Design of Steam Piping System Including Stress Analysis

5/28/2018 Design of Steam Piping System Including Stress Analysis

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Design of Steam Piping including

Stress Analysis

Muhammad Sardar

Thesis submitted in partial fulfillment of requirements for the MS

Degree in Mechanical Engineering

Department of Mechanical Engineering,

Pakistan Institute of Engineering & Applied Sciences,

Nilore, Islamabad, Pakistan.

October, 2008.

Note. This is not a handbook, it is MS Thesis of a student in PakistanInstitute of Engineering & Applied Sciences, Pakistan (PIEAS).



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Department of Mechanical Engineering,

Pakistan Institute of Engineering and Applied Sciences (PIEAS)

Nilore, Islamabad, Pakistan

Declaration of Originality

I hereby declare that the work contained in this thesis and the intellectual content of

this thesis are the product of my own work. This thesis has not been previously

published in any form nor does it contain any verbatim of the published resources

which could be treated as infringement of the international copyright law.

I also declare that I do understand the terms copyright and plagiarism and

that in case of any copyright violation or plagiarism found in this work, I will be held

fully responsible of the consequences of any such violation.

Signature:

Name: Muhammad Sardar

Date:____________________

Place: PIEAS, Nilore Islamabad



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Certificate of Approval

This is to certify that the work contained in this thesis entitled

Design of Steam Piping including Stress Analysis

was carried out by

Muhammad Sardar

Under my supervision and that in my opinion, it is fully adequate, in

scope and quality, for the degree of M.S. Mechanical Engineering from

Pakistan Institute of Engineering and Applied Sciences (PIEAS).

Approved By:

Signature:________________________

Supervisor:Mr. Basil Mehmood Shams,P.E. (DTD, Islamabad)

Signature:_______________________

Co-Supervisor:Muhammad Younas, S.E. (DTD, Islamabad)

Signature:________________________

Co-Supervisor:Hafiz Laiq-ur-Rehman, J.E. (PIEAS, Islamabad)

Verified By:

Signature:________________________

Head, Department of Mechanical Engineering

Stamp:



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Dedication

Dedicated to my parents, brothers, sisters and my teachers

who always supported me and whose

prayers enabled me to

do my best in every

matter of my life



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Acknowledgement

First of all I am humbly thankful to Allah Almighty, giving me the power to think and

enabling me to strengthen my ideas. I glorify ALMIGHTY ALLAH for HIS

unlimited blessings and capabilities that HE has bestowed upon me, without HIS

blessings, I would not be able to complete my work. I offer my thanks to Holy

Prophet(Peace Be Upon Him), The mercy for all the worlds and whose name hasgiven me special honor and identity in life.

I am very grateful to my project supervisor Mr. Basil Mehmood Sham, P.E. for his

guidance for the completion of this work. I am also grateful to my co-supervisors

Mr. Muhammad Younas, S.E. and Mr. Hafiz Laiq-ur-Rehman, J.E. for their

inspiring guidance, constant encouragement and fruitful suggestions. At the end I am

also thankful to Engr. Dr. Mohammad Javed Hyder for his keen interest in the

project and constructive criticism, which enabled me to complete my report.

Muhammad Sardar



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Table of Contents

1 INTRODUCTION................................................................................................1

1.1 Thesis Introduction ........................................................................................1

1.2 Basic aim of the thesis ...................................................................................1

1.3 Steam Piping Network ...................................................................................2

1.4 Thesis Organization .......................................................................................2

2 THEORETICAL BACKGROUND OF PIPING SYSTEM ............................5

2.1 Historical background of the piping system ..................................................5

2.2 Piping Terminologies.....................................................................................6

2.2.1 Pipe.......................................................................................................................6

2.2.2 Types of pipes and its uses...................................................................................6

2.2.3 Pipe Size...............................................................................................................6

2.2.4 Nominal Pipe Size (NPS).....................................................................................6

2.2.5 Piping ...................................................................................................................6

2.2.6 Piping System ......................................................................................................7

2.2.7 Process Piping......................................................................................................7

2.2.8 Service Piping ......................................................................................................72.3 Pipe Fittings ...................................................................................................7

2.3.1 Valves...................................................................................................................7

2.3.2 Expansion Fittings................................................................................................8

2.4 Supports .........................................................................................................9

3 PIPING CODES AND STANDARDS..............................................................12

3.1 Piping Code Development ...........................................................................12

3.2 B31.1 Power Piping .....................................................................................13

3.3 ASME Code Requirements..........................................................................14

3.3.1 Stresses due to sustained loadings......................................................................14

3.3.2 Stress due to occasional loadings.......................................................................14

3.3.3 Stresses due to thermal loadings ........................................................................15

3.4 Stress analysis of piping system ..................................................................15

3.4.1 Stress and Strain.................................................................................................15

3.4.2 Failure Theories .................................................................................................15

3.4.3 Piping Design Criteria........................................................................................16



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4 PIPING DESIGN PROCEDURES...................................................................19

4.1 Process Design.............................................................................................19

4.2 Piping Structural Design..............................................................................19

4.2.1 Pipe Thickness Calculations ..............................................................................204.2.2 Allowable Working Pressure .............................................................................20

4.2.3 Sustained Load Calculations ..............................................................................21

4.2.4 Wind Load Calculations.....................................................................................21

4.2.5 Thermal Loads Calculations ..............................................................................22

4.2.6 Occasional Loads ...............................................................................................22

4.2.7 Seismic Loads ....................................................................................................22

4.3 Pipe Span Calculations ................................................................................23

4.3.1 Span Limitations ................................................................................................23

4.3.2 Expansion Loop Calculations ............................................................................24

5 SUPPORT DESIGN...........................................................................................25

5.1 Beam Design................................................................................................25

5.1.1 Bending Stress....................................................................................................26

5.1.2 Shear Stress ........................................................................................................26

5.1.3 Deflection...........................................................................................................27

5.2 Column.........................................................................................................27

5.3 Base Plate.....................................................................................................29

5.4 Base Plate Bolts ...........................................................................................29

6 PIPE DESIGN CALCULATIONS...................................................................30

6.1 Design Parameters .......................................................................................30

6.2 Physical Properties.......................................................................................32

6.3 Design Calculations .....................................................................................32

6.3.1 Pipe Thickness Calculations ..............................................................................32

6.3.2 Allowable Working Pressure .............................................................................36

6.3.3 Wind load Calculations ......................................................................................38

6.3.4 Dead Loads Calculation .....................................................................................40

6.3.5 Pipe Span Calculations (based on limitation stress)...........................................42

6.3.6 Calculation for Supports based on Standard Spacing ........................................45

6.3.7 Thermal Expansion (deflection).........................................................................47

6.3.8 Expansion Loops Calculations...........................................................................496.3.9 Impact Loading on Bends ..................................................................................53



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6.3.10 Normal Impact Load on elbow ..........................................................................54

7 THERMAL CALCULATIONS........................................................................56

7.1 Thermal Analysis .........................................................................................56

7.2 Verification from Code................................................................................67

7.3 Static Loads Calculations.............................................................................68

7.3.1 Manual Calculations...........................................................................................68

7.3.2 Verification from Code ......................................................................................71

7.4 Piping Analysis on ANSYS.........................................................................72

7.4.1 Comparison of Analysis.....................................................................................74

7.5 Seismic Loads Calculations .........................................................................74

7.5.1 Seismic stress .....................................................................................................747.5.2 Seismic Lateral load...........................................................................................74

7.5.3 Verification from Code ......................................................................................75

8 SUPPORT DESIGN CALCULATION............................................................77

8.1 Design Parameters .......................................................................................77

8.2 Beam Design................................................................................................77

8.3 Beam Analysis .............................................................................................79

8.3.1 Manual Analysis.................................................................................................798.3.2 ANSYS Analysis................................................................................................80

