CAD in Process Plant Engineering - Society of Piping ...

CAD in process plantengineeringby James MaddenIsopipe Ltd.

Developing CAD systems for the design and layout of process plantinvolves an investment of millions of pounds. Today the provenbenefit of using such systems is apparent, but without commitmentand foresight from software developers such tools may never beseen in the market. One such product, PDMS, was a jointdevelopment between CADCentre, Isopipe and Akzo Engineering,started in 1974 and first sold in 1977. Since then many thousandsof man-hours have gone into developing the system.

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Introduction

Computers have been used in process plantengineering for more than 20 years, and itis difficult to imagine engineering nowwithout computing, even in the limited andrather fragmented forms that have so fargained general commercial acceptance. Theusage of computers is accelerating in scaleand in scope; acronyms such as CAD(computer-aided design), CAM (computer-aided manufacturing) and CAE (computer-aided engineering) have appeared, andcommercial vendors are offering to solvealmost any problem known to designers ormanagers. Computer aids to engineeringoffer great benefits, but the dynamic stateof the techniques and the cost of faultychoices, either in computing systems orapplications, inhibit engineers from reapingtoday's benefits or from planning the futureof their art.

'Design' never exists in abstract or inisolation. It exists only as part of a properlymanaged process intended to transform anidentified need into a working engineeringmeans of satisfying that need — in our case,a plant. As such, 'design' must embrace notonly the creative, analytical processclassically (but confusingly) called design;it must also cover the drafting operation andthe use of associated data generated fromdrafting which enables management tomobilise and control the resources neededto build the plant.

Since 'design' in this definition is such an

integral part of the engineering profession,we must set out clearly the aims that wewish to attain in the design process by usingcomputer-aided design. Appropriate aimsfor CAD are therefore suggested as:

• extending the designer's capabilities toperform calculations, assemble, manipulate,retrieve and present data about the design,and visualise and communicate the design• not only enlarging the scale of thedesigner's capabilities but also increasingthe reliability of calculation, data, drawingsand communication• reducing the time spent by designers,draftsmen and detailers in the whole designprocess.

The plant engineering process

Process plant design is more than the taskof performing calculations and makingdrawings. The complexity of a processplant, the large number of peoplesimultaneously engaged on its design andthe wide range of engineering disciplinesand functions represented by those peoplerequire an orderly environment in whichcorporate control, project control,competent design, inter-discipline co-ordination and plant construction can becarried out.

Corporate management must setperformance standards, arbitrate betweenconflicting demands of different disciplinesand promote good communications

Computer-Aided Engineering Journal December 1987

between designers, managers, suppliers andclients.

Designers must apply their specialistengineering discipline to the problems inhand, co-ordinate their own efforts withinthe project team, and provide the finaldrawings and specifications for plant con-struction.

There is, therefore, no single 'designproblem' amenable to settlement by a single'design solution'. There is, instead, a set ofidentifiable design tasks which mustproceed in an orderly sequence through adefined management structure fromspecification to construction. Theprogression is illustrated by Fig. 1, and threemain consecutive phases of the project fromconception to completion are characterisedby the principal (but not exclusive) concernof the phase: namely, design, drafting andmanagement. In practice, the phases oftenoverlap in timing and do not have rigidboundaries, but Fig. 1 highlights the gradualshift of emphasis from specifying the plant,through design and drafting to its finalmanufacture and construction inaccordance with the specification.

The design phase

The design phase is examined in moredetail in Fig. 2. Starting with a projectspecification which states what is to beachieved, a single designer or small groupof designers apply their own experience andcreativity to establish an overall designconcept that defines how the specificationwill be met. Development of this conceptis constrained by the level of engineeringscience and physical property data availableto the group. In process plant terms, thisprocedure would start with a productionrequirement, which would be translatedinto a flowsheet by chemical engineersusing chemical data, physical chemistry andchemical engineering science.

The overall design concept expressed in

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the flowsheet is then available for specialistengineering disciplines (such as equipment,piping, electrical or instrumentation) toproduce more detailed design informationon the components of the plant called forby the flowsheet through the application oftheir own skills, physical data and engin-eering sciences. During this stage, forexample, a distillation column specified onthe flowsheet by its diameter and heightwould be worked up into an outlineengineering drawing by an equipmentdesigner, combining considerations ofstructural analysis, stress analysis, metalproperties and fabrication techniques intoan outline engineering design of thecolumn.

