries (Japan)

Process Flow Diagram (PFD)PFD includes:Process stream namesProcess pipingMajor equipment symbols, names and identification numbers Control valves and valves that affect operation of the system Interconnection with other systems

Major bypass and recirculation lines System ratings and operational data such as minimum, normal and maximum flow, temperature and pressure, etc., often with reference to a mass balanceComposition of fluids

Process Flow Diagram (PFD)PFD excludes:Pipe class and/or line numbers Process control instrumentationSecondary or Minor flowsMinor bypass lines Isolation and shutoff valves Maintenance vents and drains Relief and safety valvesFlangesCode class informationSeismic class information

Process Flow Diagram StandardsISO 10628: 1997 Flow Diagrams For Process Plants General Rules ANSI Y32.11: Graphical Symbols For Process Flow Diagrams (withdrawn 2003) SAA AS 1109: Graphical Symbols For Process Flow Diagrams For The Food IndustryDIN

Process Flow Diagram (PFD)

Block Flow Diagram (BFD)a.k.a. as Schematic Flow DiagramPFD of multiple units as schematic illustration of major processes

Block Flow Diagram (BFD) GuidelinesUnit operations are usually denoted by a simple block or rectangle and labeledGroups of unit operations may be noted by a single block or rectangleProcess flow streams flowing into and out of the blocks are represented by neatly drawn horizontal or vertical linesDirection of flow of each of the process flow streams must be clearly indicated by arrowsFlow streams should be numbered sequentially in a logical orderDiagram should be arranged so that the process material flows from left to right, with upstream units on the left and downstream units on the right

Block Flow Diagram (BFD)

Process and Instrumentation Diagram (P & ID)Pictorial representation ofKey piping and instrument details Control and shutdown schemes Safety and regulatory requirementsBasic start up and operational informationPurposeTo have a common language for instrument technicians, process engineers and suppliersTo properly document plant designs for installation in graphical formTo help in maintenance, failure analysis and troubleshooting

Process and Instrumentation Diagram (P & ID)IdentifyProcess Lines from Instrument LinesLocation of the instrumentFunction of the instrumentProvide other relevant information

Elements of P&IDFlow DiagramEquipment LocationElevation PlanElectrical LayoutLoop DiagramTitle Block and LegendsFoundation Drawings

P&ID TypesProcess and UtilityUtility DistributionInterconnecting LinesAuxiliarySpecial Controls

Process and Instrumentation Diagram (P & ID)P&ID includes:Instrumentation and designations Mechanical equipment with names and numbers All valves and their identifications Process piping, sizes and identification Miscellanea vents, drains, special fittings, sampling lines, reducers, increasers and swaggers Permanent startup and flush lines Flow directionsInterconnections references

Control inputs and outputs, interlocks Interfaces for class changes Seismic categoryQuality levelAnnunciation inputsComputer control system input Vendor and contractor interfacesIdentification of components and subsystems delivered by othersIntended physical sequence of the equipment

Process and Instrumentation Diagram (P & ID)P&ID excludes:Instrument root valves Control relays Manual switches Equipment rating or capacity Primary instrument tubing and valves Pressure temperature and flow data Elbow, tees and similar standard fittings Extensive explanatory notes

ISA Standard for P&IDISA 5.1 Instrumentation Symbols and IdentificationISA 5.2 Binary Logic Diagrams for Process OperationsISA 5.3 Graphic Symbols for Distributed Control / Shared Display Instrumentation, Logic and Computer SystemsISA 84.01 Application of Safety Instrumented Systems for the Process Industries

ISA Standard[ Sec 5.1 1984 (Rev 1994) ]OR

Common Connecting Lines*Process or Instrument LineUndefined SignalPneumatic SignalElectric SignalHydraulic SignalCapillary TubeElectromagnetic or Sonic Signal (Guided)

ISA Standard[ Sec 5.1 1984 (Rev 1994) ]*Following abbreviation used to denote type of supplyIA Instrument Air GS Gas SupplyHS Hydraulic SupplyAS Air Supply NS Nitrogen SupplySS Steam SupplyPA Plant Air ES Electric SupplyWS Water Supply

