ISO/FDIS 20815

ISO/TC 67/WG 4
Secretariat: NEN
Date: 2026-01-1202-05
Oil and gas industries including lower carbon energy — Production
assurance and reliability management
Industries du pétrole et du gaz, y compris les énergies à faible teneur en carbone — Assurance production et
gestion de la fiabilité
FDIS stage
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ii
Contents
Foreword . iv
Introduction . vi
1 Scope . 1
2 Normative references . 2
3 Terms, definitions and abbreviated terms . 2
3.1 Terms and definitions . 2
3.3 Abbreviated terms . 25
4 Production assurance and decision support . 26
4.1 Framework conditions . 26
4.2 Optimization process . 30
4.3 Production assurance programme . 33
4.4 Alternative standards . 37
5 Production assurance processes and activities . 38
Annex A (normative) Production assurance programme (PAP) and reliability management
programme (RMP) — Structure and content . 42
Annex B (informative) Core production assurance processes and activities . 45
Annex C (informative) Interacting production assurance processes and activities . 57
Annex D (informative) Production performance analyses . 62
Annex E (normative) Reliability and production performance data . 69
Annex F (informative) Performance objectives and requirements . 72
Annex G (normative) Performance measures for production assurance . 76
Annex H (informative) Relationship to major accidents . 85
Annex I (informative) Outline of techniques . 87
Bibliography . 116

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
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International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of
ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
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www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 67, Oil and gas industries including lower carbon
energy., in collaboration with the European Committee for Standardization (CEN) Technical Committee
CEN/TC 12, Oil and gas industries including lower carbon energy, in accordance with the Agreement on
technical cooperation between ISO and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 20815:2018), which has been technically
revised.
The main changes are as follows:
— Clause 3— Clause 3:: several new terms, definitions and abbreviated terms added;
— Clause 4— Clause 4: 4.1: 4.1 updated, new subclause 4.1.2subclause 4.1.2 added, Figure 5Figure 5 and
Table 2Table 2 revised;
— — Main clauses and Annex AAnnex A:: text updated to clarify that establishment and use of production
assurance programme or reliability management programme both imply conformity to this document;
— Annex B— Annex B and Annex CAnnex C:: text updated to align with production assurance processes for
life cycle phases in the revised Table 2Table 2;;
— Annex A— Annex A and Annex EAnnex E:: status changed to normative;
— Annex D— Annex D:: new text and figures added;
— Annex F— Annex F: Figure F.1: Figure F.1 revised, new text added in Clauses F.3Clauses F.3 and F.4F.4;;
iv
— Annex G— Annex G:: text updated to reflect the relationship between this document and ISO/TS
3250:2021; some text in the second edition (ISO 20815:2018) has been removed since the next edition of
ISO/TS 3250 is planned to cover production loss categories for also midstream, downstream and
petrochemical;
— Annex I— Annex I:: sequence of clauses changed; text updated in Clauses I.1Clauses I.1, I.8, I.8 to I.9,
I.14I.9, I.14, I.16, I.16 to I.18I.18.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
Introduction
The oil and gas industries, including petrochemical and lower carbon energy activities, involve large capital
expenditure (CAPEX) and operating expenditure (OPEX). The safety and profitability of the associated assets
are dependent upon the reliability, availability and maintainability of the systems and components that are
used. Therefore, production assurance and reliability management are essential for optimal production
availability. This contributes to delivering affordable energy in a sustainable manner.
The concept of production assurance, introduced in this document, enables a common understanding with
respect to use of reliability technology in the various life cycle phases. Production assurance covers the
activities implemented to achieve and maintain an optimal performance level in terms of the overall economy,
which is consistent with applicable regulatory requirements and framework conditions.
vi
Oil and gas industries including lower carbon energy — Production
assurance and reliability management
IMPORTANT — The electronic file of this document contains colours which are considered to be useful
for the correct understanding of the document. Users should therefore consider printing this
document using a colour printer.
1 Scope
This document specifies requirements and guidance for production assurance and reliability management as
applicable to the assets and operations associated with exploration drilling, exploitation, processing and
transport of petroleum, petrochemical and natural gas resources. It covers the assets and associated activities
for upstream, midstream, downstream and petrochemical business categories. It focuses on the production
assurance of oil and gas with respect to production and associated activities and covers the analysis of
reliability and maintenance of the equipment. This includes a variety of associated systems and equipment in
the oil and gas value chain. Production assurance addresses not only hydrocarbon production, but also
associated activities such as drilling, pipeline installation and subsea intervention.