An important element at the specialistengineering stage of the design process isthe creation of a three-dimensionalconceptual model which establishes howall the components of the design conceptare to be arranged so that they fit within thespace available and fulfil the projectspecification. The conceptual model mustbe set up also in accordance withrelationships existing in the design concept:for example, equipment must be connectedby pipes in strict conformity with processflow; equipment elevations must be correctetc. Relationships are an important part ofthe conceptual model, even though theymay be implied or stated in words ratherthan being obvious physical attributes suchas diameter, flow rate or direction.

The principal characteristic of thedesign is the problem solving approach, bywhich specific design features (for exampleheat exchanger designs) are subjected tological, well established and oftenextremely complex mathematicalprocedures. Normally, in these proceduresa small number of design parametersundergo large-scale analytical andnumerical manipulation to yield a relativelysmall amount of data defining a designanswer.

The obvious difficulties of solving theproblem tend to obscure a considerableamount of manual design work devoted tofinding and checking design parameters andto communicating information through theteam of specialist designers.

The drafting phase

One main communication task is that ofproviding a single, visible manifestation ofthe conceptual model to all staff to ensurethat all design work is carried out on acorrect, up-KxJate, management-authoriseddesign basis. Since engineers communicatemost easily through pictures, drawings areaccepted as the best means ofcommunicating and co-ordinating informa-tion flow within and between all phases ofthe project. Two principal drawings ofparamount importance for these purposesin process plant design are the co-ordinated

layout drawing and the piping andinstrumentation diagram (or P&ID). Theco-ordinated layout drawing controls andrecords the arrangement of the plantcomponents in the available space, and theP&ID expands the information of therelationships contained in the flowsheet.

Production of these (and most other)drawings is centred in the drafting phase ofFig. 1, when the overall design concept isreleased for detailed engineering to beperformed by specialist engineering disci-plines such as civil, equipment, piping,instrumentation and electrical engineeringgroups. Each of these specialist disciplineshas a design task of applying its ownengineering science to an aspect of theoverall design concept to produce detailedspecifications of the components(steelwork, vessels, pipes, valves, motors,control valves etc.) making up theconceptual model. An integral and majormethod of validating and communicatingthese detailed specifications is theengineering drawing, produced by eachspecialist discipline to its own format by thedrafting process (Figs. 3a and b), employingdrafting conventions to convey informationin a stylised common format.

Because drafting is such a large andintgral part of the detailed design engin-eering process, drafting and design are oftentreated as a single operation. They are,however, quite separate, as Fig. 3 shows.An essential preliminary to drafting is thedetailed specialist design work thatestablishes the physical characteristics (type,shape, dimensions etc.) of the componentswhich will fulfil the design concept.

These components and theircharacteristics will vary for each specialistdiscipline, and they are represented ondrawings by symbols and techniquesappropriate to that discipline. The draftingtechniques used to present the componentson all drawings, however, are totallyformalised in their use of projection, scale,symbolic representation and dimensioningand in standards adopted for annotation,drawing sheets etc. across all disciplines.

To illustrate the process, consider Fig. 3a,where the overall design concept in theform of the flowsheet is taken up by thelayout designer. His first task is to obtainoutline sizes and shapes of the processequipment (the 'components') and considerhow they should be arranged to satisfy theprocess by applying the specialistdisciplines of layout design. The result ofthis operation is a layout that exists in thedesigner's mind and which must be trans-ferred to paper so that other engineers canvisualise and understand the layout.

Accordingly, very simple representationsof the equipment are conceived todistinguish between equipment types.These representations are then drawn toscale, usually in plan using the draftingconventions, and the resulting specialist

engineering drawing is the equipmentlayout, understandable by any otherengineer. Addition of material obtainedfrom drawings produced in other disciplines(representing their aspect of the designconcept) converts the equipment layout intothe co-ordinated layout drawing, used as themaster plan for allocating space in the plantamong the conflicting demands of thevarious disciplines.

