3.Plot Plants

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H P T E R

The plot plan is one of the key documents producedduring the engineering phase in any processing facil-ity It is used to locate equipment and supporting in-frastructure and to establish the sequence of majorengineering and construction actiVities Plot plans areused by almost every engineering group within a project task force from estimating and scheduling throughconstruction. The plot plan is developed by the plantlayout designer, usually at the proposal stage of theproject, and remains the responsibility o the designerthroughout construction. Similar process units engineered for two clients may look vastly different forvarious reasons, including available real estate, soiland climate conditions, and client philosophy o operation, maintenance, and safety. For these reasons,standardization o process unit plot plans is difficult.Nevertheless, as most operating facilities use commonequipment e.g., shell and tube heat exchangers, pressure vessels, pumps, and compressors , it is possibleto apply a few basic rules that suit most clients andprocesses and that enable the plant layout designer toapproach the task o arranging the equipment andsupporting facilities in an orderly manner.

THE PLOT PL N IN THE PRO ESS UNIT

This chapter highlights the general requirements forprocess unit plot plan arrangement. It identifies theinformation reqUired to locate operating eqUipmentand supporting facilities to suit operator and maintenance access, constructibility, process operat ion,safety, and cost-effective design.

DEFINITION

The process unit plot plan an arrangement draWingthat highlights the equipment and supporting facilities

e.g., pipe racks and buildings . These are reqUired fora given process integrated within a common battery

Plot Plans

limit area, usually designed for independent operationand shutdown. The final plot plan identifies all thecomponents by designated numbers and shows, toscale, the basic shapes of the equipment and supporting facilities, locating them in both the vertical and thehorizontal planes. Generally, the arrangement isshown in the plan with elevated views furnished onlyfor clarity e.g., in the vertically structured plant Plotplans developed with three-dimensional C D modeling have the advantage of producing multiple plans,elevations, and isometric views with no additional ef-fort. The plot plan is used for the functions discussedin the follOWing sections.

Piping design The plot plan is used to produceequipment arrangement studies that facilitate the in-terconnection of above- and below-ground processand utility piping systems and to. estimate piping material quantities.

Civil engineering The plot plan is used to developgrading and drainage plans, holding ponds, diked ar-eas, foundation and structural designs, and all bulkmaterial estimates.

Electrical engineering The plot plan is used to produce area classification draWings, to locate SWitchgearand the incoming substation and motor control center, to rOute cables, and to estimate bulk materials.

Instrument engineering The plot plan is used to lo-cate analyzer houses and cable trays, assist in the location of the main control house, and estimate bulk ma-terials.

Systems engineering The plot plan is used to facili·tate hydraulic design, line sizing, and utility block flowrequirements.

Scheduling The plot plan is used to schedule theorderly completion of engineering activities.


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XHI IT 3 1Sample roposal lo tPlan

Construction The plot plan is used to schedule theerect ion sequence of all plant equipment, which in-cludes rigging studies for large lifts constructibility

reviews, marshaling, and lay-down areas throughoutthe entire construction phase.

Estimating The plot plan is used to estimate theoverall cost of the plant.

Client use The plot plan is used for safety, operator,and maintenance reviews and to develop an as-builtrecord of the plant arrangement.

PLOT PL N EVELOPMENT

Developing a plot plan is not an exact science, becausethe arrangement of the plant must be set at the beginning of the project before all equipment requirementsand configurations are finalized and before all of themechanical problems associated with the design aresolved. Plot plan arrangement is a reflection of thedesigner s ability to anticipate mechanical problemsand proVide the necessary access for operat ion andmaintenance as well as the designer s general experience with plant layout requirements. The intendedgoal is to produce a safe, cost-effective operationalplant, which will probably remain in use for at least 25years. Therefore, it is important that any errors in

Process P anl Layout a nd Piping esign

arrangement be recognized and eliminated during theplot plan development phase of the project becausethey can be costly to correct once the plant is in opera

tion.Plot plans are generally developed in stages, from

the initial concept to the fully dimensioned documentat the construction issue stage.

The proposal plot plan, shown in Exhibit 3 1 isdeveloped during the estimate phase of the projectand is used to estimate bulk materials. It is also in-cluded in the proposal as a representation of the unitarrangement to the prospective client. The proposalplot plan is based on limited information and generally indicates only the principal items of equipment,main supponing (acilities, and overall dimensions.