The document also supports production assurance and reliability management for lower carbon energy assets
and associated operations, e.g. carbon capture and storage (CCS), hydrogen, ammonia, and wind energy. It
describes the processes, activities, requirements and guidelines for systematic management, effective
planning, execution and use of production assurance and reliability technology.
This document defines 12 processes, of which seven are denoted as core production assurance processes and
addressed in this document. The remaining five processes are denoted as interacting processes and are
outside the scope of this document. The relationship of the core production assurance processes with these
interacting processes, however, is within the scope of this document as the flow of information to and from
these latter processes is required to ensure that production assurance requirements are fulfilled.
The document specifies how to establish and execute a production assurance programme (PAP) and a
reliability management programme (RMP).
This document lists processes and activities that can be initiated to add value for the stakeholder (e.g.
operator), where the selected process can depend on their business strategy and application area.
This document is intended for the following users and associated activities by their personnel:
— — Operators: Production assurance and reliability management activities. Related activities
include project management and control, technology development, technology qualification, concept and
system design, risk management (including HSE), integrity management, and maintenance management.
— — Contractors: Activities by the main contractor for engineering, procurement, construction, drilling,
installation, operation, maintenance services, etc.
— — Vendors: Activities by manufacturer or supplier related to equipment design and quality management,
technology development and qualification.
— — Authorities: Activities by regulatory bodies to ensure HSE, resource utilization and economics in
operations.
— — Consultants: Consultancy services aimed at supporting production assurance and reliability
management.
— — Universities: Activities associated with educating industry professionals, as well as conducting
fundamental or applied research projects, when related to production assurance, reliability management,
and technology development. This includes improvement of the methods and frameworks described
herein.
— — Research institutions: Research activities related to production assurance, reliability management,
and technology development. This includes equipment qualification testing and advanced engineering
assessments using the methods and frameworks described herein.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 14224:2016, Petroleum, petrochemical and natural gas industries — Collection and exchange of reliability
and maintenance data for equipment
ISO/TS 3250:2021, Petroleum, petrochemical and natural gas industries — Calculation and reporting
production efficiency in the operating phase
ISO 15663:2021, Petroleum, petrochemical and natural gas industries — Life cycle costing
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— — ISO Online browsing platform: available at https://www.iso.org/obp
— — IEC Electropedia: available at https://www.electropedia.org/
3.1.1 3.1.1
active repair time
effective time to achieve repair of an item (3.1.29(3.1.29))
Note 1 to entry: The expectation of the effective time to repair is called MART (mean active repair time).
Note 2 to entry: ISO 14224 distinguishes between the terms mean active repair time (MART), mean time to repair
(MTTR), mean time to restoration (MTTRes), and mean overall repairing time (MRT). See ISO 14224:2016, 3.59, 3,61,
3.63 and 3.64 for further details.
Note 3 to entry: The mean active repair time (MART) is defined as “expected active repair time” in ISO/TR 12489:2013,
3.1.34. See also ISO/TR 12489:2013, Figures 5 and 6.
[SOURCE: ISO 14224:2016, 3.2, modified — Notes 1 to 2 to entry have been added; the original notes 1 and 2
to entry have been consolidated to become note 3 to entry.]
3.1.2 3.1.2
asset
item (3.1.29(3.1.29),), thing or entity that has potential or actual value to an organization
Note 1 to entry: Assets can be physical or non-physical.
Note 2 to entry: A grouping of assets referred to as an ‘"asset system,," can also be considered as an asset.
Note 3 to entry: In this document, 'asset'"asset" only refers to the physical assets, which are tangible assets. An
organization can also operate assets that are wholly owned or partly owned through joint ventures or other
arrangements. Typically, an asset is a facility or an installation, or a group of facilities. The facility corresponds to an
installation category in ISO 14224:2016, Table A.1. These installations can be subdivided into plants or units, systems
(3.1.75(3.1.75),), equipment classes (see ISO 14224:2016, 3.18), subunits, components, etc. as described in ISO
14224:2016, Table 2.
[SOURCE: ISO 55000:2024, 3.1.1, modified — Note 3 to entry has been added.]
