Syed Aamir
MSc (Eng) Process Safety and Loss Prevention
MANAGING AN
ONSHORE OIL & GAS
PRODUCTIOON
FACILITY
MSc Process Safety & Loss Prevention
0
Dissertation Project
A study on the comparison of
different preventive maintenance
strategies using PESTEL technique
Submitted by:Syed Aamir Abbas Shah
Syed Aamir
MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
Table of Contents
List of Figures ............................................................................................................................................. 1
Abbreviations .............................................................................................................................................. 2
1.0 Executive Summary .............................................................................................................................. 3
2.0 Introduction ........................................................................................................................................ 5
3.0 Literature Review .............................................................................................................................. 7
3.1 What is ageing plant ......................................................................................................................... 7
3.2 Ageing Mechanism........................................................................................................................... 7
3.2.1 Material degradation............................................................................................................................... 7
3.2.1 Obsolescence ......................................................................................................................................... 8
3.2.1 Organizational Issues ............................................................................................................................ 8
3.3 Current Work .................................................................................................................................... 8
3.4 Evolution of maintenance strategies ................................................................................................. 9
4.0 Maintenance Strategies, Challenges & Performance measurement .................................... 12
4.1 Remaining Useful Life (RUL) prediction in oil & gas industry .................................................... 13
4.2 Risk-Based Maintenance Strategy .................................................................................................. 15
4.3 Reliability-Centered Maintenance Strategy.................................................................................... 17
4.4 Condition-Based Maintenance Strategy ......................................................................................... 21
4.5 Planned-Preventive Maintenance Strategy ..................................................................................... 24
4.6 Importance of maintenance planning ............................................................................................ 26
4.7 Challenges in maintenance for an oil and gas production facility ................................................. 31
4.8 Maintenance Performance Measurement and Indicators ............................................................... 33
5.0 Comparison of maintenance strategies using PESTEL ......................................................... 37
5.1 PESTEL Technique ....................................................................................................................... 37
5.2 RBM strategy analysis using PESTEL framework ........................................................................ 39
5.3 RCM strategy analysis using PESTEL framework ........................................................................ 42
5.4 CBM strategy analysis using PESTEL framework ........................................................................ 46
5.5 PPM strategy analysis using PESTEL framework ......................................................................... 50
6.0 Conclusion & Future Work .......................................................................................................... 55
6.1 Conclusion ...................................................................................................................................... 55
Syed Aamir
MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
6.2 Future Work .................................................................................................................................. 58
References ............................................................................................................................................... 60
Syed Aamir
MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
List of Figures:
Figure 1: Development of maintenance philosophies…………………………………………10
Figure 2: Development of consequence scenario……………………………………………...11
Figure 3: Possibility of life extension via performing inspection. ……………………....…….11
Figure 4: Systematic approach for managing plant aging……………………………………...12
Figure 5: Typical decision framework of the CCEB method…………………………………. 22
Figure 6: Bathtub curve……………………………………...…………………………………24
Figure 7: Maintenance-related accident scenario for the Texas City Refinery……………...…28
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Syed Aamir
MSc (Eng) Process Safety and Loss Prevention
Abbreviations:
RUL-Remaining useful life
RBI-Risk-based inspection
RBM-Risk-based maintenance
O&G- Oil ang gas
CBM-Condition-based maintenance
PPM-Planned preventive maintenance
RCM-Reliability-centered maintenance
I&M-Inspection & maintenance
PM-preventive maintenance
NDT-Nondestructive testing
MPIs- Maintenance performance indicators
PI-Performance indicators
TBM-Time based maintenance
PESTEL-Political, Economic, Technological, Environmental and Legal
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Dissertation Project
Syed Aamir
MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
1. Executive Summary
Managing an ageing oil and gas production facility is very challenging task due to various
factors like cost of maintenance, degradation and wear and tear in machinery/equipment, risk of
sudden failure due to ageing and other factors that are explained in section 4.7. Numerous
preventive maintenance strategies have been developed over the past few decades, like PPM,
CBM, RCM and RBM to effectively counter these issues and successfully run an ageing oil and
gas production facilities. Remaining useful life estimation (RUL) is a quite helpful in condition
monitoring and it is very effective for cost-effective operations and developing maintenance
requirement for an aged plant. This study compares different maintenance strategies being used
in oil and gas industries based on PESTEL and two other factors (section 5).
PESTEL technique has never been used before to analyze or compare the maintenance strategies.
This paper considers all the factors of PESTEL (Political, economic, social, technological,
environmental and legal) for the comparison of the maintenance strategies. There is very less to
no information related to political, social and legal aspects of the different maintenance
strategies. However, economic, technological and environmental aspects provide sound basis for
the comparison.
This paper reviews the different aspect of preventive maintenance strategies in relation to their
effectiveness to an ageing oil and gas production facility. Maintenance requirement for static and
rotatory equipment installed in an oil and gas production facility are different. One single
strategy is not sufficient to deal with the issues of every equipment. In section-5, the study shows
that CBM strategy is suitable for rotatory equipment and static vessels but it is unable to predict
the hidden faults in protective devices and redundant equipment. Similarly, RCM is more
focused on the function of the equipment and machinery and is perfect strategy in providing
maximum availability of the equipment and reducing unnecessary maintenance. RBM strategy
covers the wide range of issues of an ageing oil and gas production facility (section 4.2 & 5.2).
RBM requires to carry out the quantitative risk assessment in addition to the failure mode
analysis and prediction/likelihood estimation. This strategy is most effective in quantification of
the physical risks, like fire, explosion due to loss of containment. In addition to this, it provides
deep insight to the top management in cost cutting related to unnecessary maintenance of low
risk equipment and machinery.
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MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
Overall one single strategy is not enough to cover all the issue of an ageing oil and gas
production facility. PESTEL analysis performed in section 5, brings forward the strengths and
weaknesses of these preventive maintenance strategies to decide on which strategy should be
used for the concerned problem. This paper looks how each PM strategy influence risk reduction,
equipment availability, cost reduction and increasing design life of an ageing oil and gas
production facility.
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MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
2. Introduction:
Managing an onshore oil & gas aged production facility: Management of
‘an Oil & Gas aged production facility’ is a challenging task. With the passage of time
certain factors greatly influence the management of ageing oil and gas plant. This
include decrease in oil and gas production, high maintenance cost or breakdowns due to
ageing and technological advancement issues. Plant and its installation start deteriorating
after some time and this issue escalates when production start decreasing, plant
experiences wear and tear and oil prices fall. This is because with low production and
high maintenance requirement overall revenue and profit falls greatly and it becomes
difficult for the owners and operators to spend more money on maintenance related
requirements and running the plant with profit. Owners and operating companies face
big challenge of maintaining those aged assets with high risk and low profit. Section 4.7
explains the challenges due to ageing plant.
Different strategies are used to reduce the risk arising from ageing of these onshore oil
and gas plants and run them with acceptable risk. Preventive maintenance strategies are
thoroughly explained in section 4 of this project.
Maintenance strategies for new and old oil and gas production facility cannot be same
due to various reasons. For example, with time the production starts decreasing as the
well pressure drops after couple of years of production, this greatly reduces the revenue
and profit of the operating company. Therefore, the same conventional ‘Time based’
maintenance strategy is not adequate to operate the facility with fixed interval of
maintenance as it requires significantly high cost. Another important factor related to
ageing is the age itself. Wear and tear of all the critical devices and equipment like ESD
devices, pressure vessels, storage tanks, rotatory and static equipment at the field
increases with the time. After some time, chances of hazardous chemical release and fire
and explosion increase. At this stage, operating companies and clients normally perform
cost to benefit analysis to check whether the running the plant any further is cost
effective or not. Risk analysis and different maintenance strategies are discussed to
reduce the risk and keep the plant running. PESTEL framework in section 5 of this
dissertation project is used to makes a comparison of the maintenance strategies.
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MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
Different companies adopt different strategies to encounter the ageing plant issue. For
example, some companies do risk transfer by selling the ageing plant, some outsource
their operations, while some work on maintenance strategies to reduce the operational
cost and keep the plant running.
In this project, the focus will be on the maintenance strategies for managing an ageing
onshore oil and gas plant. Maintenance activity is the key to run the plant and control the
risk arising from wear and tear of the plant with ageing. At the same time, the cost
related to the maintenance is a significant issue, therefore, conventional preventive
maintenance strategies are not effective. Moreover, different maintenance strategies
focus on different aspects of the plant and equipment, therefore, a thorough comparison
will be made to find out which maintenance strategy is best for an old oil and gas
production facility.
Challenge in the maintenance strategy selection is not only the cost reduction but at the
same time risk reduction which is the major concern once the operator or client decides
on running the plant. Comparison of maintenance strategies will be based on the main
risk reduction with minimum cost and resources.
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MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
3. Literature Review
3.1. What is ageing plant?
The term ageing plant is often construed and it is not just about the total age of the plant and
its expected life. There are many old plants that are fit for their intended purpose and do not
pose high risk. Ageing plant is the one which may or may not be considered fit for the
intended purpose due to significant deterioration that had occurred within the plant and could
increase the chances of its failure. This has been defined in the following way by HSE UK in
“Managing Ageing Plant”.
Ageing is not about how old your equipment is; it is about its condition, and how that is
changing over time. Ageing is the effect whereby a component suffers some form of material
deterioration and damage (usually, but not necessarily, associated with time in service) with
an increasing likelihood of failure over the lifetime.
3.2. Ageing Mechanism
Plants and equipment can suffer deterioration, degradation and wear and tear due to
various potential reasons. Once the equipment is installed or manufactured various
factors may contribute to their ageing that are:
3.2.1. Material degradation: Material degradation or physical ageing is dependent on
the properties of the plant and equipment and the environment in which it is
operated. It is also caused by the operational condition of the plant and equipment
and installation. All type of materials rotating parts and machinery suffer from
ageing due to the following factors that cause material degradation (Håbrekke,
2011).
7
•
Corrosion
•
Weathering
•
Stress Corrosion Cracking
•
Physical damage
•
Fatigue
•
Instrument drift
•
Embrittlement
•
Dry joint development
•
Erosion
•
Detector
•
Subsidence
•
Contraction & expansion
poisoning
Syed Aamir
Dissertation Project
MSc (Eng) Process Safety and Loss Prevention
3.2.2. Obsolescence: Obsolescence means when equipment is outdated, replaced by
new technology, equipment or system. The older technology is no longer used for
the certain activities and processes and pose big challenges to meet certain demands.
