Post on 12-Mar-2015
Piping Failure in Water Utilities 2011
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Group Name Group 10 Student Name Student
Number Email Contact Phone
Contact Enji M. Lazuardi
07622805 enji.puapua@connect.qut.edu.au 0420907711
Hannibal Nasserie
07266553 hannibal.nasserie@student.qut.edu.au 0413535838
Mohammad Motamedi
06090613 m.motamedi@student.qut.edu.au 0433930025
Wildan Pradana Yulianto Putra
07622848 wildan.yuliantoputra@connect.qut.edu.au 0450882904
Piping Failure in Water Utilities ENB 432 – Asset Management and Maintenance Group Report
Piping Failure in Water Utilities 2011
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Work Plan Certificate The Work Plan shows the equitable distribution of work that everyone in the group is
satisfied with. Students as listed in the table certify that we worked equitably and
diligently on the research, preparation and submission of the report as per the Work
Plan.
This signature also certifies that this is our original work for this course and has not
been presented in any other course as part of any workplace task.
Group Name Group 10 Student Name Student
Number Responsibility (in the Report Part) Signature
Enji M. Lazuardi
07622805 Executive Summary, Introduction, Conclusion, Recommendation, FMECA Worksheet
Hannibal Nasserie
07266553 Description of Loss Production Event, Asset Management Issues Discussion, FMECA Worksheet
Mohammad Motamedi
06090613 Literature Review, FMECA and Risk Management Method Discussion, FMECA Worksheet
Wildan Pradana Yulianto Putra
07622848 Asset Management Issues Discussion, Loss Prevention and Mitigation Solution, FMECA Worksheet
Piping Failure in Water Utilities 2011
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Executive Summary
As we all know that the final report is about to manage the productive assets of the
water utility. We are concern to understand the faults and how they impact on the
production goals of the assets. The other things that concern are how these faults
can be prevented and how to maintain the productive assets of water utility.
After several discussions, we found out some of the faults in water utility. There are a
lot of things that affect the assets of water utility, such as; natural disaster, human
error, machinery failure, and failure in infrastructure that can cause a catastrophic
damage to the water utility component.
Therefore, the project that we are going to do for the final report is The Piping
Failure in Water Utilities. The reason we are doing this as our final report is failures
that occur in the pipeline needs a very expensive repairing cost, cutting water supply
to a large numbers of customers and sometimes producing millions of dollars in
damage. Understanding the causes of these failures is essential to preventing a
repetition on the same line.
We also want to describe briefly about the failure modes in the pipeline system in
water utility. We are going to describe the failure on the components of the pipeline
system, such as the fittings, valves, tapping, etc.
Last, some preventive measures will also be explained briefly in this report and some
action that must be done to maintain the water utility in its best performance.
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Table of Contents
Work Plan Certificate ............................................................................................................................ 1
Executive Summary .............................................................................................................................. 2
Table of Contents .................................................................................................................................. 3
List of Table .......................................................................................................................................... 4
1.0 Introduction ..................................................................................................................................... 5
2.0 Literature Review ............................................................................................................................ 6
2.1 Inspection on FMECA Analysis ................................................................................................... 6
2.2 Inspection of Failures in Pipe ...................................................................................................... 7
2.3 The New SAE FMECA ................................................................................................................ 9
3.0 Description of Loss Production Event ........................................................................................... 10
4.0 FMECA and Risk Management Method Discussion ..................................................................... 12
4.1 Selection of Critical Components .............................................................................................. 12
4.2 Failure Mode and Effect Analysis .............................................................................................. 13
4.3 RPN and Corrective Actions ..................................................................................................... 13
4.4 FMECA discussion .................................................................................................................... 15
4.4.1 Fitting ................................................................................................................................. 15
4.4.2 Valves ................................................................................................................................ 15
4.4.3 Pipeline .............................................................................................................................. 16
4.4.4 Hydrants ............................................................................................................................. 16
4.4.5 Tapping Bands ................................................................................................................... 16
4.4.6 Pump .................................................................................................................................. 16
5.0 Asset Management Issues Discussion.......................................................................................... 17
5.1 Treatment of Piping Operation .................................................................................................. 17
5.2 Piping Main Repairs .................................................................................................................. 18
5.3 Source of Water Loss Due to Piping Leakage .......................................................................... 18
5.4 Risk Issues ................................................................................................................................ 19
6.0 Maintenance Management Issues Discussion .............................................................................. 20
7.0 Loss Prevention and Mitigation Solution Discussion ..................................................................... 23
7.1 Measurement of Unaccounted Water ........................................................................................ 23
7.2 Searching the Leakage ............................................................................................................. 24
7.3 Repair the leakage .................................................................................................................... 26
7.4 Measurement of Unaccounted Water (Second Measurement) ................................................. 28
8.0 Conclusion .................................................................................................................................... 30
9.0 Recommendation .......................................................................................................................... 31
10.0 Reference List ............................................................................................................................. 32
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List of Table
FMECA Worksheet ............................................................................................................................. 34
RPN Format ........................................................................................................................................ 38
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1.0 Introduction
Many water treatment companies run their company without knowing how to manage
their productive asset in the right way. They are aware that major disruptions to
production could be avoided if there was a better understanding of faults and failures
and how these could be addressed through better understanding and application of
asset management and maintenance practices. They realize that, for triple bottom
line reasons, they need to establish a new baseline of asset management protocols
within the organization.
