Piping Layout Unit V

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1.Flow diagram or System flow diagram or Process flow

diagram(PFD)

2.Pipe Sizing

3.Piping and Instrumentation Diagram(P&ID)

4.Piping Layout

5.3D Modelling

6.Piping Stress Analysis

7.Detailing or Detail Drawing Preparation

HIERARCHY OF PIPING

DESIGN


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Flow DiagramWhat is that?It is a diagram schematically showing the operational relationships among themajor system components and by stating the design and expected process

variables for selected modes of operation

Flow Diagrams should show the following:

All major equipment

Equipment names

Equipment identification numbers

Major bypass and recirculation lines

Control valves

Interconnections to other systems

Equipment ratings or capacities

Pipe sizes if required by office practice


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Flow Diagram

Flow Diagrams should not show the following:

Pipe class

Pipe line numbers, unless required by office practice

Minor bypass lines

Isolation and shutoff valves

Maintenance vents and drains

Relief and safety valves

Instruments

Code class information

Seismic class information


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Pipe SizingInput Parameters:

1.Mass flow rate

2.Pressure

3.Temperature

Steps:

1.Find out the diameter(ID) required for given flow rate by usingequation

Qv=AV (V is assumed initially based on guidelines)

2.Based on ID select OD

3.Now calculate minimum thickness As per code

4. Check provided Thk > Min.Thk

5. Actual Velocity < Assumed Velocity


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Pipe SizingExample:

1.Steam mass flow rate(Qm): 130 tons/hr.2.Steam pressure: 92 kgf/cm2

3.Steam temperature: 520 C

Qm=AV

Qm=130 tons/hr=36.11 kg/s

Qv=Qm / density =36.11 / 0.037857

Qv=1.367 m3/s

1.367=A (55)A=0.02485 m2 Min.internal dia Di=177.9mm

From available market diameter Do=219.1mm


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Specification of Materials

Carbon Steels:ASME SA 106 Gr.A/B/C

Alloy Steels:ASME SA 335 P11,SA 335 P22 Nickel and Nickel Alloys - ASTM B-366, ASME SB-366.

Stainless Steel:ASTM A-403 and ASME SA-403, 304 etc.,

Chrome-molybdenum:ASTM A-234 & ASME SA-234

Aluminum:ASTM B-361, 5083, 66061, 5086

Titanium:ASTM B-363 & ASME SB-363,

Other Materials: Nylon Bronze Polyamide

CPVC Polyethylene (PE)

EPDM PVC (Polyvinyl Chloride)

Fiberglass / Composite

Iron (Gray / Cast/ Ductile)

brass


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Piping And InstrumentationDiagram(P&ID)

What is that?

It provides a schematic representation of the piping, process control,and instrumentation which shows the functional relationships amongthe system components.

The P&ID should show the following:

Mechanical equipment

All valves associated with the process piping

Vents and drains

Special fittings

Sampling lines


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Instrument designations

Equipment names and numbers

Pipeline identification no.

Valve identification

Reducers and increasers, swages, etc.

Direction of flowInterfaces for class changes

Seismic category

Interconnection references

Vendor and contractor interfacesIdentification of components and subsystems by others

Cont..


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The P&ID should not show the following unless there is a

compelling need to do so for clarity. Items identified by an

asterisk may be shown, if necessary.

Instrument root valves*

Equipment rating or capacity

Control relays*

Manual switches*

Indicating lights*

Primary instrument tubing and valves

Pressure, temperature, and flow data

Vendor package piping which has no interface withengineering or construction*

Elbows, tees, and similar standard fittings

Extensive explanatory notes

Cont..


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Piping LayoutP&ID is the piping designers roadmap for laying out pipingsystems.Equipment Layout,Structural Drawings of the plant are neccessaryinput to the piping layout.

Some important Piping layout considerations:

One of the most important aspects of piping layout is the avoidanceof interferences

Piping Flexibility -based on the temperature, sufficient looping orexpansion joints should be provided to accommodate expansion.

Vents and DrainsPipe Supports Location of supports, guides, and anchors is a vital

point

Heat Tracing


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Cont...Desired location and orientation of valves should be provided.

Desired location and orientation of instruments and other pipecomponents are to be checked and maintained, like some strainers

can only be installed in horizontal position.

Minimum Hydraulic resistance i.e. minimum pressure drop.

Specific requirements of STRAIGHT LENGTH of pipe for some

components to be maintained, like for flow orifice we need to provide15 times diameter straight pipe length at upstream of orifice and 5times diameter straight at down stream of orifice.


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Documents

Piping Layout Unit V