Piping - Introduction

7/21/2019 Piping - Introduction

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Power Plant Fundamental

Piping System

Piping System - What is that?

Concept - Layout Development

Piping Components & their access requirement.

Straight length requirements.

Orientation of various tapings, components, etc.

Piping Drains & Vents

Insulation.

Material & Sizing, PDT/VDT selection.

Critical piping system consideration.

Pipe Stress Analysis.

Pipe Supports

Special Considerations

Piping Designer’s Input & Output

GET-DET Training Prog.,2003-Somnath Kundu

1



Let us first Discuss about WHAT IS PIPE

PIPING SYSTEM

It is a Tubular item made of metal,

plastic, glass etc. meant for conveying

Liquid, Gas or any thing that flows.

It is a very important component for any

industrial plant. And it’s engineering plays

a major part in overall engineering of a

Plant.

In next few pages we shall try to

familiarize about pipe and it’s

components.



PIPING SYSTEM

Now we will try to understand step

by step how a piping system is

formed based on the requirements

We shall start with a plane white

sheet



This is the plane white

sheet we start with

Let us start drawing asimple piping system

In any plant various fluids f low through pipes

from one end to other.

Now let us start with a plant where we see three

tanks.

Tank-1, Tank-2 and Tank-3

We have to transfer the content of Tank no. 1 to

the other two tanks.

We will need to connect pipes to transfer the

fluids from Tank-1 to Tank-2 and Tank-3

LET US BRING THE PIPES.



We have just brought the pipes, now we

need to solve some more problems.

Pipes are all straight pieces.

We need some

branchconnections

We need some bend

connections

E v e n

s o m e

p i p e

s a r e

o f d i f f e

r e n t s i z e

s !

To solve these

problems we need thepipe components,

which are called

PIPE FITTINGS



These are the pipe fit tings,

There are various types of fi ttings for various

purposes, some common types are -

Elbows/Bends, Tees/Branches,

Reducers/Expanders, Couplings, Olets, etc.

Anyway, the pipes and

fitt ings are in place, but the

ends are yet to be joined

with the Tank nozzles.

We now have to complete the

end connections.

These, in piping term, we call

TERMINAL CONNECTIONS.



These are flanged joints

This is a welded joint

So far this is a nice arrangement.

But there is no control over the flow from Tank-1

to other tanks.

We need some arrangement to stop the

flow if needed

To control the flow in a pipe line we

need to fit a special component.

That is called - VALVE



There are many types of valves, categorized

based on their construction and funct ionality,

Those are - Gate, Globe, Check, Butterfly, etc.

Other than valves another important

line component of pipe line is a filter,which cleans out derbies from the

flowing fluid. This is called a

STRAINER



Here we see a more or less functional piping

system, with valves and strainer installed.

Let us now investigate some aspects of p ipe

flexibility.

If this tank

nozzle expands,

when the tank is

hot.

In such case we need to f it a flexible

pipe component at that location,

which is called an EXPANSION

JOINT



When some fluid is flowing in a pipe we may

also like know the parameters like, pressure,

temperature, flow rate etc. of the fluid.

To know these information we need

to install INSTRUMENTS in the

pipeline.



There are various types instruments to measure various

parameters. Also there are specific criteria for installation

of various pipe line instruments.

Next we shall look

into how toSUPPORT the

pipe/and it’s

components.



Here are some of the pipe support ing arrangements.

There can be numerous variants. All depend on

piping designer’s preference and judgement.

Let us see some OTHER types of supports







We have just completed a pipe line design.

We shall rewind and check how it is really done in practice.

First the flow scheme is planned,

1) What, 2) From what point, 3) To which point

Pipe sizes are selected, pipe material and pipe wall thickness are selected.

Types of Valves are planned

Also the types of instruments required are planned

We represent the whole thing in a drawing which is called Piping andInstrumentation Drawing, in short P&ID. For P&ID generation we use CADME

software.

By this time you have already come to know that while we prepare P&IDs in

CADME, we enter all the pipe lines system information in the drawing.

So the CADME drawing is an Intelligent drawing which under it’s surface carries all

the information about a pipe like, Pipe size, Flowing Fluid, etc.

Let us see a P&ID prepared in CADME



This is screen picture of

P&ID made by CADME

If we click on any line it wil l

show the Data embedded.