In this project, we were given task to help the water treatment company to assist the
company itself to protect and maintain their valuable assets. Their concern is that
they do not understand faults and how they impact on the production goals of their
assets. So what we need is to work as a group and identify a major loss of
production or other risk that can happened to the company due to poor asset
management or maintenance practices. We have to analyse the loss the production
and by using the FMECA, we must identify at least 10 reasons for the event. In this
task we act as a consultant of water Utilities Company by providing the assistant of
managing the company by applying all methods and material that already given on
the course, and we also need to advise the client for what they need to do to prevent
or mitigate production loss events.
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2.0 Literature Review
2.1 Inspection on FEMCA Analysis
In June 1996 in North Korea, the failure mode, effect and critically analysis
(FMECA) on mechanical Subsystems of Diesel Generator performed. In their report
it is discussed that for the implementation of RCM in nuclear power plant, three steps
are required; (1) Functional failure analysis (FFA), (2) Failure mode, effect and
criticality analysis (FMECA), (3) Logic tree analysis (LTA). It is stated that the
emergency or standby diesel generators in nuclear power plant take an important
role in the accident situations. In this report the FMECA results for six mechanical
subsystems of the diesel generators of nuclear power plants to improve the reliability
is performed. The six mechanical subsystems are (1) Starting air, (2) Lub oil, (3)
Governor, (4) Jacket water cooling, (5) Fuel, and (6) Engine subsystems. Generic
and plant-specific failure and maintenance records are reviewed to identify critical
components/ failure modes. Kim and Singh (1996).
In 2008 Jacques Virasak carried out the (FMECA) Analysis for a typical helicopter
main rotor Scissor bearing assembly. As he stated the main rotor scissor rotating
bearing assembly has only two functional failure modes:
1. Loss of its ability to allow relative motion between the rotating scissors and the
rotating swash plate.
2. Loss of its ability to accommodate various combinations of loads and motions
between the rotating scissors and the rotating swash plate.
The loss of relative motion between the rotating scissors and the rotating swash
plate will result in loss of the controllability of the main rotor, increase rotor vibration,
and decrease response to control input. The loss of load transmission from the
rotating scissor to the rotating swash plate will create an unbalanced rotor and
increase rotor vibration. Virasak (2008)
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2.2 Inspection of Failures in Pipe
Pipe leakage in Australia is perceived to be a major problem by many water
authorities, both from an environmental point of view, as well as the associated costs
that are incurred due to overdesign of sewerage systems (to cope with wet weather
loads) and the treatment of additional potable water that is lost due to leakage.
Burn and Desilva (1999)
In many water distribution systems, a significant percentage of water is lost while in
transit from treatment plants to consumers. According to an inquiry made in 1991 by
the International Water Supply Association (IWSA), the amount of lost or
“unaccounted for water” (UFW) is typically in the range of 20–30% of production
(Cheong 1991). In the case of some systems, mostly older ones, the percentage of
lost water could be as high as 50% (AWWA 1987). In Australia and Canada the
problem is not quite as severe due to relatively newer systems. For example, water
authorities in Australia report UFW levels varying between 8 and 28% with the
average being 15% in 1997/98 (WSAA Facts 1998).
UFW is usually attributed to several causes including leakage, metering errors and
theft. According to the IWSA survey, however, leakage is the major cause. Water
leakage is a costly problem, not only in terms of wasting a precious natural resource
but also in economic terms. The primary economic loss due to leakage is the cost of
raw water, its treatment and transportation. Leakage inevitably also results in
secondary economic loss in the form of damage to the pipe network itself, e.g.
erosion of pipe bedding and major pipe breaks, and in the form of damage to
foundations of roads and buildings. Diminution of supply security as a result of a
reduction in water stored per capita may also represent a cost if such diminution
requires augmentation of supply to maintain security. Besides the environmental and
economic losses caused by leakage, leaky pipes create a public health risk, as every
leak is a potential entry point for contaminants if a pressure drop occurs in the
system. Burn and Desilva (1999).
Leakage occurs at both designed overflow points and from joints and cracks in
pipelines. The purpose of designed overflow structures is to relieve pressure in pipes
Piping Failure in Water Utilities 2011
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at controlled locations, i.e. adjacent to storm water drains, so that overflows do not
occur at private residences or businesses or environmentally sensitive locations.
They function when pipe capacity is exceeded due to infiltration or blockage during
storms. Except in the most poorly designed systems, they do not function in dry
weather when no blockage exists. Cracks, on the other hand, may function at any
time, releasing sewerage into local waterways or soils (exfiltration) or allowing storm-
flow to enter sewers (infiltration), leading to pressure build up and possible overflows
during heavy weather.
The environmental impacts of leakage include impacts on ecosystems, aesthetic
impacts and human health risk. These impacts, however, need to be considered in
context. The Sydney Water Corporation has recently completed a series of
Environmental Impact Statements (EISs) looking, in part, at the environmental effect
of overflows and sewer system leakage (Sydney Water Corporation 1998). These
documents listed the potential environmental effects of overflows as being:
Eutrophication as a result of nutrient-rich sewage reaching receiving waters.
Toxicant impacts (especially chlorpyrifos and dieldren (respectively,
organophosphate and organochlorine pesticides) copper and ammonia).
Faecal coliforms; oxygen reduction in receiving waters (which may lead to fish
kills and other impacts).
Increased turbidity and increased sediment loads (and litter).
Each of these has potentially serious impacts. Their actual environmental effect
depends, however, on the volume and concentration discharged and the receiving
water environment. So too must the general environmental conditions at the time of
discharge be considered (i.e. rain or dry weather).