After contract award, the proposal plot plan is updated to suit the latest information and is reviewedand approved by the client. This document becomesthe basis for the plant layout phase of the project andis called the planning plot plan. A sample planningplot plan is shown in Exhibit 3 2 On completion ofthe plant layout phase when all the equipment hasbeen sized and is in the best posi tion to suit the project requirements and when all access roads, buildings,and pipe racks have been located the plot plan isfinally issued for construetion. This is illustrated inExhibit 3 3 as the construction plot plan.

To develop a plot plan, the designer must assemblethe information discussed in the follOWing sections.


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EXlUBIT 3 Sample Planning Plot Plan

The equipment list This document lists all the itemsof equipment and buildings by number and descrip-tion to e included within the unit battery limits. Asample equipment list is given in Exhibit 3-4.

The process flow diagram The process flow diagramis one of the most important documents reqUired bythe designer to position equipment. It indicates flowrates, temperatures, n d pressures and how the vari-ous pieces of equipment are interconnected. The pro-cess flow diagram generally does not show utiliryequipment e.g., drives, surface condensers, and injec-tion packages . These can e obtained from the equip-ment list. The process flow diagram does not alwaysshow the true representation ofthe equipment. Ashelland tube exchanger shown as a single item could turnOut to e two or more shells for a large load. Exhibit

3-5 shows a process flow diagram that incorporatesthe items the sample equipment lis .

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The block flow diagram The block flow diagramshows all primary interconnecting lines between pro-cess units, utiliry plants, and storage facilities. Althoughnot absolutely essential, it is a useful document forequipment location.

Specifications Similar to the plant layout specifica-tion discussed in Chapter 2 this document highlightsmaintenance, operator access, clearances, and equip-ment spacing.

Process design data The process design data givessite information on a map or an overall existing plotplan. The existing plot plan, or site map, shows suchgeographic details as roads, railroads, rivers or sea-shore, land contours, and inhabited areas. It also indi-cates the location and extent of real estate available for

the new faciliryor

expansion. The process design dataindicates weather conditions e.g., average seasonal

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XHmlT 4 Sample Equipment l i s t

Item

Furnaces101-F

Exchangers101-E102-E103-El04-E105-E106-E107-E/A to H108-El09-E

Pumps101 PA101-PB102-P103 PA103-PB104 PA104-PB105 PA105-PB

Towers101-T

ReaCtors101 R

Orums101-01 2

1 3·1 4

1 5·

Compressors101-C102-CA102-CB

MiscellaneouslOl OJlOl-L101·H101 H ..

Description

Charge furnace

Stripper reboilerStripper feed/effluent exchangerStripper overhead trim condenserReaCtor effluent [rim coolerStripper overhead condenserReaCtor effluent coolerCombined feed exchangersSurface condenserProduCt cooler

Charge pumpSpare charge pumpWater injection pumpStripper bonoms pumpSpare s t ri ppe r bonoms pumpStripper reflux pumpSpare stripper reflux pumpCondensate pumpSpare condensate pump

Stripper

ReaCtor

Feed surge drumRecycle compressor suCtion drumMake-up compressor sUCtion drumWater injection drumStripper reflux drum

Recycle compressorMake-up compressorSpare make-up compressor

Lube oil consoleCorrosion inhibitor injection systemCompressor house

Overhead travelingcrane

temperatures, rainfall records, and prevailing winds .It also gives the plant elevation datum and referencecoordinates for plant location.

Equipment sizes At this phase of the project, theequipment sizes for the plant are furnished by thesupponing groups on the basis of preliminary information and cover such general items as floor spacerequirements e.g., for a pump of known size or ashell and tube exchanger with only the tube diameterand length given. As the project progresses, eqUipment configurations and sizes become firm and theplot plan is updated accordingly. Exhibit 3 6 lists sample information that must be supplied.