3.1.3 3.1.3
availability
ability to be in a state to perform as required under given conditions
Note 1 to entry: For a binary item (3.1.6(3.1.6),), the measure of the availability is the probability to beof being in up state
(3.1.79(3.1.79)) (i.e. in a state belonging to the up state class).
Note 2 to entry: Figure 1 Figure 1 shows a system that is available at time t1 and unavailable at time t2.
Note 3 to entry: See ISO 14224:2016, Annex C for a more detailed description and interpretation of availability.
Note 4 to entry: Technical availability (3.1.76(3.1.76)) or operational availability (3.1.50(3.1.50)) can be used as derived
performance measures (3.1.51(3.1.51)) to reflect estimate availability. Case specific definition of system availability is
needed to reflect the system (3.1.75(3.1.75)) being addressed.
Note 5 to entry: Further terms are given in ISO/TR 12489.
Note 6 to entry: See Figure G.1Figure G.1 for further information.
[SOURCE: IEC 60050-192:2015, 192-01-23, modified — The original notes to entry have been replaced by the
new notes 1 to 6 to entry.]
3.1.4 3.1.4
average availability
mean availability
Ā(t , t )
1 2
average value of the instantaneous availability (3.1.26(3.1.26)) over a given time interval (t , t )
1 2
Note 1 to entry: The average availability is the ratio between the accumulated time spent in up state (3.1.79(3.1.79)) and
the length of the considered period of observation. For example, Figure 1Figure 1 shows the average availability of the
system over the interval [0, t ] which is equal to (δ + δ + δ + δ + δ + δ + δ + δ )/t , i.e. 1 ̶ δ /t where δ /t is the
3 1 2 3 4 5 6 8 9 3 7 3 7 3
average unavailability of the system. This formula is similar to the formula obtained for production availability
(3.1.59(3.1.59)) calculations when only two levels, 100 % and 0 %, are considered.
Note 2 to entry: The average availability can be interpreted as the long-run proportion of time where the item is able to
function. Mathematically speaking, the average availability is the mathematical expectation of the term availability
(3.1.3(3.1.3),), as this term does not have the mathematical property of a normal probability and cannot be handled as
such.
[SOURCE: IEC 60050-192:2015, 192-08-05, modified — The original note 1 to entry has been replaced by the
new notes 1 and 2 to entry.]
3.1.5 3.1.5
barrier
functional grouping of safeguards or controls selected to prevent a major accident (3.1.40(3.1.40)) or limit the
consequences
[SOURCE: ISO 17776:2016, 3.1.1, modified — Notes to entry have been removed.]
3.1.6 3.1.6
binary item
item (3.1.29(3.1.29)) with two classes of states
Note 1 to entry: The two classes can be up state (3.1.79(3.1.79)) and down state (3.1.15(3.1.15).).
EXAMPLE 1 An item that only have an up state and a down state is a binary item. Components A and B in
Figure 1Figure 1 are binary items.
EXAMPLE 2 A system made up of two redundant binary items, components A and B, has four states: φ (both A and
B in up state), φ (A in up state and B in down state), φ (A in down state and B in up state), φ (both A and B in down
2 3 4
state). If the system is able to operate as required in states φ1, φ2 and φ3 and not able in state φ4, it is a binary item with
the up state class {φ , φ , φ } and the down class {φ }. This is illustrated in Figure 1Figure 1.
1 2 3 4
Key
A component A
B component B
S system
δ period of time
t time
X state of component A (binary item)
A
B component BXB state of component B (binary item)
S systemφ state of the system S (multi-state item)
δ period of timeC class of states of system S (binary item)
t timeNOTE The two components each have states 1 (Up) and 0 (Down). System S as a binary item
has classes 1 (Up) and 0 (Down).
Figure 1 — Illustration of availability behaviour of an 1oo2 system
3.1.7 3.1.7
capital expenditure
CAPEX
investment used to purchase, install and commission an asset (3.1.2(3.1.2))
Note 1 to entry: See further information regarding estimation of CAPEX in ISO 15663:2021, Clause C.2.
[SOURCE: ISO 15663:2021, 3.1.7]
3.1.8 3.1.8
common cause failure
failure of multiple items (3.1.29(3.1.29),), which would otherwise be considered independent of one another,
resulting from a single cause
Note 1 to entry: Common cause failures can also be common mode failures (3.1.9(3.1.9).).