Common Connecting Lines*Electromagnetic or Sonic Signal (Not Guided)Internal System Link (Software or Data Link)Mechanical Link

ISA Standard[ Sec 5.1 1984 (Rev 1994) ]Graphical ElementsDiscrete instruments[Circular Element]Shared control/display[Circle circumscribed by a square]Computer function[Hexagon]Programmable logic controller (PLC)[Triangle inside a square]Location Categories*Primary location[Single Horizontal Line Across Graphical Element]Auxiliary location[Double Horizontal Line Across Graphical Element]Field mounted[No Horizontal Line Across Graphical Element]*Inaccessible Devices (Mounted Behind Panel Board) [Dashed Horizontal Line]

ISA Standard[ Sec 5.1 1984 (Rev 1994) ]General Instrument or Function SymbolsSymbol size may vary according to the user's needs and type of documentAbbreviations of the user's choice may be used when necessary to specify locationInaccessible (behind the panel) devices may be depicted using the same symbol but with a dashed horizontal bar

ISA Standard[ Sec 5.1 1984 (Rev 1994) ]Letter and Number CombinationsAppear inside each graphical elementNumbers are user assigned schemes varySome companies use of sequential numberingSome tie the instrument number to the process line numberOthers adopt unique and sometimes unusual numbering systems

ISA Standard[ Sec 5.1 1984 (Rev 1994) ]Instrument Identification or Tag Number1st letter defines the measured or initiating variables Succeeding letters definingReadoutPassive functionOutput functionModifierNumber refers to loop number where instrument belongsPRC101Measured Process VariableOutput FunctionFunction ModifierBalloon (or Bubble)

ISA Standard[ Sec 5.1 1984 (Rev 1994) ](2)(3)(1)(4,5)(2,12)(2)(2)(2)(6)(7)(8,9,10)(8,9)(8,9,10)(8)(11)(14)(13)

ISA Standard[ Sec 5.1 1984 (Rev 1994) ](5)(2)(6,17,22)(6)(6)(15)(16)(17)(18)(19)(20)(21)

ExamplePRC meansPressureRecordingController101 means that instrument belongs to Loop # 101

P&ID Symbols[ Sec 5.1 1984 (Rev 1994) ]Insulated PipeJacketed PipeCooled or Heated PipePipeFlexible PipeManual ValveValveButterfly ValveNeedle ValveControl ValveDiaphragm ValveGlobe ValvePressure Reducing ValveBall ValveSteam TrapCovered Gas VentCurved Gas VentFunnelFilterDust Trap

P&ID Symbols[ Sec 5.1 1984 (Rev 1994) ]Back Draft DamperViewing GlassCoolerCooling TowerPumpVacuum Pump or CompressorAxial FanFanRadial FanBagGas BottleDryerFurnaceHeaterPressurized Horizontal Vessel

P&ID Symbols[ Sec 5.1 1984 (Rev 1994) ]Autoclave or Jacketed Mixing VesselHalf Pipe Mixer or ReactorHeat Exchangerw/ no crossflowHeat Exchangerw/ crossflowSpiral Heat ExchangerPlate and Frame Heat ExchangerUTube Heat ExchangerDouble Pipe Heat ExchangerFixed Straight Tube Heat ExchangerPacked or Fluid Contacting ColumnTray ColumnPressurized Vertical Vessel

P&ID Symbols

P&ID Symbols

P&ID Symbols

P&ID Symbols

Example of P&ID

Example of a P&IDA Heat Exchanger Control SystemReactant inSteam in Reactant outSteam out

Example of P&ID

Constructing An Instrument Flow SheetIdentify the processDefine the control objective/sCreate a process flow diagramIdentify the equipment and process linesDetermine the instrument and connecting linesUse of standard symbology like ISA codes to identify instrument and functions

ReferencesHughes, Thomas A. Measurement and Control Basics, 3rd ed. Research Triangle Park, NC: The Instrumentation, Systems, and Automation Society, 2002.

