---
title: "Doing an EVA"
slug: "doing-an-eva"
updated: 2026-10-27T23:11:52Z
published: 2026-10-27T23:11:52Z
canonical: "ims-handbook.cenosco.com/doing-an-eva"
---

> ## 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.

# Doing an EVA

![](https://cdn.document360.io/e492a0e0-a4ba-4aca-8fc6-76b95f91fdf3/Images/Documentation/pic%201(329).png?sv=2026-02-06&spr=https&st=2026-10-28T13%3A36%3A53Z&se=2026-10-28T14%3A36%3A53Z&sr=c&sp=r&sig=PNeKgL1NBlcvh3XCBk2u5UaY6zANnKCedSvot%2BNvO3A%3D)Doing the EVA.

You are ready to start the Extreme Value Analysis when:

- EVA is activated;
- The CMLs have measurements;
- The Nominal WT and Renewal thickness are filled in for all the CMLs with measurements; and
- The Equipment has a start date.

(See [Preparing for an EVA](/v414/docs/preparing-for-an-eva).)

## Open the EVA Page

To open the EVA page:

- Click on the EVA button.![](https://cdn.document360.io/e492a0e0-a4ba-4aca-8fc6-76b95f91fdf3/Images/Documentation/doing-an-eva-image-sxbberey.png?sv=2026-02-06&spr=https&st=2026-10-28T13%3A36%3A53Z&se=2026-10-28T14%3A36%3A53Z&sr=c&sp=r&sig=PNeKgL1NBlcvh3XCBk2u5UaY6zANnKCedSvot%2BNvO3A%3D)EVA button.
- You are directed to the EVA page.

## Define Stratification(s)

ImportantAt least one Stratum is required to do an EVA calculation. 

Note: It is recommended to use 20-30 tubes per Stratum. More than this can lead to non-conservative estimates.

To define the Stratifications:

- First, create a Default Stratum for all CMLs:
  - Select the CMLs in the CML grid or hold <Ctrl> and select the CMLs directly from the HX Overview.
  - Click the *Stratification* button on the CML toolbar (small EVA icon) & fill in the New stratum name.
  - Click **Confirm**.![](https://cdn.document360.io/e492a0e0-a4ba-4aca-8fc6-76b95f91fdf3/Images/Documentation/doing-an-eva-image-o5qm2kdt.png?sv=2026-02-06&spr=https&st=2026-10-28T13%3A36%3A53Z&se=2026-10-28T14%3A36%3A53Z&sr=c&sp=r&sig=PNeKgL1NBlcvh3XCBk2u5UaY6zANnKCedSvot%2BNvO3A%3D)Stratification button.![](https://cdn.document360.io/e492a0e0-a4ba-4aca-8fc6-76b95f91fdf3/Images/Documentation/doing-an-eva-image-e86ykybq.png?sv=2026-02-06&spr=https&st=2026-10-28T13%3A36%3A53Z&se=2026-10-28T14%3A36%3A53Z&sr=c&sp=r&sig=PNeKgL1NBlcvh3XCBk2u5UaY6zANnKCedSvot%2BNvO3A%3D)Stratification window.
- Look at the Histogram below the CMLs (and change the Step Value if desired). This gives an indication of the measurement spread.

ImportantFor each Stratum one should aim for a homogenous spread, i.e., only CMLs or tubes subject to the same Degradation Mechanisms and thus corrosion behavior.

- If required, create more Stratums:
  - Select desired CMLs.
  - Click the *Stratification* button to define / redefine a Strat.
- Review the Histograms (per Strat) again.

![](https://cdn.document360.io/e492a0e0-a4ba-4aca-8fc6-76b95f91fdf3/Images/Documentation/doing-an-eva-image-f9f7qf8i.png?sv=2026-02-06&spr=https&st=2026-10-28T13%3A36%3A53Z&se=2026-10-28T14%3A36%3A53Z&sr=c&sp=r&sig=PNeKgL1NBlcvh3XCBk2u5UaY6zANnKCedSvot%2BNvO3A%3D)Histogram with homogeneous data. You can change the Step value.

## Run the EVA Calculations

To run the EVA calculations:

- Press the *Calculate* button at the top of the EVA page.

![](https://cdn.document360.io/e492a0e0-a4ba-4aca-8fc6-76b95f91fdf3/Images/Documentation/doing-an-eva-image-wxxoznf3.png?sv=2026-02-06&spr=https&st=2026-10-28T13%3A36%3A53Z&se=2026-10-28T14%3A36%3A53Z&sr=c&sp=r&sig=PNeKgL1NBlcvh3XCBk2u5UaY6zANnKCedSvot%2BNvO3A%3D)EVA *Calculate* button.

- IMS will fit a Gumbel distribution for every Strat and do an extrapolation in space.
- When the calculation is done, the EVA Calculation Charts grid will be populated - one row for each Strat, showing CR, etc.

## Review the Results

Now it is time to [review the results](/v414/docs/review-the-eva-results).