Note 2 to entry: The potential for common cause failures reduces the effectiveness of system redundancy.
Note 3 to entry: It is generally accepted that the failures occur simultaneously or within a short time of each other.
Note 4 to entry: Components that fail due to a shared cause normally fail in the same functional mode. The term common
mode is therefore sometimes used. It is, however, not considered to be a precise term for communicating the
characteristics that describe a common cause failure.
Note 5 to entry: Explicit and implicit common mode failures are defined in ISO/TR 12489:2013, 5.4.2.
Note 6 to entry: Regarding interpretation rules for common cause failure parameters, see also ISO 14224:2016, C.1.6.
[SOURCE: IEC 60050-192:2015, 192-03-18, modified — Notes 3- through 6 to entry have been added.]
3.1.9 3.1.9
common mode failures
failures of different items characterized by the same failure mode
Note 1 to entry: Common mode failures can have different causes.
Note 2 to entry: Common mode failures can also be common cause failures (3.1.8(3.1.8).).
Note 3 to entry: The potential for common mode failures reduces the effectiveness of system redundancy.
[SOURCE: IEC 60050-192:2015, 192-03-19]
3.1.10 3.1.10
condition monitoring
obtaining information about physical state or operational parameters
Note 1 to entry: Condition monitoring is used to determine when preventive maintenance (3.1.57(3.1.57)) may be
required.
Note 2 to entry: Condition monitoring may be conducted automatically during operation or at planned intervals.
Note 3 to entry: Condition monitoring is part of condition-based maintenance. See also ISO 14224:2016, Figure 6.
[SOURCE: IEC 60050-192:2015, 192-06-28, modified — The original note 3 to entry has been replaced by a
new one.]
3.1.11 3.1.11
corrective maintenance
maintenance (3.1.36(3.1.36)) carried out after fault (3.1.23(3.1.23)) detection to effect restoration
Note 1 to entry: See also ISO/TR 12489:2013, Figures 5 and 6, which illustrate terms used for quantifying corrective
maintenance.
[SOURCE: IEC 60050-192:2015, 192-06-06, modified — The original noteNote 1 to entry has been replaced
by a new one.]
3.1.12 3.1.12
deliverability
ratio of deliveries to planned deliveries over a specified period of time, when the effect of compensating
elements, such as substitution from other producers and downstream (3.1.17(3.1.17)) buffer storage, is
included
Note 1 to entry: See Figure G.1Figure G.1 for further information.
3.1.13 3.1.13
design life
planned usage time for the total system (3.1.75(3.1.75))
Note 1 to entry: It is important not to confuse design life with the mean time to failure (MTTF) (3.1.41(3.1.41).). Several
items can fail within the design life of the system. As long as repair or replacement is feasible, the design life of the system
is not affected by such failures.
Note 2 to entry: The design life is decided during the life cycle phase ‘Define’."Define". Design life in this document can
thus mean a lifetime that can change and that can be chosen based on production assurance (3.1.58(3.1.58)) activities or
life cycle costing (3.1.30(3.1.30).).
3.1.14 3.1.14
demand availability
ability of the production facility to satisfy the demand over a specified period of time
Note 1 to entry: This performance measure (3.1.51(3.1.51)) expresses the fraction of time or number of times the
produced volume that is exported is equal to or above demand. See also Table G.1Table G.1.
3.1.15 3.1.15
down state
state of being unable to perform as required, due to internal fault (3.1.23(3.1.23),), or preventive maintenance
(3.1.57(3.1.57))
Note 1 to entry: This concept is related to a binary item (3.1.6(3.1.6),), which can have several down states forming the
down state class of the item. All the states in the down state class are considered to be equivalent with regard to the
unavailability of the considered item.
EXAMPLE In Figure 1Figure 1,, the down state class of the system S comprises only one state {S } and the system S
is in down state at time t .
[SOURCE: IEC 60050-192:2015, 192-02-20, modified — The original note 1 to entry has been replaced, and
the original note 2 to entry has been removed; EXAMPLE has been added.]
3.1.16 3.1.16
down time
time interval during which an item (3.1.29(3.1.29)) is in a down state (3.1.15(3.1.15))
Note 1 to entry: The down time includes all the delays between the item failure and the restoration of its service. Down
time can be either planned or unplanned (see ISO 14224:2016, Table 4).