A similar, but somewhat simpler,procedure can be seen in Fig. 3b for theelectrical engineering discipline. Theoverall design concept is still the start point,but the part of the model under electricalengineering consideration is, say, the powerdistribution required to serve the equipmentshown on the flowsheet. Again, a necessarydetail design stage is required to establishthe 'components' needed for powersupplies (motors, switchgear, cabling etc.),but in this case the relationships betweenthe components must be considered toestablish cabling connectivity. Once thesecomponents and relationships have beenestablished, however, and the electricaldrafting conventions are defined, thecommon drafting process is applied toproduce a totally different form of drawing— a power distribution diagram. Laterdrafting work will use this diagram as a basisfor detailed drafting and scheduling formanufacture.

The important feature of Figs. 3a and bis the commonality of the actual draftingwork, which, when applied to differentengineering disciplines, produces manydifferent forms of drawing. Thecommonality of drafting and the largeamount of drafting work in a project haveattracted much management attention in thepast to improve company performance inthe whole drafting phase.

The management phase

Production of the detailed engineeringdrawings initiates a change of focus fromthe tasks of drafting to those of managingthe manufacture and construction stages,and management becomes the majorpriority in the project. Manufacture andconstruction must be based on the engin-eering data contained in the specialistengineering drawings, combined with thecost and schedule parameters set by projectbudgets and completion requirements. Fig.4 illustrates some of the essential steps ofthis, the 'management phase', and showsa further necessary consideration in theinjection of company managementdocument formats so that design and projectdata can be presented in a recognisableauthorised form, enabling staff to proceedwith procurement, manufacture etc.Although the management phase mayappear to many creative engineers anddesigners to be less interesting than thepreceding design and drafting phases, the

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238 Computer-Aided Engineering Journal December 1987

challenges of management are no lessdemanding on the ability and creativity ofengineers.

Evolution of CAD use

The three project execution phasesdiscussed above impose diverse andapparently conflicting requirements on anintegrated plant design and managementsystem. An obvious difference appears inthe 'problem solving' and 'data handling'aspects.

'Problem solving' is often based on a fewimput parameters which are fed into acomplex mathematical algorithm, fromwhich an answer emerges as a smallamount of data. In cases where an overallsolution is required for a set ofinterdependent problems in a sequence orin a loop, the data volume in terms of bothinput parameters and the answer isrelatively small, even if intermediate datatransfer between design stages requiresdesigner intervention to accept or modifyparameters. Single- or multi-columndistillation processes represent one typicaldesign task employing complexmathematical computing routines based onsmall data volumes.

'Data handling' requires the input,processing and distribution of large volumesof data, with little or no mathematicalprocessing. The data usually consists ofsingle simple facts established by the project

team, and covers diverse topics such asprocess temperatures and pressures, pipesizes, piping component quantities, drawingnumbers and costs. Processing is usually inthe form of extremely simple addition,sorting or merging of individual items ofdata. The problems of data handling arisemainly from the volume of data and themany different types, plus the consequenteffects that changing one data item can haveon many other data items.

Historically, computer use in the industryhas attacked these two well defined typesof situation separately, partly because of thedirectly measureable benefits that wereobtainable and partly because computingequipment and techniques of scientificcomputing and data processing, developedfor general use outside the industry, couldbe most easily adapted.

In the 'problem solving' area, programsfor complex calculations in fields such as:

• distillation (CONCEPT, MULTICOL,SS19)• heat transfer (HTFS)• mass transfer• reactor design• structural analysis (STRUDL,NASTRAN)• pipe stress (PSA5, PIPESTRESS,TRIFLEX)

became available from the early 1960sonward, and are now so powerful and

economical that their use is virtuallyessential for efficient design. Benefits gainedby the use of these programs include thefollowing:

• Designers produce more design resultsin less time.• Designs are completed in shorterelapsed times.• More alternative designs can beexplored before one particular solution isadopted.• Designs are more accurate, with lesschance of arithmetical error.• Design methods can be standardisedwithin the company.• Design answers are more reliable.

Over the same period, the 'data handling'area employed conventional commercialdata processing procedures of mass datahandling, file manipulation and printedoutput reports. Most of the work was (andis still, largely) concerned with bulkmanagement information for functions suchas:

• project costing• CPM/PERT scheduling• materials management (for exampleCOMPAID, CAPICS, ISOPEDAC).