Materials of cons truct ion A materials specialistmarks up a process flow diagram identifying special orcritical piping materials e.g., alloy and large heavywall piping . The diagram assists the plant layout designer in optimizing equipment locations to suit themost economic piping runs.

lYP S OF PLOT PL NS

Plot plans are often referred to by their process e.g.,an ammonia plant or hydrotreater unit rather than bythe type of configuration of the equipment layout. Interms of equipment arrangement, process unit plotplans can basically be divided into two configurations:the grade-mounted horizontal inline arrangementseen in most refinery facilities, and the structuremounted venical arrangement found in many chemical plants.

The Grade Mounted Horizontal Inllne rrangement

The horizontal inline unit is usually located within arectangular area, with equipment placed on ei ther

side of a central pipe rack serviced by auxiliary roads.

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EXHIBIT 3-5 Sample Process Flow Diagram

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XHI IT 6 F lo o r S p ac e Sizes

Exchangers

Item Bundle Diameter length101-£ 36 in 91S mm 20 6,100 mm

102-£ 30 in 7S0 mm 20 6,100 mm

103-£ 30 in 7S0 mm 20 6,100 mm

104-£ 24 in 610 mm 20 6,100 mm1 5 £ N C 30 ft 9,1S0 mm 40 ft 12,200 mm1 6 £ N C 30 ft 9,IS0 mm 20 ft 6.100 mm

107-£ 8 shells 36 in 915 mm 24 7,300 mm

108-£ 60 in 1,500 mm 15 ft 4,600 mm

109-£ 30 in 7S0 mm 20 ft 6,100 mm

Pumps

Item length Width

10I-Pafb S ft 1,500 mm 2 ft 6 in 750 mm

102-P 2 ft 6 in 750 mm I ft 3 in 380 mm

103-Pafb 4 ft 6 in 1,370 mm 2 6JO mm

104-Pa/b 4 ft 1,220 mm I f t 6 i n 4 5 0 m m

IOS-Pafb vertical 1 ft 6 in 4S0 mm I f t 6 in 4 5 0 m m

The principal advantage of this arrangement is that theequipment is generally located at grade, which makesthis type of plant easier to construct an d more accessi

ble for maintenance an d operation. The disadvantagesare the a mo un t o f real estate required and the longruns of cabl ing, utility, feed, and product piping reqUired to service the unit. Exhibi t 3-7 shows a typicalhorizontal inline plot plan arrangement.

The Structure Mounted Vertical rrangement

The st rucrure-mount ed vertical a rrangeme nt hasequipment located in a rectangular multilevel steel orconcrete structure. The structure can be several bays

long and either open-sided or fully enclosed, to suiteither client preference or climate conditions. Piping

and cabling usually enter and exit the structure at on elevel and gain access to each floor by chases or aresupported from the outside members Operators usually gain access to each level bv stairs or by elevatorEquipment maintenance is usually accomplishedthrough the use of hitch pOints, trolley beams, or traveling cranes. a de qua te area must be prOVidedaround each item along with a clear drop zone atgrade for equipment removal The structure is serviced by access roads.

The advantages of this type of arrangement are thesmall amount of real estate required for the plant andth e ability to house the facility to suit process requirements or climate conditions. The disadvantages are inthe operator and main tenance access and in the construction of the plant. Exhibit 3 8 shows a typical structure-mounted vertical plot plan arrangement.

EQUIPMENT LOC TION

Various requirements dictate the locat ion of equipment and supporting facilities within the conventionaloperating plant. and manv factors muSt be consideredwhen the designer is locating equipment . They arediscussed in the following sections

Plant Layout Specification

This document highlights spacing requirements forequipment and access widths and elevation clearancesfor operator and maintenance access. A typical plantlayout specification can be found in Chapter 2 Thesample specification shown in Exhibit 3-9 highlightsthe safety spacing requirements around a process furnace.

Economic Piping

The major portion of the piping within most process

unitsis

used to interconnect equipment and supportcontrols betvveen equipment To minimize the St of

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XHI IT 3 7 Grade Mounted Horizontal Inl ine Arrangement

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this bulk material equipment should be located inprocess sequence and close enough w suit safetyneeds access requirements and piping flexibility. Thesequential interconnection of the unit is shown on theprocess flow diagram. The first step is to identify thealloy or heary wall piping. The diagram should then

be subdivided into smaller groups of process relatedequipment. These groups should contain n assembly

ro ess Plant ayout nd iping esign

of related eqUipment and controls that function s asubsystem within the main process unit. The compo-nents within the subsystem should be arranged suitthe most economic piping runs and the whole assem-bly should be positioned within the plot area to pro-vide the most economic interconnection between re-

lated process subsystems. Exhibit 3 10 shows aprocess flow diagram ivi into subsystems an r