Note 2 to entry: Down time can be equipment down time (see ISO 14224:2016, Figure 4 and Table 4), production down
time (see Figures I.1Figures I.1 and I.2I.2)) or down time for other operations (e.g. drilling). It is important to distinguish
between the equipment down time itself and the down time of the plant to which the equipment belongs.
[SOURCE: IEC 60050-192:2015, 192-02-21, modified — The original notes to entry have been replaced by the
new notes 1 and 2 to entry.]
3.1.17 3.1.17
downstream
business category most commonly used in the petroleum industry to describe post-production processes
Note 1 to entry: See ISO 14224:2016, A.1.4 for further details.
[SOURCE: ISO 14224:2016, 3.17, modified — EXAMPLE has been removed.]
3.1.18 3.1.18
failure
loss of ability to perform as required
Note 1 to entry: A failure of an item is an event that results in a fault (3.1.23(3.1.23)) (i.e. a state) of that item. This is
illustrated in Figure 2Figure 2 for a binary system S comprising two redundant components A and B.
[SOURCE: IEC 60050-192:2015, 192-03-01, modified — The original notes to entry have been replaced by a
new note 1 to entry.]
3.1.19 3.1.19
failure cause
root cause
set of circumstances that leads to failure (3.1.18(3.1.18))
Note 1 to entry: A failure cause can originate during specification, design, manufacture, installation, operation or
maintenance of an item.
Note 2 to entry: See ISO 14224:2016, B.2.3 and Table B.3, which define failure causes for all equipment classes.
[SOURCE: IEC 60050-192:2015, 192-03-11, modified — Note 2 to entry has been added.]
3.1.20 3.1.20
failure data
data characterizing the occurrence of a failure (3.1.18(3.1.18)) event
Note 1 to entry: See ISO 14224:2016, Table 6.
[SOURCE: ISO 14224:2016, 3.25]
3.1.21 3.1.21
failure mode
manner in which failure (3.1.18(3.1.18)) occurs
Note 1 to entry: See ISO 14224:2016, Tables B.6 to B.15, on the relevant failure modes, which define failure modes to be
used for each equipment class.
[SOURCE: IEC 60050-192:2015, 192-03-17, modified — The original notes to entry have been replaced by a
new note 1 to entry.]
3.1.22 3.1.22
failure rate
conditional probability per unit of time that the item (3.1.29(3.1.29)) fails between t and t + dt, provided that
it works over (0, t)
Note 1 to entry: See ISO 14224:2016, Clause C.3 for further explanation of the failure rate.
Note 2 to entry: This definition applies for the first failure (3.1.18(3.1.18)) of binary items (3.1.6(3.1.6).).
Note 3 to entry: Under the assumptions that the failure rate is constant and that the item is as good as new after repairs
the failure rate can be estimated as the number of failures relative to the corresponding accumulated up time
(3.1.80(3.1.80)) divided by this accumulated up time. In this case this is the reciprocal of MTTF (3.1.41(3.1.41).). In some
cases, time can be replaced by units of use.
Note 4 to entry: The estimation of the failure rate can be based on operating time (3.1.49(3.1.49)) or calendar time.
[SOURCE: ISO/TR 12489:2013, 3.1.18, modified — The symbol "λ(t)" has been removed; the original notes to
entry have been replaced by the new notes 1 to 4 to entry.]
3.1.23 3.1.23
fault
inability to perform as required, due to an internal state
EXAMPLE Down states (3.1.15(3.1.15)) of items A, B and system S is illustrated in Figure 2Figure 2.
Note 1 to entry: A fault of an item results from a failure (3.1.18(3.1.18),), either of the item itself, or from a deficiency in
an earlier stage of the life cycle, such as specification, design, manufacture or maintenance. See latent fault
(ISO 14224:2016, 3.44).
Note 2 to entry: An item made of several sub-items (e.g. a system) which continues to perform as required in presence of
faults of one or several sub-items is called fault tolerant.
Note 3 to entry: See also ISO/TR 12489:2013, 3.2.2.
[SOURCE: IEC 60050-192:2015, 192-04-01, modified — EXAMPLE has been added; the original notes 2 to 4
to entry have been replaced by the new notes 2 and 3 to entry.]