8.4 Column Design ............................................................................................82

8.4.1 Verification for critical load...............................................................................84

8.4.2 Verification for stresses......................................................................................84

8.4.3 Manual Analysis.................................................................................................85

8.4.4 ANSYS Analysis................................................................................................87

8.4.5 Comparison of analysis......................................................................................89

8.5 Base Plate Design ........................................................................................89

8.5.1 Base Plate Design Calculations..........................................................................90

8.5.2 Thickness of the plate due to concentric load ....................................................91

8.5.3 Thickness due to bending moment.....................................................................91

8.5.4 Specifications of base plate................................................................................93

8.5.5 Bolt specifications..............................................................................................93

9 COMPLETE SYSTEM MODELING..............................................................94

9.1 Pro-E Modeling............................................................................................94



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9.2 ANSYS 3-D Modeling and Analysis...........................................................95

9.2.1 Results and Discussion.......................................................................................98

10 CONCLUSIONS................................................................................................99

11 FUTURE RECOMMENDATIONS ...............................................................100

REFERENCES.........................................................................................................101

APPENDIXE ............................................................................................................101

VITA..........................................................................................................................113



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List of Figures

Figure 1-1 PFD of the complete piping net work ........................................................4

Figure 2-1 Full loop ....................................................................................................8

Figure 2-2 Z, L and U shaped loop .............................................................................9

Figure 2-3 Anchor support ........................................................................................10

Figure 2-4 Hanger support ........................................................................................10

Figure 2-5 Sliding support ........................................................................................10

Figure 2-6 Spring support .........................................................................................11

Figure 2-7 Snubber support .......................................................................................11

Figure 2-8 Roller support ..........................................................................................11

Figure 5-1 Effective length constants table ..............................................................28

Figure 6-1 Forces on the bend by the fluid ................................................................53

Figure 7-1 Header Pipe including an expansion loop................................................56

Figure 7-2 Header Pipe Sections................................................................................57

Figure 7-3 Symmetry of header pipe considering as a beam.....................................68

Figure 7-4 Segment A-B............................................................................................69

Figure 7-5 Segment A-B-C........................................................................................69

Figure 7-6 Shear Force Diagram................................................................................70

Figure 7-7 Bending Moment Diagram.......................................................................71

Figure 7-8 Loaded view of the meshed beam............................................................72

Figure 7-9 Deflection in Pipe....................................................................................73

Figure 7-10 Bending stress in Pipe .............................................................................73

Figure 8-1 Uniformly load distributed Cantilever Beam...........................................77

Figure 8-2 Double Cantilever beam...........................................................................79

Figure 8-3 Deformed Shape of the beam ..................................................................80

Figure 8-4 Bending Moment diagram of the beam ...................................................81

Figure 8-5 Max. Stress distribution Diagram ...........................................................81

Figure 8-6 Loads on column of the support...............................................................82

Figure 8-7 Meshed and loaded column......................................................................88

Figure 8-8 Deformation of the column .....................................................................88

Figure 8-9 Stress distribution in column ...................................................................89

Figure 8-10 Base Plate Dimensions.............................................................................90

Figure 8-11 Pressure diagram ......................................................................................91



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Figure 8-12 Bolt dimensions........................................................................................93

Figure 9-1 Anchor support along with a pipe............................................................94

Figure 9-2 Convergence line b/w no. of elements and Von Mises Stresses..............95

Figure 9-3 Meshed diagram of the support model.....................................................96

Figure 9-4 Deformed shape of the support model .....................................................96

Figure 9-5 First Principle Stress distribution in support...........................................97

Figure 9-6 Von Mises stress distribution in support..................................................97



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List of Tables

Table 3-1 Primary stresses of pipes ...........................................................................17

Table 3-2 Secondary stresses of pipes .......................................................................18

Table 5-1 Limitation of column slenderness ratio .....................................................28

Table 6-1 Characteristics of Fluid at inlet and out let of pipes and its sizing............30

Table 6-2 Material Properties ....................................................................................32

Table 6-3 Input Parameters used in pipe thickness calculation .................................33

Table 6-4 All pipes thickness along with standard thickness ....................................34

Table 6-5 Input data ...................................................................................................36

Table 6-6 Design and working Pressure ....................................................................36

Table 6-7 Wind loads for each pipe...........................................................................38

Table 6-8 Pipe, Fluid and insulation weights.............................................................40

Table 6-9 Pipe Span based on limitation of stress .....................................................43

Table 6-10 Spacing based on standard spacing ...........................................................45

Table 6-11 Thermal deflection for pipes complete segments......................................47

Table 6-12 Sizing of expansion loops..........................................................................50

Table 6-13 Input Data ..................................................................................................53

Table 6-14 Input data ...................................................................................................54

Table 7-1 Input Data ..................................................................................................56

Table 7-2 For main line magnitude of expansion and directions...............................58

Table 7-3 Vertical section magnitude of expansion and direction ............................58

Table 7-4 Summary of all Loads due to Thermal expansion.....................................66

Table 7-5 Input data ...................................................................................................67

Table 7-6 Input data ...................................................................................................71

Table 7-7 Comparison of analysis for beam..............................................................74

Table 7-8 Input data ...................................................................................................76

Table 8-1 Available loads for analysis of anchor support .........................................77

Table 8-2 Properties of the channel beam..................................................................78

Table 8-3 Comparison of analysis for beam..............................................................82

Table 8-4 Specifications of column ...........................................................................83

Table 8-5 Input data ...................................................................................................86

Table 8-6 Input data ...................................................................................................87



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Table 8-7 Comparison of analysis of column.............................................................89

Table 8-8 Base plate specifications.............................................................................93

Table 8-9 Bolts standard dimensions..........................................................................93



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Abstract

This report is about the design of steam piping and its stress analysis of a

given process flow diagram. The prime objective of this project is to design

the piping system and then to analyze its main components. Wall thicknesses

are calculated for all pipes which were found very safe for the operating

pressure. For header pipe the calculated wall thickness is 0.114 inch and the

standard minimum wall thickness is 0.282 inch which is greater than the

calculated one by more than 2.4 times. Different loads such as static loads,

occasional loads and thermal loads of all pipes were also calculated. After

load calculations, spacing of supports and designing of expansion loops were

carried out. Thermal, static and seismic analysis of main system pipe has

been done and results were compared with ASME Power Piping Code B31.1.

After calculation of all applied loads, anchor support components including

half channel beam C5 x 9 and standard circular column of 4 inch nominal size

were designed and analyzed both manually and on ANSYS software. Base

plate of size 15x15x1/4 inch and bolts of inch diameter and of length 20

inch were also designed. The results obtained from both methods were

compared and found safe under available applied loads.



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1 Introduction

1.1 Thesis Introduction

Piping System design and analysis is a very important field in any process and power

industry. Piping system is analogous to blood circulating system in human body and is

necessary for the life of the plant. The steam piping system, mentioned in the thesis

will be used for supplying steam to different locations at designed temperature and

pressure. This piping system is one of the major requirements of the plant to be

installed.

This thesis includes the following tasks:

a) Process design of the complete piping system

b) Structural design of the pipes manually

c) Stress analysis of the pipes using ANSYS

d) Structural and thermal analysis of the expansion Loops

e) Structural design of supports manually

f) Modeling and stress analysis of support

1.2 Basic aim of the thesis

The aim of the thesis was to design and analyze piping system according to standard

piping Codes. The design should prevent failure of piping system against over stresses

due to:

I. Sustained loadings which act on the piping system during its operating time

e.g. static loads including dead loads, thermal expansion loads, effects of

supports and internal and external pressure loading.