Madsen, D. A. et al. Engineering Drawing and Design. 4th ed. New York: Delmar Cengage Learning , 2006.

Perry, R. H. and D. W. Green (ed.) Perrys Chemical Engineers Handbook. 7th ed. New York: The McGraw-Hill Companies, Inc., 1997.

PIP PIC001 Piping and Instrumentation Diagram Documentation Criteria. Austin, Texas: Process Industry Practices, Construction Industry Institute, TheUniversity of Texas at Austin, Apr 2008.

Seborg, Dale E. et al. Process Dyanmics and Control. 2nd ed. New York: John Wiley & Sons, Inc, 2004.

Thomas, C. Process Technology Equipment and Systems. 2nd ed. New York: Delmar Cengage Learning , 2007.

Internet SourcesBFD Block Flow Diagram. http://www.engineeringtoolbox.com/bfd-block-flow-diagram-d_467.html

Harrold, Dave. How To Read P&ID. http://lamspeople.epfl.ch/kirrmann/ Slides/HowToReadP&ID.htm, Aug 1, 2000.

P&ID Piping and Instrumentation Diagram. http://www.engineeringtoolbox.com/p&id-piping-instrumenation-diagram-d_466.html

PFD Process Flow Diagram. http://www.engineeringtoolbox.com/pfd-process-flow-diagram-d_465.html

http://www.wikipedia.org

***A process flow diagram (PFD) is a diagram commonly used in chemical and process engineering to indicate the general flow of plant processes and equipment. The PFD displays the relationship between major equipment of a plant facility and does not show minor details such as piping details and designations. Another commonly-used term for a PFD is a flowsheet.*******Process flow diagrams of multiple process units within a large industrial plant will usually contain less detail and may be called block flow diagrams or schematic flow diagrams.

The block or rectangles used represent a unit operation. The blocks are connected by straight lines which represent the process flow streams which flow between the units. These process flow streams may be mixtures of liquids, gases and solids flowing in pipes or ducts, or solids being carried on a conveyor belt. ***Process and instrumentation diagrams are a family of functional one-line diagrams showing hull, mechanical and electrical (HM&E) systems like piping, and cable block diagrams. Abbreviated as P&ID, they show the interconnection of process equipment and the instrumentation used to control the process. They are the primary schematic drawings used for laying out a process control installation in a factory or plant. In the process industry, a standard set of symbols may be used to prepare drawings of processes, for instance the instrument symbols used may be based on Instrumentation, Systems, and Automation Society (ISA) Standard S5.1.

P&ID shows all of piping including the physical sequence of branches, reducers, valves, equipment, instrumentation and control interlocks. The P&ID are used to operate the process system.*Referring to the Example P&ID diagram, FT 101 represents a field-mounted flow transmitter connected via electrical signals (dotted line) to flow indicating controller FIC 101 located in a shared control/display device. A square root extraction of the input signal is applied as part of FIC 101s functionality. The output of FIC 101 is an electrical signal to TY 101 located in an inaccessible or behind-the-panel-board location. The output signal from TY 101 is a pneumatic signal (line with double forward slash marks) making TY 101 an I/P (current to pneumatic transducer). TT 101 and TIC 101 are similar to FT 101 and FIC 101 but are measuring, indicating, and controlling temperature. TIC 101s output is connected via an internal software or data link (line with bubbles) to the set point (SP) of FIC 101 to form a cascade control strategy.

Typical YIC indicates an on/off valve is controlled by a solenoid valve and is fitted with limit switches to indicate open (ZSH) and closed (ZSL) positions. All inputs and outputs are wired to a PLC thats accessible to the operator (diamond in a square with a solid horizontal line). The letter 'Y' indicates an event, state, or presence. The letter 'I' depicts indication is provided, and the letter 'C' means control takes place in this device. ***A piping and instrumentation diagram/drawing (P&ID) is defined by the Institute of Instrumentation and Control as follows:A diagram which shows the interconnection of process equipment and the instrumentation used to control the process. In the process industry, a standard set of symbols is used to prepare drawings of processes. The instrument symbols used in these drawings are generally based on Instrumentation, Systems, and Automation Society (ISA) Standard S5. 1.The primary schematic drawing used for laying out a process control installation.