3.1.24 3.1.24
fault tolerance
attribute of an item (3.1.29(3.1.29)) that makes it able to perform a required function (3.1.69(3.1.69)) in the
presence of certain given sub-item faults (3.1.23(3.1.23))
3.1.25 3.1.25
human error
discrepancy between the human action taken or omitted and that intended
EXAMPLE Performing an incorrect action; omitting a required action.
Note 1 to entry: Discrepancy with intention is considered essential in determining human error; see Reference [91[91].].
Note 2 to entry: The term ‘human error’ is often attributed in hindsight to a human decision, action or inaction considered
to be an initiator or contributory cause of a negative outcome such as loss or harm.
Note 3 to entry: In human reliability assessment, human error is defined as any member of a set of human actions or
activities that exceeds some limit of acceptability, this being an out of tolerance action or failure (3.1.18(3.1.18)) to act
where the limits of performance are defined by the system (see Reference [88[88]).]).
Note 4 to entry: See IEC 62508 for further details.
Note 5 to entry: See also ISO/TR 12489:2013, 5.5.2.
[SOURCE: IEC 60050-192:2015, 192-03-14, modified — The words "or required" have been removed at the
end of the definition; in the EXAMPLE, "miscalculation; misreading a value" have been removed; notes 1 to 5
to entry have been added.]
3.1.26 3.1.26
instantaneous availability
A(t)
probability that an item (3.1.29(3.1.29)) is in a state to perform as required at a given instant
[SOURCE: IEC 60050-192:2015, 192-08-01, modified — The admitted term ‘"point availability’availability"
has been removed; the symbol "A(t)" has been added.]
3.1.27 3.1.27
integrity
condition in which an asset (3.1.2(3.1.2)) is safe and reliable for its purpose
Note 1 to entry: For some application areas, more specific terms and definitions exist. such as asset integrity (see ISO/TS
3250:2021, 3.1.2), mechanical integrity, plant integrity, safety integrity (see ISO/TR 12489:2013, 3.1.2), structural
integrity (see ISO/DIS 19900:2025,20—, 3.58), system integrity, technical integrity and well integrity (see ISO/DIS
16530-1:2025,:20—, 3.73). These integrity terms can encompass various failure (3.1.18(3.1.18)) consequences (e.g.
safety, environmental, production, and operation; see ISO 14224:2016, Table C.2).
Note 2 to entry: Integrity is also defined for use in pipeline integrity management (3.1.28(3.1.28)) for onshore gas
infrastructure in EN 17649:2022, 3.7. see also DNV-ST-F101:2017 and ISO 19345-1:2019, 3.1.32.
Note 3 to entry: The integrity can be expressed mathematically by using specific performance measures (3.1.51(3.1.51))
as described in Annex GAnnex G.
[SOURCE: EN 17649:2022, 3.7, modified — Notes 1 to 3 to entry have been added.]
3.1.28 3.1.28
integrity management
set of processes and procedures used to proactively manage the safe, environmentally responsible and reliable
service of an asset (3.1.2(3.1.2)) throughout its life cycle
Note 1 to entry: The integrity management program covers a set of processes and practises used in reliability
management (3.1.68(3.1.68).). See e.g. ISO 19345-1:2019, 3.1.21.
3.1.29 3.1.29
item
subject being considered
Note 1 to entry: The item can be an individual part, component, device, functional unit, equipment, subsystem, or system.
Note 2 to entry: The item may consist of hardware, software, people or any combination thereof.
Note 3 to entry: In this document, item can also be plant or unit, or installation. See ISO 14224:2016, Figure 3.
[SOURCE: IEC 60050-192:2015, 192-01-01, modified — In note 1 to entry, "material", "product" and "service
or process" have been removed; in note 2 to entry, "can" has been changed to "may"; note 3 to entry has been
added.]
3.1.30 3.1.30
life cycle costing
process of evaluating the difference between the life cycle cost of two or more alternative options
Note 1 to entry: Life cycle costing can involve quantitative and qualitative assessment.
[SOURCE: ISO 15663:2021, 3.1.27, modified — Note 1 to entry has been adjusted.]
3.1.31 3.1.31
life cycle phase
discrete stage in the life cycle with a specified purpose
Note 1 to entry: The different life cycle phases are further described in ISO 15663:2021, 4.5.