II. Occasional loads which act percentages of the systems total operating time

e.g. impact forces, wind loads, seismic loads and discharge loads etc.

While piping stress analysis is used to ensure:

1) Safety of piping and piping components

2) Safety of the supporting structures

3) Safe stress relieving of the expansion loops



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1.3 Steam Piping Network

Basically the sizing of this steam piping has already done and contained nearly on

750x300m2area, including 48 pipes and 52 junctions. The detail of the piping system

e.g. length of each pipe, Nominal Pipe Size (NPS) with pipe no. starting from 208 and

ending on pipe no. 256 are shown from the following Figure 1-1. The rest of the data

e.g. inlet and out let velocities of each pipe, inlet and out let pressure of each pipe and

inlet and out let temperature of each and every pipe are arranged in Table 6-1, which

will be used in further calculations.

1.4 Thesis Organization

Chapter 1

In this chapter introduction to the project, basic aim of the project and process flow

diagram of the complete piping system with information about sizing has been

discussed.

Chapter 2

Literature survey has been done in this chapter. Detail study about the pipes and

piping system along with the code development has been included. This chapter also

consists on some of the basic terminologies relating to pipes, explanation of the piping

components and supports.

Chapter 3

Explanation about piping codes and standards and stress analysis of the piping system

has been included in this chapter.

Chapter 4

In this chapter piping design procedure, pipe span and expansion loop calculations

and support design methodology has been discussed.

Chapter 5

This chapter included all the detail about Anchor support and its components.

Chapter 6

This chapter related to all calculations of pipe design. All loads applied on the pipes

during operation have been calculated.

Chapter 7

This chapter included on thermal, static and seismic loads on pipes and their analysisalong with verification from the code has been done.



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Chapter 8

This chapter consists on the piping support design calculations, in which selection and

analysis of beam, column, base plate and bolts has been done.

Chapter 9

This chapter contained full modeling of anchor support in Pro-E and ANSYS and its

analysis in ANSYS.



Steam Piping Network

Figure 1-1 PFD of the complete piping network



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2 Theoretical Background of Piping

System

A piping system is generally considered to include the complete interconnection of

pipes, including in line components such as pipe fittings, valves, tanks and flanges

etc. The contributions of the piping systems are essential in industrialized society.

They provide drinking water to cities, irrigation water to farms, cooling water to

buildings and machinery. Piping system are the arteries of our industrial processes;

they transmit the steam to turn the turbines which drive generators, thus providing

electricity that illuminates the world and power machines [1].

2.1 Historical background of the piping system

Initially there were no basic concepts of the piping system engineering when wind,

water and muscle were the prime movers. The advent of the industrial revolution,

especially the practical use of steam in the seventeenth century required the design

and manufacturing of piping to withstand the rejoins of conveying pressurized and

heating fluids. The combination of very high pressures, thermal stresses and thermal

deformations required that fundamental design requirements and analytical technique

be developed. However, piping system design progressed with little or no design

standards or code limitations during the early years of industrial revolution [3].

In the 1920s, the introduction to meet the electrical demand of turbine plants

with super heated steam at temperature up to 600oF and gauge pressure of 300 psi

posed to the next major piping system design challenge. These design conditions

exceeded safe cast iron values, thus requiring the introduction of cast steel for critical

components. By 1924, the steam gauge pressure had increased to 600 psi, doubling in

just a few years. One year later, steam pressure and temperature of 1200 psi and

700oF were achieved, demonstrating the advances made in the development of steam

generator and attached piping. By 1957, some 900oF designs were in service with

1200oF designs projected, using austenitic stainless steel materials in the high

temperature zones, currently, the top gauge pressure is 2400 psi for most fossil fuel

plants. With new materials available, the boiler, turbine and piping have equal

strength capabilities [3].



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2.2 Piping Terminologies

Detail of some of the basic terminologies like pipe, pipe sizes and pipe system are

given below.

2.2.1 Pipe

A pipe is a closed conduit of circular cross section which is used for the

transportation of fluids. If pipe is running full, then the flow is under pressure and if

the pipe is not running full, then the flow is under gravity.

2.2.2 Types of pipes and its uses

Standard Pipe: Mechanical service pipes, low pressure service e.g. refrigeration pipes

Pressure Pipe: It is used for liquid, gas or vapor for high pressure and temperature

application.

Line Pipe: Threaded or Plain ends used for gas, steam and as an oil pipe.

Water Well: Pump pipe, turbine pipe and driven well pipe etc [1].

2.2.3 Pipe Size

Initially a system known as iron pipe size (IPS) was established to designate the pipe

size. The size represented the approximate inside diameter of the pipe in inches e.g.

an IPS 6 pipe is one whose inside diameter is approximately 6 inches (in). With the

development of stronger and corrosion-resistant piping materials, the need for thinner

wall pipe resulted in a new method of specifying pipe size and wall thickness. The

designation known as nominal pipe size (NPS) replaced IPS, and the term schedule

(SCH) was invented to specify the nominal wall thickness of pipe.

2.2.4 Nominal Pipe Size (NPS)

NPS is a dimensionless designator of pipe size. It indicates standard pipe size when

followed by the specific size designation number without an inch symbol.

For example, NPS 2 indicates a pipe whose outside diameter is 2.375 in [2].

2.2.5 Piping

Pipe sections when joined with fittings, valves, and other mechanical equipment and

properly supported by hangers and supports, are called piping.



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2.2.6 Piping System

The piping system means a complete network of pipes, valves, and other parts to do a

specific job in plant. There are two types of piping systems.

2.2.7 Process Piping

It is used to transport fluids b/w storage tanks and processing unites.

2.2.8 Service Piping

It is used to convey steam, air, water etc. for processing.

2.3Pipe Fittings

Fittings permit a change in direction of piping, a change in diameter of pipe or a

branch to be made from the main run of pipe. Some of the fittings are elbows, long

radius and short radius elbow reducing elbow, reducer, bends and mitered bends etc.

2.3.1 Valves

A valve is a mechanical device that controls the flow of fluid and pressure within a

system. There are different types of valves some of them are discussed below [3].

a) ON/OFF Valves

These are the kind of valves which are used to stop of start the fluid flow e.g. Gate

valve, Globe valve, rotary ball valve, Plug valve and diaphragm valve etc.

b) Regulating Valve

These are the kind of valves which are used to start, stop and also to regulate the fluid

flow e.g. Needle valve, butterfly valve, Diaphragm and Gate valve etc.

c) Safety Valve

This valve reacts to excessive pressure in piping system. They provide a rapid means

of getting rid of that pressure before a serious accident occur. Safety valve is used

normally for gasses and steams. In safety valve the steam is discharge to the air

through a large pipe.



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d) Pressure Regulating Valve

These valves regulate pressure in a fluid line keeping it very close to a pre-set level.

The valve is set to monitor the line, and make needed adjustments on signal from a

sensitive device.

2.3.2 Expansion Fittings

Expansion loops are used to release the stresses which produced due to thermal

gradients. All pipes will be installed at ambient temperature. Pipes carrying hot fluids

such as water or steam operate at higher temperatures. It follows that they expand,

especially in length, with an increase from ambient to working temperatures. This will

create stress upon certain areas within the distribution system, such as pipe joints,

which, in the extreme, could fracture. Therefore the piping system must be

sufficiently flexible to accommodate the movements of the components as they

expand [1].

The expansion fitting is one of method of accommodating expansion. These

fittings are placed with in a line, and are designed to accommodate the expansion,

with out the total length of the line changing. They are commonly called expansion

bellows, due to the bellows construction of the expansion sleeve. Different kinds of

expansion loops are used, some of which are given below.