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35EXHI IT 3 8 Structure Mounted Vertical rrangement

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EXHI IT 9Sample Plant LayoutSpecification for SafetySpacing Requirements

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36EXHIBIT 3-10 Planning Piping with a Process Flow Diagram

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b. Subsystem Arrangement

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c. Interconnection of Subsystems

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G A ITF e

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ypical ravityFeed Arrangement

rangement of a subsystem, and the interconnection ofa g ro up o f subsystems.

Process Requirements

Equipment often must be located in a specific positionto suppon the plant s process operation e.g., for pressure drop, line pocketing, and gravity feed). The plantlayout designer must be familiar with the process because the process flow diagram rarely indicates thisinformation. It is recommended that the designer discuss these requi rements with the process engineerbefore proceeding with the plant arrangement. Ex-hibit 3 shows the effects of an arrangement with agravity feed process requirement.

Common OperationEquipment that requires continuous operator attention or shares common utility and maintenance facilities should be located in the same area. For example,compressors generally require 24-hour operator at-tention. Compressors with condensing steam turbinedrives often share the same surface condenser and arelocated in a compressor house using a common fixedhandling facility e.g., an overhead traveling crane).Although this arrangement is often more expensive interms of piping components, the use of common facil-ities e.g., the surface condenser, building, and equipment-handling facilities) makes up the difference in

cost Exhibit 3-12 shows a typical compressor area arrangement.

Real Estate Availability

Generally, most new process units are built within anexisting facility in which a piece of land is dedicated tothe new expansion. Older process units, which haveundergone many expansions, often leave a less-thandesirable piece of real estate for the next new facility.This can be a problem for inline horizontal arrangements b ut is less so for venical s tructure arrangements, which require less ground space. When an inline arrangement is constructed, it is recommendedthat parts of the unit be located in elevated structureswith related equipment located adjacent to it if theprocess permits. For an already-elevated plant, adjustments can be made in the overall size of the structureand extra floors can be added. Care must be taken toadjust usual p lan t configurations to suit min imumspace requirements so that the plant is not too difficultto maintain. Exhibit 3 3 shows an arrangement before and after it has been adjusted suit minimumspace requirements.

Equipment Sizes

Ideally, all the different types of equipment within theprocess unit would be the same size. This rarely occurs, however, and the plant layout designer often

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38

EXHIBIT 3· 3 Floor Space Comparison

XHI IT 3 2

Typical Compressor rea rrangement

a Before Minimum Space Adjustment

Process Plant ayout and Piping esign

b After Minimum Space Adjustment


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X mIT 3 4 Fluid Catalytic Cracking Unit Plot Plan

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struggles to place a large, cumbersome piece of equipment into an area while retaining the aesthetics of theunit. Generally, most plants are dominated by conventional rectangular and circular equipment of a reasonable size. Some processes, however, require muchlarger and more awkwardly shaped items e.g., anorthoflow convener and expander train in a fluid catalytic cracking unit, as displayed in Exhibit 3-14 a reformer furnace in an ammonia unit, or a waste heat

recovery system in a large cogenerat ion plant . Inthese situations, the designer should place these items

first and plan the remainder of the unit around them.Whether the planned plant is an inline arrangement

o r housed in a structure, the plant layout designermust make provisions for operator and maintenanceaccess. The designer must review the items of equipment that are included in the process and plan fortheir operation and maintenance requirements. Forexample, towers must be located in a position to allowfor the removal of internals, reactors require space for

catalyst loading and unloading, shell and tube exchangers require space for bundle removal, and rotat-

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XHI IT 3· 5Typical Access equirements n a

Vertical rrangement

ing equipment needs space for drive and casing removal.

All these aspects of the equipment design add tothe floor space requirements of the plant. Equipment

that requires servicing during regular operat ion orplanned shutdown periods should be accessible fromthe auxiliary roads or internal access ways From theproject specification the plant layout designer shoulddetermine operator access requirements and the devices to be used for servicing before proceeding withthe plant arrangement. Exhibit 3 15 shows typical ac-cess requirements in a vertical arrangement and Ex-hibit 3 16 displays an inline arrangement.

