What is a Bill of Materials (BOM) in Asset and Tag Data Management?

A Bill of Materials (BOM) is the structured, hierarchical list of every component, part, and material that makes up a piece of equipment, package, or system — typically including manufacturer, part number, specification, quantity, and revision. It is one of the most granular data layers in a capital project, sitting directly beneath the tag in the information hierarchy.

Where a master tag register identifies that a pump exists and what it is called, the BOM tells you exactly what it is built from and what is required to maintain, repair, or replace it. Without reliable BOM data, maintenance planners cannot order the right spare part, and procurement teams cannot validate that a replacement component actually fits.

What does a Bill of Materials actually contain?

A BOM typically includes the manufacturer name, part or model number, technical specification, quantity required, unit of measure, and the current revision of each component. For rotating equipment, packages, and instrumentation, BOMs are often multi-level: a top-level BOM for the package references sub-BOMs for each major component, which in turn reference the individual parts inside them.

This multi-level structure mirrors the way asset hierarchy breaks a facility down from site to system to component — a BOM is, in effect, the parts-level continuation of that same hierarchy.

Why BOM data is so often incomplete at handover

BOM information is generated by dozens of vendors and sub-suppliers across engineering and procurement, and it rarely arrives from all of them in a consistent format or at a consistent level of detail. Some vendors deliver full multi-level BOMs with certified part numbers; others deliver a single line item and a datasheet PDF. Reconciling this into one governed structure is one of the most time-consuming parts of supplier data management.

The most common failure mode is not missing data outright — it is BOM data that exists somewhere in a vendor document but was never linked back to the correct tag. That gap is precisely what turns a technically complete document handover package into one that is unusable in practice: the documents exist, but nobody can find the right one from the tag they are looking at.

How BOM data connects to the tag and equipment register

In a well-structured data model, every BOM line item is linked to a parent tag in the asset register, and every component is traceable back to the vendor documentation gathered during procurement. This turns three separate questions — what is this asset, what is it made of, and where is the proof — into one connected answer instead of three separate lookups across three different systems.

Sharecat validates these tag-to-BOM-to-document relationships as part of handover, so a maintenance planner can go from a tag number to its full parts breakdown and underlying vendor documentation without leaving one system or chasing down the original supplier.

Bill of Materials vs. equipment list vs. tag register

These three terms are often used interchangeably, but they answer different questions:

• Tag register: what exists, and what is it called?
• Equipment list: what are its performance specifications and design parameters?
• Bill of Materials: what components and parts is it physically built from?

Treating these as one flat spreadsheet is a common source of incomplete data models on capital projects. Sharecat keeps them as distinct, but linked, record types — so each question can be answered precisely rather than approximated.

BOM data in maintenance and spares planning

Once an asset is in operation, the BOM becomes the primary reference for spare parts planning and procurement. A reliability engineer who needs to replace a failed component depends on the BOM being both accurate and current — including tracking revisions when a component is superseded or a vendor part number changes.

How Sharecat supports Bill of Materials management

Sharecat structures BOM data as a governed, linked record type within the wider asset information model — connected to the Master Tag Register, validated against supplier submissions, and made available to downstream Enterprise Asset Management systems such as IBM Maximo, IFS, and SAP. This is the same data-first approach behind Sharecat's role as the industrial document and data platform for oil & gas, chemicals, utilities, pharmaceutical, shipping, and mining & metals projects.

Frequently asked questions about the Bill of Materials

Is a BOM the same as a parts catalogue? No — a parts catalogue is typically a vendor's general product listing, while a project BOM is specific to the exact components installed on a specific tag.

Who owns BOM data on a capital project? Ownership typically sits with engineering during design and shifts to the owner-operator's maintenance organisation once the asset is handed over — which is exactly the point at which BOM data most often gets lost if it isn't governed through a structured handover process.