[SOURCE: ISO 15663:2021, 3.1.28]
3.1.32 3.1.32
logistic delay
delay, excluding administrative delay, incurred for the provision of resources needed for a maintenance action
to proceed or continue
Note 1 to entry: Logistic delays can be due to, for example, travelling to unattended installations, pending arrival of spare
parts, specialists, test equipment and information, and delays due to unsuitable environmental conditions (e.g. waiting
on weather).
Note 2 to entry: See also ISO/TR 12489:2013, Figure 5.
[SOURCE: IEC 60050-192:2015, 192-07-13, modified — The original NOTE has been replaced by the new
notes 1 and 2 to entry.]
3.1.33 3.1.33
lost revenue
LOSTREV
income loss that occurs when generated income are less than expected due to external or internal factors
Note 1 to entry: Production loss (3.1.61(3.1.61)) categories are defined in ISO/TS 3250:2021. Time loss categories are
described in Clause G.3Clause G.3.
[SOURCE: ISO 15663:2021, 3.1.29, modified — The original notes 1 and 2 to entry have been replaced by the
new note 1 to entry.]
3.1.34 3.1.34
maintainability
ability to be retained in, or restored to a state to perform as required, under given conditions of use and
maintenance (3.1.36(3.1.36))
Note 1 to entry: Given conditions would include aspects that affect maintainability, such as: location for maintenance,
accessibility, maintenance procedures and maintenance resources.
Note 2 to entry: Maintainability can be quantified using appropriate measures. See IEC 60050-192:2015, 192-07,
Maintainability and maintenance support: measures.
Note 3 to entry: See Figure G.1Figure G.1 for further information.
[SOURCE: IEC 60050-192:2015, 192-01-27, modified — Note 3 to entry has been added.]
3.1.35 3.1.35
maintainable item
item (3.1.29(3.1.29)) that constitutes a part or an assembly of parts that is normally the lowest level in the
equipment hierarchy during maintenance (3.1.36(3.1.36))
[SOURCE: ISO 14224:2016, 3.48]
3.1.36 3.1.36
maintenance
combination of all technical and management actions intended to retain an item in, or restore it to, a state in
which it can perform as required
[SOURCE: IEC 60050-192:2015, 192-06-01, modified — Note 1 to entry has been removed.]
3.1.37 3.1.37
maintenance data
data characterizing the maintenance action planned or done
Note 1 to entry: See ISO 14224:2016, Table 8.
[SOURCE: ISO 14224:2016, 3.51, modified — The original notes 1 and 3 to entry have been removed; Newnew
note 1 to entry added.]
3.1.38 3.1.38
maintenance management
all activities of the management that determine the maintenance requirements, objectives, strategies, and
responsibilities, and implementation of them by such means as maintenance planning, maintenance control
and the improvement of maintenance activities and economics
[SOURCE: EN 13306:2017, 2.2]
3.1.39 3.1.39
maintenance supportability
ability to be supported to sustain the required availability (3.1.3(3.1.3)) with a defined operational profile and
given logistic and maintenance resources
Note 1 to entry: Maintenance supportability of an item result from the inherent maintainability (3.1.34(3.1.34),),
combined with factors external to the item that affect the relative ease of providing the required maintenance and logistic
support.
Note 2 to entry: See ISO 14224:2016, Annex C for further details regarding the interpretation of maintainability.
3.1.40 3.1.40
major accident
hazardous event that results in
— — multiple fatalities or severe injuries; or
— — extensive damage to structure, installation or plant; or
— — large-scale impact on the environment (e.g. persistent and severe environmental damage that can lead
to loss of commercial or recreational use, loss of natural resources over a wide area or severe
environmental damage that will require extensive measures to restore beneficial uses of the environment)
Note 1 to entry: In ISO 17776:2016, a major accident is the realization of a major accident hazard.
[SOURCE: ISO 17776:2016, 3.1.12, modified — The abbreviated term ‘MA’ has been removed; note 2 to entry
has been removed.]
3.1.41 3.1.41
mean time to failure
MTTF
expected time before the item (3.1.29(3.1.29)) fails
Note 1 to entry: See further details in ISO/TR 12489:2013, 3.1.29.
Note 2 to entry: IEC 60050-192:2015 defines MTTF as "expectation of the operating time (3.1.49(3.1.49)) to failure".