The key point to stress, however, is that quantification of leakage impacts and, by
expansion, the degree of corrective action required would depend on the situation
and the degree of risk we judge acceptable. That leakage causes environmental
impacts on receiving waters, land (e.g. water logging and nutrient enrichment),
recreational amenity, flora and fauna, and air quality is, however, undeniable.
Burn and Desilva (1999)
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2.3 The New SAE FMECA
In regard to avoid some of the mathematical difficulties of the RPN analysis, the new
SAE FMECA has accomplished through three major changes.
The new standard describes the FMECA procedure as a process to be
used throughout the product development cycle, rather than as a task
to be done after the design is complete. It emphasizes the role of
functional and interfaces FMECAs as well as that of the traditional
piece part FMECA.
The concept of “failure mode equivalence” enables failure modes that
have equivalent effects to be analyzed together and reduces much of
the duplicative work generated by traditional component-by-component
fault analyses. This concept allows the analyses of functional failure
modes done early in the design process to be carried over to the
effects of interface and piece-part failure modes analyzed later in the
design.
Criticality is assessed using a Pareto ranking procedure based on the
probability and the severity of the failure mode. This is more broadly
applicable than the use of criticality numbers SAE J1739. Bowles
(1998)
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3.0 Description of Loss Production Event
FMECA Description of loss production is an estimate of damage inflicted on an
industry in terms of quantities of finished products denied the enemy from the
moment of attack through the period of reconstruction to the point when full
production is resumed. This event can possibly cause by faults or failures due to
many reason (mostly poor asset management). Loss production may also occur
because of human error (like causing fire or contamination of water supply) or
natural disaster (such as volcanoes, flood, etc). There are several reasons of faults
or failures that may occur in this water utility. These failures if not being taken
seriously will cause greater damage to environment and will cost loss production,
even harm human being.
1. Breakdown in the water treatment system
2. Contamination of water supply
3. Clusters of illness potentially due to the former
4. Limitation of water supply due to droughts
5. Piping leakage due to failure of material
6. Disaster such as petrochemical accident
7. Infrastructure damage due to accident like fire
8. Corrosion in pipe, causing contamination to community’s water supply
9. Machinery damage due to poor asset maintenance
10. Infrastructure and machinery damage due to major natural disasters such as
volcanoes, flooding, insect plagues, etc
Piping failure in water utilities is chosen as the main topic, therefore this report will
mainly discuss about piping failure. The main reason why it is chosen is because
piping failure waste both money and a precious natural resource, and they create a
public health risk. The primary economic loss is the cost of raw water, its treatment,
and its transportation. Piping failure leads to additional economic loss in the form of
damage to the pipe network itself, e.g., erosion of pipe bedding and pipe breaks, and
to the foundations of roads and buildings (Figure 1). Risk to public health can be
Piping Failure in Water Utilities 2011
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caused by contaminants entering the pipe through leak openings if water pressure in
the distribution system is lost.
Figure 3. Leakage leads to damage to the pipe network, e.g., erosion of pipe bedding and
pipe breaks, and to foundations of roads and buildings.
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4.0 FMECA and Risk Management Method Discussion
4.1 Selection of Critical Components
In terms of critical components, a few critical components in pipe are identified by
researching through the exits data of failures and maintenance in pipe.
Critical components are known as those kinds of components that have a critical failure
mode. A component failure mode having significant operational, safety or maintenance
effects that warrants the selection of maintenance tasks to prevent the failure mode from
occurring. Figure below shows logical diagram for critical component selection.
Consequences of the
failure mode
Impact on Safety?
Impact on Generation?
Impact on Cost of
Repairs?
Non-critical Components Critical Component
Yes
Yes
Yes
No
No
No
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4.2 Failure Mode and Effect Analysis
Failure modes are the way in which a failure is observed, usually a description of
how a failure occurs. General types of failure modes are: I – premature operation, II
– failure to operate at a prescribed time, III – failure to cease operation at a
prescribed time, IV – failure during operations, V – intermittent failure, VI – and
dormant failure.
Once the failures are determined they need to be catalogued and analysed in a very
systematic and robust way. The three main analysis methods are: qualitative,
quantitative and risk priority number.
Failure effects are identified and inserted in each row of the FMECA matrix by taking
into consideration the criteria identified in the ground rules. Effects are categorized
as: I – local, II – next higher and III – end levels. System level effects would then
include system failures, degraded operation, system status failure, or no immediate
effect.
4.3 RPN and Corrective Actions
Risk Priority Number (RPN) is a measure used when assessing risk to help identify
critical failure modes associated with your design or process. It is rated using the
probability of the failure occurring, its severity and the unlikelihood of its detection.
These variables are rated with a number from 1 to 10 with 10 being the worst case.
The RPN values range from 1 (absolute best) to 1000 (absolute worst). The graphic
below shows the factors that make up the RPN and how it is calculated for each
failure mode. The risk priority number rating is found using the following formula:
Severity (S) - Severity is a numerical subjective estimate of how severe the customer
(next user) or end user will perceive the EFFECT of a failure.
Occurrence (O) - Occurrence is a numerical subjective estimate of the likelihood that
the cause, if it occurs, will produce the failure mode and its particular effect.
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Detection (D) - Detection is a numerical subjective estimate of the effectiveness of
the controls to prevent or detect the cause or failure mode before the failure reaches
the customer. The assumption is that the cause has occurred.
RPNs have no value or meaning in themselves. Although it is true that larger RPN
values normally indicate more critical failure modes, this is not always the case. For
example, here we have three cases where the RPNs are identical, but clearly the
second case would warrant the most attention.