Underground Facilities

There are a variety of underground facilities that couldaffect the positioning of equipment. Depending on

ro ess Plan t Layout n d iping Design

soil conditions the foundations for the equipment areeither piled or spread footings. Spread footing foundations require more space than piled applications andcare should be taken to locate equipment so that

enough space exists between equipment for the foundations of larger items. In certain cases equipmentcan be supported on a common foundation. Depending on the project specification instrument and electrical cabling can be located above or below grade. Iflocated below grade adequate space should be designated during the plot plan development stage. Underground piping is aI \other factor that the designer mustconsider when locating equipment. Most process unitsare serviced by an underground oily water sewerstorm sewer and fire water system and a chemicaldrainage system reqUired. In addition the unit cooling system could be positioned below ground. All ofthese facilities reqUire plot space and it is recom-


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E X G ~ E t T o . . 1 ~

e>lollo jDL E Pl..lu lto.I ;, A l i : . ~ AEXHIBIT 3-16Typical AccessRequirements anInline Arrangement

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mended that the plant layout designer investigate whatfacilities are to be posit ioned below ground beforeproceeding with the equipment arrangement. Exhibit3-17 shows a typical elevation through a unit belowground.

Climate Conditions

Weather conditions could influence the location ofequipment. In a severely cold climate, equipmentshould be housed; this can be done by encasing

the whole unit, as epi e in Exhibit 3 18 or by in-dividually housing groups of equipment e.g., compressors or pumps , as illustrated in Exhibit 3 19. Forindividual housing, consideration must be given tolocating equipment out of process sequence to minimize cost.

The wind can influence the location of such equipment as furnaces, compressors, control houses, cooling towers, and stacks. Furnaces or other fired equipment should be located so as not to allow flammablevapors to constantly drift. Smoke from stacks or vapors

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42

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EXHI IT 3 7

Typical ndergroundElevations

EXHI IT 3 8

Total Unit ncasement

from cooling towers should not be in the direct pathof main operating areas (e,g compressor houses, control rooms, and structures

PIPE R CKS

Generally, most in line plant ar rangements are furnished with a central pipe rack system that acts as themain artery of the unit support ing process interconnection, feeds, product and utility piping, instrumentand electrical cables, and, sometimes, air coolers anddrums, Usually, the p ipe rack is made of structUralsteel, either single level or multilevel, suit the widthand capacity of the uni t it is serving, The pipe rack baysare usually spaced at 20-ft 6,000-mm centers Thewidth is determined by such factors as the quantity of

piping and cabling to be carried on the main run ofthe p ipe rack with an allowance for future expan-

Process Plant ayout an d Piping esign

sion , the equipment and access way located beneaththe pipe rack, or the equipment if any supportedabove the pipe rack. The layout that results in the mosteconomical design should be chosen.

At the estimate stage, when most plot plans are

developed , the pipe rack width is specified on thebasis of l imited information; process flow diagramsusually ar e not available to accurately work out theexact requirements, Using the process flow diagram,the designer can prepare a l ine routing diagram on aprint of the preliminary p lo t plan, similar to the instructions given in Chapter 11, This establishes themain process lines supp orted in the pipe rack forequipment interconnection, feed, and production, allowance of 20 of the main lines sh oul d be ad dedto the total for unknowns, The pipe rack width canbe adequately sized on the basis of approximate line

sizing, utility piping, and insulation requi rementsby the process system engineer; cable tray require-


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XHI IT 3·19IndiVidual EqUipmentHouses

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ments by the electrical and instrument engineers; anda 20 future piping allowance. Most rypical units require a two-level pipe rack with a width of2 ft 6,000mm 40 ft 12,000 mm . If the total requirementsexceed 80 ft 24,000 mm , an extra level s hould beintroduced.

After establishing the pipe rack width to suit thepiping and cable requirements, the designer mustcheck the design for the accommodation of air coolersuPPOrt, if specified, and pumps and access ways beneath the pipe rack. The air cooler is specified by tubebundle length and is established at the estimate stageof the project. It can overhang the rack width equallyon e ither side. An air coole r with a 40-ft 12,OOO-mm)tube bundle length can be adequately supported on apipe rack that is 35 ft 10,500 mm wide. Pumps maybe located beneath pipe racks on either side of anaccess way that is 10 ft 3,000 mm wide.