P&IDs play a significant role in the maintenance and modification of the process that it describes. It is critical to demonstrate the physical sequence of equipment and systems, as well as how these systems connect. During the design stage, the diagram also provides the basis for the development of system control schemes, allowing for further safety and operational investigations, such as the popular Hazards and Operability (HAZOP) study.

**There are a lot of symbols being used but the ISA's are the most common. Italians (Snamporgetti, etc) and Japanese (Mitsubishi Heavy Industries, etc) uses their own. Koreans, Americans and British are using ISA. ISA symbols has been used for AUTOCAD and VISIO programs.*In process control applications, pneumatic signals are almost always 3 to 15 psig (i.e., pounds per square inch, gauge pressure), and the electric signals are normally 4 to 20 mA (milliamperes) DC (direct current).**ISAs S5.1-1984 (R 1992) Instrumentation symbols and identification standard. S5.1 that defines how each symbol is constructed using graphical elements, alpha and numeric identification codes, abbreviations, function blocks, and connecting lines.*Number 4 is the symbol for Distributed Control System.

A line across the center of the balloon symbol indicates that the controller is mounted on the front of a main control panel. No line indicates a field-mounted instrument, and two lines means that the instrument is mounted in a local or field-mounted panel. Dashed lines indicate that the instrument is mounted inside the panel.**A balloon symbol with an enclosed letter and number code is used to represent the instrumentation associated with the process control loop. This letter and number combination is called an instrument identification orinstrument tag number.

The first letter of the tag number is normally chosen so that it indicates the measured variable of the control loop. The succeeding letters are used to represent a readout or passive function or an output function, or the letter can be used as a modifier. For example, the balloon marked TE represents a temperature element and that marked TIC is a temperature-indicating controller.

Normally, sequences of three- or four-digit numbers are used to identify each loop. In the example, the number 101 represents a process loop. Smaller processes use three-digit loop numbers; larger processes or complex manufacturing plants may require four or more digits to identify all the control loops.