Obsolescence also include certain needs like extraction of oil and gas from wells
that
require
specific
equipment
and
technology
(Håbrekke,
•
Equipment out of date
•
New technology
•
New needs
•
New
2011).
requirement
3.2.3. Organizational Issues: This deals with the need of clear cut responsibilities for
the operation and maintenance of the equipment and transferring of knowledge and
skills from the retiring personnel to the new young stuff. Competency of young
operator and engineer is critical. Factors that can contribute are (Håbrekke, 2011):
•
Reorganization
•
Ageing of personnel
•
Transfer of knowledge
3.3. Current Work:
There is currently a lot of published material and work available about the strategies
and techniques for the life extension of the oil and gas installations. Over the past few
years lots of researcher and veterans have tried to assess the viability of an aged plant
and scope of its life extension. Mahmood Shafiee published a paper “Life extension
decision making of safety critical systems: An overview”, that comprehensively
gives an insight in decision making of life extension of an existing aged facility. In this
paper author compares the existing strategies that are currently being used to manage
different hazardous industries plant’s and how the best strategy could be applied in to
extend the useful life of the ageing facility.
Isaac Animah published a paper “Condition assessment, remaining useful life
prediction and life extension decision making for offshore oil and gas assets”. In this
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MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
paper, author lists different techniques that are currently being used for the offshore
plant condition assessment, predicting remaining useful life and how life extension
decision could be made.
Inspection and maintenance is one of the key element in oil and gas plant operations
and these processes also play instrumental role in the decision making of plant useful
life extension. In this key area, numerous studies have been carried out optimize the
processes and increased the critical devices life. ‘Journals of Loss Prevention in the
Process Industries’ has published many articles on risk based inspection and
maintenance strategies to give insight into the ways of increasing reliability and
availability of the plant.
Khan and Sadiq (2004), published a paper on risk-based maintenance and its economic
viability. Khan & Mahmoud (2004) published another paper on RBM. This paper
details how the RBM can be implemented in process plant through risk estimation and
defining optimum maintenance interval that reduces the unnecessary maintenance cost.
Shiao (2005), wrote a paper on RBM optimization using probabilistic algorithm. This
paper is quite useful in accurate estimation of the probability and likelihood of failure.
With the growing complexity and advancement in the technology, it has become
difficult for operators and clients to decide about the most suitable maintenance
strategy. (Ahmad 2012) gives an overview of the TBM and CBM strategies and their
application in the industry. This paper gives deep insight in decision making about how
these strategies could be implemented in process industries. Endrenyi (2001) also
presented a paper on the comparison of the existing maintenance strategies. In this
paper author also explains the advantage of RCM as it gives insight to the management
to decide on maintenance interval rather than following fixed planned interval.
3.4. Evolution of Maintenance Strategies: Initially the corrective or break down
maintenance was the main form of maintenance. But with the passage of time other
strategies were developed that include, preventive maintenance, condition based
maintenance, reliability centered maintenance and risk based inspection and
maintenance. Below picture show the evolution of the maintenance strategies with the
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Syed Aamir
MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
time. In 1940s, there was conceptive of corrective maintenance only. But within few
decades preventive maintenance gained huge importance and many strategies like PPM,
CBM and RBM have developed to cater the issues of economic and safety (Ratnayake,
2012).
Figure 3:Development of maintenance philosophies. (Ratnayake, 2012)
Preventive maintenance is an effective tool to reduce the unexpected failures, downtime
cost and possibility of catastrophic failures. RBM is the latest of the maintenance
strategies and has been affectively applied in offshore oil and gas (O&G) industry. This
technique as described in detail is quite useful in process industry in predicting the
likelihood of the failure and its possible consequence. Therefore, gives great insight to
the owners and management to decide on the optimum time interval for the maintenance
of critical equipment. Around 80 percent of the total risk in process industry are caused
by 20 percent of the equipment. Therefore, RBI and RBM can effectively be used to
prioritize the maintenance activities for the equipment and installation based on the
calculated quantified risk. There is a little difference between the RBI and RBM
strategies in terms of implementation. In general, these strategies require dividing the
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Syed Aamir
MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
system into sub system then calculating risk using consequence modeling and in the end
planning maintenance. Below pictures clearly explains this (Ratnayake, 2012).
Figure 4: Development of consequence scenario. (Ratnayake, 2012)
Ageing is not only about the equipment but also the changes that have occurred in the
equipment over time. Therefore, life extension of an ageing equipment is the process of
continuous inspection and maintenance of the right equipment, on the right time based
on the accurate data and information. Below picture explain the life extension through
inspection and maintenance. This shows that with adequate inspection failure can be
predicted and with proper maintenance design life could be extended (Ratnayake, 2012).
Figure 3: Possibility of life extension via performing inspection. (Ratnayake, 2012)
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Syed Aamir
MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
4. Preventive Maintenance Strategies, Challenges & Performance
Measurement:
Since the oil & gas facility ageing is a big challenge for the operators and stake-holders, its
maintenance and continual operation require rigorous review of the strategies and techniques
being used for the life extension and operating ageing plant. Various factors are involved
while deciding on whether to continue operating the current facility equipment or installation
or to abandon it. These factors include, high cost, low profitability, increased risk, increased
maintenance and inspection intervals, technological advancement, increased downtime and
oil and gas prices (Ramírez, 2011).
There are several existing maintenance strategies to assist operators and stake-holders to
extend the useful life of existing plant and operate it with controlled risk. The aim of this
dissertation is to elaborate various such strategies that are currently being used to manage the
aged oil and gas facility and make a comparison of them based on their advantages and
disadvantages (Ramírez, 2011).
Figure 5 (Ramírez, 2011)
Figure 4: Systematic approach for managing plant aging. ( Ramírez, 2011)
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Syed Aamir
MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
The above picture explains the management of an aged plant in a flow chart. This shows
that a huge data is required for managing the aging plant. Then this data and information
is interpreted to focus on the critical equipment. Ageing monitoring for the critical
equipment is carried out in the later phase and in the end decision is made for the
maintenance or replacement. This circle is repeated for the aged plant. The focus of this
dissertation project will be on the maintenance strategies for an aged oil and gas facility.
These techniques include monitoring, inspection and maintenance strategies that could
be developed for the ageing plant.
First a brief description of different maintenance strategies will be given to give
understanding of the procedure of carrying out them, what is their focus and application.
4.1. Remaining Useful Life RUL prediction in oil & gas industry:
It is the estimation of the life of the equipment installation during which it could be
operated safely at acceptable level. There is various critical equipment in an onshore oil
and gas facility that require a life estimation near their end of useful life. These
equipment for example includes, safety critical devices, separators, oil & gas pipelines,
generators and compressors. RUL is a quite helpful in condition monitoring and it is
very effective for cost-effective operations and developing maintenance requirement for
an aged plant. For an aged oil and gas plant, where there is big challenge of low
production, high operational cost and increased risk, this technique is quite useful in
giving insight to the management in decision making. There are different ways of
estimating useful life, that are physics based approach, data-driven and fusion which is
hybrid of both physics based and data driven (Animah, 2017)
Physics based approach: In this approach, theoretical mathematical model is built to
estimate the degradation and damage to the equipment over time. Corrosion, wear and
crack propagation and their rate can be predicted by using this approach. This model
requires using partial differential equation and can be useful when access to data is
limited or not available. Various studies have been carried out for offshore and onshore
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MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
plants to estimate corrosion, cracks and erosion issues. This technique is quite useful for
critical equipment’s life estimation once they are aged enough and require a decision to
be replaced or be used further (Animah, 2017).
Data-driven approach: This approach relies on the historical data of safety related of
the equipment to establish the connection and develop the future trend of failure and
useful life. However, in some cases, there may not be sufficient data available or the
data may not be very reliable to be used to predict the further trend, therefore, this one of
the big limitation of this approach. If the data is accurate and available this technique
can be used for measuring the current condition, cause and condition of the issues with
the equipment and predicting its useful life. Data accusation is done through sensors
signal using artificial networking and other models (Animah, 2017).
Fusion:
In this technique both the physics based approach and data-driven are
combined in a way to use their strengths and reduce the effect of their weaknesses. This
technique uses the principles behind the physics of failure approach to select the system
for data-driven technique for diagnosis and prognosis. Therefore, the eventual RUL
model is based on both the techniques fusion (Shafiee, 2017).
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MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
4.2. Risk based Maintenance RBM Strategy: Risk based maintenance methodology
is aims to reduce the overall risk of the plant. In high and medium risks situations,
focused inspection and maintenance is required whereas in low risk scenarios, less effort
is needed. RBM suggests sets number or recommendation to for preventive action and
tasks required. Quantitative risks are normally calculated and sets the basis for
prioritization of inspection and maintenance. In RBM the whole system is divided in to
small units and for each unit risk is calculated and compared with the tolerable risk. If
the risks accede the acceptable risk, the hazardous scenarios are re-evaluated for optimal
inspection/maintenance duration that would bring it down to the tolerable risk. The
results obtained for all the units are then combined to develop an overall maintenance
plan for the system (Khan 2004).
Risk estimation: risk estimation is the first step in the RBM. It includes, development
of failure scenario, consequence assessment, probabilistic failure analysis and finally
risk estimation. In development of failure scenario, a typical failure situation is
described. It describes what could happen, so that a preventive strategy could be
developed.
Failure scenarios depend upon the physical condition, operating
environment and characteristics of the system and inputs. In consequence assessment,
quantification of the consequence is carried out. Consequence are quantified in terms of
damage radii, damage to property, environment and people. In consequence assessment,
wide range of models are used. For example, in source model, rate of release, flashpoint
and evaporations are calculated. Models for fire and explosion are used to calculate the
characteristics of the fire and explosion. In total four different categories of
consequences are combined in consequence assessment, that are system performance
loss, financial loss, human health loss and environment and ecological loss. After
completion of consequence assessment, probabilistic failure analysis is carried out. This
is done by using fault tree. It’s an analytical tool to determine the occurrence of a
hazardous undesired event. This can be done by using equipment failure data and human
reliability data to determine the probability and frequency of the hazardous event. In this
step of RBM, many fault tree analyses are carried out for different initiating events that
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Syed Aamir
MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
may lead to the final event of the hazardous scenario. In the end, risk estimation is
performed based on the results of consequence analysis and probability/frequency
estimates. The risk estimation includes factors of fatality, environment, economics and
system/production losses. This risk is the total risk of the system and it is compared with
the tolerable risk (khan,2004).