2.3.2.1 Full loop

This is simply one complete turn of the pipe and, on steam pipe work, should

preferably be fitted in a horizontal rather than a vertical position to prevent

condensate accumulating on the upstream side as shown in Figure 2-1 below. When

space is available, it is best fitted horizontally so that the loop and the main are on the

same plane.

Figure 2-1 Full Loop [6]



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2.3.2.2 Z, L, and U shaped loops

In majority of these loops guided cantilever method is used to find the deflection in

the loop. These loops are shown in the Figure 2-2 below.

Figure 2-2 Z, L and U shaped Loop [2]

2.4 Supports

Pipe support specifications for individual projects must be written in such a way as to

ensure proper support under all operating and environmental conditions and to

provide for slope, expansion, anchorage, and insulation protection. Familiarity with

standard practices, customs of the trade, and types and functions of commercial

component standard supports and an understanding of their individual advantages and

limitations, together with knowledge of existing standards, can be of great help in

achieving the desired results [1]. Good pipe support design begins with good piping

design and layout. For example, other considerations being equal, piping should be

routed to use the surrounding structure to provide logical and convenient points of

support, anchorage, guidance, or restraint, with space available at such points for use

of the proper component. Parallel lines, both vertical and horizontal, should be spaced

sufficiently apart to allow room for independent pipe attachments for each line. There

are different types of supports used in the piping system; some of them are discussed

below [2].

a) Anchor support

A rigid support providing substantially full fixity for three translations and

rotations about three reference axes. Figure 2-3 shows the model along with



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the pipe and welding positions. Detail of this support will be discussed in

chapter 8.

Figure 2-3 Anchor Support [3]

b) Hanger support

A support for which piping is suspended from a structure, and so on, and

which functions by carrying the piping load in tension as shown below in

figure.

Figure 2-4 Hanger Support [3]

c) Sliding support

A device that providing support from beneath the piping but offering no

resisting other than frictional to horizontal motion as shown in Figure 2-5

below..

Figure 2-5 Sliding Support [3]



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d) Spring support

Spring support is used when there is an appreciable difference b/w operating

and non operating conditions of the pipes. Constant load support is used when

loading condition change up to 6%.

Figure 2-6 Spring support [1]

e) Snubber support

These supports are used to restrain the dynamic load such as seismic loads,

water hammer and steam hammer etc. These supports are not capable of

supporting gravity loads. A simplified snubber support view is shown in

Figure 2-7 below.

Figure 2-7 Snubber support [3]

f) Roller support

A means of allowing a pipe to move along its length but not side ways. Roller

support is shown in Figure 2-8 below.

Figure 2-8 Roller support [3]



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3 Piping Codes and Standards

Before the selection of codes for the steam piping, a little detail about codes,

standards and its historical background is given below.

3.1Piping Code Development

The increase in operating temperatures and pressures led to the development of the

ASA (now ANSI) B31 Code for pressure piping. During the 1950s, the code was

segmented to meet the individual requirements of the various developing piping

industries, with codes being published for the power, petrochemical and gas

transmission industries among others. The 1960s and 1970s encompassed a period of

development of standard concepts, requirements and methodologies. The

development and use of the computerized mathematical models of piping system have

brought analysis, design and drafting to new levels of sophistication. Codes and

standards were established to provide methods of manufacturing, listing and reporting

design data [3].

A standard is a set of specifications for parts, materials or processes intendedto achieve uniformity, efficiency and a specified quality. Basic purpose of the

standards is to place a limit on the number of items in the specifications, so as to

provide a reasonable inventory of tooling, sizes and shapes and verities [4]. Some of

the important document related to piping are:

I. American Society of Mechanical Engineers (ASME)

II. American National Standards Institute (ANSI)

III. American Society of Testing and Materials (ASTM)

IV. Pipe Fabrication Institute (PFI)

V. American Welding Institute (AWS)

VI. Nuclear Regulatory Commission (NRC)

On the other side A code is a set of specifications for analysis, design,

manufacture and construction of something. The basic purpose of code is to provide

design criterion such as permissible material of construction, allowable working

stresses and loads sets [4]. ASME Boiler and Pressure vessel codeB31, Sectiion-1 is



13

used for the design of commercial power and industrial piping system. This section

has the following sub section [1].

B31.1: For Power Piping.

B31.3: For Chemical plant and Petroleum Refinery Piping.

B31.4: Liquid transportation system for Hydrocarbons, liquid petroleum gas, and

Alcohols.

B31.5: Refrigeration Piping.

B31.8: Gas transportation and distribution piping system.

B31.1 Power piping code concerns mononuclear piping such as that found in

the turbine building of a nuclear plant or in a fossil-fueled power plant. Detail of this

code is given below in section 3.2. B31.3 code governs all piping within limits offacilities engaged in the processing or handling of chemical, petroleum, or related

products. Examples are a chemical plant compounding plant, bulk plant, and tank

farm. B31.4 governs piping transporting liquids such as crude oil, condensate, natural

gasoline, natural gas liquids, liquefied petroleum gas, liquid alcohol, and liquid

anhydrous ammonia. These are auxiliary piping with an internal gauge pressure at or

below 15 psi regardless of temperature. B31.5 covers refrigerants and secondary

coolant piping for temperatures as low as 320

o

F. B31.8 governs most of the pipe linesin gas transmission and distribution system up to the outlet of the customers meter set

assembly. Excluded from this code with metal temperature above 450oF or below -

20oF. As for as the steam piping is concerned, B31.1 Power piping is used because of

its temperature and pressure limitations which is discussed below in detail.

3.2B31.1 Power Piping

This code covers the minimum requirements for the design, materials, fabrication,

erection, testing, and inspection of power and auxiliary service piping systems for

electric generation stations, industrial institutional plants, and central and district

heating plants. The code also covers external piping for power boilers and high

temperature, high-pressure water boilers in which steam or vapor is generated at a

pressure of more than 15psig and high-temperature water is generated at pressures

exceeding 160psig or temperatures exceeding 250oF. This code is typically used for

the transportation of steam or water under elevated temperatures and pressure as



14

mentioned above, so this is the reason that why this code is selected for the steam

piping system which is external to the boiler [5].

3.3ASME Code Requirements

As it already mentioned in the previous section 3.2, Boiler outlet section of the steam

system comes under the category of ASME Code B31.1 Power. In order to ensure the

safety of the piping system, code requirements should be fully satisfied. For different

loads this code incorporates different relationships for stress level as given below.

3.3.1 Stresses due to sustained loadings

The effects of the pressure, weight, and other sustained loads must meet the

requirements of the following equation [1].

0.751.0

4

o A

L h

PD i MS S

t Z

= + (3.1)

Where

P = Internal Pressure, psi

Do = Out Side diameter of Pipe, in

t = nominal wall thickness, in

Z = Section modulus of pipe, in3

MA = Resultant moment due to loading on cross section due to weight and other

sustained loads, in-lb

Sh = Basic material allowable stress at design pressure, psi

3.3.2 Stress due to occasional loadings

The effects of pressure, weight, and occasional loads (earthquake) must meet therequirements of the following equation [1].

0.75 ( )

4

o A B

h

PD i M MKS

t Z

++ (3.2)

Where

MB = Resultant moment loading on cross section due to occasional loads, psi

K= Constant factor depend on plant operation time

The rest of the terms are same to above equation.



15

3.3.3 Stresses due to thermal loadings

The effects of thermal expansion must meet the following equation [1].

( )

C

A h L

iM

S f S S Z + (3.3)

where

f = Stress range reduction factor

Mc =Range of resultant moment due to thermal expansion, in-lb

SA = Allowable stress range for expansion

The rest of the terms are same to above equation.