Note 3 to entry: See also ISO 14224:2016, Annex C.
[SOURCE: ISO/TR 12489:2013, 3.1.29, modified — The original notes to entry have been replaced by the new
notes 1 to 3 to entry.]
3.1.42 3.1.42
midstream
business category involving the processing, storage and transportation sectors of the petroleum industry
Note 1 to entry: See ISO 14224:2016, A.1.4 for further details.
[SOURCE: ISO 14224:2016, 3.65, modified — EXAMPLE has been removed.]
3.1.43 3.1.43
modification
combination of all technical and administrative actions intended to change an item (3.1.29(3.1.29))
Note 1 to entry: In this document, the use of the term modification is primarily meant to cover major modification
activities. See further details in ISO/TS 3250:2021, 8.2.2 with respect to how such major modifications are reflected in
production efficiency (3.1.60(3.1.60)) reporting.
[SOURCE: ISO 14224:2016, 3.67, modified — The original notes 1 to 3 to entry have been replaced by the new
note 1 to entry.]
3.1.44 3.1.44
multi-state item
item (3.1.29(3.1.29)) with more than two classes of states
Note 1 to entry: This is an extension of the binary items (3.1.6(3.1.6)) beyond the concepts of up state (3.1.79(3.1.79))
and down state (3.1.15(3.1.15).). This can characterize single items with degraded states or systems made up of several
components in a production facility.
EXAMPLE An oil production system comprising two wells, A and B, that can be considered as binary items has four
states: φ (both A and B in up state), φ (A in up state and B in down state), φ (A in down state and B in up state), φ
1 2 3 4
(both A and B in down state). If, when they are in up state, A produces 200 bpd and B produces 100 bpd, then the system
has four classes of production 300 bpd, {φ1}, 200 bpd, {φ2}, 100 bpd, {φ3} and 0 bpd, {φ4}. With regards to oil production,
it is a multi-state item. This is illustrated in Figure 2Figure 2.

Key
A item A
B item B
S system
δ period of time
Y state capacity of item A (binary item)
A
B item B  YB state capacity of item B (binary item)
S systemφ production output of system S (multi-state item) [in bpd]
δ period of timet time
NOTE Max X is 200 bpd and max X is 100 bpd. System S as a multi-state item has four discrete states of production
A B
output: {φ , φ , φ , φ }, where the max production output is 300 bpd.
1 2 3 4
Figure 2 — Illustration of production availability behaviour of a multi-state system
3.1.45 3.1.45
observation period
time period during which production performance (3.1.62(3.1.62)) and reliability data (3.1.67(3.1.67)) are
recorded
3.1.46 3.1.46
on-stream availability
ability of a production facility to deliver a volume above zero over a specified period of time
Note 1 to entry: This performance measure (3.1.51(3.1.51)) expresses the fraction of time or number of times produced
volume is above zero. See Table G.1Table G.1.
3.1.47 3.1.47
operating expenditure
OPEX
expenses used for operation and maintenance, including associated costs such as logistics and spares
Note 1 to entry: See further information regarding estimation of OPEX in ISO 15663:2021, Clause C.3.
[SOURCE: ISO 15663:2021, 3.1.31]
3.1.48 3.1.48
operating state
state of performing as required
Note 1 to entry: See ISO 14224:2016, Table 4.
Note 2 to entry: In some applications, an item in an idle state is considered to be operating.
Note 3 to entry: The state capacities (3.1.72(3.1.72)) of a multi-state item (3.1.44(3.1.44)) characterize various levels of
operation and consequently, the definition of the operating state of a multi-state item depends on the situation, for
example, if:
— — no other requirement is given, any state with a capacity greater than zero is an operating state;
— — a minimum capacity is required, it provides the limit to split the states between up and down classes;
— — a given capacity is specified, then only the states with this capacity are operating states;
— — no other requirement is given, any state with a capacity greater than zero is an operating state (300 bpd, 200 bpd
and 100 bpd in Figure 2Figure 2););
— — a minimum capacity is required, it provides the limit to split the states between up and down classes (300 bpd,
200 bpd in Figure 2Figure 2,, if the minimum allowed production is 200 bpd);
— — a given capacity is specified, then only the states with this capacity are operating states (200 bpd in
Figure 2Fig
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