Risk Evaluation: In risk evaluation first thing is to set up an acceptable risk criterion
and then comparing the risk against acceptable risk. Setting up an acceptable risk is
different from company to company. There is no strict rule for that. In this step company
sets up the acceptable risk for its system or hazard. Some of the common risk criteria is
ALARP (as low as reasonably practicable). In risk comparison, the computed risk is
compared with the set tolerable risk. The risk for any component/unit if exceeds than the
tolerable risk is marked for further analysis to reduce it further (Khan, 2004).
Maintenance Planning: Once the risk evaluation is completed, maintenance plan is
developed. The first step in developing maintenance plan is estimation of optimal
maintenance duration. In it, those equipment and units having increased risks are subject
to detail investigation. This investigation includes details analysis of the basic causes of
failures and their functions. A detailed reverse fault tree is constructed using this
information to achieve the targeted failure probability. This study gives optimal
maintenance time for the equipment under study. A maintenance plan then could be
organized based on the maintenance time that comes out in first place. Re-estimation
and re-evaluation of the risk is performed for the equipment and systems to check that
the proposed maintenance plan has decreased the risk to the sufficient level or not. This
gives a kind of validation and verification of the planned maintenance program (Khan,
2004).
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MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
4.3. Reliability Centered Maintenance (RCM) Strategy: Reliability-CenteredMaintenance is method of maintenance planning development in aircraft, oil & gas,
nuclear and several other industries. Main objective of the RCM is to reduce the cost of
maintenance by focusing on the key performance related function of the system and
avoiding maintenance programs that not very important. If there already exist a
preventive maintenance plan then RCM analysis helps to eliminate or reduce
insignificant maintenance (Rausand, 1998).
Cost is a big issue in aged oil and gas production facility. With increased risk and less
production qualitative preventive maintenance techniques are not very effective.
Therefore, to find an alternate quantitative preventive maintenance strategy are
considered to extend the life of the plant and controlling the risk at the same time. RCM
technique is therefore, a useful tool to manage the old oil and gas production facility.
RCM analysis is carried out in a sequence of steps that are;
Study preparation: The first thing in RCM is to set the objective and defined the scope
of the analysis. Requirements, policies, procedures and acceptance criteria with respect
to the safety aspects should be set to define the boundaries. All the resources should be
available including human resource, data, unfractured and process and equipment detail
(Rausand, 1998).
System Selection & Definition: In this step, a decision is normally taken about the
plant, system or equipment on which RCM analysis is to be carried out. And on what
system the RCM analysis could be beneficial as compared to the traditional maintenance
techniques. Principally, RCM benefits all system, but due to limited resources as in
ageing plant, priorities are set to limit the cost. Similarly, the system or the plant which
is normally comprises of several equipment and installation is broken down into small
sub-systems and units. This is done to pick the safety critical equipment for the RCM
analysis (Rausand, 1998).
Function failure analysis FFA: In this step, the systems required functions and criteria
are defined, input interfaces for the system operation are defined and ways in which
system can be failed.
System usually have many different functions. In this step, all the necessary functions
are identified. These functions include, essential functions which are instrumental to
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MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
fulfill the intended purpose of the equipment, auxiliary function which are required to
support essential function, protective function which are required to protect people,
environment and equipment, information function which are required for condition
monitoring like gauges and alarms, interface function which are required for interface
between the item in question and other, online functions which are required to update the
user about the status of the system, off-line functions which are used infrequently and its
availability is not known unless tested this include emergency shut down valves and
other emergency instruments (Rausand, 1998).
Failure fraction analysis is to identify the different failure modes of the system. Failure
mode include, sudden failure which cannot be predicted in advance by any testing or
examination, gradual failure which can be predicted by inspection and testing. An
important failure is the ageing failure, which likelihood increases with the time and wear
out. Ageing failures are sometime termed as the gradual failures. In other cases, these
failures can be termed as sudden failure, as with the passage of time the systems inherent
resistance and capability reduces and failures occur (Rausand, 1998).
Critical item selection: In this step those items in the system are identified which have
critical functions. These items are termed as functional significant items. In complex
system, there is a need of formal approach to identify the functional significant items.
This can be done by using fault tree, event tree or reliability block diagram. In addition
to this, equipment and machinery with high maintenance cos, long repair time, low
maintainability and items that require external maintenance are identified (Rausand,
1998).
Data collection and analysis. Input data is required at various step of the RCM analysis
strategy. This data includes, design parameters, drawings, reliability and operational
data. Reliability data is important to describe the criticality of the function of the system
and optimize the preventive maintenance for it. This include mean time to failure MTTF,
mean time to repair MTTR and failure rate. In ageing facilities, failure rate increases
with the time indicating that the equipment or item is deteriorating with the time. This
reliability data is collected from the monitoring of the existing equipment and from the
external sources where similar equipment and installations are used (Rausand, 1998).
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MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
Failure Modes, effect and criticality analysis (FMECA): Objective of this step is to
identify the dominant failure modes of the maintenance significant items MSI. FMECA
is a detailed analysis in which critical items are selected, there functions are described,
failure mode is explained, effect of failure is outlined and failure cause is explained. This
gives the pretty good idea of the possible failure ways and criticality of the equipment or
item. For each failure mode, maintenance action is proposed, which is explained in the
next step (Rausand, 1998).
Selection of Maintenance Action: This step is a bit novel as compared to the other
maintenance program. RCM logic input is used to assist the analyst through FMECA
described failure modes. The main idea of this step is to decide whether preventive
maintenance is applicable and effective or let the failure occur and corrective actions is
sufficient afterwards. The basic maintenance task that are decide in this step are,
scheduled on-condition task, scheduled overhaul, scheduled replacement, scheduled
function test and run to fail. Preventive maintenance does not prevent all failures. If
there is a failure that cannot be addressed through this technique then for sure the
modification or redesigning is inevitable. The selection of different preventive
maintenance task depends upon criteria and need. For example, for ageing oil and gas
production facility, in a situation of hidden function with ageing failure, both function
test and scheduled replacement are required (Rausand, 1998).
Determination of maintenance interval. Optimal interval determination for the
maintenance is a challenging task and it must be based on the failure rate of function,
cost involved in the consequence and maintenance. Since with the ageing equipment and
unit manufacturer proposed interval is less reliable, therefore, based on the failure rate
data, picking the periodicity that seems optimal. Later, based on the characteristics of the
equipment periodicity can be increased or decreased (Rausand, 1998).
Preventive maintenance comparison analysis:
The criteria for selecting RCM is
based on the two things, that are, applicability and cost-effectiveness. Applicability
means the preventive maintenance task should be applicable in terms of reliability
knowledge and failure mode. PM task is applicable if it can eliminate the failure mode or
at least it should be able to reduce the probability of its occurrence. The PM cost include
the cost of failures related to maintenance, risk of exposure to the personnel, risk and
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cost of failures of another component and the cost of physical resources. Cost of failures
include the loss of production, violation of laws and regulations, plant and personnel
safety reduction, increased premiums, emergency repairs and high replacement repair
(Rausand, 1998).
Treatment of non-maintenance significant items: Non-critical items are not analyzed
in RCM. Brief cost analysis need to be carried out for the existing maintenance program
for these items. If the cost is insignificant then this program should be run as it is.
Implementation: Implementation of the results of the RCM requires that the
organizational and technical maintenance support functions are available. Many of the
accidents happen during or after the maintenance, therefore, it is extremely important to
carry out human behavior risk assessment and task risk analysis. This will greatly reduce
the chances of failures resulting from human error (Rausand, 1998).
In service data collection and updating: One of the major advantage of the technique
is that the data we collect during operation after the RCM analysis can be incorporated
into the RCM analysis. For example, if some failures occur and it is not covered in the
FMECA, it can be included into it with little revision. This revision does not require
significant resources as the basis of the analysis has already been done. It does not
require to consider all the steps in the analysis. During revision, it is not sufficient to
consider only plant being analyzed, it is mandatory to consider all the factors like,
contractual requirements and development in the legislation while performing review
and update (Rausand, 1998).
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4.4. Condition-based Maintenance (CBM): Condition based maintenance is one of
the most advance maintenance techniques. It is a management philosophy in which the
decision of repair and replacement are based on the current and future condition of the
asset. Changes in the condition and performance of the assets are observed and the
decision of the maintenance is based on them. Optimum time for the CBM is determined
through actual monitoring of the equipment/unit and its subparts. This condition
monitoring varies from the simple visual inspection to the automated tools for the
condition monitoring (Ellis, 2008).
The heart of the CBM is the condition monitoring, where the condition is continuously
monitored through the certain sensor and other appropriate devices. Monitoring
parameters include, vibration, noise, lubrication oil, contaminants and temperature.
Maintenance is performed only when there is need for it or there is likelihood of failure.
Main objective of the CBM is to assess the real-time condition of the equipment/system,
to decide about the maintenance to reduce the time and unnecessary cost related to the
maintenance. In general, the purpose of the monitoring is twofold. First thing is to
identify the condition of the equipment and second thing is to identify the causes of the
failure and increase knowledge about the deterioration due to ageing and usage (Ahmad,
2012).
Condition monitoring (CM) can be performed in two ways: on-line and off-line. On line
monitoring is performed while the equipment is running condition. While in off-line
monitoring equipment is required to stop running. CM can also be done either by
continuously or at certain specified intervals (Ahmad, 2012).
Maintenance decision in CBM strategy can be categorized into two ways: diagnosis and
prognosis. Diagnosis is the process of finding the source of faults in the unit/equipment,
while in prognosis probability or likelihood of failure is estimated. The aim of prognosis
is to find the early warnings and signs of failure and its likelihood in the equipment and
system. If the equipment is run in abnormal condition it does not mean the equipment
has failed, it may run for certain period. Therefore, prognosis is compulsory to perform
(Ahmad, 2012).
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Prognosis is better than diagnosis from maintenance point of view in a way that it can
prevent unexpected faults and failures hence, saving cost of unplanned maintenance. In
CBM, decision can be made using prognosis for equipment deteriorating modeling. This
model as shown in the below picture gives insight of the current equipment condition
and can predict future deterioration. Current condition data is collected for modeling
purpose, then modeling is carried out to estimate the equipment condition at present.
Then this is compared with predefined failure limit. If the condition of the equipment is
over or exceed the limit, the equipment maintenance will be mandatory at this point.