3.4Stress analysis of piping systemPiping stress analysis is a discipline which is highly interreralated with piping layout

and support design. The layout of the piping should be performed with requirements

of piping stress and pipe support in mind. If necessary, layout solutions should be

iterated until a satisfactory balance b/w stress and layout efficiency is achieved [1].

3.4.1 Stress and Strain

Stress is defined as the reactive force per unit area which is developed when an

external force is being applied on the body. The stress is responsible for the

deformation and deterioration of the material.

There are two types of stresses, normal stress and shear stress. The normal

stresses are perpendicular stress on a body and they are directed normal of the surface

of the body. The tensile stresses are those stress which produces tension in the

material whereas compressive stresses are those stresses which produce the

compression in the material.

On the other side shear stress is the force per unit area of shearing plane. The

shear stresses are those stresses which tend parallel plates of the material to slip past

each other. The strain is the deformation in the dimension a material when it is under

stress. The strain is of two types shear strain and normal strain [3].

3.4.2 Failure Theories

The failure theories most commonly used in describing the strength of the piping

system are the:



16

1) Maximum principle stress theory

2) Maximum shear stress theory (Tresca theory)

3.4.3.1 Maximum principle stress theory

This theory states that failure will always occurs, whenever the greatest tensile stress

tends to exceed the uni-axial tensile strength or whenever the largest compressive

stress tends to exceed the uni-axial compressive strength. This theory has been found

to correlate reasonably well with test data for brittle fracture [3]. The maximum

principle stress theory form the basis for piping system governed by ANSI/ASME

B31 and subsection (class2 and class3) of section III of the ASME boiler and pressure

vessel codes [1].

3.4.3.2 Maximum shearing stress theory

Where on the other side the maximum shear stress theory states that failure of a

piping component occurs when the maximum shear stress exceed the shear stress at

the yield point in a tension test. In tensile test, at yield, 1= Sy, where 2= 3 = 0. So

yielding in the component occurs when

1 3max

( )

2 2

yS

= =

(3.4)

This theory correlates reasonably well with the yielding of ductile materials [3]. This

maximum shear stress theory forms the basis for piping of subsection NB (calss1) of

ASME section III [1].

3.4.3 Piping Design Criteria

There are various failure modes which could affect a piping system. The piping

engineer can provide protection against some of these failure modes by performing

stress analysis according to the piping codes. Protection against other failure modes is

provided by methods other than stress analysis. For example, protection against brittle

fracture is provided by material selection. The piping codes address the following

failure modes, excessive plastic deformation, plastic instability or incremental

collapse, and high-strainlow-cycle fatigue. Each of these modes of failure is caused

by a different kind of stress and loading. It is necessary to place these stresses into

different categories and set limits to them. The major stress categories are primary,



17

secondary, and peak. The limits of these stresses are related to the various failure

modes as follows [3].

3.4.3.3 Primary Stress

The primary stress limits are intended to prevent plastic deformation and bursting.

Primary stresses which are developed by the imposed loading are necessary to satisfy

the equilibrium between external and internal forces and moments of the piping

system. Primary stresses are not self-limiting. Therefore, if a primary stress exceeds

the yield strength of the material through the entire cross section of the piping, then

failure can be prevented only by strain hardening in the material. Thermal stresses are

never classified as primary stresses. They are placed in both the secondary and peak

stress categories [1].

Primary stresses are the membrane, shear or bending stress resulting from imposed

loadings which satisfy the simple laws of equilibrium of internal and external forces

and moments as arranged in table below;

Table 3-1 Primary stresses of pipes

Type of primary stress Due to type of sustained load

Circumferential membrane stress Pressure

Longitudinal membrane stress Pressure, Dead weight

Primary bending stress Pressure, Dead weight, wind

Primary stresses which considerably exceed the yield strength of the piping material

will result in gross distortion or failure [5].

3.4.3.4 Secondary Stresses

The primary plus secondary stress limits are intended to prevent excessive plastic

deformation leading to incremental collapse. Secondary stresses are developed by the

constraint of displacements of a structure. These displacements can be caused either

by thermal expansion or by outwardly imposed restraint and anchor point movements.

Under this loading condition, the piping system must satisfy an imposed strain pattern

rather than be in equilibrium with imposed forces. Local yielding and minor



18

distortions of the piping system tend to relieve these stresses. Therefore, secondary

stresses are self-limiting [1].

Secondary stresses are self equilibrium stresses which are necessary to satisfy

the continuity of forces within a structure. As contrasted with stresses from sustained

loads, secondary stresses are not a source of direct failure in ductile with only a single

application of load. If the stresses exceed the material yield strength, they cause local

deformation which result in a redistribution of the loading and upper limit of the stress

in the operating condition. If the applied load is cyclic, however these stresses

constitute a potential source of fatigue failure e.g. the secondary stresses due to

different type of loads are given below in Table 3-2, [5].

Table 3-2 Secondary stresses of pipes

Type of secondary stresses Due to type of load

Bending and Torsional Thermal loading (expansion or contraction)

Bending and TorsionalNon-uniform distribution of temperature

with in a body



19

4 Piping Design Procedures

The following are the steps which need to be completed in mechanical design of any

piping system.

Flow chart:Complete stage designing of piping system

4.1Process Design

This process is based on the requirement of the process variables. It defines the

required length & cross sectional area of pipe, the properties of fluid inside the pipe,

nature & rate of flow in it. These variables affect the positioning and placements of

equipments during lay outing and routing. The operating and design working

conditions are clearly defined. The end of Process Plan Design is the creation of a

Process Flow Diagram (PFD) and Process & Instrumental diagram (PID), which are

used in the designing & lay outing of the Pipe. The process design step in this project

is already been done and the data obtained from this step is arranged in Table 6-1.

4.2Piping Structural Design

In piping structural design, according to pressure in pipelines, the design and

minimum allowable thicknesses are calculated; according to the required codes and

standards. ASME codes for various standards are available, for process fluid flow,

ASME B31.1 is used.

ProcessDesign

Lay outing

Analysis

of PipesAnd

ExpansionLoops

Support

Designand

Analysis

Structural Design Loads

Calculations

Piping SystemDesign



20

In the structural design of pipes, when all the loads are calculated then the required

span is also calculated for supporting the pipes.

4.2.1 Pipe Thickness Calculations

Piping codes ASME B31.1 Paragraph 104.1.2 require that the minimum thickness tm

including the allowance for mechanical strength, shall not be less than the thickness

calculated using Equation [2].

2 ( )m

P Dot A

S Eq P Y

= +

+ (4.1)

Or

mt t A= + (4.2)where

tm= minimum required wall thickness, inches

t = pressure design thickness, inches

P = internal pressure, psig

Do= outside diameter of pipe, inches

S = allowable stress at design temperature (known as hot stress), psi

A = allowance, additional thickness to provide for material removed in threading,corrosion, or erosion allowance; manufacturing tolerance (MT) should also

be considered.

Y = coefficient that takes material properties and design temperature into account.

For temperature below 900F, 0.4 may be assumed.

E q= quality factor.

4.2.2 Allowable Working Pressure

The allowable working pressure of a pipe can be determined by Equation [2].

2( )

( 2 )

S Eq t P

Do Yt

=

(4.3)

where

t = specified wall thickness or actual wall thickness in inches.

For bends the minimum wall thickness after bending should not be less than the

minimum required for straight pipe.



21

4.2.3 Sustained Load Calculations

Sustained loads are those loads which are caused by mechanical forces and these

loads are present through out the normal operation of the piping system. These loads

include both weight and pressure loadings. The support must be capable of holding

the entire weight of the system, including that of that of the pipe, insulation, fluid

components, and the support themselves [2].