The bottom suPPOrt elevation of the main pipe rackis dictated bv the maintenance and piping clearancebeneath the pipe rack, with additional levels spaced at6-ft l,800-mm intervals. On projects with very larged iameter piping, increasing this d imens ion to suitclearance requirements should be considered whenpipe direction is changed. External clearances e.g.,over main roads or intersections with off-site piperacks need close attention. Exhibit 3-20 shows a rypical pipe rack elevation.

Pipe rack configurations are dictated by the equipment layout, site conditions, client requirements, andplant economy. The ideal situation would be astraight-through arrangement, with process feeds andutilities entering o ne e nd of the uni t and products anddisposals exiting the other end. The final layout of thepipe rack to meet the specific requirements of theproject could result in a variety of configurations e.g.,

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EXHIBIT 3 20Typical Pipe RackElevation

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aT , L or U shape , as shown in Exhibit 3-21 Changesof direaion in pipe racks muSt be accommodated bychanges in elevation and are usually equally spacedabout the midpoint of the main pipe rack elevations tosuit required clearances

Pipe racks within vertically structured or housedfacilities cannot be derined as easily as for inline ar

rangements, because the equipment is usually locatedon several levels. The vertical units are usually fed byconventional pipe racks at established elevations enter ing the structure at a designated area. Once insidethe structure, piping s ho uld b e routed in an orderlymanner according to economic, construaibility, an dsupport requirements. Exhibit 3 22 displavs a typICalprocess structure

RO DS CCESS W YS NP VING

For maintenance and safety, the principal access toand from most process units is by auxiliary roads. Ideally, the unit banery limits should be positioned 50ft 15,000 mm from the centerl ine of the main plantroads. This allows adequate space for ditch drainageand firefighting faCilities an d avoids Obstructing roadswhen such items as heat exchanger tube bundles areremoved. Access ways or spur roads should be provided within the unit for access to items that requireservicing or for components that require removalfor off-site repair. Clearance according to project

speCification sh ou ld b e proVided over roads and ac


cess ways for mobile equipment access. Most clientsrequire that the equipment areas, the area beneaththe pipe rack, and the areas around buildings bepaved with concrete for housekeeping. Exhibit 3-23illustrates a typical process unit road and paving arrangement.

BUILDINGS

Apart from buildings that house equipment eg , compressor houses , it is often necessary to position control houses, substations, analyzer houses, and operatorshelters within the process unit battery limits. Administration buildings and warehouses ar e generally located away from process uni t areas. Control housesand subs tations are usually located at the edge of theunit adjacent to a plant road, 50 15,000 mm fromthe operating equipment. As seen in Exhibit 3-24, ana

lyzer houses and operator shelters should be locatednext to the equipment that they service.

EQUIPMENT SP CING

The previous sections have outlined the informationreqUired to locate equipment and the general contentof the typical process unit. At this stage, the plant lay-out designer should prepare a sketch of the unit configuration and a line ru n to confirm that the equipment is pos ition ed for the most favorable piping

interconnection. The line ru n can be prepared by dia-


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EXHIBIT 3 2 Pipe Rack onfigurations

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EXHmIT · ypical Pipe Rack in a ertical rrangement

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graming the principal process piping s shown on theprocess flow diagram ont o a print of the plot planarrangement sketch

The final step in the plot plan arrangement is tospace equipment and supponin facilities for operatorand maintenance access safety piping flexibility andsuppon and platforming requirements t this stagethe layout designer must rely on experience because

the final information is not available for calculating

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46

XHI IT 3 3 Typical Process Unit Road an d Paving rrangement

exact distances between equipment or solving unfore-seen mechanical problems The spacing of the compo-nents within the unit is an important exercise i t fi-nalizes real estate requirements for the facility andassists in the pricing of the plant t is also used s thebasis for the plant layout design

Before spacing the equipment the layout designer

ro ess Plant ayout and Piping esign

should review the sketched arrangement of the unit toconfirm the exact requirements needed for safe andorderly operation of the plant Consultation with pro-cess engineers is recommended to obtain general linesizing requirements for control spacing allowancesthis stage the designer should be completely familiarwith the project specification requirements for safety


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XHI IT 3 24

BUilding Locations

~U t f]{]L t c use and for operator and maintenance access.

