Piping Fundamentals - For Freshers Engineers

Piping Fundamentals - For Fresher Engineers Piping System - What is that? Concept Layout Development

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In any plant various fluids flow through pipes from one end to other. TANK-2

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Now let us start with a plant where we see three tanks. Tank-1, Tank4 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.

TANK- 1

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These are the pipe fittings, There are various types of fittings for various purposes, some common types are

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TAN K-2

ElbowslBends, TeeslBranches, ReducerslExpanders, Couplings, Olets, etc.

: fittings are in place, but the I ends are yet to be joined

We now have to complete the end connections. These, in piping term, we call g/d%06*

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TERMINAL CONNECTIONS.

So far this is a nice arrangement. But there is no control over the flow from Tank-1 to other tanks.

I TAN K-2

We need some arrangement to stop the

.................... I This is a welded joint

To control the flow in a pipe line we need to fit a special component.

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That is called VALVE g/&%ofi

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There are many types of valves, categorized based on their construction and functionality,

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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 g/#"fi

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Here we see a more or less functional piping system, with valves and strainer installed.

When some fluid is flowing in a pipe we may also like know the parameters like, pressure, temperature, flow rate etc. of the fluid.

Next we shall look into how to SUPPORT the

There are various types instruments to measure various parameters. Also there are specific criteria for installation of various pipe line instruments.

Here are some of the pipe supporting arrangements. There can be numerous variants. All depend on piping designer's preference and judgement.

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~ L S ~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

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We represent the whole thing in a drawing which is called Piping and Instrumentation Drawing, in short P&ID. For P&ID generation we use SPP&ID software.

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By this time you have already come to know that while we prepare P&IDs in SPP&ID, we enter all the pipe lines system information in the drawing.

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So the SPP&ID 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 SPP&ID

After the P&ID is ready we start the layout work. Here we carryout pipe routing Ilayout in Virtual 3D environment. We use PDS 3D 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.

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Not Preferable

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

+ Valves, strainers, instruments on the pipe should be easily accessible. 3 If needed separate ACCESS PLATFORMS to be provided to facilitate these.

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+ Desired location and orientation of valves Iinstruments and other pipe components are to be checked and maintained, like some valves or strainers can only be installed in horizontal position.

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+ 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.

3 Specific requirements of STRAIGHT LENGTH of pipe for some components to be maintained, like for flow orifice we need to provide 15 times diameter straight pipe length at upstream of orifice and 5 times diameter straight at down stream of orifice. FLOW MEASURING ORIFICE A I - W

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FLOW DIRECTION

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MORE THAN 1

Example of Straight length requirement for Flow Orifice

-4 For Pipeline which shall carry liquid, 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. Also arrangement is kept in the pipeline so that liquid can be drained out if required.

VENT WITH VLAVE

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HIGHEST POINT IN PIPELINE

-4 To achieve this a DRAIN connection with Valve is provided at the lowest point of the pipeline

+ Pipes are also slopped towards low points. Let us look into typical Vent and Drain arrangement in a pipeline

LOWEST POINT IN PIPELINE

\ DRAIN WITH VALVE

lNSULATlON

- 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

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.

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INSULATION MATERIAL The insulating material should be bad conductor of heat. There are two basic categories

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1) 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.

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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.

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INSULATION CLADDING Insulation materials are generally soft or fragile. So the outer surface of insulation are protected with Aluminum sheet or GI sheet cladding.

Have a look at how pipes are insulated, and general components of insulation

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Pipe Material Selection to select appropriate pipe material based on flowing fluid property.

Note-I : 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 listed.

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

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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.

-4 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 to withstand the high pressure and may be also high temperature.

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

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are not transferred to the nozzles of Turbine or Pumps

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

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mandatory requirements for design of such piping. 4 The most important codes used by power plant piping engineers are I

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-4 ASME ANSI 831.1- Power Piping Code & IBR the Indian Boiler Regulation

PIPE STRESS ANALYSIS

Types of Pipe Supports

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Constant Load Spring

Variable Spring

Rigid Suppo

Some Special Considerations for Piping

Freeze Protection of outdoor Piping:

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+ In the areas where the ambient temperature goes below freezing there is a possibility that the liquid content of pipe may freeze while the plant is under shut down. -$

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

+ Electric Heat tracing is done by wrapping electric coil 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.