Otherwise it is assumed the condition is good and does not require any further
maintenance for certain period (Ahmad, 2012).
Figure 5: Typical decision framework of the CCEB method. (Ahmad, 2012).
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Vibration Monitoring: most popular technique of rotating equipment is vibration
monitoring. In oil and gas industry like generator and compressors condition can be
monitored using this technique. It requires certain sensor to be installed on the
equipment to measure the vibration and the changes or increase pattern of the vibration
over time. This can be done either using continuous monitoring strategy or at specific
intervals (Ahmad, 2012).
Sound or acoustic monitoring: This has a strong relation with the vibration monitoring
technique of CM but there is a fundamental difference between them. Vibration
monitoring sensor are mounted on the equipment and measure the motion while in
sound monitoring, sensors measures the sound of the equipment. Again, this technique is
quite useful in measuring the difference in the sound with the time and usage of the
equipment and help the maintenance team in deciding on the maintenance time and
interval (Ahmad, 2012).
Oil analysis or lubrication monitoring: This is another important CM technique used
for the rotatory equipment. In this technique condition of the lubricating oil is tested
regularly to measure weather the oil is effective to be used further or should be
discarded. This also gives the insight of the internal condition of the oil wetted parts of
the equipment. This technique has two general purpose, one to check the quality of oil
and other to safeguard the component involved (Ahmad, 2012).
Other CM technique: Apart from above, there are few other CM techniques that
include electrical, temperature and physical condition monitoring. Electrical monitoring
involves monitoring changes in certain properties, like electrical resistance and
conductivity. This technique helps in identifying faults related to insulation and motor
rotor bars. Temperature monitoring is also applied on the condition monitoring of
electric and electronic parts of the equipment. Physical condition monitoring is used to
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monitor the physical deterioration of the equipment and material like cracks
propagation, corrosion and erosion. This technique is useful for ageing pipelines,
structures and pressure vessels (Ahmad, 2012).
4.5. Planned-Preventive Maintenance(PPM): It is a tradition maintenance strategy
which is also known as Time-based Maintenance (TBM). In this strategy failure
time/rate is estimated to determine the optimum maintenance interval. In PPM, it is
assumed that the failure rate is predictable and this assumption is based on the failure
rate trend of the equipment known as bath tub curve.
Figure 6: Bathtub curve. (Ahmed, 2012)
Age of the equipment or unit is estimated based on the failure time. Failure rate or trends
are divided into three sections: burn in, useful life and wear out. In burn in equipment
experiences decreasing trend in failure rate, useful life phase experience near constant
failure rate. In wear out phase, failure rate increases as shown in the above picture.
(Ahmad, 2012).
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Once the structure of the equipment is identified then suitable maintenance planning is
developed. Non-repairable items require replacement policy. This replacement policy is
age-related. Once the age of equipment is reached or first failure occurs, equipment is
replaced. After replacement equipment is consider as good as new (Ahmad, 2012).
For repairable items, repairing policy is used. In this policy, optimum interval is selected
for the maintenance or repairing of the equipment/machinery. In this strategy, the
interval for the maintenance is selected based on the failure time and likelihood. This
selection is based on the expected run time of the equipment machinery and its possible
failure time. Vendors or suppliers recommends the client this information to carry out
maintenance. (Ahmad, 2012).
Planned preventive maintenance is normally vendor or supplier specified. Interval
selection is usually based on the parameters like hours of operation/use. Repairing and
maintenance cost for the time-based maintenance is normally high due to overmaintenance. Sometime the parts and equipment is still can be used further but due to
schedule time and interval maintenance must be carried out and certain parts, although
usable but must be replaced as given by vendor. It has view advantages over CBM and
other maintenance strategies in a way that it does not require any formal condition
monitoring for defining the maintenance interval. In fact, PPM is planned according to
the vendor recommendations or legislation requirements. In PPM, the cost more evenly
distributed as the interval for maintenance are pre-defined and does not require any
analysis and does not require and further equipment or devices for supervision.
PPM, however, has great disadvantage of over maintenance that incurred due to already
planned intervals. With the ageing plant planned and schedule maintenance is more
often difficult to carryout due to cost implications. According to (Ahmad, 2012) 20% to
42% operational cost of the plant is related to the maintenance. Reliability is another
issue associated with PPM strategy as there is no condition monitoring and failure
likelihood prediction using analytical tools as in CBM and RCM.
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4.6. Importance of Maintenance Planning: In Oil & gas industry equipment and
installation undergo very harsh processes and conditions. In addition to it, many ageing
factors and erosion, corrosion and wear further deteriorate the condition of the
equipment. This sometime results in unpredicted failures of the plants and equipment
that causes huge financial losses, health and safety implications and catastrophic damage
to the environment. To address this issue, improvement in equipment reliability and
availability can be done using inspection and maintenance. Normally the cost associated
with inspection and maintenance is very high and is around 20 to 30 percent of the total
operating cost (Ratnayake, 2012).
A detailed analysis of aviation industry from 1959 to 1983 revealed that 12 percent of
the incident happened due lack of adequate inspection and maintenance. Similarly, in
20110, Deepwater horizon, drilling rig suffer major blowout in the Gulf of Mexico.
Later investigation revealed that this rig had not been sent to dry dock for shorerepairing for nine years. Due to this, blowout preventer certification could not be
renewed. These investigation shows the importance of the mandatory and cost-effective
inspection and maintenance of the equipment and installations in the plant (Ratnayake,
2012).
I&M management requires the understanding of ageing plant. It is not about how old
equipment is, in fact it is related to the condition of the plant and the factors that
influence it. Ageing is the process of continuous degradation which results from the time
and the usage of the equipment. Important thing is to understand and reveal the factors
and symptoms of ageing that can be detected through inspection. Once these factors are
determined, decision can be made on how to proceed with the maintenance plan to
increase availability (life extension) and reduce chances of unexpected failure
(Ratnayake, 2012).
Maintenance & some major accidents: Despite numerous efforts and technology
advancement to control and minimize the risks and major accidents, the number of
accidents in the past has shown that the control is not sufficient. Examples of such
accidents in the oil and gas and chemical industry includes, Bhopal Disaster, Phillips 66
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Disaster, Sodegaura Refinery Disaster, Flixborough Disaster and Texas City Refinery
Explosion (Okoh, 2013).
To control and minimize the risk, safety barriers are put in place but these barriers may
fail due to vulnerabilities or the deficiencies in maintenance or because of postponing the
maintenance. After each incident, lessons are learnt and efforts are made to control the
risk and avoid recurrence of the same incident with the same cause. However, major
accident rate has not shown positive trend, despite these efforts. In Norwegian oil and
gas industry the number of major hydrocarbons leaks has increased from 2008 to 2010.
Major accidents do not happen just because of one cause, but often it involves many
combined factors. Advance technology and innovation and complexity is a common
element of the oil and gas and chemical industry with high potential of major accident.
Due to this reason, many independent barriers are installed to control and mitigate
consequences of major hazards. In oil and gas industry these barriers are referred as
layers of protection and can be categorized as mechanical, physical and
electrical/electronics (Okoh, 2013).
The integrity of these barriers requires certain maintenance at specific intervals.
Maintenance is therefore, key aspect of preventing major accidents in oil and gas
industry. However, maintenance may result in negative effect on the integrity of the
system if it is performed in incorrect, delayed, insufficient or excessive. Maintenance
can also be initiating event of a major accident, for example, operating the equipment
wrongly. Maintenance also put people on the risk, therefore, it should be minimized as
much as possible. Many authors, like (Khan, 1999), (Kletz, 2001), (Lees 2005) and
(CSB 2007) have investigated the major accidents with the view of maintenance
involvement as one of the main reasons.
Some authors have explained the factors related to maintenance management and
involvement of maintenance in the major accidents in the oil and gas industry. Few of
the examples are poor communication between the maintenance staff and operators
(Sanders, 2005), lack of mandatory maintenance (Hale et al 1998), maintenance
management cyclee (Smith and Harris 1992) and maintainability (Hale et al 1998).
Few of the major accidents are explained in relation to the accident process and
maintenance management structure.
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Texas City Refinery Explosion (March 23, 2005): In Texas City Refinery on March
23, 3005, raffinate tower of the isomerization unit was overfilled. This led to overheating
of the raffinate tower and eventually all the pressure relief devices were open. This
resulted in eruption of hot flammable liquid from the blowdown stack which was not
equipped with flare stack. A huge fire and explosion occurred that killed 15 workers and
injuring several others (Okoh, 2013).
The factors related to maintenance that resulted in this disaster include (CSB, 2007)
failure to correctly calibrate level transmitter (maintenance fault), Sight glass was not
cleaned (no maintenance) and failure of high level alarm (no maintenance). This shows
the maintenance plan was not sufficient to deal with the critical equipment, business
targets and maintenance cost were not balanced and the mechanical integrity program
was ineffective. Below picture illustrates this explosion and the maintenance failure
(Okoh, 2013).
Figure 7: Maintenance-related accident scenario for the Texas City Refinery. (Okoh, 2013).
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Stockline Plastics Explosion (May 11, 2014): On May 11, 2014, in Stockline Plastics
industry, an ageing liquified petroleum gas (LPG), a pipe was buried underground
without any corrosion protection, leaked due to rapid corrosion and flammable gas
released which caught fire and explosion occurred. The whole building was razed to
ground, nine workers were killed and several got injured. One of the main maintenance
factor which contributed to this incident is failure to inspect and maintain the pipe of
LPG (OSHA, 2012). Other failure factors include, inadequate risk assessment of the
plant and very weak and ineffective procedures and standards of health and safety
(Okoh, 2013).
DSM Chemical Plant Explosion (April 1, 2013): In DSM Chemical plant on April 1,
2013, an explosion occurred, when maintenance crew tried to start the oven. Oven cover
at the top imploded and all the three workers standing on the top, fell into the oven and
died.
The main issue was the flammable gasses and other dangerous gasses from the plant.
These gasses caught up by a stray spark and huge explosion resulted. Normal procedure
for the restart requires filtering all the gasses and plant has to be shut down, which
requires a lot of time. To avoid this, delay a quick procedure was adopted without taking
appropriate measures. Maintenance factors that causes this accident are difficult
maintenance, flammable mixture development due to failure of testing and adopting new
quick procedure. Management failures include business goals and cost control on
maintenance. Poor safety culture and failure to develop the plan for the critical
maintenance (Okoh, 2013).