Special marks or graphics are used to represent process equipment and instruments. For example, two parallel lines represent the orifice plate.*Notes on Identification Letters:A "user's choice" letter is intended to cover unlisted meanings that will be used repetitively in a particular project. If used, the letter may have one meaning as a first-letter and another meaning as a succeeding-letter. The meanings need to be defined only once in a legend, or other place, for that project. For example, the letter N may be defined as "modulus of elasticity" as a first-letter and "oscilloscope" as a succeeding-letter.Any first-letter, if used in combination with modifying letters D (differential), F (ratio), M (momentary), K (time rate of change), Q (integrate or totalize), or any combination of these is intended to represent a new and separate measured variable, and the combination is treated as a first-letter entity. Thus, instruments TDI and TI indicate two different variables, namely, differential temperature and temperature. Modifying letters are used when applicable.The grammatical form of the succeeding-letter meanings may be modified as required. For example, "indicate" may be applied as "indicator" or "indicating," "transmit" as "transmitter" or "transmitting," etc.First-letter A (analysis) covers all analyses not described by a "user's choice" letter. It is expected that the type of analysis will be defined outside a tagging bubble.First-letter V, "vibration or mechanical analysis," is intended to perform the duties in machinery monitoring that the letter A performs in more general analyses. Except for vibration, it is expected that the variable of interest will be defined outside the tagging bubble.A device that connects, disconnects, or transfers one or more circuits may be either a switch, a relay, an ON-OFF controller, or a control valve, depending on the application. If the device manipulates a fluid process stream and is not a hand-actuated ON-OFF block valve, it is designated as a control valve. It is incorrect to use the succeeding-letters CV for anything other than a self-actuated control valve. For all applications other than fluid process streams, the device is designated as follows:A switch, if it is actuated by hand.A switch or an ON-OFF controller, if it is automatic and is the first such device in a loop. The term "switch" is generally used if the device is used for alarm, pilot light, selection, interlock, or safety.The term "controller" is generally used if the device is used for normal operating control.A relay, if it is automatic and is not the first such device in a loop, i.e., it is actuated by a switch or an ON-OFF controller.The passive function G applies to instruments or devices that provide an uncalibrated view, such as sight glasses and television monitors.The use of modifying terms "high," "low," "middle" or "intermediate," and "scan" is optional.The modifying terms "high," and "low," and "middle" or "intermediate" correspond to values of the measured variable, not to values of the signal, unless otherwise noted. For example, a high-level alarm derived from a reverse-acting level transmitter signal should be an LAH, even though the alarm is actuated when the signal falls to a low value. The terms may be used in combinations as appropriate.The terms "high" and "low," when applied to positions of valves and other open-close devices, are defined as follows: "high denotes that the valve is in or approaching the fully open position, and "low" denotes that it is in or approaching the fully closed position."Indicate" normally applies to the readoutanalog or digitalof an actual measurement. In the case of a manual loader, it may be used for the dial or setting indication, i.e., for the value of the initiating variable.Modifying-letter K, in combination with a first-letter such as L, T, or W, signifies a time rate of change of the measured or initiating variable. The variable WKIC, for instance, may represent a rate-of-weight-loss controller.Succeeding-letter K is a user's option for designating a control station, while the succeeding-letter C is used for describing automatic or manual controllers.A pilot light that is part of an instrument loop should be designated by a first-letter followed by the succeeding-letter L. For example, a pilot light that indicates an expired time period should be tagged KQL. If it is desired to tag a pilot light that is not part of an instrument loop, the light is designated in the same way. For example, a running light for an electric motor may be tagged EL, assuming voltage to be the appropriate measured variable, or YL, assuming the operating status is being monitored. The unclassified variable X should be used only for applications which are limited in extent. The designation XL should not be used for motor running lights, as these are commonly numerous. It is permissible to use the user's choice letters M, N or O for a motor running light when the meaning is previously defined. If M is used, it must be clear that the letter does not stand for the word "motor," but for a monitored state.

*Notes on Identification Letters:The word "record" applies to any form of permanent storage of information that permits retrieval by any means.The term "safety" applies to emergency protective primary elements and emergency protective final control elements only. Thus, a self-actuated valve that prevents operation of a fluid system at a higher-than-desired pressure by bleeding fluid from the system is a back-pressure-type PCV, even if the valve is not intended to be used normally. However, this valve is designated as a PSV if it is intended to protect against emergency conditions, i.e., conditions that are hazardous to personnel and/or equipment and that are not expected to arise normally. The designation PSV applies to all valves intended to protect against emergency pressure conditions regardless of whether the valve construction and mode of operation place them in the category of the safety valve, relief valve, or safety relief valve. A rupture disc is designated PSE.For use of the term "transmitter" versus "converter.Use of first-letter U for "multivariable" in lieu of a combination of first-letters is optional. It is recommended that nonspecific variable designators such as U be used sparingly.Use of a succeeding-letter U for "multifunction" instead of a combination of other functional letters is optional. This nonspecific function designator should be used sparingly.The unclassified letter X is intended to cover unlisted meanings that will be used only once or used to a limited extent. If used, the Letter may have any number of meanings as a first-letter and any number of meanings as a succeeding-letter. Except for its use with distinctive symbols, it is expected that the meanings will be defined outside a tagging bubble on a flow diagram. For example, XR-2 may be a stress recorder and XX-4 may be a stress oscilloscope.First-letter Y is intended for use when control or monitoring responses are event-driven as opposed to time- or time schedule-driven. The letter Y, in this position, can also signify presence or state.It is expected that the functions associated with the use of succeeding-letter Y will be defined outside a bubble on a diagram when further definition is considered necessary. This definition need not be made when the function is self-evident, as for a solenoid valve in a fluid signal line.***************