Figure 4.a. RPN 1
As a general rule, any failure mode that has an effect resulting in a severity 9 or 10
would have top priority. Severity is given the most weight when assessing risk. Next,
the Severity and Occurrence (S x O) combination would be considered, since this in
effect, represents the criticality.
Below, the failure modes with the lowest RPN values are actually the most critical. It
shows that the first line is most critical even though it has the lowest RPN value, then
the second line, and finally the third line.
Figure 4.b.: RPN 2
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4.4 FMECA discussion
Critical components/ failure modes of pipe subsystem are identified as below:
Leak at seal or gasket on fittings, valves, hydrants and tapping bands.
Internal corrosion on fitting and hydrants.
Ball valve jammed.
Rusty pipeline and pipe leakage on pipelines.
Spindle failure on gate valves
Over flow and over heat on pump.
4.4.1 Fitting
Fittings are used in pipeline systems in order to connect straight pipe or tubing
sections. It has various connections such as threaded pipe, solvent welding,
compression fittings, and flared fittings. It also can be made from many materials
provided by the nature, but most often it is the same base material as the pipe or
tubing being connected, for example copper, steel, brass, or PVC. Fittings have
many types, from reducer, elbow, tee, cap, plug, and nipple.
4.4.2 Valves
The most common control failure in the Pipe system is valve failure. Valves fail to
operate most frequently by not closing completely or sticking open. Dirt or water in
the air starting system may cause this to happen. Water transports dirt and metal
particles and creates rust. The valve may stuck because of dirt and/ or water but
additionally is susceptible to overheating and coil failure. If, there is no maintenance
for valves, then there is no need to find out the cause of failure. Only replacement is
the solution. So time should be fixed according to old failure and maintenance
records.
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4.4.3 Pipeline
Polluted pipeline and leakage in pipe lines are two failure modes that can be occur
due to improper material as well as improper insulation. The effects of these failure
modes can be led up to stop the water supply or/and contaminate the water. The
severity of these failure modes is high and the RPN number is the highest. Highest
RPN number shows that these failure modes are the most critical failures.
4.4.4 Hydrants
Hydrant is an outlet from water main often consisting of an upright pipe with a valve
attached from water can be tapped. The most frequent hydrants failure is internal
corrosion. Internal corrosion can occur due to aging and improper material. The end
failure effect is having no water supply, so it can be classified as a critical failure
mode. Acoustic leakage detector method can be used to prevent this failure in
hydrant.
4.4.5 Tapping Bands
Tapping bands provide an economical and effective way of tapping into new or
existing pipelines. Leak at seal or gasket is the failure modes that can be occur due
to improper gasket or sealant. Loss of water can be the most important effect of
these failures on the pipeline.
4.4.6 Pump
We could assume that pump is a third-party component in the pipeline system, but it
is still an important component thus it pumps the water and distribute the water to the
consumer. The two primary failure modes of pumps over flowing and overheating of
the pump. Lack of lubrication in the pump can cause the overheating while wrong
pump setting can make overflow in the pipeline. Other reason that can make an
overflow is the pump breakdown (e.g. due to age) thus gives the wrong pressure to
the water. So we have to check the usage time of the pump and check periodically
the pressure that produce by the pump.
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5.0 Asset Management Issues Discussion
There are several issues regarding of asset management for water utility system.
Infrastructures such as tank storage, source of water and of course piping system to
distribute the water need to be taken seriously. We need to do as best as we can to
prevent bad things that will happen to provide clean drinking water for the protection
of public health against cholera and other water borne diseases for examples. Later
challenges included:
Securing sufficient quantities of water often through the building of dams
Providing satisfactory water distribution systems
Building sewerage systems to protect the environment and public health
Responding to the growing expectations of the community and the impact of
competition policy
Water authorities were generally invested with strong powers and were, by design,
fairly independent from governments. This independence was thought to be
necessary to ensure that the building of long-life infrastructure was not compromised
by shorter-term considerations. This chapter will mainly discuss about some issues
that mainly occur in water utilities regarding to piping failure such as, treatment of
piping operation, piping main repairs, the source of water loss due to piping leakage
and risk issues that mostly occur from implementing a water loss management.
5.1 Treatment of Piping Operation
A number of factors can contribute to the condition of water pipes and cause them to
crack, break or leak, including ground movement, corrosion, and external traffic
loading. This will affect the quality of water source. It is important to keep regular
maintenance for the piping system to prevent such a failure. Maintenance can also
be tricky. It can cost lots of money if we don’t do it as the procedure. On the other
hand, if we didn’t do regular maintenance, we can’t be sure whether the piping
system is still in good condition or not. We will briefly discuss about maintenance
process in the next chapter.
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5.2 Piping Main Repairs
Once we done the maintenance, we can actually found if there is any failure in that
pipe. Regarding to the failure, if it doesn’t do much damage to the pipe, we can try to
repair the pipe instead of replacing it. Replacing pipe can cost the company more so
if the failure is not too serious then repair seems to be the best option. Repairing is
not as easy as it seems. If it doesn’t do right as the procedure, it can cost lots of
money from the company. Moreover, bad repairing can cause more failures and
eventually producing malfunction to the entire piping system.
5.3 Source of Water Loss Due to Piping Leakage
System water loss can be over 30% in some schemes. Sources of water loss are illustrated
below
Figure 5. Schematic diagram of Sources of water loss
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As we can see from the diagram above, leakage can produce real losses. It is
something that the company would like to avoid. For example, if the leakage
happens it will affect the water source. The water source will be gone fast, causing
drought in drain area during dry season, or worse; contamination. If the contaminate
water reach the consumer and causing public disease such as cholera and other
water borne diseases, surely it would become great disaster for people. That is why
real losses have to be taken seriously to prevent such a disaster.