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a layout drawing), a highly structured dataentry system is necessary. Similarly, outputreports for use by designers or managerstend to be rigid in format, terminology andcontent because of the limitations of dataprocessing techniques. These disadvantageshave not prevented widespread use of theprograms because the management benefitsgained have justified the imposition of extradata disciplines on designers. Principalbenefits identified include the following:

• reduction in detail drafting and clericalhours spent in counting, listing etc.• more accurate and reliable reports• better project management based onbetter and faster information on, forexample, material or cost changes.

Both types of program were originally runon large mainframe computers as batchprocesses. Input data was converted topunch cards or tapes for entry to thecomputer, and answers were output almostentirely as printed lists. Some programs hada graphic facility for making a drawing fromthe input data, but only drawings whosestyle, symbology and format could bepredetermined were possible. COMPAIDand ISOPEDAC are programs for producingstylised drawings of this nature (piping

isometrics).Developments in mainframe computers

and computing languages which allowedmultiple-user time sharing encouraged thedevelopment of conversational programshaving facilities for questioning, promptingand helping the user to enter and check datafed to the program. A later development ofthis type of program also permits the userto see and act on the data created by theprogram from the user's input parametersduring the running of the program. This'interactive' facility means that the designercan ensure that the program processes onlyvalid parameters and stores only validaccepted data, which can be refined orchanged in a future interaction with theprogram.

Historical developments

Advances in computer hardware led in thelate 1960s to the 'minicomputer', aphysically small but powerful machine,capable of operating in normal officeconditions and available at low cost. Theperformance/cost characteristics ofminicomputers permitted them to bededicated to specific functions whoseimmediate cost benefits covered therelatively low cost of the machine. New

methods in computer graphics, whenprogrammed for dedicated minicomputers,produced the now familiar drafting systems.These systems, combining humaninteraction and computer graphics, enablea draftsman to create and modify anengineering drawing very rapidly.

Drawings are produced by systemcommands which set up lines, curves,symbols, letters etc. in the computermemory. The draftsman can see thedrawing as he develops it by means of avisual display unit, on which the computerdisplays the drawing currently held inmemory. Repeated interaction between thesystem and the draftsman develops theinitial blank sheet into a finished drawing,which can then be computer-plotted onnormal drawing office media. High-qualitydrafting and appreciable draftingproductivity gains can be made, but thedraftsman must start from a designer'ssketch or instruction, and must have aknowledge of his engineering discipline tomake good drawings. Hence these systemsonly affect the drafting phase, and have noimpact on design.

A later (and still current) development incomputing systems concerns the way inwhich data is stored and handled within acomputer as a database. Before the


development of database techniques, eachprogram held its own data separately in aformat suited only to the needs of thatprogram. Consequently, one data item tobe used by several design programs had tobe entered separately to each program,possibly in different formats. Also, data inthe format used or output by one programcould not easily be used by anotherprogram, and manual inter-program trans-cription was required.

In a database, however, each data itemis stored only once in a generalisedcomputer format. Data items can be enteredto a database in designer-specific terms andformatted by the computer; more signifi-cantly, the formatted data items can beaccessed by any suitable design or datamanagement program.

Since a data item is generally available,it need be entered only once by theengineering discipline responsible for itsgeneration, but it can be accessed and usedby any other discipline, which may generatefrom it dependent data items that are alsostored in the database. When the basic dataitem is changed by its designer in responseto a project change, the dependent dataitems can be located and changedcorrespondingly by the database operatingsystem. Access to single data items orgroups of items can be made quickly, easilyand in designer terms; thus project or designchanges can be made relatively easily, andtheir consequent effects highlighted fordesign action.

All these developments — minicom-puters, workstations, databases and graphics— have already been employed commer-cially to provide new forms of CAD systemsthat suggest a pattern for developments offuture installations which will integratedesign, manufacture and management.

Integrated plant engineering systems

Improvements in process plant engineeringwill be greatest when the three phases ofdesign/drafting/management are based ona common store of data, starting at thedesign concept and expanding throughdetail design to final construction. Underthese conditions, all design and manage-ment action can be based on accurateinformation; thus performance and pro-ductivity improvements can be expected.Application of some current and possiblefuture concepts to the problem solving,drafting and data handling requirements ofthe engineering process discussed enablesthe followingaims to be suggested for anintegrated engineering system:

• Integrate the design/drafting/manage-ment process through a common store ofdata defining all aspects of the project, anda common management procedure definingall inter-stage communications.• Create a computer model of the overalI

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design concept, and progressively updateit to the final detailed three-dimensionaldesign model of all components, their pro-perties and their relationships.• Transfer all necessary data from themodel to the common data store.• Produce pictures or drawings of themodel or any group of components in themodel.• Develop problem solving programs toreceive input parameters from the commondata store and to return output answers tothe store for incorporation into the model.• Employ database technology tomanipulate all the data in the store.• Employ the computer model to drivecomputer-aided techniques for plantcomponent manufacture and construction.

