---
title: "Age-Related and Non-Age-Related Failure Characteristics"
slug: "age-related-and-non-age-related-failure-characteristics-theory"
tags: ["PEI", "S-RBI", "Theory"]
status: "update"
updated: 2026-10-27T23:11:38Z
published: 2026-10-27T23:11:38Z
canonical: "ims-handbook.cenosco.com/age-related-and-non-age-related-failure-characteristics-theory"
---

> ## 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.

# Age-Related and Non-Age-Related Failure Characteristics

As mentioned in [Degradation Classification](/v414/docs/degradation-classification-theory), the DMs can be classified in terms of the failure characteristics (see the figure below):

- Age-Related (AR) failures (e.g., Pitting, [general Corrosion](/v414/docs/corrosion-and-remnant-life)), and
- Non-Age-Related (NAR) failures (e.g., Cracking).

Strategy Based (SB) failures fall in a third category which are closely related to NAR failures. Corrosion Under Insolation (CUI) is currently the only predefined Strategy Based failure in IMS.

![A screenshot of a cell phone  Description automatically generated](https://cdn.document360.io/e492a0e0-a4ba-4aca-8fc6-76b95f91fdf3/Images/Documentation/age-related-and-non-age-related-failure-characteristics-image-g17j7g35.png?sv=2026-02-06&spr=https&st=2026-10-28T13%3A39%3A18Z&se=2026-10-28T14%3A39%3A18Z&sr=c&sp=r&sig=dws47R7k%2F6TZFC%2BbEkGRXHnpliU3pnbF7%2BNd5GxCSkE%3D)

Degradation Mechanisms can be classified in terms of failure characteristics.

The table below outlines the AR and NAR failure characteristics.

<editor360-custom-block data-preprocessing="true" data-sanitizationtags="a"><p><a></a>Age-Related vs Non-Age-Related failures:</p></editor360-custom-block>

| Age-Related failures | Non-Age-Related failures |
| --- | --- |
| The Degradation Mechanism (DM) has been designed in. Damage is controlled through Barrier management and verification. | The control of DM should be addressed in the design; Barriers are designed in. |
| It progresses at a steady rate within operating limits. | Time is not relevant. Occurrence is random when operating outside limits. |
| Time to failure should be known. - Corrosion: - Corrosion Rate (CR) - Corrosion Allowance (CA) / Allowable Wall Loss (Barrier) - Creep - Low Cycle Fatigue or Cyclic Loading | Time to fail strongly depends on process upsets/excursions. |
| Design life is known. |  |
| Progress can be quantified and (Barrier) verified. | Rapid progress possible once initiated: - Stress corrosion cracking - Short term overheating |
| Failure acceptable within normal design envelope. | Occurrence of failures not acceptable within normal design envelope. Emphasis is on control of the Integrity Operating Window (IOW). |
| Verification is done through inspection and IOW monitoring. | Verification is done through IOW monitoring and *opportunity* inspection. |
| The ***outcome of an AR RBI Analysis*** is always a Next Inspection Date (NID). | The ***outcome of a NAR RBI Analysis*** is typically a Maximum Inspection Interval (MII) or an Inspection Strategy (IS). |

> [!NOTE]
> Take Note
> 
> To learn more about the detailed Degradation Mechanisms used in IMS, see: [Degradation Modules Overview](/v414/docs/degradation-modules-1).