5.4 Risk Issues
Risk is very closely related to reliability and product safety. Risk is defined as an
economic aspect of safety as:
Risk$ = probability of a failure*exposure*$consequences
The probabililty of failure (POF) and exposure elements in the calculation lie
between 0 and 1. Consequence $s for costs vary from 1 up to and including X
millions of dollars. This statement of risk is the expected monetary value for an event
or set of events. For business management, risk could hardly be absolutely
eliminated. No matter how hard we try to prevent such a loss, there always risk
issues that need to be considered. However, most of the risk can be avoided by the
implementation of effective strategies. The top priority of the company is to survive.
In considering about how to profit from the business operation, the company must
also take account of preventing loss and confronting unexpected risk. Potential risks
associated with implementation of piping leakage strategies include:
Quality of raw data;
Implementation of sub-optimal water loss reduction strategies; and
Sustaining the levels of water loss reduction.
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6.0 Maintenance Management Issues Discussion
Water supply in general is a complex structure of different factors, i.e. .production,
transport and distribution. Within this structure, pipe networks represent one of the
largest infrastructure assets of industrial society. The management of potable water
networks encompasses all activities principally concerned with: the supply of water
from the outlet of the water treatment works to the customers’ taps; and all related
functions, including water resources provision, water treatment, customer relations,
business planning, human resources and information services.
Thus, maintenance planning designed to meet current and future system demands
of flow rate and pressure head, and to reduce future maintenance costs, represents
an integral part of a network management strategy.
Selection of the maintenance strategy for a water distribution system is a difficult
problem due to: a large number of system components, e.g. pipes, pumps, valves,
meters, etc.; dynamic evolution of the failure mode of deteriorating water pipe; the
existence of a certain degree of coupling among the various system components;
limited resources available for maintenance activities; and the associated difficulty in
quantifying many of the benefits and costs.
The problem has often been treated as a complex optimization problem with several
possible objectives used in isolation or combined, e.g. maximization of reliability,
minimization of downtime and the minimization of total maintenance costs.
A few analytic and optimization approaches have been published to assist in making
pipe replacement, relining or reinforcement decisions. Shamir and Howard (1979)
proposed an analytic model for making pipe replacement decisions based on pipe
breakage history and the cost of repairing and replacing pipes. They claim that the
optimal time for replacing existing pipes can be obtained using this methodology.
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There are 4 most common issues that come up when maintain the water utilities;
1. On the surface — dealing with utility cuts
Surveys show that pavement restoration following underground work on
utilities is a major challenge facing municipalities and utility providers, with
huge cost implications for both. Carelessness and lack of attention will lead to
accidents related to water pipes can lead to water stoppage and flooding in
large areas, directly affecting civic life (and causing damage).
Figure 6. Excavator Burst a Pipeline in Hong Kong
2. A seal in time — road maintenance
Preventive maintenance is the key to delaying road reconstruction, and
sealing cracks as they occur is an increasingly important way to do this.
Effective crack sealing can increase pavement service life by 10-20 percent
and save municipalities more than $800 million over the next 20 years.
“Effective” is the key.
3. Going underground — managing large sewers
The failure of deeply buried large sewer structures (more than 900 mm in
diameter) can have enormous consequences, both physically and financially.
And maintaining these systems can be equally difficult and expensive.
4. The sound of running water — locating leaky pipes
Most of water distribution has a lost on its transit between treatment facilities
and consumer. The major cause of thing is usually a leakage. Leakages
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usually caused by one of any failure occur on the piping system. In order to do
maintenance for this leakage, Water Company could use an acoustic device
to locate leaks, but as any other devices, it has a limitation, particularly in the
detection of plastic pipe, large diameter, or pipe in clay soils or below the
water table. To support this limitation, the use of combined leak detection
should be used.
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7.0 Loss Prevention and Mitigation Solution Discussion
As described before, we can assume that all of the failure types lead to the piping
leakage that can produce a catastrophic damage to the pipeline system thus can
stop the distribution and of water. For this reason we need some preventive measure
to reduce the probability of failure. With some good preventive measures we also
can reduce the cost of maintenance of the water utility.
The main idea to prevent the loss of water is to search for the leakage on the
pipeline system and fix it immediately. We can make a very good pipeline system
design with a best precision, but in the actual situation there is still some leakages
even a small one. This figure shows the steps that can prevent the leakage that can
leads to massive loss of water, they are:
7.1 Measurement of Unaccounted Water
There is no current comprehensive national regulatory policy that limits the amount
of water loss from a public water supply’s distribution system. Most states, however,
do have policies and regulations that address excessive distribution system water
losses. The policies vary among states, but most set limits that fall within the range
Start
Measurement of Unaccounted Water Volume
(First Measurement)
Searching for Leaking Spot
Repair the Leakage
Measurement of Unaccounted Water Volume
(Second Measurement)
Done
Below permissible
volume
Above permissible
volume
Below permissible volume
Above permissible volume
Piping Failure in Water Utilities 2011
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of 10% to 15% as the maximum acceptable value for the amount of water that is lost
or “unaccounted-for.”
Neither the term “unaccounted-for-water” nor the use of percentages as measures of
water loss is sufficient to completely describe the nature and extent of losses in
water utility operations. Unaccounted-for-water is a term that has been historically
used in the United States to quantify water utility losses. Unaccounted-for-water,
expressed as,
We can assume that if the unaccounted-for-water above 10% so we have to
continue with the second step that is searching the leakage.
