Table Of ContentTHIRD REVISED AND UPDATED EDITION
DAVID STEPHENSON
Department of Civil Engineering
University of the Witwatersrand
Johannesburg, South Africa
ELSEVlE R
Amsterdam - Oxford - New York - Tokyo 1989
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V
PREFACE TO FIRST EDITION
Pipelines are being constructed in ever-increasing diameters,
lengths and working pressures. Accurate and rational design bases
are essential to achieve economic and safe designs. Engineers have
for years resorted to semi-empirical design formulae. Much work
has recently been done in an effort to rationalize the design of
pipelines.
This book col lates pub1 ished material on rational design methods
as well as presenting some new techniques and data. Although
retaining conventional approaches in many instances, the aim of
the oook is to bring the most modern design techniques to the civil
or hydraulic engineer. It is suitable as an introduction to the
subject but also contains data on the most advanced techniques in
the field. i3ecause of the sound theoretical background the book will
al so be useful to under-graduate and post-graduate students. Many
of the subjects, such as mathematical optimization, are still in their
infancy and the book may provide leads for further research. The
methods of solution proposed for many problems bear in mind the
modern acceptance of computers and calculators and many of the
graphs in the book were prepared with the assistance of computers.
The first half of this book is concerned with hydraulics and
planning of pipelines. In the second half, structural design and
ancillary features are discussed. The book does not deal in detail
with manufacture, laying and operation, nor should it replace design
codes of practice from the engineer's desk. Emphasis is on the
design of large Pipelines as opposed to industrial and domestic
piping which are covered in other pub1 ications. Although directed
at the water engineer, this book will be of use to engineers involved
in the piping of many other fluids as well as solids and gases.
It should be noted that some of the designs and techniques
described may be covered by patents. These include types of pre-
stressed concrete pipes, methods of stiffening pipes and branches
and various coatings.
VI
The S.I. system of metric units is preferred in the book although
imperial units are given in brackets in many instances. Most graphs
and equations are represented in uni versa1 dimensionless form. Worked
examples are given for many problems and the reader is advised to
work through these as they often elaborate on ideas not highlighted
in the text. The algebraic symbols used in each chapter are
summarized at the end of that chapter together with specific and
general references arranged in the order of the subject matter in the
chapter. The appendix gives further references and standards and
other useful data.
PREFACE TO SECOND EDITION
The gratifying response to the first edition of this book resulted
in small amendments to the second impression, and some major alter-
ations in this new edition.
The chapters on transport of solids and sewers have been
replaced by data more relevant to water engineers. Thus a new
chapter on the effects of air in water pipes is included, as well as a
chapter on pumping systems for water pipelines. The latter was
reviewed by Bill Glass who added many of his own ideas.
There are additions and updating throughout. There is additional
information on pipeline economics and optimum diameters in Chapter 1.
A comparison of currently used friction formulae is now made in
Chapter 2. The sections on non-circular pipe and partly full pipes
and sewer flow are omitted. These are largely of interest to the
drainage engineer and as such are covered in the author’s book
‘Stormwater Hydrology and Drainage’ (Elsevier, 1981). A basic
introduction to water hammer theory preceeds the design of water
hammer protection of pumping and gravity lines in Chapter 4.
The sections on structural design of flexible pipes are brought
together. An enlarged section on soil-pipe interaction and limit
states of flexible pipes preceeds the design of stiffened pipes.
Although some of the new edition is now fairly basic, it is
recognised that this is desirable for both the practicing engineer who
needs refreshing and the student who comes across the problem of
pipeline design for the first time.
VIII
PREFACE TO THIRD EDITION
Recent research in cavitation and flow control has prompted additional
sections on this. There are also new sections on supports to exposed
pipes and secondary stress. Additional references and a new layout
make up this edition. Some sections appearing in previous editions,
noteably on pipe network systems analysis and optimization have been
ommitted as they were considered more appropriate in the alJthOr’S
parallel book ‘Pipeflow Analysis’ by the same publisher.
IX
ACKNOWLEDGEMENTS
The basis for this book was derived from my experience and in the
course of my duties with the Hand Water Board and Stewart, Sviridov
and 01 iver, Consulting Engineers. The extensive knowledge of
Engineers in these organizations may therefore be reflected herein
although I am solely to blame for any inaccuracies or misconceptions.
I am grateful to my wife Lesley, who, in addition to looking after
the twins during many a lost weekend, assiduously typed the first
draft of this book.