Sodegaura Refinery Disaster (October 16, 1992): In Sodegaura Refinery in Japan an
explosion occurred on October 16, 1992, which killed ten people injured seven. The lock
ring of the channel was broken, it was used to cover the heat exchanger cover. This
result in blowing-off the ring and other parts including the channel (Okoh, 2013).
In this incident, the major hazard was hydrogen which is highly flammable gas. The
main factors causing this incident include multiple ratcheting, which wore out the
diameter of the gasket which was used to keep the heat exchanger airtight, incorrect
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positioning of the of gasket which resulted in leakage of the hydrogen gas, insolation
removal which caused temperature variation and it introduced new hazard of thermal
deformation of the inner parts, internal flange set bolts were inadequately replaced,
causing their failure and putting more load on the channel cover. Management failure
include failure of the user and manufacturer on the information of the parts replacement,
poor safety management, inadequate maintenance planning and poor execution (Okoh,
2013).
The Phillips 66 Disaster (October 23, 1989): In polyethylene unit of Phillips 66 in
Pasadena USA, an explosion occurred, that killed 23 people and injured over 150. A
flammable chemical was released, which ignited later and lead to this incident. This
incident happened while a scheduled maintenance was carried out on a reactor to clear
the settling legs. The chemical was released due to wrong maintenance. The major
maintenance factors that caused this incident are, failure to include double isolation
using flange or other means in the maintenance procedure, the only isolation valve was
kept open and connected to the wrong air supply hose. Management failure include
failure to comply with industry isolation procedure, inadequate permit to work system,
failure of company’s own maintenance procedures and standards. It was also observed
that the maintenance planning and execution was wrong and inadequate to handle the
emergency (Okoh, 2013).
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4.7. Challenges in Maintenance for an oil and gas production facility: Many
of the oil and gas production facilities have exceeded their design life. Static equipment
like storage tanks, valves, pipelines, separators and vessels undergo degradation due to
ageing, corrosion and erosion. Operators and plant management usually have database
containing historical data of corrosion, erosion and wear. This data with expert
knowledge is used to identify the critical equipment of the system to develop
maintenance plan for the plant. However, development of the inspection and
maintenance plan is very challenging due to uncertainties because of human
involvement and difficult decision making. Due to this reason, ineffective inspection and
maintenance strategy could lead to escalated degradation that could cause catastrophic
failure. In ageing facility where the design life has passed and the production is
decreasing rapidly, it is very difficult to maintain the performance and reliability of the
plant while reducing the cost. Here are some of the challenges related to the ageing oil
and gas production facility (Ratnayake, 2012).
• The time for the preventive maintenance is very limited due to tight schedule of
production and limited budged. Therefore, it is not possible to carry out all the
maintenance in the given time.
• There are normally high number of parts of static equipment on the field that have
not been inspected since the date of their installation.
• Many times, the wall thickness data is not reliable due to the poor interpretation
of the NDT data.
• Personal and individuals involve in inspection and maintenance planning
frequently changes jobs, this ends up in new people taking the jobs of inspection
and planning. This makes problems severe because of the ineffective knowledge
transfer and experience.
• Quality and effectiveness of the inspection and maintenance planning of newly
recruited employee is considerably lower than the experience employee.
• The decision and views of the inexperienced persons in performing inspection is
also seemed to be narrow. This is because of lack of the information and overview
of the equipment problem and inclination to depend on the given current
information.
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• Time availability and state of mind of the person performing inspection and
maintenance planning equally effects the procedure. Knowledge and judgement of
the condition and deterioration is depended on the person performing this task
which could be limited in stress condition.
• Wastage of resources is frequent when the planned maintenance of some of the
equipment is not carried out during the shutdown maintenance.
In addition to these above challenges there are certain other issue related to the ageing
factor of the plant which are given below (Ratnayake, 2012).
• There is a need of establishing a system and procedure to collect the data and
information related to ageing of the plant and critical equipment. Most of the
time there is no sufficient data available for the equipment age and deterioration.
• Developing a model and predicting the useful life of the equipment is another
challenging task. Skills and expertise of the individual is the main factor that
upon which the reliability of the model depends.
• Old and new equipment compatibility is a challenging task. With ageing
equipment and addition of new technology is difficult to manage.
• Investigation of the factors that causes ageing and searching for appropriate
measures required to mitigate the effects of ageing.
• Review and investigation of the existing maintenance strategy for the ageing oil
and gas plant and analyzing its effectiveness in relation to the ageing plant
(Ratnayake, 2012).
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4.8. Maintenance Performance Measurement and Indicators: Maintenance
performance measurement is very important to justify the cost and resources used for the
preventive maintenance program. This can be done by implementing a performance
measurement system. The quantitative criteria for the maintenance measurement
includes downtime, accidents, injuries, output, short and long stops, risks and costs.
Qualitatively it includes, employee satisfaction, working environment, humidity and
noise. Measurement is very important because it gives the data to be compared and on
the basis or results suitable corrective/preventive action can be taken (Parida, 2007).
Decision making in maintenance involved various tier in the organization structure. At
the strategic level, it is decided that weather the maintenance program should be
centralized or decentralized, policy for in-house maintenance or it should be outsourced.
At the plant level, decision is taken about the budget, machinery, skill, experience,
inventories and time-based maintenance or any other advanced maintenance strategy.
Maintenance performance indicators MPIs are very important as they are related to
wastes, expenditures and downtime. MPIs give an analysis of the enhancement of quality,
productivity, utilization, safety and health. Therefore, they are used to compare set
parameters to give management deep insight on the cost, benefit and risk reduction
(Parida, 2007).
Maintenance performance indicators are used to measure the impact on the process
performance. MPIs can be used for many purposes, for example, financial reports, health
and safety assessment, environment monitoring, system performance as well as for many
other applications.
PIs can be differentiated into two types, leading indicators and
lagging indicators. A leading indicator gives early warning and is performance driven.
For example, downtime and number of stops gives indication of the less availability of
the plant and equipment. This in-turn gives indication of the less plant utilization.
Therefore, leading indicator is performance driver and it compares the status of the
equipment/plant performance with the reference point. From maintenance point of view,
condition monitoring indicator, for example, noise, vibration, temperature, contamination
in oil can be performance indicator. These indicators help to assess the condition of the
equipment and can be used an early warning. Therefore, these indicators are typically
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Dissertation Project
used for the effectiveness of the maintenance. Lagging indicators on the other hand, are
the outcome measures that are normally used to analyze the deviation once the
maintenance activity is completed. Expense of the maintenance and the time gap between
the breakdown are the typical examples of the lagging indicators. These lagging
indicators are effective in measuring the current performance status and the need for
further actions, for example equipment parts replacement, to meet planned target. These
are helpful in further decision for the replacement of the parts or future maintenance
based on the previous history and status (Parida, 2007).
Maintenance cost per equipment/part or the total return on the capital are the typical
paradigm of the lagging indicators. Both leading and lagging indicators are used together
to control and monitor the effectiveness the maintenance strategy. These indicators need
to be in line with the applied maintenance strategy. Lagging indicators without leading
indicators cannot help how the outcomes should be materialized (Parida, 2007).
Maintenance performance indicators (MPIs) are categorized into seven types based on
the requirements and internal organization capability and capacity and the different
strategy. Here are some of the key MPIs including both leading and lagging; (Parida,
2007).
Equipment related indicators:
•
Availability: It is the percentage of time of the equipment/machinery available
for the intended purpose. This can be calculated by taking the ratio of mean time
to failure to the total time.
•
Performance rate: this rate gives the indication of the production speed.
Maintenance activity affects the performance rate and is used for calculation
•
Number of small and big stoppages: this is used to count the number of
stoppages either big or small. These can be calculated in terms of time (hours).
•
Downtime for small and big stoppages: This gives the indication of the
availability and is calculated in terms of time (hours).
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Maintenance Task Related Indicators:
•
Quality for maintenance task: This MPI indicates the efficiency of the
maintenance task performed. This depends on the certain factors, for example,
time taken for the maintenance to meet operational requirements. Quality of the
maintenance is the conformance with the process. Maintenance can be a minimal
or major overhaul. The quality of the plant or equipment maintenance depend on
the type of parts being used like, used parts, genuine or clone. Maintenance
operator skill and expertise are the other factors that influence the quality of the
maintenance.
•
Change over time: It indicates the time required for change-over. It is calculated
in hours.
•
Planned Maintenance Task (preventive maintenance): Planned maintenance
task are calculated in terms of number planned maintenance or the
cost/expenditure required for carryout preventive/scheduled maintenance.
•
Unplanned Maintenance Tasks (corrective maintenance): This indicates the
number of unplanned maintenance tasks performed or the costs/expense incurred
on these tasks.
•
Response time for maintenance: This indicates the time taken in hours for the
maintenance activity.
Cost-Related Indicators
•
Maintenance cost/unit: It is the common indicator of the performance
measurement and it distributes the total maintenance cost by the volume of
production.
•
Return on Maintenance Investment: This indicator is used to compare the
return gained because of high maintenance cost against the past record/target.
This performance indicator is a bit complex to calculate but accurate analysis
exactly pinpoints the shortcomings in planned maintenance strategy.
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Learning & growth
•
Number of new Ideas generated: For continuous improvement of the
organization, it is essential to measure the knowledge. Number of new ideas
produced can be served as the way of innovation and development. This PI is very
essential for the management.
•
Skill & Competency development/training: Training and competency
development is very important for the company growth and this indicator gives
insight to the management of its employees’ strengths and weaknesses. Number
of trainings given, amount spent on trainings, number of employees
educated/trained are all good indicators of the human development. These
indicators are subjective and are a good measure of the competency and skill
development.
Health, Safety, Security & Environment (HSSE): Indicators of HSSE include
accidents, incidents, injuries, security breaches, near misses and environmental issues.
Accidents and incidents results in injuries that causes man hours to loss. Criteria for these
kinds of incidents could be the cost incurred and time loss. Some of the performance
indicators related to HSSE are as follows:
•
Number of accidents/incidents: This indicates the safety factors needed and
provided by the injuries, losses, accidents and fatalities. This is a very critical PI
for the management to decide on further measures requirements.
•
Number of legal cases: Number of legal cases is another important PI which
clearly gives insight about the safety factors in an organization structure.
•
Number of compensation cases/amount of compensation paid: This indicator
shows the negligence from the client/company that lead to the incident and
eventually company had to pay compensation.