7.2 Searching the Leakage
There are several methods that can be use to find the leakage in pipeline system,
they are:
Method by residue chlorine
Method by electric conductivity
Method by pH value
Method by water temperature
Method by trihalomethane
Method by acoustic leakage detector
Nowadays, the most common used method is the acoustic leakage detector. Water
leaks in underground, pressurized pipes may make many different sounds:
• “Hiss” or “Whoosh” from pipe vibration and orifice pressure reduction
• “Splashing” or “Babbling Brook” sounds from water flowing around the pipe
• Rapid “beating/thumping” sounds from water spray striking the wall of the soil
cavity
• Small “clinking” sounds of stones and pebbles bouncing off the pipe
Piping Failure in Water Utilities 2011
25
The “Hiss” or “Whoosh” sound, which often sounds like constant static noise, is the
only one, which is always present for leaks in pipes with 30 psi or higher water
pressure. The other sounds may or may not be present, and usually they are not as
loud. So we decide whether there is leak or no, by listening the “Hiss” or “Whoosh”.
The device that used in this method is the acoustic leakage detector. It can receive
the sound from the underground where the pipes located.
Figure 7.2.a. Man using the leakage detector
First thing that we have to do in searching for leakage is to survey in every hydrant,
valve, and service line is a possible location to hear the sounds of water leaks when
there is no obvious evidence like water flowing on the streets. Since the sounds
travel on the pipe walls better than through the soil, always listen at the hydrants,
valves, and meters first. As you get closer to the leak, the sound gets louder. Finally,
decide which two of these locations are the loudest. After this we can start with water
leak pinpointing.
Piping Failure in Water Utilities 2011
26
Figure 7.2.b. Listening leak sounds on hydrant Figure 7.2.c. Listening leak
sounds on meter
Water Leak Pinpointing is the term applied to the process of pinpointing the exact
leak location. For Acoustic Leak Detection, the exact leak location is usually the spot
where the leak sounds are the loudest.
Figure 7.2.d. Pinpointing
This activity can also be done regularly, for example every month check the leaking
sound, so we can prevent the loss of water.
7.3 Repair the leakage
After we find the exact spot of leakage we can determine the leaking cause. It can be
because of:
Piping Failure in Water Utilities 2011
27
Corrosion
o Water and other pollutant can cause the pipe corrosion.
Piece blown out
o Removal of a piece of pipe wall. This form of failure is brittle in nature.
Size can be vary depend on pipe material but generally greater than
100 cm2.
Broken back (circumferential break)
o A single crack extending part or full way around the pipe
circumference.
Longitudinal Split
o A crack along the pipe axis. The length can vary from a few mm to the
full length of the pipe.
Pipe rupture or tear
o A rupture to the pipe wall where the material tears and creates an
opening in the pipe wall. This form of failure is ductile in nature.
Leaking joint
o Water leakage through the joint. Often a result of a displaced rubber
ring joint or debris left in the ring groove during installation of RRJ
pipes. Lead jointed steel pipe can also leak.
Aging
o Due to long period, pipe experience many interference that can reduce
the performance itself.
Some of preventives measure can be taken before the leakage bigger and break the
pipeline system, such as change the components that leak especially at joints or
fittings, we can also use the anti-corrosive material to reduce the probability of
rusted, or we can use Split Repair Sleeve like in Osaka, Japan, they used this sleeve
Piping Failure in Water Utilities 2011
28
to cover up the leaking pipe so they can prevent the loss of water.
7.4 Measurement of Unaccounted Water (Second Measurement)
We again measure the unaccounted for water like the first one, then the number
decides do we have to look for the leakage again or finished up the preventive
measure of loss of water.
With this method we can prevent the loss of water and reduce the cost. It can be
very expensive if the pipeline system damage catastrophically, it can stop the water
distribution, the water quality, also the traffic on the ground if the water blows up.
Figure 7.3.a. Pipe leakage in Osaka pipeline
Figure 7.3.b. The leakage covered with the Sleeve split
sleeve
Piping Failure in Water Utilities 2011
29
Figure 7.4. Pipeline damage that have to be prevented
Piping Failure in Water Utilities 2011
30
8.0 Conclusion
In this report, the failure mode effect and critically analysis of the pipeline in common
water utilities. It describes of piping failure, especially on leakage on the basis of
functional analysis for pipeline itself. This report should be helpful to select the
appropriate maintenance step and prevention method to reduce any bigger losses.
With the right method of maintenance and prevention, the water distribution will not
be disturbed in a big scale.
To summarise, we think that although many of the risks that initially faced the system
have now been resolved, some risks still exist. However, with the contingency plans
(particularly the standalone system) that we have put into action, we feel that these
risks can be minimised.
We feel that risk management is a useful technique and it would have been useful to
have learnt more about it nearer to the beginning of the project rather than at this
late stage. Still, we feel that even now it can be useful and we will try to use it to
good effect in the remaining six weeks of the project.
For further preventive action, we also have some recommendation for you that will
be written in another part of this report.
Piping Failure in Water Utilities 2011
31
9.0 Recommendation
From the report above we understand that every business has it own risk. To reduce
the chance on getting a bigger loses from your asset, you need to do some
prevention for your assets. In this case, you must protect your asset from piping
failure that can cause a catastrophic damage that have a negative impact to your
business. So, our recommendation is that you must protect your asset by any
means.
To prevent the water loses, you can do a periodically maintenance for your
asset, for example you can use an acoustic leakage detector to find any leak
along the pipeline. The faster you know the leakage location, the more loss
can be reduced.