David Stephenson
1
CHAPTER 1
ECONOMIC PLANNING
I NTRODUCT ION
Pipes have been used for many centuries for transporting fluids.
The Chinese first used bamboo pipes thousands of years ago, and lead
pipes were unearthed at Pompeii. In later centuries wood-stave pipes
were used in England. It was only with the advent of cast iron,
however, that pressure pipelines were manufactured. Cast iron was
used extensively in the 19th Century and is still used. Steel pipes
were first introduced towards the end of the last century, facilitating
construction of small and large bore pipelines. The increasing use of
high grade steels and large rolling mills has enabled pipelines with
diameters over 3 metres and working pressure over 10 Newtons per
square millimetre to be manufactured. Welding techniques have been
perfected enabling longitudinally and circumferentially welded or
spiral welded pipes to be manufactured. Pipelines are now also made
in reinforced concrete, pre-stressed concrete, asbestos cement, plastics
and claywares, to suit varying conditions. Reliable flow formulae
became available for the design of pipelines this century, thereby
also promoting the use of pipes.
Prior to this century water and sewage were practically the only
fluids transported by pipeline. Nowadays pipelines are the most
common means for transporting gases and oils over long distances.
Liquid chemicals and solids in slurry form or in containers are also
being pumped through pipelines on ever increasing scales. There are
now over two million kilometres of pipelines in service throughout the
world. The global expenditure on pipelines in 1974 was probably over
55 000 million.
There are many advantages of pipeline transport compared with
other methods such as road, rail, waterway and air:-
(1) Pipelines are often the most economic form of transport
(considering either capital costs, running costs or overall costs).
(2) Pipelining costs are not very susceptible to fluctuations in
2
prices, since the major cost is the capital outlay and subsequent
operating costs are relatively small.
Operations are not susceptible to labour disputes as little
attendance is required. Many modern systems operate automatical-
lY.
Being hidden beneath the ground a pipeline will not mar the
natural environment.
A buried pipeline is reasonably secure against sabotage.
A pipeline is independent of external influences such as traffic
congestion and the weather.
There is normally no problem of returning empty containers to
the source.
It is relatively easy to increase the capacity of a pipeline by
installing a booster pump.
A buried pipeline will not disturb surface traffic and services.
(10) Wayleaves for pipelines are usually easier to obtain than for
roads and railways.
(11) The accident rate per ton - km is considerably lower than for
other forms of transport.
(12) A pipeline can cross rugged terrain difficult for vehicles to
cross.
There are of course disadvantages associated with pipeline systems:-
The initial capital expenditure is often large, so if there is any
uncertainty in the demand some degree of speculation may be
necessary.
There is often a high cost involved in filling a pipeline
(especially long fuel lines).
Pipelines cannot be used for more than one material at a time
(although there are multi-product pipelines operating on batch
bases).
There are operating problems associated with the pumping of
solids, such as blockages on stoppage.
It is often difficult to locate leaks or blockages.
PI PEL I NE ECONOM I CS
The main cost of a pipeline system is usually that of the pipeline
3
itself. The pipeline cost is in fact practically the only cost for
gravity systems but as the adverse head increases so the power and
pumping station costs increase.
Table 1.1 indicates some relative costs for typical installed
pipel i nes.
With the economic instability and rates of inflation prevailing at
the time of writing pipeline costs may increase by 20% or more per
year, and relative costs for different materials will vary. In
particular the cost of petro-chemical materials such as PVC may
increase faster than those of concrete for instance, so these figures
should be inspected with caution.
TABLE 1.1 Relative Pipeline Costs
Bore mm
Pipe Material 150 450 1 500
PVC 6 23 -
Asbestos cement 7 23 -
Reinforced concrete - 23 80
Prestressed concrete - 33 90 - 150
Mild steel 10 28 100 - 180
High tensile steel 11 25 90 - 120
Cast iron 25 75 -
<:,,-s, indicates not readily available.
1 unit = d;/metre in 1974 under average conditions
The components making up the cost of a pipeline vary widely from
situation to situation but for water pipelines in open country and
typical conditions are as follows:-
Supply of pipe - 55% (may reduce as new
materials are developed)
Excavation - 20% (depends on terrain,
may reduce as mechanical
excavation techniques im-
prove)
Laying and jointing - 5% (may increase with la-
bour costs)
Fittings and specials - 5%
Coating and wrapping - 2%
Structures (valve chambers, anchors) - 2%
