Piping Layout and PIPERACK(5)

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  • 8/11/2019 Piping Layout and PIPERACK(5)


    Chapter 5



    Piping 89

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    Normally piping layout is developed in two stages

    Piping study plan

    Final piping plan.

    Piping study plan: - It is basically a conceptual routing of pipelines based on P&ID. All thecondition laid down in P&ID is fulfilled. Routing is represented in plan viewssometime section is shown wherever it!s re"uired. Piping layout shows alllines #$ & above sometime critical small bore lines can be shown. %tudylayout starts with routing of critical lines first. ritical lines are those which areeither having large diameter high temperature or gravity flow

    Final piping plan: - Piping study plan along with the isometric is discussed with otherdepartment in order to get their comments. Now their comments are incorporated to free'ethe piping study layout to be called as final piping plan. (his document is used for





    )endor drawing*catalogue information for e"uipments

    Piping specification.

    Plot plan

    +"uipment layout. Design guide line * %tandards.

    Instrument hoo,-up drawing


    Process re"uirements indicated in P& ID should be meet.

    (he lines should be routed in orderly manner. ine should be grouped in bunch &

    run together where ever possible for the ease of supporting.

    /nly the standard Pipe fittings special parts mentioned in pipe specification should

    be used for routing. Anything outside the %pec is not permitted.

    /ver head piping should have clear headroom for man ways & movement ofcranes truc,s where applicable.

    Piping on the grade level should be minimi'ed as it bloc,s the free movement.

    (he piping component that re"uires fre"uent maintenance should be easily

    accessible from grade or platform & should have ade"uate clear wor,ing space.

    Piping should be routed so as to allow removal & lifting of e"uipment with minimum

    pipe dismantling.

    Piping 90

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    Poc,et should be avoided especially in relief & steam lines.

    0ot lines should be routed to have some fle1ibility in the form loops.

    All critical lines should be stress analy'ed.


    i. Orifice Flange2-

    It is located at a convenient place which could be accessible by temporary


    /rifice is always preferred in the hori'ontal run.

    (apping for instrument connection is usually at 34either at top or bottom.

    For li"uid service (apping is downward direction.For 5aseous service tapping is upward direction.

    6se of valve & fittings ma,es the flow more turbulent which affect the

    measurement accuracy hence straight run are recommended upstream &down stream of orifice. (his straight run is e1pressed in terms of pipe dia. Fore.g. 78D #8D. (his straight run is indicated in the P&ID else it can beobtained from process department.

    ii. Control valves:-

    5enerally control valve assembly shall be located on the grade level

    Preferably control valve should be on hori'ontal run.

    ontrol valve placed on vertical run re"uire proper support for its


    9y-pass line routed over control valve should have proper clearance

    over the actuator.

    iii. Thermo wells:-

    (hermo well are used to measure temperature of fluid service either by locally

    mounted indicator or through transmitters

    (hermo well can either be located on the elbow or on the straight run pipe.

    (o mount thermo well on elbow. (he minimum si'e of elbow should not be

    less than :$ & orientation shall be in the opposite direction of flow.

    Piping 91

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    (o mount thermo well on straight pipe minimum pipe si'e should be at least

    3$. %ome licenser consider it ;$ or

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    Preferably valve should be located with the stem in vertical position for the ease of

    maintenance & minimum bloc,age of operating area.

    )alves located on the hori'ontal run can have stem rotated to hori'ontal position but

    preferably should not be lower than hori'ontal.

    )alve si'e greater than 7#$ is normally gear operator.

    are must be given while locating gear operated valve. 0and wheel should be on

    operator side. chec, for the interference of gear bo1 with other pipe or structure.

    are must be given while locating motor operated valve. 0and wheel should be on

    operator side. chec, for the interference of actuator assembly with other pipe orstructure.

    All valves located above #.#@ should be chain operated. For chain operation valve

    stem shall be in hori'ontal position.

    )alves located below the grade level due to process consideration are usually

    provided with e1tended spindle for operation.

    ocation of chec, valve in hori'ontal or vertical depends upon its internal

    construction. Swing !"#can be either in hori'ontal or vertical. Li$ !"#can only bein hori'ontal position.

    Piping 93

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    Figure 4.7 Arrangement of valve


    or T Type strainer:- (his is located in the hori'ontal run of pipe. As the name

    suggest the shape of strainer is in the form of & ( respectively. It contains a

    removable screen from the bottom hence it is rotated to 34or sometime B8 to

    facilitate easy removal of screen.

    Conical strainer:- For installation of conical strainer a spool piece e"ual to the

    length of conical screen is re"uired

    !as"et type strainer:- 6sually this type of strainer is big in si'e & screen is

    removed from the top hence sufficient clearance should be ,ept above it.

    Piping 94

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    (he choice of eccentric or concentric reducers should be made correctly. In order tosimplify the situation following is recommended.

    All reducers located in vertical run should be oncentric reducer.

    All reducers located in hori'ontal run should be +ccentric.

    +ccentric reducers depending upon the position can be placed with flat side either

    on top or bottom.

    6sually at all pump suctions eccentric reducers have flat sides on top e1cept for

    pumps handling slurry where eccentric reducers are placed with flat sides on bottom.

    At all pipe rac, locations eccentric reducers are used with flat sides on bottom in

    order to ,eep 9/P same.

    At control valve assemblies eccentric reducers can be placed with flat sides on



    ine routed on grade level should have common 9/P which is governed by no''le

    elevation of the e"uipments & the drain re"uirement. (here should be 748mmclearance between the drain valve & paving.

    For the steam header lines on pipe rac, steam trap is provided for every :8meters of

    straight run. 6sually they are located near the rac, column for the ease of supportingsmall bore lines connected to steam trap.

    %team lines should be provided with low point drain & high point vent.

    +1pansion bellows are installed in piping where it is not possible to have in built

    fle1ibility due to process reasons.

    ondensate discharge piping for a closed system should have minimum number of

    bends. (his is to avoid high bac, pressure acting on traps.


    Piping layout is generally generated on A8 paper si'e with the scale of 7 2 ::.::.A good piping layout drawing shall contain the following information in addition to whatdiscussed in e"uipment layout. hapter.

    Piping 95

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    ines below ;$ is indicated by single line .line si'e

  • 8/11/2019 Piping Layout and PIPERACK(5)


    atwal, platform and ladder access to valves and relief valves in pipe rac,.

    @inimum headroom and clearances under overhead piping or supporting steelwithin areas

    Pipe ways and secondary access ways

    @ain access roads

    Rail roads

    %tandard to be used for minimum spacing of lines in paperac,s

    0andling and headroom re"uirements for e"uipment positioned under pipe rac,s

    /perating and safety re"uirements affecting pipe rac, and structure design

    ocation of cooling water lines underground or above ground

    () P*OC$SS F+O, %&*&/ :( Process flow diagrams show main processlines and lines interconnecting process e"uipment.

    3) P%P%' 0 %'ST*1/$'T %&*&/:- +ngineering flow diagrams are developedfrom process flow diagrams and show2

    Pipe si'es. Pipe classes and line number.



    All instrumentation.

    +"uipment and lines re"uiring services i.e. water steam air nitrogen etc.

    2) 1'%T P+OT P+&'3 O4$*&++ P+OT P+&'

    5) 1T%+%T F+O, %&*&/:-

    6tility flow diagrams show the re"uired services2 %team






    i. (he first step in the development of any pipe rac, is the generation of a line-routing diagram. A line routing diagram is a schematic representation of allprocess & utility piping systems drawn on a copy of pipe rac, generalarrangement drawing * or