Pipe Weight 2 2( )4

steel

c

gDo Di

g

= (4.4)

Fluid Weight 2( )4

fluid

c

gDi

g

= (4.5)

Insulation wt.=Insulation factor x Insulationx g/gc (4.6)Where

D0 = Out side diameter of pipe, in

Di= Inside diameter of pipe, in

t = Insulation Thickness depend on the NPS, in

g = Acceleration due to gravity, ft/sec2

gc= Gravitational constants, lbm-ft/ft-sec2

Steel= Density of steel, lb/in3

fluid =Density of water, lb/in3

insul= Density of Insulation, lb/in3

Insulation factor depends on the thickness of the insulation of the pipe.

4.2.4 Wind Load Calculations

Wind load like dead weight, is a uniformly distributed load which act along the entire

length or portion of the piping system which is exposed to air.

For standard air, the expression for the wind dynamic pressure is given below [1]:

20.00256D

P V C= (4.7)

And to calculate the wind dynamic load (lb/ft), the following expression is used [1]:

20.000213 DF V C D= (4.8)

Where

P = Dynamic pressure, lb/ft2

V = basic wind speed, miles/hr



22

CD= Drag co-efficient, dimensionless

CDcan be calculated using table and the following equation;

R = 780xVxD

R = Reynolds number

F = Linear dynamic pressure loading (lb/ft)

D = Pipe Diameter (in)

4.2.5 Thermal Loads Calculations

All pipes will be installed at ambient temperature. If pipes carrying hot fluids such

steam,

then they expand, especially in length, with an increase from ambient to working

temperatures. This will create stress upon certain areas within the distribution system,

such as pipe joints, which, in the extreme, could fracture. The amount of the

expansion is readily calculated using the following expression [6].

( )Expansion mm L T= (4.9)

Where

L = Length of pipe (m)

T = Temperature difference between ambient and operating Temperatures (C)

= Expansion coefficient (mm/m C) x 10-3

4.2.6 Occasional Loads

Occasional load will subject a piping system to horizontal loads as well as vertical

loads, Where as sustained loads are normally only vertical (weight). There are

different types of occasional loads that act over a piping system but for our analysis

we will use wind loads and seismic loads.

4.2.7 Seismic Loads

Earthquake loads are of two major types

Operation Based Earthquake Load

Safe Shutdown Earthquake Load

Piping systems and components are designed to withstand two levels of site

dependent hypothetical earthquakes, the safe shut down earthquake and the

operational basis earthquake. Their magnitudes are expressed in terms of the



23

gravitational g. There motions are assumed to occur in three orthogonal directions,

one vertical and two horizontal directions.

Earthquake loads can either be calculated by dynamic Analysis or static

Analysis. In Dynamic analysis frequency response of the system is used to calculate

the Earthquake load whereas in Static Analysis, these loads are taken to be some

factor of the Pipe Dead load [3].

4.3Pipe Span Calculations

The maximum allowable spans for horizontal piping systems are limited by three

main factors that are bending stress, vertical deflection and natural frequency. By

relating natural frequency and deflection limitation, the allowable span can bedetermined as the lower of the calculated support spacing based on bending stress and

deflection [2].

4.3.1 Span Limitations

The formulation and equation obtained depend upon the end conditions assumed.

Assumptions

The pipe is considering to be a straight beam

Simply supported at both ends

So based on limitation of stress [2]

0.33h

s

ZSL

w= (4.10)

Based on limitation of deflection [2]

4

22.5s

EIL

w= (4.11)

Where

Ls= Allowable pipe span, ft

Z = Modulus of pipe section, in3

Sh= Allowable tensile stress at design temperature, psi

w = Total weight of pipe, lb/ft

= Allowable deflection/sag, inI = Area moment of inertia of pipe, in4



24

E = Modulus of elasticity of pipe material at design temperature, psi.

4.3.2 Expansion Loop Calculations

Thermal expansion are calculated for all the pipes by using equation

Expansion (mm)

Based on thermal expansion calculated above, size of expansion loops can be

calculated from equation below as [2]

3

144

o

A

EDL

S

= (4.12)

Where

L = Length of expansion Loops, ftE, Do, SA, same as in above calculations

Size of Expansion Loops assuming to be symmetrical U shaped.

L = 2H + W

Where

H = 2W for U shaped loop.

L T=



25

5 Support Design

Pipe support specifications for individual projects must be written in such a way as toensure proper support under all operating and environmental conditions and to

provide for slope, expansion, anchorage, and insulation protection. Familiarity with

standard practices, customs of the trade, types and functions of commercial

component standard supports and an understanding of their individual advantages and

limitations, together with knowledge of existing standards, can be of great help in

achieving the desired results [3].

Good pipe support design begins with good piping design and layout. For

example, other considerations being equal, piping should be routed to use the

surrounding structure to provide logical and convenient points of support, anchorage,

guidance, or restraint, with space available at such points for use of the proper

component. Parallel lines, both vertical and horizontal, should be spaced sufficiently

apart to allow room for independent pipe attachments for each line. There are

different types of supports used in the piping system e.g. Anchor support, Guide,

hanger, sliding, snubber support etc. The type of support which we will design in this

project is anchor support. It is a rigid support providing substantially full fixity for

three translations and rotations about three reference axes.

This support mainly includes the beam, column, base plate and anchor bolts. So the

design of all these components will be discussed in this chapter [1].

5.1Beam Design

Beams are the structural members resisting forces acting laterally to its axis. Either

forces or couples that lie in a plane containing the longitudinal axis of the beam may

act upon the member. The forces are understood to act perpendicular to the

longitudinal axis, and the plane containing the forces is assumed to be a plane of

symmetry of the beam. There are some limits states that must be considered when

designing a beam that are bending, shear and deflection [3].



26

5.1.1 Bending Stress

Bending stresses which caused by bending moments are internal member moments

which resist externally applied moments in order to maintain the member in

equilibrium. Bending stresses are usually far more significant than normal stresses

due to axial forces, therefore the flexural formula in its many form is one of the most

commonly used equations in structural analysis.

The flexural formula states that the value of the bending stress at any point on the

cross section of a member is [3].

b

c

I = (5.1)

where

M = Bending moment on the cross section, in-lb

c = Distance from neutral axis to point of interest, in

I = Moment of inertia of cross section, in4

The failure mode for bending is material yielding. For this reason the allowable stress

for bending is usually limited to the material stress reduced by a safety factor.

5.1.2 Shear Stress

Theses stresses resist the relative slippage of adjacent cross-sectional planes in the

members and can cause by shear forces. Shearing stress can be find out by using the

following formula [3]:

VAy

Ib= (5.2)

where

V = shear force on cross section, lb

A = Cross sectional area, in2

y = Distance from the neutral axis to the centriod of the area, in

I = Moment of inertia of the beam cross section, in4

b = width of the beam, in

The horizontal shear stress is a maximum at the neutral axis of the beam.

This is opposite of the behavior of the bending stress which is maximum at the outer

edge of the beam and zero at the neutral axis.



27

5.1.3 Deflection

The lateral load acting on beam causes the beam to bend, deforming the axis of the

beam into a curve called the deflection of the beam. This deformation of a beam is

most easily expressed in terms of the deflection of the beam from its original

unloaded position. This deflection is measured from the original neutral surface to the

neutral surface of the deformed beam. The deflection in uniformly distributed

cantilever beam can be calculated by using the following equation [3]

4

max8

wly

EI

= (5.3)

Where

y = deflection at point l, in

w = uniformly distributed load, lb/in

l = length at which deflection is to be calculated

E = Modulus of elasticity of the material being used in beam, Mpsi

I = Moment of inertia, in4

5.2Column

A long slender bar subject to axial compression is called a column. The term column

is frequently used to describe a vertical member. Column may be divided into three

general types: Short columns, Intermediate columns and Long Column. The

compressive capacity of a column is dependent on its slenderness ratio, which is

defined as [3]

Slenderness ratio =Kl

r (5.4)

Where

K = a constant dependent on boundary conditions

r = least radius of gyration of the member = IA

, in

I = moment of inertia of cross section, in4

A = area of cross section, in2

Theoretical and recommended values of K for some typical column end conditions are

shown in Figure 5-1 below.