The sum of all these aims is the totalcomputer-based integration of the entiremanagement of a plant project from con-ception, through design, manufacture,construction and operation to final obsoles-cence — which may represent a 15-yeartime span. Although this goal is beyond ourreach today, enough proven commercialwork has been done to indicate that it isrealistic. To illustrate the current state of theart, two systems in commercial use can beexamined briefly and their featurescompared against the aims set out above.

Current commercial design systems

The systems considered, PEGS (ProjectEngineering Graphics System) and PDMS


(Plant Design Management System), operatein different parts of a project for differentpurposes at different times, but both sharesome important common system designfeatures:

• a database holding all system data• a partial model of the design, held inthe database• operating programs which accesssystem data for performance of design, orinformation processing tasks• graphics capabilities for presentation ofdatabase information on drawings• interactive operation using designers'terms and language• operation on minicomputers andgraphics workstations• ability to transmit or receive data to orfrom other computer systems.

Both systems therefore fulfil in part someof the aims defined above for the total inte-grated system.

PECSPEGS is concerned mainly with managing

the 'process data' — that large amount ofdata items needed to define the propertiesof plant components, process conditionsand piping, together with the relationshipsbetween components and their sharedproperties. The properties of a componentconsidered in PEGS are factual data itemswhich are specific to that component. Forexample, a pipe has the properties ofidentity number, specification, terminal

241

points, nominal size, material, process fluid,temperature range, pressure range, flow rateetc. The properties are not unique; onespecification applies to many pipes, or oneprocess fluid may flow between severalvessels through several pipes.

Relationships may be either hierarchical,through which one component 'owns' othercomponents on a designer-specified basis,or relationships may arise throughcomponents having certain properties incommon. For example, a pipe is a memberof the hierarchy:

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etc.and these relationships can be held in the

database. A pipe also may haverelationships arising from properties whichare common to other pipes (for examplespecification, connection to a vessel,nominal size, process fluid etc.), and pipeswhich are related by any of these propertiescan be identified in the database (Fig. 5).The relationships shown do not include allpotential relationships between a pipe andother parts of the project; of those shown,PEGS handles many of greatest interest tothe process engineer.

Understanding relationships is madeeasier when they can be visualised; thepiping and instrument diagram serves thisvisualisation need in plant and pipingdesign. PECS is able to use the hierarchicalrelationships in the database to assistdraftsmen to produce these vital drawingscorrectly and quickly. In this, the systememploys conventional interactive graphicstechniques and information transfer fromthe database driven by instructions from adraftsman.

While the P&ID is a major project

document, it must be supported by reportslisting groups of project components ofinterest to designers and managers,normally on the basis of commonproperties. Examples of reports familiar todesigners and managers include theequipment list, pipe schedule, valveschedule, list of users of one particularutility, instrument schedule etc. These andany other required report can be producedfrom the PEGS database.

Experience of the system indicatesbenefits in the following areas (Ref. 1):

• data input — simplified, since each dataitem need only be entered once to beavailable thereafter to all users• data consistency — improved, since thesame data item often appears on manydocuments and is always identical on eachone• design consistency — checks can bemade to prevent some errors; for example,no item numbers can be duplicated, andtwo single-phase process streams from a

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common source must have identicalcomposition and properties• P&ID production —improved accuracy• change management — simplified,because once a data item is changed itsimpact on other parts of the design can behighlighted for action.

PECS can thus be seen as a manager ofplant data and relationships in a logical butabstract sense which takes no account of thegeometric properties of the plant. Plantgeometry and its design and datamanagement consequences are the concernof the second system to be considered,PDMS.