You need to calculate the usage time of each of your asset so that you can
plan to spend some of your money on renewing your asset. For example, pipe
has it owns lifetime, and pipe needs to be replaced by the end of its lifetime.
Calculating this renewal cost can reduce your chance from getting trouble
from aging.
It is also good to prevent unwanted accident during maintenance, like we
have mentioned before, you need to pay more attention to heavy machinery
that used for maintenance purposes.
We also recommending to you to increase the security for the facility, to
prevent the illegal usage of your asset. For example, irresponsible people
may take out the water without your permission due to low supervision. This
kind of illegal usage of this facility can increase in water loses that lead to
bigger losses for your assets.
Piping Failure in Water Utilities 2011
32
10.0 Reference List
seqwater.(2000). seqwater.Available: ttp://www.seqwater.com.au/public/home.
Last accessed 13th May 2011.
AWE. (2010). Water loss control. Available:
http://www.allianceforwaterefficiency.org/Water_Loss_Control_-_What_Can_Be_Done.aspx.
Last accessed 13th May 2011.
NSW government. (2004). NSW health responce protocol. Available:
http://www.health.nsw.gov.au/publichealth/environment/water/response.asp. Last accessed
13th May 2011.
Quiggin, John. (2000). Urban water supply in Australia: the option of diverting water from
irrigation. School of Economics and School of Political Science and International Studies
University of Queensland
Sydney Water Corporation (1998), Licensing Sewerage Overflows, Environmental Impact
Statement: Volume 1 – Sydney-wide Overview.
AWWA (1990), Water Audits and Leak Detection, Manual of Water Supply Practices No. M36,
American Water Works Association, Denver, CO.
Drucker, Professor Peter F. (1999). The End of Distance. Sydney Morning Herald, 18th November,
1999 (reproduced from the Atlantic Monthly).
Piping Failure in Water Utilities 2011
33
Horvath, B., Leakage Management: Assessing the effect of pressure reduction on losses from water
distribution systems, Urban Water Research Association of Australia, Research Report No. 5,
December 1989.
Piping Failure in Water Utilities 2011
34
Asset: WATER UTILITIES' PIPELINE
Function
SUFFICIENT WATER SUPPLY
Notes: RPN=Severity X Occurrence X Detection
System:
WATER UTILITIES
Function #:
SUPPLY FRESH WATER
Sub-system:
PIPELINE Analyst:
a b c d e f g h i j k l m n o p q
Failure Mode Failure Cause Failure Effects Operational Indication
Ref
Item Functio
n Letter
Description
Numbe
r
Description
Local Next
Higher End Normal Abnormal
Failed
Severity
Occurrence
Detection
RPN
Action
1 FITTIN
GS
CONNECTING PIPELI
NE
A
LEAK AT
SEAL OR
GASKET
1 IMPROPE
R SEALANT
WATER DRIPPING
FROM LEAKAGE
WATER LOSS
INCREASED
NO WATER COULD SUPPLI
ED
SUFFICIENT
WATER SUPPLY
LESS WATER
SUPPLIED
NO WATER SUPPLIED
6 4 4 96 USE THE
RIGHT SEALANT
2 2
IMPROPER
INSTALLATION
WATER DRIPPING
FROM LEAKAGE
WATER LOSS
INCREASED
NO WATER COULD SUPPLI
ED
SUFFICIENT
WATER SUPPLY
LESS WATER
SUPPLIED
NO WATER SUPPLIED
6 4 3 72
FOLLOW THE
STANDARD
PROCEDURE OF
INSTALLATION
3 B
INTERNAL
CORROSION
1 AGING CONTAMINATING WATER
CAN CAUSE MAJOR
LEAKAGE
NO WATER COULD SUPPLI
ED
SUFFICIENT
WATER SUPPLY
WATER SUPPLY
CONTAMINATED
BAD WATER QU
ALITY
9 6 3 162
CHECK THE TIME-USAGE OF
THE COMPONE
NT
4 2 IMPROPE
R MATERIAL
CONTAMINATING WATER
CAN CAUSE MAJOR
LEAKAGE
NO WATER COULD SUPPLI
ED
SUFFICIENT
WATER SUPPLY
WATER SUPPLY
CONTAMINATED
BAD WATER QU
ALITY
9 6 4 216
USE ANTI-CORROSI
VE MATERIAL
Piping Failure in Water Utilities 2011
35
5 VALV
ES
REGULATING THE
FLOW
A
LEAK AT