28

Figure 5-1 Effective length constants for different columns [7]

Combination of K and L is also called effective length, l eff= Kl. A generally accepted

relationship between the slenderness ratio and type of column is as follows.

Table 5-1 Limitation of column slenderness ratio [7]

Type of Column Limits of slenderness Ratio

Short column 0 60eff

l

r

Intermediate column 60 120eff

l

r

Long column 120 300eff

l

r

Critical load and critical stress can be find out from the following equations [7]

2

2cr

eff

EIP

L

= (5.5)

2

2cr

eff

E

L

r

=

(5.6)

For column subjected to both axial and bending stress, AISC subsection H1

specification requires that the following equations must be satisfied [7].



29

10.6

bya bx

y bx by

ff f

F F F+ + (5.7)

Also, when fa/Fa< 0.15, following equation can be used,

1bya bx

a bx by

ff f

F F F+ + (5.8)

Where

fa= axial stress in column = P/A

Fa= allowable axial stress

Fb, x/y = Bending stress in x or y direction = Mc/I

Fb, x/y= allowable bending stresses in x or y direction

5.3Base Plate

Base plate is used to provide ground support to the column concentric and bending

load. Base plate may either be of the anchor bolted type or embedded type. Base

plates with anchor bolts are normally used in cases where the building concrete has

already been poured, while embedded plates are used when they can be specified prior

to pouring the concrete [3].

5.4Base Plate Bolts

The strength of the bolts is a function of the embedment depth, the bolt or stud head

diameter, the concrete strength and the spacing between adjacent bolts. Anchor bolts

are installed by drilling a hole through the concrete into which the bolts are inserted.

Depending on the type of bolt the bolt expands to grip the concrete either by

hammering the bolt or by torquing the nut against the base plate [7].



30

6 Pipe Design Calculations

In this chapter piping thickness as well as all the basic loads are calculated and the

characteristics are also given below.

6.1Design Parameters

As already sizing of this piping system has been done and the available

information are;

Number of pipes = 48Number of junctions = 49

Wind Velocity = 100 miles/hr

Pipe Nominal Size, Inlet-Out let velocities, Temperatures and Pressure of steam for

every pipe are given below in the following Table 6-1.

Table 6-1 Characteristics of Fluid at inlet and out let of pipes and its sizing

S.No

Pipe

Line

No.

NPSDo,

(in)TIn,

C

TOut,

C

VIn,

m/sec

Vout

m/sec

Pin

(static)bar

POut

(static)

bar

1 P-208 8.00 8.63 169.59 168.70 35.37 36.21 7.98 7.78

2 P-209 2.00 6.63 168.20 167.04 13.98 14.03 7.77 7.73

3 P-210 8.00 8.63 168.70 167.04 35.27 36.43 7.78 7.52

4 P-211 8.00 8.63 167.04 166.20 36.46 37.58 7.51 7.27

5 P-212 8.00 8.63 165.92 165.04 28.15 28.65 7.29 7.14

6 P-213 4.00 4.50 164.81 158.09 27.77 31.10 7.14 6.30

7 P-214 8.00 8.63 165.04 164.92 21.61 21.62 7.14 7.13

8 P-215 6.00 6.63 166.20 166.09 16.27 16.29 7.27 7.26

9 P-216 2.00 2.38 165.87 162.92 20.79 21.03 7.26 7.13

10 P-217 4.00 4.50 166.04 164.70 31.60 32.27 7.23 7.07

11 P-218 3.00 3.50 164.65 164.31 17.70 17.81 7.08 7.03

12 P-219 4.00 4.50 157.37 157.20 18.15 18.14 4.00 3.99

13 P-220 4.00 4.50 164.59 161.42 22.01 22.29 7.06 6.92

14 P-221 2.00 2.38 161.26 153.81 17.99 18.21 6.92 6.72



31

Table 6-1 Characteristics of Fluid at inlet and out let of pipes and its sizing (continued)

S.No

Pipe

Line

No.

NPSDo,

(in)TIn,

C TOut,

C

VIn,

m/sec

Vout

m/sec

Pin

(static)

bar

POut

(static),

bar

15 P-224 4.00 4.50 161.31 157.81 17.56 17.62 6.92 6.83

16 P-225 2.00 2.38 157.76 151.53 18.07 18.28 6.83 6.65

17 P-226 3.00 3.50 157.92 156.42 22.18 22.38 6.82 6.74

18 P-227 2.00 2.38 155.87 132.75 10.95 10.55 6.74 6.59

19 P-228 3.00 3.50 156.37 155.09 17.43 17.46 6.73 6.70

20 P-229 2.00 2.38 154.65 147.09 10.26 10.15 6.70 6.64

21 P-230 2.00 2.38 134.14 123.87 23.95 25.66 2.00 1.89

22 P-231 1.00 1.32 133.92 119.20 37.41 43.79 1.98 1.63

23 P-232 3.00 3.50 154.92 149.98 12.81 12.76 6.69 6.64

24 P-233 2.00 2.38 149.20 140.09 6.93 6.79 6.64 6.61

25 P-236 1.50 1.90 126.81 117.36 23.32 23.84 1.99 1.90

26 P-237 1.00 1.32 126.81 118.70 32.02 34.36 1.99 1.82

27 P-238 2.00 2.38 150.09 145.42 21.20 21.65 6.63 6.42

28 P-239 1.00 1.32 145.09 130.70 21.74 22.91 6.42 5.88

29 p-240 2.00 2.38 145.31 140.48 16.06 16.12 6.42 6.31

30 P-241 1.00 1.32 140.37 125.70 29.15 35.66 6.30 4.99

31 P-242 2.00 2.38 140.03 130.87 8.63 8.45 6.31 6.28

32 P-243 2.00 2.38 130.31 112.98 5.52 5.27 6.28 6.24

33 P-244 1.00 1.32 130.64 95.31 11.43 10.80 6.28 6.00

34 P-250 3.00 3.50 159.15 158.87 12.28 12.32 4.00 3.98

35 P-251 1.00 1.32 158.53 121.48 29.53 36.80 3.97 2.97

36 P-252 2.00 2.38 158.87 152.87 19.58 19.77 3.98 3.89

37 P-253 1.50 1.90 152.48 146.31 16.82 16.84 3.89 3.83

38 P-254 1.00 1.32 152.59 132.53 37.37 48.68 3.86 2.83

39 P-256 2.00 2.38 155.87 150.03 37.39 41.14 4.00 3.59

40 P-257 6.00 6.63 152.70 152.37 21.55 21.59 4.00 3.99

41 P-259 3.00 3.50 142.09 137.09 27.65 28.75 2.00 1.90

42 P-260 3.00 3.50 139.81 138.42 27.50 28.06 2.00 1.95

43 P-261 3.00 3.50 118.25 116.42 20.90 21.16 1.50 1.47

44 P-262 3.00 3.50 134.81 133.98 15.23 15.21 2.00 2.00



32

Table 6-1 Characteristics of Fluid at inlet and out let of pipes and its sizing (continued)

6.2Physical Properties

Physical properties of pipe material, insulation and water are arranged in Table 6-2

below;

Table 6-2 Material Properties [Appendix Table A14]

Material Parameter Value

Modulus of Elasticity E 27.5 Mpsi

Allowable stress Sall 14.4 ksiCarbon Steel

Density, steel 0.283 lb/in

3

Insulation Density, Rock wool 0.00343lb/in

3

Water Density, water 0.0361 lb/in3

6.3Design Calculations

Piping design calculation means to find out the pipe thickness for the available

size and operating pressure of the fluid. This thickness is then compared to the

allowable minimum standard thickness defined by the code. After thicknesscalculations all loads applied on this pipe can be calculated, which will form the

basis for spacing of supports and sizing of expansion loops.

