Page 14 - Pipeline Risk Management Manual Ideas, Techniques, and Resources

Introduction

As with previous editions of this book, the chief objective of uncover new information. Ideally, the degree of belief would
this edition is to make pipelines safer. This is hopefully accom- also be determined in some consistent fashion so that any two
plished by enhancing readers’ understanding of pipeline risk estimators would arrive at the same conclusion given the same
issues and equipping them with ideas to measure, track, and evidence.
continuously improve pipeline safety. This is the purpose of this book-to provide frameworks in
We in the pipeline industry are obviously very familiar with which a given set of evidence consistently leads to a specific
all aspects of pipelining. This familiarity can diminish our sen- degree of belief regarding the safety of a pipeline.
sitivity to the complexity and inherent risk of this undertaking. Some of the key beliefs underpinning pipeline risk manage-
The transportation of large quantities of sometimes very haz- ment, in this author’s view, include:
ardous products over great distances through a pressurized
pipeline system, often with zero-leak tolerance, is not a trivial Risk management techniques are fundamentally decision
thing. It is useful to occasionally step back and re-assess what support tools.
a pipeline really is, through fresh eyes. We are placing a very We must go through some complexity in order to achieve
complex, carefully engineered structure into an enormously “intelligent simplification.”
variable, ever-changing, and usually hostile environment. One In most cases, we are more interested in identifying locations
might reply, “complex!? It’s just a pipe!” But the underlying where a potential failure mechanism is more aggressive,
technical issues can be enormous. Metallurgy, fracture rather than predicting the length of time the mechanism must
mechanics, welding processes, stress-strain reactions, soil- be active before failure occurs.
interface mechanical properties of the coating as well as their Many variables impact pipeline risk. Among all possible
critical electrochemical properties, soil chemistry, every con- variables, choices are required to strike a balance between a
ceivable geotechnical event creating a myriad of forces and comprehensive model (one that covers all of the important
loadings, sophisticated computerized SCADA systems, and stuff) and an unwieldy model (one with too many relatively
we’re not even to rotating equipment or the complex electro- unimportant details).
chemical reactions involved in corrosion prevention yet! A Resource allocation (or reallocation) towards reduction of
pipeline is indeed a complex system that must coexist with all failure probability is normally the most effective way to prac-
of nature’s and man’s frequent lack of hospitality. tice risk management.
The variation in this system is also enormous. Material and
environmental changes over time are of chief concern. The (The complete list can be seen in Chapter 2)
pipeline must literally respond to the full range of possible The most critical beliefunderlying this book is that all available
ambient conditions of today as well as events of months and information should be used in a risk assessment. There are very
years past that are still impacting water tables, soil chemistry, few pieces of collected pipeline information that are not useful
land movements, etc. Out of all this variation, we are seeking to the risk model. The risk evaluator should expect any piece of
risk ‘signals.’ Our measuring ofrisk must therefore identify and information to be useful until he absolutely cannot see any way
properly consider all of the variables in such a way that we can that it can be relevant to risk or decides its inclusion is not cost
indeed pick out risk signals from all of the background ‘noise’ effective.
created by the variability. Any and all expert’s opinions and thought processes can and
Underlying most meanings of risk is the key issue of ‘proba- should be codified, thereby demystifymg their personal assess-
bility.’ As is discussed in this text, probability expresses a ment processes. The experts’ analysis steps and logic processes can
degree ofbelief: This is the most compelling definition of prob- be duplicated to a large extent in the risk model. A very detailed
ability because it encompasses statistical evidence as well as model should ultimately be smarter than any single individual or
interpretations and judgment. Our beliefs should be firmly group of individuals operating or maintaining the pipeline
rooted in solid, old-fashioned engineering judgment and rea- including that retired guy who knew everything. It is often useful to
soning. This does not mean ignoring statistics-rather, using think of the model building process as ‘teaching the model’ rather
data appropriately-for diagnosis; to test hypotheses; to than ‘designing the model.’ We are training the model to ‘think’