In a typical tower area depicted in Exhibit 3 25 thetower and such related equipment as drums and heatexchangers are located adjacent to the malO pipe rackwith maintenance access from the auxiliary road. Theassociated pumps are located beneath or adjacent tothe pipe rack and are serviced by a central access wayShell and tube heat exchangers can e located as sin-gle items or in pairs. If the process permits they canbe suppone venically or located in structures tomeet gravity feed requirements. Vertical reboilersshould be suppone from their related towers. Multi-ple shell heat exchangers operating in series or in

parallel may e stacked three highi

size permits.Pumps beneath the pipe rack may if size permits e

paired in each bayCompressors and their related equipment are usu-

ally located in on e area for common operat ion andservicing adjacent to the main pipe rack and the auxil-iary road. The suction drum for the machine should e positioned for flexibility in the piping and to ac-commodate orifice run requirements. the compres-sor is driven by a condensing turbine a surface con-denser and condensate pumps are reqUired. Ifservicing on e machine. the condenser may e locatedbeneath the turbine. If it services two or more thecondenser must e located adjacent to the machines itservices. In both cases space must e provided for

condenser tube bundle removal.The condensate pumps are usually vertical pumps

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EXHI IT 3 5Typical Tower AreaSpacing

and should e located as close to the condenser aspossible to sui t f1exibility in the piping and verticalremoval space. The lube oil console should be locatedas close to the compressor as possible with operatOraccess on all sides of the skid with space to remove

the cooler tube bundle filters and pumps. Interstagecoolers if needed should be located adjacent to the

Process Plant Layout a n d Pip ing Des ign

compressor and suction drum. Adequate space shouldbe prOVided around the compressor and turbine forthe installation of a platform and staircase. If the facil-ity is housed a drop area must e proVided. Exhibit3 26 illustrates a typical compressor area arrangement.

Air coolers shown in Exhibit 3 27 are generallysuppone from the central pipe rack adjacent to their


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EXHIBIT 3-26Typical Compressor AreaSpacing

related equipment and are serviced by platforms at theheader boxes and beneath the air coolers for motormaintenance. Care should be taken to position aircoolers to allow flexibility for interconneaing piping.A poorly positioned overhead condenser could resultin additional large overall diameter piping and expensive suppons. Unless furnished with fixed fire water

sprays pumps containing hydrocarbons and operating higher than autoignition conditions should not be

located directly beneath air coolers. Space should beavailable on the plot plan for maintenance access bymobile cranes for removal of air cooler tube bundles.

Furnaces should be located at a safe distance andupwind from unrelated equipment containing hydrocarbons Steam drums or deaerators can be located asrequired for operation and maintenance. Reactors can

be located closer to furnaces than other equipmentcontaining hydrocarbons as long as adequate space is

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EXHIBIT 3 27Typical Air CoolerSpacing

EXHIBIT 3·28Typical Furnace AreaSpacing

Process P k l n t a yo ut and Piping esign


25/28

XHI IT 3 9 Subsystems Within th e rocess Flow Diagram

provided for catalyst loading and unloading. Exhibit3 8 shows a rypical furnace area.

SAMPLE PLOT PLAN ARRANGEMENT

The following illustrated examples show the varioussteps in arranging a na phtha hydrotre ater unit andidentify the process subsystems within the processflow diagram Exhibit 3-29 , the initial arrangement

sketch of the unit Exhibit 3-30 , the line r un check Exhibit 3-31 , a nd the final plot plan a rrange ment Exhibit 3-32 .

This chapter has highlighted s om e o f the principalfeatures involved in th e arrangement of processequipment with regard to operation, maintenance,constructibility, safety, nd economics. Subsequentchapters deal with the needs of each equipment itemin more detail, thereby offering greater insight toproper equipment location on a plot plan.

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XHI IT · nitial Arrangement Sketch


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5

EXHIBIT · Line Run Check

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5

XHI IT 3-32 Final Plot Plan Arrangement

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Documents

3.Plot Plants