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Table of Contents
Pipeline Condition Assessment
PREFACE
 Pipe failures occur
when the pipe cannot contain the fluid internally within the pipeeither the strength
is too low (from wrong material selection, fatigue, stress corrosion, etc.)
or the stress is too high (overloads, loss of wall thickness etc.) resulting
in an interference zone between loads and strengths. Such factors lead to
condition deterioration of pipelines. While the pipe is above ground such
failures are assessable but if the pipe is underground its condition
assessment is a difficult process and at times almost impossible. Another
point to remember is that the condition deterioration is a continuous process
which gets accelerates with the age and other external or internal
conditions. So a pipe with a small crack one day can be a completely
collapsed pipe five years down the line. This process can be arrested with
proper repair and maintenance on a regular basis. The decision to repair and
maintain heavily banks upon the present condition and therefore the need to
assess the pipe condition.
Present day subsurface networks in India
are leading the life of neglect since they are out of sight as well as mind.
Networks are dogged with the situations of Hydraulic Failures, Structural
Failures, Environmental Failures, & Operational Failures on a regular
basis and need substantial repairs and maintenance actions to contain the
situations. Ways and means to assess their conditions are, in the first place
not applied and even if applied are too simplistic where the results are just
suspect. Present day repair and maintenance of subsurface pipelines is mostly
of emergency nature where the maintenance is done only to repair the damaged
parts. This practice needs to be changed and a system to evaluate the
pipeline condition on a regular basis needs to be evolved. Non destructive
and non invasive condition assessment methods play a vital role in such project
planning and execution and therefore quite important.
The compilation in your hands discusses some
of such methods where the subsurface pipelines are assessed on the basic
engineering principles like direct and indirect assessments methods. Condition
grading and recording is another important facet of condition assessment
process as without them it is almost impossible to conclude the assessment
process and thereafter the rehabilitation or renewal process.
Importance of these methods to Trenchless fraternity
is quite obvious since two of the major sectors of Trenchless Industry viz.
rehabilitation and renewal are dependent entirely on the findings of
condition assessment process and therefore this compilation.
Intent of this book is to provide the readers
with the information about all the above issues so that they are better
equipped to deal with the pipeline failures, consequences of failures and
their management cycle. Information provided here is only of informative
nature. As the methods discussed herein are specialized processes it is
advisable to consult experts prior to applying any of these methods as they
may or may not be suitable for any given set of parameters connected to any
particular pipeline. The principles behind the process are dealt herewith but
the complete analysis would need a deeper study.
Prof Niranjan
Swarup
Executive Director
Indian Society for
Trenchless Technology
Table of Contents
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1.
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Pipeline Failures
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01 12
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2.
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Uniform Defect Codes
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13 22
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3.
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Subsurface Utility Engineering
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23 32
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4.
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Review of Pipe Failure Detection & Location Techniques
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33 46
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5.
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Direct Condition Assessment Methods
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47 58
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6.
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Indirect Condition Assessment Methods
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59 64
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7.
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Network Condition Survey & Recording
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65 120
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8.
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Safety Issues
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121 152
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9.
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Life Cycle of Subsurface Networks
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153 166
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10.
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Sewer System Evaluation & Management
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167 172
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11.
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References & Acknowledgements
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173 174
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