SEAL OR
GASKET
1
IMPROPER GASKET
OR SEALANT
WATER DRIPPING
FROM LEAKAGE
WATER LOSS
INCREASED
NO WATER COULD SUPPLI
ED
SUFFICIENT
WATER SUPPLY
LESS WATER
SUPPLIED
NO WATER SUPPLIED
6 4 4 96
USE THE RIGHT
SEALANT/GASKET
6 B
BALL VALVE JAMME
D
1
ACCUMULATED
POLLUTION
VALVE DIFFICULT
TO OPERATE
THE VALVE GOT
STUCK
NO WATER COULD SUPPLI
ED
VALVE OPERAT
E REGULA
RLY
NO FLOW THROUGH THE VALVE
NO WATER SUPPLIED
6 4 4 96
CLEAN UP THE
COMPONENT
7 2 MISSALIG
NMENT
VALVE DIFFICULT
TO OPERATE
THE VALVE GOT
STUCK
NO WATER COULD SUPPLI
ED
VALVE OPERAT
E REGULA
RLY
NO FLOW THROUGH THE VALVE
NO WATER SUPPLIED
6 4 4 96
FOLLOW THE
STANDARD
PROCEDURE OF
INSTALLATION
8 PIPEL
INE
WATER DRAINAGE
A PIPELINE GOT RUSTY
1 IMPROPE
R MATERIAL
CONTAMINATING WATER
CAN CAUSE MAJOR
DAMAGE TO THE
PIPE
BROKEN PIPE
SUPPLYING THE WATER
HALT THE WATER SUPPLY
PROCESS
NO WATER SUPPLIED
8 5 3 120
USE ANTI-CORROSI
VE
9 2
IMPROPER
INSULATION
CONTAMINATING WATER
CAN CAUSE MAJOR
DAMAGE TO THE
PIPE
BROKEN PIPE
SUPPLYING THE WATER
HALT THE WATER SUPPLY
PROCESS
NO WATER SUPPLIED
9 7 6 378
USE THE RIGHT
INSULATION
METHOD
10
B
PIPE LEAKA
GE 1
IMPROPER
INSTALLATION
DECREASING
WATER FLOW
CAUSING MAJOR
DAMAGE TO
PIPELINE
BROKEN PIPE
SUPPLYING THE WATER
HALT THE WATER SUPPLY
PROCESS
NO WATER SUPPLIED
9 7 6 378
FOLLOW THE
STANDARD
PROCEDURE OF
INSTALLATION
Piping Failure in Water Utilities 2011
36
11
2 ACCIDENT
AL EVENTS
DECREASING
WATER FLOW
CAUSING MAJOR
DAMAGE TO
PIPELINE
BROKEN PIPE
SUPPLYING THE WATER
HALT THE WATER SUPPLY
PROCESS
NO WATER SUPPLIED
6 4 4 96
INCREASE PROTECTI
ON TO PIPELINE
12
GATE VALV
ES
USED IN LOW PRESS
PIPE
A
LEAK AT
SEAL OR
GASKET
1
IMPROPER GASKET
OR SEALANT
WATER DRIPPING
FROM LEAKAGE
WATER LOSS
INCREASED
NO WATER COULD SUPPLI
ED
SUFFICIENT
WATER SUPPLY
LESS WATER
SUPPLIED
NO WATER SUPPLIED
6 5 3 90
USE THE RIGHT
SEALANT /GASKET
13
B
SPINDLE
FAILURE
1 BEARING FAILURE
UNUSUAL NOISE
DEACREASE IN TOOL LIFE
SCRAP
SPINDLE OPERAT
S REGULA
RLY
6 5 3 90
CHECK THE TIME-USAGE OF BEARING
14
HYDRANTS
SUPPLY
ADEQUATE
WATER
A
LEAK AT
SEAL OR
GASKET
1
IMPROPER GASKET
OR SEALANT
WATER DRIPPING
FROM LEAKAGE
WATER LOSS
INCREASED
NO WATER COULD SUPPLI
ED
SUFFICIENT
WATER SUPPLY
LESS WATER
SUPPLIED
NO WATER SUPPLIED
6 2 2 24
USE THE RIGHT
SEALANT / GASKET
15
B
INTERNAL
CORROSION
1 AGING CONTAMINATING WATER
MAJURE LEAKAGE
NO WATER COULD SUPPLI
ED
SUFFICIENT
WATER SUPPLY
WATER SUPPLY
CONTAMINATED
BAD WATER QU
ALITY
9 6 6 324
CHECK THE TIME-USAGE OF
THE COMPONE
NT
16
2 TEMPERA
TURE
CONTAMINATING
THE WATER
BROKEN
HYDRANTS
GOOD WATER DISTRIBUTION
AFFECT THE
WATER QUALITY
STOP
THE WATER SUPPLY
7 3 3 63
USE ANTI-CORROSI
VE MATERIAL
Piping Failure in Water Utilities 2011
37
17
3 OXIDATIO
N
CONTAMINATING
THE WATER
BROKEN
HYDRANTS
GOOD WATER DISTRIBUTION
AFFECT THE
WATER QUALITY
STOP
THE WATER SUPPLY
7 3 3 63
USE ANTI-CORROSI
VE MATERIAL
18
TAPPING
BANDS
GIRIPPING THE PIPE AND
PROVIDING THE
WATERTIGHT SEAL
A
LEAK AT
SEAL OR
GASKET
1
IMPROPER GASKET
OR SEALANT
WATER DRIPPING
FROM LEAKAGE
WATER LOSS
INCREASED
NO WATER COULD SUPPLI
ED
SUFFICIENT
WATER SUPPLY
LESS WATER
SUPPLIED
NO WATER SUPPLIED
6 4 4 96
USE THE RIGHT
SEALANT AND
INSTALL IT
CORRECTLY
19
PUMP PUMP THE
WATER A
OVERFLOW
1 REGULAT
OR FAILURE
STRESS ON PIPE
OVER STRESS ON PIPE
WATER COME OUT
FROM THE PIPE
GOOD WATER FLOW
TOO MUCH FLOW
INSIDE THE PIPE
WASTE ON WATER
9 6 6 324
CHECK THE TIME-USAGE OF THE PUMP
20
B OVER HEAT
1 LACK OF
LUBRICATION
COMPON
ENTS FAILURE
PUMP STOP
WORKING
GOOD WATER DISTRIBUTION
REDUCE WATER
DISTRIBUTION
NO WATER SUPPLY
9 6 6 324
CHECK THE
PERFORMANCE OF
THE PUMP REGULAR
LY
Piping Failure in Water Utilities 2011
38
RPN Format