Definition(s)

Fault

Abnormal, undesirable state of a system element induced by the presence of an improper command or absence of a proper one, or by a failure

  • Note 1 to entry: All failures cause faults; not all faults are caused by failure.
  • Note 2 to entry: System elements can include, for example, an entire subsystem, an assembly, or a component.

Source: ISO 16530-1:2017, Petroleum and natural gas industries — Well integrity – Part 1: Life cycle governance, First Edition, March 2017. Global Standards

Fault

State of an item characterized by inability to perform a required function, excluding such inability during preventive maintenance or other planned actions, or due to lack of external resources.

Source: API STD 689, Collection and Exchange of Reliability and Maintenance Data for Equipment, First Edition, July 2007. GlobalStandards

 

Fault

State of an item characterized by inability to perform a required function, excluding the inability during preventive maintenance or other planned actions, or due to lack of external resources. NOTE A fault is often a result of a failure of the item itself but the state can exist without a failure.

Source: ISO 20815:2008, Petroleum, petrochemical and natural gas industries – Production assurance and reliability management. Global Standards

 

Fault

inability to perform as required

  • Note 1 to entry: A fault of an item is a state, as distinct from a failure of an item which is an event (see Figure 8).
  • Note 2 to entry: A fault of an item may result from a failure of the item or from a deficiency in an earlier stage of
  • the life cycle, such as specification, design, manufacture or maintenance.
  • Note 3 to entry: Qualifying terms may be used to indicate the cause of a fault, such as specification, design,
  • manufacture, maintenance or misuse.
  • Note 4 to entry: Inability to perform due to preventive maintenance, other planned actions, or lack of external
  • resources does not constitute a fault.
  • Note 5 to entry: Figure 8 illustrate the relationship between the concepts of failure and fault:

— The Failure x occurs at stage 1 and leads to the state Fault x which is not detected.

— from stage 2 point of view Fault x is a pre-existing fault.

— The Failure y occurs at stage 2 and lead to the state Faults x,y which is not detected.

— From stage 3 point of view Fault x,y is a pre-existing fault.

— and so on.

[SOURCE: IEC 60050 −191]

 

FIG.8

 

Source: ISO/TR 12489:2013(E) Reliability modelling and calculation of safety systems. Global Standards

 

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