---
title: "RCM Systems - Functions and Functional Failures"
slug: "rcm-systems-functions-and-functional-failures"
description: "Define system functions and identify functional failures to enhance reliability-centered maintenance analysis and improve asset performance."
tags: ["Systems", "RCM"]
updated: 2026-10-27T23:11:57Z
published: 2026-10-27T23:11:57Z
canonical: "ims-handbook.cenosco.com/rcm-systems-functions-and-functional-failures"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://ims-handbook.cenosco.com/llms.txt
> Use this file to discover all available pages before exploring further.

# RCM Systems - Functions and Functional Failures

The **Functions and Functional Failures** section allows you to define what a System is expected to do and identify the ways in which it can fail to meet those expectations. This information forms the basis of the Reliability-Centered Maintenance (RCM) analysis and supports the first three of the [seven RCM questions](/v414/docs/rcm-basics):

1. What are the functions and associated performance standards of the asset in its present operating context?
2. In what ways does it fail to fulfill its functions?
3. What causes each functional failure?

In IMS-RCM, the asset is represented by a System. Functions describe the intended performance of the System, while Functional Failures describe the states in which the System is unable to perform those functions. Failure Modes are then defined to identify the causes of each Functional Failure.

After defining the Functional Failures for a System, enter the Failure Modes for the prioritized Equipment that may cause each Functional Failure. These Failure Modes provide the basis for the subsequent RCM analysis.

A System can have multiple Functions, including both Primary Functions and Secondary Functions. These Functions and their associated Functional Failures are typically documented in the Terms of Reference (ToR) for the RCM study. Enter this information in IMS-RCM.

Expand the accordion below to view examples of Functions and Functional Failures from an [HDS RCM ToR](/v414/docs/rcm-analysis-term-of-reference-hds).

**Functions and Functional Failures from the HDS RCM ToR.**

#### Reaction section

**Function**

- Treat 17.2 t/h diesel
- Remove 99.9 % sulphur.

**Functional Failures**

- Diesel throughput falls below 17.2 t/h.
- Unable to heat the product to 350°C at 17.2 t/h.
- Unable to remove 99.9% sulfur.
- Product leakage with high H₂S content resulting in a plot clear.

#### Stripper section

**Function**

- Treat 17.2 t/h diesel.
- Remove 99.9 % sulphur/H₂S.

**Functional Failures**

- Diesel throughput falls below 17.2 t/h.
- Unable to heat the feed at reboiler to 170°C at 15.4 t/h.
- Unable to keep stripper top temperature at 35°C.
- Product leakage with high H₂S content resulting in a plot clear.

#### Recycle gas section

**Function**

- Feed H₂-rich gas to the high pressure feed stream.

**Functional Failures**

- Compressor fails to deliver discharge pressure at rated gas-flow (2400 Nm³/h).
- High H₂S content causes plot clear around the compressor (and off-spec purge gas).
- Product leakage with high H₂S content resulting in a plot clear.

> [!NOTE]
> Note
> 
> Before entering Functions and Functional Failures, ensure that at least one Production Loss Event (PLE) has been defined for the site. You can verify this under [Settings > Company > Top Level > Unit > TA & Prod Loss](/v414/docs/configuring-the-toplevel-via-settings#defining-production-loss-equations). A PLE is required when creating Functional Failures.

## Adding Functions and Functional Failures

You can add Functions and Functional Failures to a System in one of the following ways:

- Manually from the System Details page.
- By copying and pasting existing Functions and Functional Failures from another System.
- By importing a System using the import template.

### Manually Entering Functions and Functional Failures

To manually enter the Function and Functional Failures in the System Details page:

1. In the **Functions** section click the *Plus* button.

![](https://cdn.document360.io/e492a0e0-a4ba-4aca-8fc6-76b95f91fdf3/Images/Documentation/pic 1-DL0BQDKH.png?sv=2026-02-06&spr=https&st=2026-10-28T16%3A00%3A19Z&se=2026-10-28T17%3A00%3A19Z&sr=c&sp=r&sig=U5lDGrIMH1nhGmXdJpvwEqxHnGJ%2B7kfxAbDfEh73ymw%3D)

1. Fill in the Details of the Function.
2. Click **Save**.
3. Click the *Plus* button to launch a **New Functional Failure** dialogue.