PDMSThe principal feature of PDMS is its

construction under designer control of afull-size three-dimensional computer modelof the plant layout, held in a database. Themodel can contain all components —structure, equipment, piping, cabling,ducting, access areas etc. — which take upspace in the plant. The layout designer mustarrange these components in the spaceavailable and must exercise judgment onwhich components have the greatest claimon available space. PDMS provides thedesigner with two principal aids at thisstage:

• graphical — a picture of the model inthe database can be drawn from anyviewpoint (Fig. 6)• logical — clashes between any twocomponents interfering with each other canbe detected.

As the three-dimensional layout progresses,the piping is added in increasing detailaccording to the requirements of the P&ID.Although piping is the principal concern ofPDMS, all other layout-related data fromother disciplines is input to the PDMSmodel to ensure that the final plant layoutis fully co-ordinated and error-free.

To make the computer model usable anduseful to designers and management, thePDMS database also stores properties andrelationships of the plant and piping com-ponents. PDMS is generally concerned withthose properties defining dimensions,positions, identities etc. necessary for three-dimensional modelling, and with therelationships defined for piping designorganisation. Reports necessary for pipingdesign and management which combinedata on component properties, dimensionsand relationships can be produced from thedatabase in familiar formats: nozzleschedules, pipe schedules, valve schedules,material quantities etc.

When the plant, and piping layout, iscompleted, conventional engineeringdrawings (for example Fig. 7) can beproduced automatically from the databaseto link the design model with the drafting

phase. This linkage can be pursued furtherthrough PDMS interfaces to piping detaildrafting and material management systemssuch as COMPAID or ISOPEDAC to conveyinformation from the design model throughdrafting into the management phase.

PDMS users report (Ref. 2) generallyfavourable reactions to the system facilities,particularly:

• manhour savings — significant, but notthe major benefit• improvement of information fed intothe management phase for fabrication,construction etc.• improved plant records• interference detection, saving on-sitetrouble and expense• improved drawings and new forms ofdrawings especially suited to construction.

PDMS is, therefore, a means of linking thedesign concept to the three-dimensionaldesign model and managing plant space,geometry and data in both a logical andphysical sense. The system linkages into themanagement phase for manufacture andconstruction of piping introduce an elementof CAM for the first time into plantengineering.

Possible future developments

Although these (and probably other similar)systems have found acceptance oncommercial-benefit grounds, their truesignificance is the reasonably advanceddegree to which they fulfil the aims set outfor 'ideal' CAD techniques of plant design.Much remains to be done to produce the'ideal'; how much can be gauged byconsidering that the PDMS data represents,perhaps, only 5% of the total data neededto define the plant and manage its design.Current PDMS projects have databasesaround 100 Mbytes, which must be held in

active store and available for interactiveaccess at all times. The computerequipment and software strategies requiredfor an interactive data access managementproblem of 400 Mbytes will almost certainlybecome readily available in the medium-term future, and will enable a fullyintegrated plant engineering system to beconceived and implemented.

How quickly such a system can bepostulated will probably be determined byprogress in the database area. Whether asingle, unitary database can be structuredto contain, for all plant components, theirproperties and all their potential relation-ships is not yet clear. Current practice hasfound separate partial databases to be morepractical and economical in software andcomputing terms, as experience with PEGSand PDMS has shown. Progress towardsunifying these partial databases has, so far,been limited to inter-system data transfer atthe input/output language level. Directdatabase-to-database information transfer ispossible, but has not yet been achieved.However, this method of system designprobably offers more promise in the shortterm than the unitary database concept.

Engineers in design and managementhave an important role in databasedevelopment, which they must recognise.As databases (even for partial databasesystems) become more complex andcontain more data, rapid and meaningfulaccess to designer-selected parts of the databecomes an important factor in the effectiveuse of a system. The fastest and mostpowerful access means is through a datahierarchy, embodied in the databasestructure. The hierarchy must, however,relate primarily to the design ormanagement task for which the computersystem and database are used. Specificationof the design/data hierarchy is thus thedirect responsibility of the engineer, basedon his knowledge of the engineering pro-

Fig. 6 Process plant layout — pictorial views

Computer-Aided Engineering Journal December 1987 243

Fig. 7 Process plant layout — elevation

cess, which must be conveyed to the com-puter system specialist to ensure that thesystem will work properly in an engineeringenvironment. Successful single-purposedesign systems have been produced witheffective single-purpose hierarchies, but thedevelopment of integrated systemscombining several design/data hierarchieswith a single database has not yet beenachieved.

