ISO 14224.
ISO 14224 is the international standard for collecting and exchanging reliability and maintenance data for equipment in the petroleum, petrochemical, and natural gas industries. It defines a hierarchical equipment taxonomy and a standard set of failure and maintenance data so that operators, and the reliability databases they draw on, describe the same equipment the same way. Most plant CMMS and asset hierarchies are built to this taxonomy.
What ISO 14224 means.
An operating plant records failures against thousands of individual devices, and reliability data is only useful in aggregate if every contributor describes an item the same way. ISO 14224 solves that by defining a hierarchical taxonomy that runs from the industry and business category down through the installation, the plant or unit, and the section or system, to the equipment unit itself, and further down into the subunit, the maintainable item, and the part. Alongside the taxonomy, the standard defines the equipment classes and attributes to record for each type, and the failure and maintenance data: failure mode, failure mechanism, failure cause, and the detection method by which the failure was found. The result is that a pump on one facility and a pump on another are describable, and comparable, in the same structure. For an instrumentation and controls team, the practical consequence shows up at handover: the tag register has to carry an equipment class and a parent equipment unit for every item, not just a tag number and a service description.
The taxonomy, level by level.
ISO 14224 runs a single equipment hierarchy from the most general to the most specific. The upper levels place equipment in its industry and business context: industry, business category, installation. The middle levels locate it physically: the plant or unit, then the section or system it belongs to. From there the taxonomy narrows to the equipment unit itself, for example a pump, then its subunit, a lubrication system within that pump, its maintainable item, a bearing, and finally the part, a seal. A failure is recorded against the level it actually occurred at, not against the equipment unit as a whole, which is what lets a reliability database tell a bearing problem apart from a seal problem on the same pump.
Equipment classes and what gets recorded.
Each equipment unit is assigned to a standard class, so a centrifugal pump on one project is classed the same way as a centrifugal pump on another. Against that class, the standard defines the attributes to capture: design data such as rated capacity and materials, and the operating data that changes over time. When a failure occurs, it is recorded with a failure mode, what stopped working, a failure mechanism, how it failed, a failure cause, why it failed, and the method by which the failure was detected. That structure is what makes the resulting dataset usable for failure-rate analysis rather than a free-text maintenance log.
Why a CMMS is built to this taxonomy.
A computerized maintenance management system needs an asset hierarchy to hang work orders, spare parts, and failure history against, and ISO 14224 is the taxonomy most reliability and maintenance systems in these industries are built to. Loading a plant into a CMMS means mapping every physical item onto the hierarchy: which equipment unit it belongs to, what class it is, and where it sits in the section and plant structure above it. Getting that mapping right the first time avoids a maintenance system full of orphaned work orders that cannot be rolled up into meaningful reliability statistics at the equipment or plant level.
What a handover tag register needs to carry.
The tag register handed over from engineering is the source most CMMS loads start from, so it has to carry more than a tag number and a description. Each instrument or equipment item needs an equipment class and type, the parent equipment unit it belongs to, and a clear boundary between what is inside that unit and what is a separately tagged item on it. A pressure transmitter mounted on a pump, for instance, is its own tag but belongs under the pump as its parent equipment unit. Without that parent link recorded at handover, the CMMS load has to reconstruct the relationship by hand, item by item.
ISO 14224 equipment taxonomy levels
Each level narrows from business context to the physical part. A failure is recorded at the level it actually occurred at.
| Level | What it represents | Example |
|---|---|---|
| Industry | The sector the equipment operates in | Oil and gas, upstream |
| Business category | The type of operation within the industry | Production |
| Installation | The facility or site | Unit 12 gas plant |
| Plant or unit | A defined process area within the installation | Compression train A |
| Section or system | A functional system within the plant or unit | Lube oil system |
| Equipment unit | The main piece of equipment | P-302A, centrifugal pump |
| Subunit | A functional subdivision of the equipment unit | Mechanical seal system |
| Maintainable item | The assembly that is repaired or replaced as a unit | Bearing |
| Part | The individual replaceable component | Seal ring |
What a handover register needs for an ISO 14224 CMMS load
Beyond the tag number and description most registers already carry.
| Field | Why it is needed | Source document |
|---|---|---|
| Equipment class | Groups the item with equipment of the same type across the plant | P&ID equipment list, datasheet |
| Equipment unit, parent | Links the tag to the equipment unit it is mounted on or part of | P&ID, instrument index |
| Section or system | Places the equipment unit within its functional system | P&ID, process description |
| Maintainable item boundary | States what is inside the equipment unit versus a separately tagged item | Datasheet, vendor drawing |
Common questions
What does ISO 14224 stand for.
What is the ISO 14224 equipment taxonomy.
Why does a CMMS use the ISO 14224 taxonomy.
What is the difference between an equipment unit and a maintainable item.
What data does ISO 14224 ask for on a failure.
Does ISO 14224 tell you how to fix a failure.
What does a tag register need for an ISO 14224-shaped handover.
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