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5. Comparison of maintenance strategies using PESTEL:
In above
section, a detail description and overview of four major maintenance strategies is given. In
this section, the data will be analyzed based on various factors to come up with the best
maintenance strategy for the onshore oil and gas production facility. Since due to strengths
and weaknesses of each strategy it is not compulsory that one maintenance strategy itself is
enough to fulfill the requirement on an ageing oil and gas production facility.
Many techniques and tools are used to analyze the effectiveness of maintenance strategies
with respect to their use in oil and gas industry. Here we are using PESTEL (Political,
Economic, Social, Technological, Environment and Legal) technique for the analysis of the
each of the maintenance strategy. In addition to the PESTEL factors, few more factors will
be incorporated for analysis. These factors are, risk reduction, safety culture,
5.1. PESTEL Technique: It is a simple technique to be used to analyze the macroexternal factors that affect the organization. The PESTEL framework consist of political,
economic, social, technological, environmental and legal factors. PESTEL framework uses
macro-indicators for analysis to give big picture to the strategists for decision making. This
gives deep insight to take advantage from the opportunities and reduce the risk factors faced
by the organization (Issa, 2010).
Political: Political factor is directly related to the government laws and regulations that an
organization is compelled to adhere with. From this perspective organization is bound to
implement the laws of the country in which it is operating. Since maintenance strategies are
directly related to the reliability and risk of the organization, different countries have different
set of laws and regulations for the maintenance of the high-risk industries that include oil and
gas industries (Issa, 2010).
Economic: Economic factors are related to the cost and the amount of financial benefit an
organization can gain. While adopting any maintenance strategy there are certain financial
implications on the company. Experts analyze the total cost incurred on the specific
maintenance strategy and the cost it saves in comparison to the other related maintenance
strategies (Issa, 2010).
Social: Social factor is the changes to the organization by adopting certain strategy. Social
aspects include, customer awareness, public attitude and individual response to the strategy
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Dissertation Project
adopted. It is the moral duty of the organization to adhere to the set of ethics and be aware of
the critical information of the strategy and its implications (Issa, 2010).
Technological: Technological aspects include the advancement in the technology and the
compatibility of the maintenance strategies with them. And how certain techniques have
additive advantage over other in that aspect (Issa, 2010).
Environmental: With growing concern over environment globally, it has gain equally high
importance in the industries specially in oil and gas industry. In the past, certain incident has
shown that if sufficient measures are not taken big disaster can occur which could have
catastrophic environmental implications. This factor holds equally high importance in
evaluating the maintenance strategy with respect to its effectiveness (Issa, 2010).
Legal: for each industry, there are legal implications for its operations and maintenance.
These days goal setting legislation practices are common worldwide to cope up with risk
arising and taking advantage of the technological advancements (Issa, 2010). Before adoption
to any maintenance strategy it is legal responsibility of the company to show that the adoption
of this strategy is certainly helpful and robust enough to minimize the risk to the ALARP
region.
Risk reduction & Availability of the plant/machinery: In addition to the factors mentioned in
PESTEL framework, I also included two other factors for the analysis of the preventive
maintenance strategies that are “risk reduction & availability of the equipment/machinery”.
Preventive maintenance strategies that are described in earlier section have direct relation to the
risk reduction to the plant, people environment and reputation of the company. In onshore oil
and gas production facility the biggest hazard is the crude oil and gas release. With the aging
production plant, the chances of these releases can become bigger as the wear and tear of the
plant is high. Maintenance of these plants highly critical with respect to the risk reduction and
smooth operation of the plant.
Availability at the same time is very important in oil and gas organization. Maintenance
strategies equally influence the availability of the plant/machinery at the same time. Since in
ageing oil and gas production facility usually with the depleting oil and gas reservoir, availability
for continuous and maximum production is very important. Therefore, maintenance strategies
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Dissertation Project
hold huge importance in keeping the plant running and reducing or eliminating the breakdowns
due to faults and malfunction in the equipment/machinery.
5.2. RBM Strategy analysis using PESTEL framework: Risk based maintenance
strategy which is now very common in many highly hazardous industries will be analyzed
using PESTEL technique. How this technique influences the macro-environment level in
onshore oil and gas production facility.
Each PESTEL factors will be analyzed with respect to RBM.
PESTAL Factors
Description and example in relation to the RBM
strategy
• Political stability and likely changes: RBM strategy does
not directly deals with this element of the political factor.
However, during risk calculation which is the main aspect of
the RBM strategy these factors are analyzed in highly
Political
volatile political environment.
• Environment Law: RBM strategy thoroughly addresses
environmental issues related to the maintenance of the oil
and gas production facility
• Health and Safety Law: During risk calculation and
estimation legal requirements are addressed.
• Significant cost reduction: RBM strategy often results in
significant cost reduction. RBM prioritize the maintenance of
item that require frequent maintenance and reduces the
frequency of low risk items.
Economic
• Life extension of the plant: RBM strategy by rigorous
maintenance planning and risk assessment aids to increase
the design life of the plant and expensive equipment hence
saving a lot of money.
• Cost cutting of unnecessary maintenance: RBM strategy
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another monetary benefit is the removal of all unnecessary
periodic maintenance. Maintenance of low risks are reduced
and minimized.
• Emphasis on Safety: RBM strategy itself is based on safety
aspects of the plant and maintenance. RBM stresses on
safety more than all other maintenance strategy.
• Lifestyle & work attitude: workers lifestyle and working
attitude is greatly influenced by RBM strategy. Risk-based
Social
maintenance strategy gives awareness to the workers of the
potential hazards and catastrophic consequence. This
consciousness changes their lifestyle and work attitude more
positive, safe and responsible.
• Impact on public: Adjacent community and public gets
more satisfied with the management of the production
facility once they know how much plant management is
working on risk reduction and reducing chances of high
consequence events.
• Basic
infrastructure
level:
RBM
is
relative
new
maintenance strategy. It requires skilled engineers and staff
to
carryout
quantitative risk assessment. With new
technology and software, it has become easier to perform
quantified risk assessment.
• Technology changes & Compatibility. Technological
changes in oil and gas industries are very rapid over the past
Technological factors
few decades. RBM strategy in this regard is quite flexible,
for example, the development of new software for quantified
risk assessment and frequency calculation software and
models could generate near real events and these
developments assist the RBM in its effectiveness.
• Access to new Technology: RBM strategy encourages
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Dissertation Project
adoption of new technology when comes to development and
planning for the maintenance plan using RBM technique. For
example, Fault tree analysis and consequence modeling
software have made it easy for the engineers to carryout
quantified risk assessment for criticality analysis of the
process or equipment.
• Laws regulating environment pollution: With the growing
concern over global warming, countries have made their laws
strict for oil and gas companies regarding environmental
pollution. Since RBM strategy is based on risk estimation
before for maintenance planning, therefore, this strategy
Environmental factors
considers all kind of risks including environmental pollution
and damage while estimating risk.
• Air & water pollution: this factor is related to the legal
requirements. These factors are considered during the
development of the maintenance interval t
• Health & safety Law: When it comes to maintenance of the
Legal
ageing oil and gas facility, operators and clients must satisfy
the government bodies about the risk arising from ageing
facility. This require aggressive risk assessment and
maintenance strategy that could show that the current risk is
within the ALARP (as low as reasonably practicable) region.
• Ageing oil and gas production facility poses big risk to the
environment, people, asset and reputation of the company. In
section 2 and 3, it is explained thoroughly how ageing plant
poses threat. To overcome these risks and to extend the life
of an oil and gas production facility RBM is a very useful
Risk reduction
strategy. In section 4.2 it is comprehensively explained that
adoption of RBM strategy purely works on the risk
estimation through probability/frequency calculation and
consequence estimation.
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• At the same time, any misleading result or calculation could
lead to non-essential maintenance. This could also lead to no
decrease in the risk, if the results are not properly calculated
or based on incorrect data, as explained in the section 4.2.
• Maximum availability of the plant and equipment is the
major reason for any maintenance. In RBM frequency
estimation of the equipment plant failure is carried out to get
Availability
an idea of the expected equipment failure or malfunction.
Different techniques are used for the failure frequency
estimation as discussed in section 4.2. this gives the
management an idea to decide on the interval frequency to
avoid sudden break downs and increase the availability of the
plant.
5.3. Reliability centered maintenance RCM analysis using PESTEL
framework: In section 4.3 RCM strategy has been explained thoroughly. Now in this
section an analysis will be carried out to assist in judgement for the adoption, feasibility of the
RCM maintenance technique for the ageing oil and gas production facility, based on the
PESTEL factors.
PESTAL Factors
Description and example in relation to the RCM
strategy
• Political stability and likely changes: RCM strategy is
purely based on technical aspects of the maintenance and
does not deals with the political stability of the region.
• Health and Safety Law: Government bodies restrict the oil
Political
and gas production facilities using HSE laws and set legal
boundaries for them for health and safety of the employees
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and the other stack holders.
• Significant cost reduction: RCM aims at cost reduction in
addition to the maintenance of the plant and equipment. This
strategy focuses on the selection of critical equipment for
maintenance and avoiding unnecessary maintenance of noncritical equipment by reducing the frequency of the
planned/schedule maintenance. This way a lot cost could be
saved. Section 4.3 explained this in detail.
• Life extension of the plant: Another important benefit of
the RCM strategy is the life extension of the plant. FFA &
FMECA, the two-important elements of this strategy,
explained in section 4.3, focus on the possible failure modes
Economic
and their analysis. This analysis is directly related to the
ageing of the plant. Prevention of the failures in the
equipment
and
timely
decision
for
the
preventive
maintenance could eventually reduce the wear and tear in the
plant and in-turn increase the expected life of the
equipment/plant.
• Cost cutting of unnecessary maintenance:
One of the
main point in RCM strategy is the selection of critical
equipment for the maintenance and reducing scheduled
maintenance for non-critical equipment has direct impact in
reducing maintenance cost. This element has already been
explained above
• Emphasis on Safety: FFA & FMECA analyze the failure
modes and their impact. These two elements are focused on
the availability of the equipment (section 4.3) but in these
analysis safety features are also studied, for example the
failure analysis of any safety critical equipment.
Social
• Lifestyle & work attitude: RCM strategy gives insight to
the maintenance personnel about the possible failure modes
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and their impact on the plant/equipment. It brings about the
positive change in the workers attitude toward the criticality
of the equipment. Those involved directly in maintenance
could also be the source of bringing awareness to the other
employees on the reliability and safety of the equipment.