These are the embedded

data of this line



Let us look in to a simple P&ID for understanding of P&IDs.

This is part

P&ID for DM

water transfer

system

Click to see Iso



After the P&ID is ready we start the layout work.

Preferable

Not Preferable

We use PDWB software to route piping in the Plant virtual 3D space.

We call this as piping modeling or physical design.

While development of piping layout we have to consider the following

Piping from source to destination should be as short as possible with minimum

change in direction.

Should not hinder any normal passage way. Also should not encroach any

equipment maintenance space.

Here we carryout pipe routing / layout in Virtual 3D environment.



While carrying out pipe routing we also need to consider the following

Example of Straight length requirement for Flow Orifice

Valves, strainers, instruments on the pipe should be easily accessible.

If needed separate ACCESS PLATFORMS to be provided to facili tate these.

Desired location and orientation of valves / instruments and other pipe

components are to be checked and maintained, like some valves or strainers

can only be installed in horizontal position. Specific requirements for instrument installation to be checked, like

temperature gauge can not be installed in pipe which is less than 4 inch in size.

Specific requirements of STRAIGHT LENGTH of pipe for some components to

be maintained, like for flow orifice we need to provide 15 times diameterstraight pipe length at upstream of orifice and 5 times diameter straight at down

stream of orifice.



Also arrangement is kept in the

pipeline so that liquid can bedrained out if required.

To achieve this a DRAIN

connection with Valve is provided

at the lowest point of the pipeline

For Pipeline which shall carry l iquid, we have to make sure that all air is allowed

to vent out of the line when the line is filled with liquid.

To achieve this a VENT connection with Valve is provided at the top most point

of the pipeline.

Let us look

into typical

Vent and

Drain

arrangement

in a pipeline

Pipes are also slopped

towards low points.

Pipe line Vents

and Drains



Let us have a look into a piping model done by PDWB

The Term PDWB stands for Piping Design Work Bench



This is a PDWB

model of Feed

water line along

with pumps andother accessories



Let us look in to a Piping Isometric Drawing

From the Piping 3D Model we create the Piping Isometric drawings.

These piping isometric drawings are used to fabricate and erect the piping

at job site.

Let us look in to a Piping

Isometric DrawingFrom the Piping 3D Model

we create the Piping Isometric

drawings.

These isometric drawings

are used to fabricateand erect the piping

at job site.

This is part

Isometric for DMwater transfer

system

Click to see P&ID



INSULATION - When hot fluid flows through pipe then generally pipe is insulated.

There are two primary reasons for insulating the pipe carrying hot fluid.

Containing the heat inside the pipe. Insulation preserves the heat of the fluid. It

is called Hot Insulation

Personnel safety, so that people do not get burn injury by touching hot surface

of pipe. It is called Personnel Protection Insulation

Cold pipes are also insulated

Cold or chilled fluid carrying pipes are insulated to prevent heating of cold fluid

from outside. It is called Cold Insulation.

Some times cold pipes are insulated to prevent condensation of atmospheric

water vapor on pipe surface. It is called Anti-Sweat Insulation.

Other types of Insulation

When gas flows through pipes at high velocity, it creates noise. In such cases

pipes are insulated to reduce noise. It is called Acoustic Insulation.

Some times pipe and it’s content are heated from outside, by heat tracing

element. In that case pipe along with heat tracing element are insulated to

conserve the heat of the tracer. It is called Heat Tracing Insulation.



INSULATION MATERIAL - The insulating material should be bad conductor of heat.

There are two basic categories1) Fibrous Material, which has large voids full of air between fibers - Cork, Glass Wool,

Mineral Wool, Organic Fibers. Note stagnant air is a bad conductor.

2) Cellular Material, which has closed void cells full or air - Calcium Silicate, Cellular

Glass (Foam Glass), Polyurethane Foam (PUF), Polystyrene (Thermocol), etc.Some times Cast material like Cement Plaster or Plaster of Paris are also used.

INSULATION CLADDING - Insulation materials are generally soft or f ragile. So the

outer surface of insulation are protected with Aluminum sheet or GI sheet

cladding.

Have a look at how

pipes are insulated,

and generalcomponents of

insulation



Pipe Sizing Calculation - to select required pipe diameter based on velocity and pressure drop.

Find out

Flow volume

per second

Check Velocity

Allowable per

second

Calc. flow area

required and

Pipe size

Calc. Press.