6.3.1 Pipe Thickness Calculations

Piping codes require that the minimum thickness tm including the allowance for

mechanical strength, shall not be less than the thickness calculated using Equation

(4.1) as follows.

S.No

Pipe

Line

No.

NPSDo,

(in)TIn,

C TOut,

C

VIn,

m/sec

Vout

m/sec

Pin

(static)

bar

POut

(static),

bar

45 P-263 2.00 2.38 127.87 126.70 22.37 22.36 2.00 1.99

46 P-264 2.00 2.38 119.20 115.70 17.26 17.35 2.00 1.97

47 P-270 3.00 3.50 157.31 152.37 28.44 29.92 3.99 3.75

48 P-271 1.00 1.32 156.48 151.48 24.31 24.67 4.00 3.89



33

Design thickness2 ( )

om

q

P Dt A

S E P Y

= +

+ (4.1)

or

= t + ALet take Pipe no. 208 and calculate its minimum thickness by using equation.

Where all the parameters are arranged in Table 6-3 below;

Table 6-3 Input Parameters used in pipe thickness calculation

Parameter Value Reference/Reason

Do 8.625 in Appendix Table A2

Pg 193.3 Psi Table 6.1

E 1 For seamless pipe

Y 0.4 b/c Temperature < 900oF

S 14400 Psi Appendix Table A1

Tolerance limit 12.5% Assuming maximum limit

A 3 mm = 0.03937 in data provided

Putting all these values in above equation of minimum thickness

193.3 8.625 0.039372 (144000 1 193.3 0.4)

mt = +

+

0.09984mt In=

0.0998

0.85

0.12

2.9

m

m

m

t

t in

t mm

=

=

=

Standard tm = 0.282 in

For all 48 pipes the thickness were calculated and arranged in the Table 6-4 below

along with the standard minimum wall thickness. From the table it is cleared that

nearly 2 to 3 times, so our calculated thickness is safe.



Table 6-4 All pipes thickness along with standard thickness (Continued)

S

.No

PipeL

ine

No.

PipeNominal

S

ize,

Ou

tside

Diameter,D(in)

Design

Pressure

(stat.),

P(lb/In2)

Veloc

ity,Inlet

(m

/sec)

TotalHead,(m)

H=(P/W

+V^2/2*

g)

Pab

s(Psi)=

*g*H

Design

Pressure

(gage.),

P(lb

/In2)=

Psa

t-14.7

Allowable

Stress

s,S(psi)

D.T.Factor

(y)

Min

.Wall

thickness,t(in)=P

*D/2*

(S+.4*P)

Cor

rosion

allowance(in)

thick

t(t)(in)

26 P-237 1 1.315 29.27 32.02 72.901 103.67 88.97 14400 0.4 0.0043 0.0394 0.0

27 P-238 2 2.375 97.40 21.21 91.441 130.04 115.34 14400 0.4 0.0100 0.0394 0.0

28 P-239 1 1.315 94.34 21.74 90.466 128.65 113.95 14400 0.4 0.0055 0.0394 0.0

29 p-240 2 2.375 94.30 16.06 79.478 113.02 98.32 14400 0.4 0.0085 0.0394 0.0

30 P-241 1 1.315 92.67 29.15 108.524 154.33 139.63 14400 0.4 0.0067 0.0394 0.0

31 P-242 2 2.375 92.80 8.63 69.054 98.20 83.50 14400 0.4 0.0072 0.0394 0.0

32 P-243 2 2.375 100.25 5.52 72.050 102.46 87.76 14400 0.4 0.0076 0.0394 0.0

33 P-244 1 1.315 92.27 11.43 71.549 101.75 87.05 14400 0.4 0.0042 0.0394 0.0

34 P-250 3 3.5 58.80 12.28 49.046 69.75 55.05 14400 0.4 0.0070 0.0394 0.035 P-251 1 1.315 58.33 29.53 85.499 121.59 106.89 14400 0.4 0.0051 0.0394 0.0

36 P-252 2 2.375 58.54 19.58 60.724 86.35 71.65 14400 0.4 0.0062 0.0394 0.0

37 P-253 1.5 1.9 57.15 16.82 54.626 77.68 62.98 14400 0.4 0.0044 0.0394 0.0

38 P-254 1 1.315 56.77 37.37 111.180 158.11 143.41 14400 0.4 0.0069 0.0394 0.0

39 P-256 2 2.375 58.80 37.39 112.691 160.25 145.55 14400 0.4 0.0126 0.0394 0.0

40 P-257 6 6.625 58.80 21.55 65.042 92.49 77.79 14400 0.4 0.0188 0.0394 0.0

41 P-259 3 3.5 29.40 27.66 59.703 84.90 70.20 14400 0.4 0.0089 0.0394 0.0

42 P-260 3 3.5 29.40 27.50 59.258 84.27 69.57 14400 0.4 0.0089 0.0394 0.0

43 P-261 3 3.5 22.05 20.90 37.781 53.73 39.03 14400 0.4 0.0050 0.0394 0.0

44 P-262 3 3.5 29.40 15.23 32.510 46.23 31.53 14400 0.4 0.0040 0.0394 0.0

45 P-263 2 2.375 29.40 22.37 46.194 65.69 50.99 14400 0.4 0.0044 0.0394 0.0

46 P-264 2 2.375 29.40 17.26 35.877 51.02 36.32 14400 0.4 0.0031 0.0394 0.0

47 P-270 3 3.5 44.10 28.44 72.267 102.77 88.07 14400 0.4 0.0112 0.0394 0.0

48 P-271 1 1.315 14.70 24.31 40.496 57.59 42.89 14400 0.4 0.0021 0.0394 0.0



36

6.3.2 Allowable Working Pressure

After calculating the design thickness, now checking the working pressure by using

the standard thickness to find the maximum pressure that the pipe material can

withstand. The allowable working pressure of a pipe can be determined by Equation

(4.3) given below.

2( )

( 2 )o

S Eq t P

D Yt

=

(4.3)

Let take Pipe no. 208 and calculate its minimum thickness by using Table 6-5.

Table 6-5 Input data

Parameter Value Reference/Reason

Do 8.625 in Appendix Table A2

E 1 For seamless pipe

Y 0.4 b/c Temperature < 900oF

S 14400 Psi Appendix Table A1

t 0.322 in Appendix Table A2

t = specified wall thickness or actual wall thickness in inches, in

So the allowable working pressure comes out to be P = 993.87 psi

Where as the designed working pressure =117.23 psi (From Table 6-1). For all the 48

pipes the working pressures are calculated and arranged in the following table.

Table 6-6 Design and working Pressure

S.NoPipe Line No.

NPS,

inDo(in)

Pressure (gage)

psiAllowable Pressure psi

1 P-208 8 8.625 193.31 993.877

2 P-209 2 6.625 113.69 1955.074

3 P-210 8 8.625 189.93 993.877

4 P-211 8 8.625 192.17 993.877

5 P-212 8 8.625 149.94 993.877

6 P-213 4 4.5 146.28 1479.188

7 P-214 8 8.625 124.09 993.877

8 P-215 6 6.625 111.40 1156.616



37

Table 6-6 Design and working Pr

Design of Steam Piping System Including Stress Analysis

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