• Impact on public: Since RCM is reliability focused
maintenance strategy, it has direct impact on the public
where the onshore ageing production facilities are built close
the public. This is because RCM can greatly influence in
reduction of the predicted failures which could cause
catastrophic incident like fire and explosion by carrying out
timely and accurate maintenance. In that way, it could
develop a sense of safety in the public about their safety.
• Basic infrastructure level: RCM strategy as discussed in
section 4.3 require reliable monitoring data of the
equipment/machinery for the FFA and FMECA, therefore, it
require basic monitoring equipment like sensors for
temperature, pressure flow, vibration and so on for the
analysis and prediction of the failure mode and likelihood.
• Technology
Technological factors
changes
&
Compatibility.
With
the
advancement in technology, RCM is compatible with these
development as new digital data storage devices and
monitoring equipment could make the equipment history
data more reliable. This could help in development of more
effective and reliable maintenance planning.
• Access to new Technology: RCM strategy could be
benefitted from the new advanced monitoring equipment and
software.
• Laws regulating environment pollution: RCM does not
directly relate to the laws and legal obligations related to the
environment. However, during the failure mode analysis for
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the different equipment, it indirectly ensures that preventive
Environmental factors
maintenance would take place and any potential failure could
be avoided which could result any catastrophic release of the
chemicals which damage environment.
• Air & water pollution: one of the drawback of RCM is that
it completely focuses on the function of the critical
equipment and their continuous safe performance and does
not account for the air or water pollution factors.
• Health & safety Law: Government and legal bodies
governing the operation of onshore oil and gas production
facilities, has made certain laws regarding the maintenance of
Legal
the running and static equipment. RCM strategy conforms to
the requirement in a way that its focus is equally on the safe
plant operation and avoidance of any potential breakdown
that could cause catastrophic failure (section 4.3)
• RCM is an advanced maintenance strategy and its key
objective is the increase functional reliability of the
equipment/machinery. It plays important role in decreasing
the risk arising from the ageing of the plant. This is because
Risk reduction
with the ageing the risk increases as described in the bathtub
curve in section 4.5. Therefore, at this stage planned
preventive maintenance is not sufficient to avoid increased
frequency of equipment function failure that result in
catastrophic failure. But as explained in section 4.3, RCM
predicts equipment functional failure to decide the optimum
maintenance interval, therefore, RCM is effective in reducing
the risk arising from the ageing of the onshore oil and gas
production facilities.
• However, one of the drawback of this strategy is, it does not
require any formal risk assessment which is key part of the
RBM strategy.
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• Risk reduction in RCM is dependent on the accurate
maintenance. And this rely on the reliable data analysis and
accurate use of FMECA for prediction of the likelihood of
the failure rate of equipment/machinery.
• RCM is the best strategy in assuring availability of the plant.
As described in section 4.3, the objective of this strategy is
Availability
functional reliability of the plant/equipment. Due to this
factor, it can be fairly argued that RCM is most effective in
assuring smooth running and functionality of the plant’s key
equipment and machinery
5.4. Condition-Based Maintenance analysis using PESTEL framework: CBM
is one of the advance maintenance strategy, as explained in section 4.4. The key focus of this
strategy is on the condition monitoring of the equipment that is continuously deteriorating
with the time. This analysis helps management to analyze it and decide on the maintenance
interval for equipment machinery (section 4.4). Here in this section, analysis of CBM will be
performed using PESTEL factors to evaluate its effectiveness in an ageing oil and gas
production facility.
PESTAL Factors
Description and example in relation to the CBM
strategy
• Political stability and likely changes: Like RCM, CBM is
purely a technical element of the organization and does not
have any direct relation with the political situation of the
organization/company following this strategy
Political
• Health and Safety Law: CBM is not mandatory technique
in any legislation that govern the operations of the oil and gas
industry. However, this strategy could be said as a factor in
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risk reduction, since in an ageing oil and gas production
facility, condition monitoring of the plant equipment is very
important to avoid any hazardous incident caused by failures
in equipment/machinery.
• Significant cost reduction: CBM is another very effective
technique in cost reduction in a way that it predicts the
likelihood of failure of any equipment machinery before it
fails. In that way that failure could be avoided before it
happens by replacing the damage or worn out part (Ellis,
Byron, 2008).
• Life extension of the plant: With that strategy of continuous
monitoring management can focus on the just in time (JIT)
replacement. Just in time replacement can maximize the life
Economic
of plant (Ellis, Byron, 2008).
• Cost cutting of unnecessary maintenance: Like RBM and
RCM, CBM is also focused on avoiding unnecessary planned
schedule maintenance. It monitors the condition using
sensors
and
when
alarms
give
a
signal
for
the
maintenance/repairing, maintenance is performed (Ellis,
Byron, 2008).
• False alarms needed to be avoided or detected for the
successful implementation of the CBM strategy (Ellis, Byron,
2008).
• Emphasis on Safety: CBM strategy uses certain analytical
tools for the prediction and analysis of the failure modes.
This include FMEA and FMECA, to know the likelihood of
failure and how it would occur (Ellis, Byron, 2008).
This information is quite useful in early detection of the fault
Social
that could eventually result in the catastrophic disaster.
• Lifestyle & work attitude: CBM strategy is based on the
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condition
monitoring
through
sensor
for
vibration,
temperature, lubricating oil and similar other factors. This in
a way gives early warning for the certain failures in the
equipment and makes the maintenance vigilant of the
potential failure (Tsang 1995).
This influence workers perception and understanding of the
potential failures and increases their understanding in
understanding the change in these monitoring tools.
• Impact on public: As explained above, CBM strategy relies
on monitoring of certain factors before giving signal for the
maintenance or replacement of any damaged part. Therefore,
it is quite useful in avoiding catastrophic failures due
machinery/equipment sudden failure.
Often bigger fire and explosion effects the public living in
the proximity of the oil and gas production facility. But using
CBM many potential disasters could be avoided by timely
maintenance and replacement of the parts and public can be
saved from these risks.
• Basic infrastructure level: CBM is one of the advanced
maintenance strategy and it require digital sensor for
monitoring accurate changes in temperature, flow, pressure,
Technological factors
vibration and current changes to decide on the maintenance
requirement.
• Technology changes & Compatibility. Technological
changes and advancement has greatly influenced this
technique. Since with more precise and accurate condition
monitoring sensor, CBM can be more reliable and save
strategy for the ageing oil and gas production facilities.
• Access to new Technology: CBM strategy could be
benefitted from the new advanced monitoring equipment and
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software.
• Laws regulating environment pollution: CBM is not
directly related to the legislation.
Environmental factors
• Air & water pollution: CBM equipment monitoring and
timely part replacement strategy could be effective in
reducing the air pollution in case of pumps and generators
used in oil and gas production facility, where wear and tear
can increase the emissions if not maintained timely.
• Health & safety Law: CBM is not directly related to the
health and safety law. Government bodies governing the oil
Legal
and gas production facilities lay down certain maintenance
requirement for the owners and operators of the production
facilities.
• In ageing oil and gas facility, the corrosion and wear and tear
effects are more prominent than the new facility. And the risk
of failure of equipment like production pipelines, storage
tanks and pressure vessel is high as explained in the bathtub
curve in section 4.5. CBM as explained in section 4.4 is
totally depended on the accurate condition monitoring of the
Risk reduction
equipment/machinery, therefore, it is very effective in
reducing the risk of loss of containment due to corrosion and
wear and tear due to other factors like, temperature, pressure
and flow rate.
• In addition to it, in rotating equipment like compressor and
pumps and generator, factors like monitoring and analysis of
vibration, temperature, noise, and change in resistance, gives
early warning of the equipment failure and management can
take prompt action to avoid any catastrophic failure due to
these failures in the rotating equipment (Tsang 1995).
• However, the use of CBM is not effective in standby units
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and protective devices like ESD valves because there are
hidden faults in this equipment and which only come to
know when there is a demand (Tsang 1995).
• CBM is effective in assuring maximum availability of the
rotating equipment in a way that it could avoid potential
Availability
failure of the equipment due to monitoring sensors installed
on them, which give early warning and just in time
replacement/repairing
of
equipment
avoids
sudden
breakdown (Ellis, Byron, 2008).
5.5. Planned-Preventive Maintenance Strategy (PPM) analysis using
PESTEL framework: Time based maintenance is a conventional maintenance technique. In this
section, PPM will be analyzed using PESTEL factors to measure its effectiveness for the ageing oil
and gas production facility.
PESTAL Factors
Description and example in relation to the PPM
strategy
• Political stability and likely changes: PPM is purely related
to the maintenance of the plant/equipment and has no direct
relation to the political stability and changes in political
environment.
Political
• Health
and
Safety
Law:
Maintenance
of
the
plant/equipment is a key part of the operations of an oil and
gas industry. Government bodies lay down laws related to
health and safety of the employees. These laws restrict oil
and gas companies to ensure proper maintenance to reduce
the risk and safety of employees, and environment. Accurate
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PPM strategy could help preventing incident related plant.
• Significant cost reduction: Planned-preventive maintenance
as described in section 4.5 is based on the pre-defined
maintenance interval recommended by supplier or vendor.
The cost associated with this strategy is evenly distributed as
all the repairing and replacement items are already know.
However, the cost associated with PPM strategy is high due
to over maintenance. Maintenance interval decisions and
likelihood prediction analysis are not carried out to reduce
maintenance requirement and to predict the failure rate.
Economic
• Life extension of the plant: life extension of the ageing oil
and gas production facility is difficult with PPM strategy.
Since
PPM
is
totally
dependent
on
the
vendor
recommendation and with ageing facility and increased wear
and tear failure rate increases and these could result in further
deterioration of the plant. Likelihood of failure and failure
mode analysis are not carried out in PPM; therefore, this
strategy does not predict the sudden failures and brings no
help in increasing the design life of the plant.
• Cost cutting of unnecessary maintenance: One of the
major drawback of this strategy is the cost implications. PPM
does not offer any assistance in reducing the unnecessary
costs associated with the ageing plant and it completely relies
on the vendor/supplier recommendations as explained in
section 4.5.