Drop for that

Pipe size

Check Press.

Drop meets

Press. Budget

Pipe

Size

OK

YES

Increase

Pipe Size

NO

Pipe Material Selection - to select appropriate pipe material based on flowing flu id property.

Find out type

of Fluidflowing

Check Pipe

lifeExpectancy

Select suitable

Material perpractice (Note-1)

Check Mat.

Listed inDesign Code

Pipe

MaterialOK

YES

See

Note-1

NONote-1 : Material is selected per past experience with cost in mind

and per material listed in design code. If material is not

listed in code we may select next suitable material lis ted.

Find out

Fluid Temp.& Pressure

Pipe Thickness Selection - to select appropriate pipe thickness based on flowing fluid property.

Select Mat.& Diameter

as above

Decide onCorrosion

allowance

Calc. PipeThickness per

Code (Note-2)

Check if S&LPDT matches

requirement

SelectedS&L PDT

for Project

YES

Create new

PDT for

Project

NONote-2 : S&L has a standardized sets of piping materials suitable for various

fluids and various service conditions, These are call - Piping Design

Table (PDT). If calculated pipe thickness do not match with standard

PDT, Project Specif ic PDT are created with PDTS software.

Find outFluid Temp.

& Pressure

Created

new PDT

for Project



Piping Design Table and Valve Design Table

S&L has standardized sets of pipe and valves grouped based of various application.

These sets are call Piping Design Table (PDT) for pipes and fittings, and Valve Design

Table (VDT) for valves.

These Tables with all their physical data are consolidated in the PLADES 2000

Database.

When we create piping 3D model by using PDWB software all Pipe and Valve data are

fetched from Database and automatically inserted in the piping model based on the

PDT selected.

While we select pipe or valve material for any intended service we try to select the best

suited S&L PDT already available in the Database.

If in any case we can not find a suitable match we have to create a new project specific

PDT or VDT.

This creation of PDT and VDT is done through PDTS software.

The created design table is reviewed and approved by authorized person.

As it is approved PLADES Database is updated, and the NEW PDT can be used in

generation of piping model.



This is an example of

project specific PDT



In Power plant there are some piping which carries steam at high pressure and

temperature. And also there are piping which carries water at High pressure.

These pipes carries the main cycle steam and water of the steam power plant.

These pipelines are call the CRITICAL PIPING.

Very special care are taken for design of these piping.

First the pipe material selection for such piping is very important as it has towithstand the high pressure and may be also high temperature.

As these pipes carry the main system fluid of the power plant, they are given

the right of way, and routed at beginning of the overall plant layout.

Steam pipes run at very high temperature and the hot pipes expand. We have tobuilt in flexibility in the high temperature pipe routing so that the expansion

force is absorbed within the piping.

Also there should be enough flexibility in these pipe routing so that high loads

are not transferred to the nozzles of Turbine or Pumps

There are many recognized international codes which lay down guide lines and

mandatory requirements for design of such piping.

The most important codes used by power plant piping engineers are

ASME ANSI B31.1- Power Piping Code & IBR - the Indian Boiler Regulation



Pipe Stress Analysis

We have already seen that some of the pipes are subjected to high pressure

and high temperature. Also pipes carry the load of the flowing fluid.

We need to check and confirm the pipe is not going to fail with these loading.

This process of checking the stress developed in the piping due to various

loading is called Pipe Stress Analysis/Flexibility analysis.

In the process of Analysis we apply various postulated loading on the pipe and

find out the stress resulted from these loading.

Then we check with governing codes if those stresses generated are

acceptable or not.

We check support load & movement for various loading condition.

We also check out the terminal point loading generated from pipe to the

equipment connected to the pipe. This loading are to be within acceptable

limits of the equipment suggested by the vendors.

We also f ind out the pipe growth due to change in temperature and need tokeep the movement of pipe within acceptable limits.

Pipe Stress Analysis is an Interactive and Iterative process. Each step is

checked

If a check fails we have to go back, modify the layout and restart the analysis.



PIPE STRESS ANALYSIS

InputsGeometric layout of Pipe

Pipe supporting configuration

Pipe Diameter and Thickness

Pressure inside Pipe

Cold and Hot temperatures of Pipe

Weight of Pipe and insulation

Weight of carrying Fluid

Pipe material Property (Young’s Modulus,

Thermal Expansion Coefficient)

Thrust on pipe due to blowing wind.