Trends in computer equipment can bediscerned in the workstations alreadyavailable, which employ microcomputertechnology to provide low-cost devices withconsiderable local computing power forgraphics and data processing. Use of thesedevices may well remove large parts of suchactivities as problem solving, graphics andspecialist data handling from the centralcomputer. If appropriate software anddatabase methods emerge, the centralcomputer may then be able to handle datavolumes of total integrated plant designproportions.

Preparing for the future

The benefits of present-day computer tech-niques are sufficiently recognised to ensurethat development will continue towardsintegrated systems and more sophisticatedhardware. Future techniques of design,drafting and information handling will beradically different from those now practisedby traditionally trained engineers inconventional design offices. Changes intraining, attitudes and management will beneeded if engineers are to control the newtechnology and their professional future.Aspects of plant engineering which meritcareful study and preparation for change areas follows:

• Education: Future students will haveseen computers, VDUs and electronicgames from childhood. They will need to

use complex, industrial-scale computing inhigher education as a precursor to indust-rial careers. Present emphasis on scientificprogramming languages and problemsolving should expand to include datahandling. Could the use of graphics anddrafting systems replace the time consuminglearning of drafting skills? The industry musthelp — by making programs and systemsavailable to educators and by releasingpractising engineers and managers to assistin engineering courses. Mid-career coursesto update the skills and knowledge ofpractising engineers in computing tech-nology must be developed by universitiesand the industry.• Engineers: Engineers must regardcomputers and systems as their professionaltools, and use them to improve productivityin the engineering process. Faster designturnround will mean that a larger numberof jobs are simultaneously in the designer'smind, competing for his attention, judgmentand creativity. However, much less detailedwork in extracting and checking data willbe required. Computing will encouragecreativity and allow designers to create andevaluate more alternative solutions in amore rational, more numerate manner.However, computer techniques even todaytend to mask unreasonable answers, andengineers must retain a firm grasp of basicsand cultivate a critical approach tocomputer answers to trap absurdities.

• Managers: Managers will have betterinformation, available more quickly, moreobviously relevant to the design and moreuseful in transforming the design into aplant. Budgets and timescales will be corres-pondingly tighter, and management is notlikely to be an easier task — even thoughit will be better informed. Increased capitalinvested in computers and systems willdemand more attention from designmanagement to smooth peak loads andmaintain technical and productionstandards. Inevitably, more attention will berequired in a non-computerisable area: themanagement and motivation of intelligent,educated people.

The process industry

Plant design and construction will be fasterand cheaper in real terms; hence theindustry's efficiency in utilising capital canbe increased. Better documentation of plantfor statutory, operational and maintenancepurposes will be available. Facilities willbecome available to improve design tominimise noise and pollution; perhaps themajor advance will be in hazard analysis.In this area, increasing public concern willprobably demand that the reasoning andmethods underlying adoption of a particulardesign be recorded, together with thereasons for rejecting alternatives. Thecombination of public pressures (expressedthrough legislation) and availability of morepowerful hazard analysis techniques maywell lead the industry to a similar situationas exists in the aeronautical industry, whereexternal validation of sophisticated engin-eering technology has improved publicconfidence in the integrity of the industryand its products.

The process industry will be served in thefuture by engineers who will be working ina more critical social environment, and theywill need the best design and managementtechniques. To improve these techniqueswill not be easy; it will require engineersand managers to cultivate an innovativeapproach to the practice of engineering. Theindustry and its managers, in particular,must recognise that innovation is difficult,costly and fallible. It is, however, theindustry's only hope of survival, andinnovators must be encouraged andsupported so that we can look forward tothe computer-based integration of plantengineering.

References

1 THOMSON, I. M.: 'Computer aided data management in process design'. Chemasia 81 Congress,Singapore, 1981

2 ARMOUR, D. B.: 'PDMS: its impact on engineering design'. 1981 Annual Meeting of AmericanInstitute of Chemical Engineers, New Orleans, LA, USA, Nov. 1981

J. Madden is Managing Director of Isopipe Ltd., Barker Gate House, Belward Street, NottinghamNG1 1JZ, England.This article is based on a paper presented at the Institution of Chemical Engineers jubilee Symposium,held in London, England, in April 1982.


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