•
• Emphasis on Safety: PPM does not require any analysis to
be performed for the failure rate and mode prediction as
required in other maintenance strategies described above. In
ageing plant, these analyses are mandatory to be performed
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Social
Dissertation Project
to predict the failure rates and modes because of increase rate
of failures due to ageing. Therefore, this strategy does not
have very great emphasis on the safety as have other
strategies.
• Lifestyle & work attitude: In PPM, maintenance team and
workers are stick to the vendor/supplier recommendations
and do not perform any failure analysis themselves to know
the failure trends. Therefore, PPM strategy does not
influence the lifestyle and working attitude of the
maintenance team and workers and does not bring awareness
to the team of the sudden failures and ageing plant risks.
• Impact on public: Public is concerned with the safety of
environment and safety of resident in proximity of an oil and
gas production facility. Since PPM does not reduces the risks
associated with the ageing plant, like increased failure rates,
therefore, to continue with this strategy could be a concern
for the public safety and possible environment disasters due
to loss of containment.
• Basic infrastructure level: PPM is a simple strategy and it
does not require any condition monitoring devices or any
other failure analysis. It is the simplest of all the preventive
Technological factors
maintenance strategies, in terms of the requirement and
technical resources needed for it.
• Technology changes & Compatibility. Since with the
changing and development in technology PPM is rarely
relied and most often RCM, CBM and RBM are used due to
the cost implications and increased risk associated with the
ageing oil and gas production facility.
• Access to new Technology: PPM cannot be benefitted from
the new technology as it is strictly based on the pre-defined
intervals.
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• Laws regulating environment pollution: PPM has no direct
relation with the environment regulations.
Environmental factors
• Air & water pollution: PPM could be helpful in controlling
the emissions and effluents. Vendor/suppliers normally
define
optimum
interval
for
the
replacement
and
maintenance, therefore, for the rotatory equipment when the
emissions and effluent start to increase due to wear and tear,
maintenance is normally performed according to the predefined interval and hence air and water pollution can be
controlled.
• Health & safety Law: PPM has no direct relation to the
Legal
legislation but sometimes it is often stated in the legislation
to carry out the maintenance of the equipment as desired by
vendor/supplier.
• In an ageing oil and gas production facility, risk due to
sudden failure and loss of containment is high. PPM as
explained in section 4.5 is only based on the maintenance
interval recommended by the supplier or vendor and it does
not account for the risks arising from the ageing of plant and
increased wear and tear. Therefore, this strategy is least
Risk reduction
effective in controlling risk arising from the ageing of the
plant.
• In addition to it, condition monitoring and risk assessment
are very important in ageing oil and gas production facility as
explained in section 4.3 and 4.4. But this strategy does not
have any requirement for the risk assessment or condition
monitoring of the ageing plant.
• PPM strategy is not very effective in maintaining or assuring
Availability
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facility. This is because there is no failure prediction analysis
is carried out in this strategy and maintenance interval
selection
is
based
on
recommendations
of
the
supplier/vendor. Factors like equipment deterioration and
wear tear due ageing are not accounted for in this strategy
and due to this sudden failure keep on happening that reduces
the availability of plant/equipment as explained in section
4.5.
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6. Conclusion & Future Work
6.1. Conclusion
In this section, a conclusion will be drawn through the analysis performed in section 5.
All the four major maintenance strategies, that are RBM, RCM, CBM and PPM that are
now being used in oil and gas industry and other high-risk industries like, aviation,
nuclear, transmission lines and marine are analyzed using PESTEL factors and two other
factors including risk reduction and availability in previous section.
•
RBM provides a new approach in asset integrity management. It not only considers the
reliability of the system while deciding the time interval of the maintenance but also
analyzes the consequences of the risks that arises due to failure. Since in ageing oil and
gas production facility the biggest issue is the potential release of the hazardous
flammable chemical, therefore, it is more important to carefully examine and carryout
risk assessment and make it a part of the maintenance strategy of the plant. RBM is the
maintenance strategy as explained in earlier section which is primarily focusing on the
risks and consequence of failure. Different installation on the plant like separator, oil and
gas pipelines, storage tanks and compressors pose a high risk if loss of containment
incident happens. Therefore, loss of containment is nearly unacceptable from such
equipment and installation in the oil and gas production facility. Since with the ageing as
explained in bath tub curve (section 4.5), failure rate increase in the in these critical
equipment and installation, therefore, in addition to the normal failure analysis like
Failure mode effect analysis (FMEA) which is a common method for RCM and CBM
strategy, quantitative risk assessment is mandatory for the ageing plant. And this is the
biggest advantage of the RBM strategy. In literature review section, certain past accidents
are briefly explained that they are happened either due to lack of maintenance or poor
maintenance strategy/technique. RBM not only analyzes the risk posed by
equipment/machinery ageing but also analyzes the risk while carrying out maintenance.
Author considers the ageing itself the biggest risk and all the other three maintenance
strategy, although focus on the function, availability and possible failure and its
likelihood, but they don’t analyze the physical risk like fire, explosion and possible
escalation, which is a key part of RBM. Due to these factors RBM could be said to be
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best suited for the many static and rotatory equipment maintenance and for the protective
devices and redundant equipment.
However, there are certain limitations of RBM strategy. Quantitative risk assessment is a
specialized job and need careful analysis to analyze the possible failures that could lead
to the catastrophic incident in the oil and gas industry. This require expertise and
accurate risk assessment to decide on the optimum interval. Therefore, this strategy
completely relies on the quantitative risk analysis and if the information is not sufficient
or if the engineer judgement is wrong or lack adequate expertise, could give rise to
wrong maintenance planning and the sole purpose of risk reduction fails. At the same
time, this require enough time and resources to carryout quantified risk assessment,
which in case of ageing plant are very small. Cost to benefit analysis is required for the
selection of this strategy.
•
RCM is more focused on the continuous functions of the critical equipment and reduction
of the unnecessary planned maintenance. This strategy has great relative advantage of the
cost reduction as it selects the key component failure analysis. With the ageing oil and
gas production, functions of the redundant equipment and protective devices become very
important as the need of these installation is expected to increase. Other maintenance
strategies do not particularly focus on these elements of the plant. However, RCM in that
way provides a better edge and could be more useful. Apart from that other rotatory
equipment installed on the plant including compressors, generators, and pumps smooth
running is equally important to reduce the downtime and increase productivity in ageing
plant to maximize the production. Therefore, RCM provides relative better advantage as
explained in section 5.3 of the PESTEL analysis.
RCM on the other hand is not adequate for the static equipment like pipelines, pressure
vessels and storage tanks installed in oil and gas industry. The continuous degradation in
these installations may require other monitoring technique to identify their failures like
in CBM (section 4.4 and 5.4) where sensors and condition monitoring devices are
installed to monitor the condition of the equipment. At the same time, no formal risk
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assessment is carried out in this strategy to evaluate the risk arising due to ageing of the
plant. Which author believes, is mandatory to enlighten top management about the
potential catastrophic incident scale and their scale.
•
CBM strategy has distinct advantage with respect to an ageing oil and gas facility as far
as ageing is concerned. It has prominent features like continuous monitoring of the
condition of static as well as rotatory equipment installed in the oil and gas facility.
Through this feature as explained in section 4.4 & 5.4, it gives early warning to the
maintenance team of any potential failure and breakdown. Maintenance team and
department can take prompt action based on the alarm and signal of the monitoring
devices and can swiftly replace/maintain defective part and ensure smooth operation with
minimum downtime. This strategy like RCM has great economic advantage in terms of
availability and maximum production. Just in time replacement of the parts helps
increased design life of the plant and reduced further deterioration of the
equipment/machinery as explained in section 5.4. Although it does not require any formal
risk assessment but due to continuous condition monitoring of the plant equipment it has
additive advantage in foreseeing the hazard due to failure. This indirectly reduces the
chances of catastrophic disaster due to the sudden failures and greatly effective in
reducing risk arising from the ageing of the plant. At the same time CBM like RCM has
advantage in cost cutting and avoiding any unnecessary planned maintenance. This is
because maintenance intervals are based on the condition monitoring devices signals and
interpretation. When any variation in the temperature, pressure, flow rate or changes in
lubricating oils occur, it gives signal to the maintenance team to carryout
maintenance/replacement of the equipment. Therefore, maintenance cost related to
unnecessary repairing/replacement can be reduced to the maximum (section 5.4).
Like other maintenance strategies CBM has also few limitations. Protective devices and
redundant equipment has many hidden faults. These faults appear only when these
equipment/devices are needed. Monitoring devices has limitation and they cannot predict
those hidden failures as explained in PESTEL analysis of section 5.4. Therefore, this
strategy of maintenance is not sufficient for the redundant and protective devices.
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PPM is simple and straight forward methodology of managing asset. It does not require
any condition monitoring devices and equipment and failure mode analysis and failure
likelihood is not performed. This strategy provides even distribution of cost estimation as
the maintenance intervals are already defined. It is easier for the maintenance team to
follow and does not require expertise to carryout failure analysis and mode of failure
identification.
In an ageing oil and gas production facility where the failure rate and mode are very
important to foresee the sudden breakdowns and failures, PPM does not provide adequate
assistance to prevent these failures. Due to these reasons, this strategy is not reliable in
preventing sudden failures. Over-maintenance is another issue in implementing this
strategy as explained in section 4.5. This strategy can be effective in new oil and gas
production facilities where the cost is not a big issue and equipment and machinery is
relatively in better condition without severe degradation.
6.2. Future Work:
•
This study was used to compare the maintenance strategy using PESTEL factors, but was
restricted due to less information available for certain factors. PESTEL technique is never
used to compare the advanced and conventional maintenance strategies before. There is
no work available on the comparison using PESTEL framework. There is huge scope to
relate maintenance strategies with legal, political and social factors.
•
There is little information available on the fusion technique. In which multiple
maintenance strategies could be used at the same time. Static and rotatory equipment may
not be effectively maintained by single maintenance strategies. In addition to it,
protective devices and redundant equipment has hidden faults which pop up on demand.
Therefore, fusion strategy, study should be carried out for RBM, CBM and RCM to
enable owners and operators to resolve this problem.
•
Information of maintenance performance measurement is adequately available. But most
of the maintenance performance indicators (MPIs) and the work is general, that is, it
could be used for any maintenance strategy. To measure true performance of the specific
58
Syed Aamir
MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
maintenance strategy maintenance strategy, specific performance measurement indicators
and information should be available to analyze the actual performance of the maintenance
strategy.
59
Syed Aamir
MSc (Eng) Process Safety and Loss Prevention
Dissertation Project
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