Thrust on pipe due to earthquake

Load of Snow on pipe

Any transient loading like Steam Hammer

load

Any other load on the piping

Tools we usePIPSYS - is an integrated pipe stress

analysis module of PLADES 2000

CEASER - Commercial Piping analysis

software

There are many other commercial software

available

Outputs

Stress of the pipe at various loading

conditions

Load at various supports and restrains.

Movement of pipe at support locations

Pipe terminal point loading.

Codes and Standards

In general Power Plant Piping have to

comply stipulations of ASME ANSI B31.1

In India Power cycle Piping to comply IBR

code requirements.



PIPSYS - the analysis module of PLADES 2000

It is a very powerful and flexible,integrated stress analysis

module of PLADES 2000.

We work in PIPSYS in close

interaction with PDWB piping

Models.

Here are some of the Screen

views

Opening screen - It has a Nick

name - The Blue Screen

Geometry Plot screen - Itshows the model geometry



Types of Pipe Supports

In the beginning of this discussion we

talked about various types of pipe

supports. Here is some elaboration

There are three general types

Rigid type (no flexibi lity in the

direction of restrain)

Spring type (Allows pipe

movement in direction of

loading)

Dynamic Support (Degree ofrestrain depends on acceleration

of load)

There are two types of spring

support

Variable load type, here supportload changes as the pipe moves.

Constant load support, the load

remains constant within some

range of movement.

Constant Load Spring

Variable Spring

R i g i d H a n g e r

R i g i d S u p p o r t

Dynamic Support,

Snubber

Rigid Support



Some Typical Pipe Support Drawings

Here is some typical Pipe support drawings showing some typical vendor supplied

component numbers. (See Support Catalogues in G drive g:\snl\techdocs)



Some Pipe Support Hardware DetaIs

Here is some typical Pipe support hardware Pictorial views



Some Special Considerations for Piping

When pipes are routed UNDER GROUND (Buried) following points to be kept in mind:

Minimum pipe size to be routed under ground shall be not less than 1 inch.

Avoid flange joint in U/G piping.

Keep in mind if pipe leaks U/G, it will be difficult to detect, so avoid U/G routing of pipe

carrying hazardous fluid.

Pipe to be laid below Frost Zone at areas where ambient temperature goes below freezing.

U/G, Buried piping should be properly protected from corrosion.

Pipe may be properly wrapped and coated to prevent corrosion.

Or U/G piping be protected by using Cathodic protection.

Freeze Protection of outdoor Piping:

In the areas where the ambient temperature goes below freezing there is a possibil ity that

the liquid content of pipe may freeze while the plant is under shut down.

For similar case pipes are wrapped with heat tracing elements to maintain the contenttemperature above freezing (around 4 deg. C) even when the ambient temp. is below

freezing.

Electric Heat tracing is done by wrapping electric coi l around pipe, which turns on as the

ambient temperature goes down. Pipes are insulated over the heat tracing coils.

Heat tracing can also be done by winding Steam tubes around main pipes.



Piping Designer’s Input & Output

INPUTS TO PIPING DESIGNER

From Process

What Fluid

From Where to Where.

Pressure, Temp. and Flow rate.

Type of Flow control.From Project

What Project Specific

Requirements.

Any existing facility or U/G work

From MechanicalEquipment Locations and

terminal parameters

From Civil

Locations of foundations and

structures

From C&I

Types of control and instrument

installation, tapping requirements

From Electrical

Locations of electrical equipment,

cable tray and bus ducts

OUTPUT OF PIPING DESIGNER

To Process

Final Pipe Size and Pressure

class

Piping system Material

To Project

Plant Interface drawing

Interface with exist ing facili ty

To Mechanical

Pipe layout both A/G and U/G

Equipment terminal Loading

To Civil

Locations of Pipe supports

Pipe support loading to

foundations and structures

Wall Penetrations

To C&I

Locations instruments, control

valves on piping isometrics

To Electrical

Pipe layouts both A/G and U/G tomatch cable, duct bank routing



Congratulations

!!!

We have come to the

End of Session for Piping

Hope you have gathered enough knowledge

to talk intelligently

on the subject of piping

and also start work on piping

Documents

Piping - Introduction