![](https://cdn.document360.io/e492a0e0-a4ba-4aca-8fc6-76b95f91fdf3/Images/Documentation/pic 1-23CJ7PVP.png?sv=2026-02-06&spr=https&st=2026-10-28T16%3A00%3A19Z&se=2026-10-28T17%3A00%3A19Z&sr=c&sp=r&sig=U5lDGrIMH1nhGmXdJpvwEqxHnGJ%2B7kfxAbDfEh73ymw%3D)

1. Fill in the Functional Failure details.
2. Verify that a PLE is selected.
3. Optionally, provide additional information in the **Description** and **Consequence** fields.
4. Click **Save**.
5. Repeat the above steps to add more Functional Failures to the System.

![](https://cdn.document360.io/e492a0e0-a4ba-4aca-8fc6-76b95f91fdf3/Images/Documentation/pic 1-8BBKTF74.png?sv=2026-02-06&spr=https&st=2026-10-28T16%3A00%3A19Z&se=2026-10-28T17%3A00%3A19Z&sr=c&sp=r&sig=U5lDGrIMH1nhGmXdJpvwEqxHnGJ%2B7kfxAbDfEh73ymw%3D)

IMS-RCM allows PLEs from other units to be selected for a System. When a PLE from another unit is selected, a warning is displayed.

![](https://cdn.document360.io/e492a0e0-a4ba-4aca-8fc6-76b95f91fdf3/Images/Documentation/pic 1-DZYR8D3N.png?sv=2026-02-06&spr=https&st=2026-10-28T16%3A00%3A19Z&se=2026-10-28T17%3A00%3A19Z&sr=c&sp=r&sig=U5lDGrIMH1nhGmXdJpvwEqxHnGJ%2B7kfxAbDfEh73ymw%3D)

To view PLEs from other units, click **Show All** in the PLE selection list.

![F:\M080.04.jpg](https://cdn.document360.io/e492a0e0-a4ba-4aca-8fc6-76b95f91fdf3/Images/Documentation/pic 1-MYUD86VV.png?sv=2026-02-06&spr=https&st=2026-10-28T16%3A00%3A19Z&se=2026-10-28T17%3A00%3A19Z&sr=c&sp=r&sig=U5lDGrIMH1nhGmXdJpvwEqxHnGJ%2B7kfxAbDfEh73ymw%3D)

### Copying existing Functions and Functional Failures

You can copy Functions and Functional Failures from one System and paste them into another System. This is useful when multiple Systems share similar Functions and Functional Failures.

To copy the Function and Functional Failures in the System Details page:

1. In the desired **Functions** section, click the **Copy** button.
2. Choose the Functional Failures to be copied.
3. Open the target System.
4. Click **Paste** to add the selected Functions and Functional Failures

> [!NOTE]
> Note
> 
> Only Functions, Functional Failures, and associated PLEs are copied. Equipment and Failure Mode relationships are not included.

![](https://cdn.document360.io/e492a0e0-a4ba-4aca-8fc6-76b95f91fdf3/Images/Documentation/pic 1-YK2B6MXZ.png?sv=2026-02-06&spr=https&st=2026-10-28T16%3A00%3A19Z&se=2026-10-28T17%3A00%3A19Z&sr=c&sp=r&sig=U5lDGrIMH1nhGmXdJpvwEqxHnGJ%2B7kfxAbDfEh73ymw%3D)

### Importing Functions and Functional Failures

You can also use the System Import Wizard to create Systems and import their Functions and Functional Failures in a single operation.

For more information, see [RCM Systems - Creating / Importing](/v414/docs/rcm-systems-creating-importing).

## Adding Tags to Functional Failures

After adding Functions and Functional Failures to a System, you must add Tags to Functional Failures.

1. Go to the **Functions** section of the System details page and look for a **Functional Failure**.
2. Click the *Plus* button to launch the **Add Tags to Functional Failure** dialogue.
3. Select Tag to add to the Functional Failure.
4. Click **OK**.