---
title: "Amine Stress Corrosion Cracking"
slug: "amine-stress-corrosion-cracking-1"
updated: 2026-10-27T23:12:43Z
published: 2026-10-27T23:12:43Z
canonical: "ims-handbook.cenosco.com/amine-stress-corrosion-cracking-1"
---

> ## 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.

# Amine Stress Corrosion Cracking

## Summary

Amine stress corrosion cracking (also known as amine cracking or amine SCC) is a specific form of alkaline stress corrosion cracking that can occur in carbon steel or low-alloy ferritic steels exposed to aqueous solutions containing alkanolamines. The cracking is predominately branched and intergranular, and typically occurs as a network of very fine, corrosion product filled cracks. Amine cracks are usually located parallel to welds in adjacent base metal, but may also be found in the weld deposit or the heat-affected zones of welds that have not been postweld heat treated. Amine cracking has also occurred in highly cold-worked bends or components that were not given a stress-relieving heat treatment after fabrication. Susceptibility to amine cracking depends on the amine solution characteristics (type of amine, amine concentration, type and level of impurities, and temperature) and the level of tensile stress (residual and applied) present.

### Detailed Guidance

For detailed Guidance, see the attached PDF. A summary of the information, as it pertains to use in IMS is shown below.

[PDF document](https://cdn.document360.io/e492a0e0-a4ba-4aca-8fc6-76b95f91fdf3/Images/Documentation/CEN.16.10634%20-%20Amine%20Stress%20Corrosion%20Cracking%20Degradation%20Module%20rev%200.pdf?sv=2026-02-06&spr=https&st=2026-10-28T13%3A38%3A35Z&se=2026-10-28T14%3A38%3A35Z&sr=c&sp=r&sig=JfNXD8WgLAEymvGxDHMkqYCMoe7qXDSbVzrj8Qw%2FOhc%3D)

<editor360-custom-block data-preprocessing="true" data-sanitizationtags="a"><h2><a></a><a></a>Parameters Affecting IOW – Step 2</h2></editor360-custom-block>

See [Step 2](/v414/docs/step-2-identify-threats-and-barriers-define-the-cl-1).

See below the relevant parameters affecting amine SCC severity and, also, an indication of those that should be included in the IOW.

<editor360-custom-block data-preprocessing="true" data-sanitizationtags="a"><p><a></a><a></a>Amine SCC Parameters affecting severity &amp; IOW:</p></editor360-custom-block>

| Parameter | Influence | IOW |
| --- | --- | --- |
| Material | Carbon & low alloy steels |  |
| Type of amine | Determine what type of amine is being handled in this Equipment/piping. |  |
| Amine solution composition | Fresh amine has not been exposed to H2S or CO2. Lean amine contains low levels of H2S or CO2. Rich amine contains high levels of H2S or CO2. For Equipment exposed to both lean and rich amine solutions (i.e., amine contactors and regenerators), indicate lean. | Yes |
| Maximum Process Temperature | Determine the maximum process temperature in this Equipment/piping. This is an indication of metal temperatures. Under special conditions, the metal temperature may be higher! Note: Lean amine tank temperature should stay below 37°C (98°F) and upstream process temperature monitored. | Yes |
| Heat traced? (Yes or No) | Determine whether the Equipment/piping is steam-traced or electric-traced (e.g., for freeze protection). |  |
| Steamed out? (Yes or No) | Determine whether the Equipment/piping has been steamed out prior to water flushing to remove residual amine. |  |
| Stress Relieved? (Yes or No) | Determine whether the Equipment/piping has been properly stress relieved after welding and cold forming. |  |

<editor360-custom-block data-preprocessing="true" data-sanitizationtags="a"><h2><a></a><a></a>StF – Step 7</h2></editor360-custom-block>

See [Step 7](/v414/docs/step-7-determine-susceptibility-to-failure-stf-1).

Susceptibility to amine cracking depends on the amine solution characteristics (type of amine, amine concentration, type and level of impurities, and temperature) and the level of tensile stress (residual and applied) present.

#### Not Susceptible:

- Not exposed to lean Amine; or
- Stress Relief Heat Treated, and appropriate guidelines are followed.

#### Low Susceptibility:

- Stress Relief Heat Treated, but appropriate guidelines are not followed.

#### Else:

If not Stress Relief Heat Treated, then further consider the below-mentioned parameters (as well as the Parameters table above in Step 2) to determine the Susceptibility:

*Type of Amine*: The likelihood is very dependent on the amine type. Cracking is most prevalent in MEA systems, with the likelihood decreasing according to MEA -> DIPA -> DEA -> MDEA -> DGA -> Sulfinol.

*Amine Concentration*: Increasing the concentration of the amine reduces the likelihood of amine cracking. Amine cracking typically occurs in lean amine solutions, which are alkaline and contain relatively low levels of acid gases along with other impurities.

*Impurities*: The presence of CO2 or other corrosive impurities in the lean amine solution is considered essential for cracking to occur.

*Temperature*: Cracking is most pronounced at the highest temperatures in amine treating units, e.g., 115°C (240°F) and above. Amine cracking has however been reported at ambient temperatures in many MEA systems, and in low concentration (15-20%) DIPA systems. Note: The metal temperature is most important, not the normal process temperature. *Heat-traced* /*steamed-out* Equipment may experience higher metal temperatures (even if operating at low temperatures) and will therefore have a higher likelihood of cracking.

*Stress Relieve Heat Treated*: Amine cracking is controlled primarily by application of a stress-relieving heat treatment to reduce tensile stresses. If appropriate stress relieve guidelines are followed, the likelihood of cracking will be low (e.g., API RP 945 specifies for what type of amine and at which temp should post-weld heat treatment (PWHT) be applied). Note: It is however common practice to still stress relieve steel Equipment and piping that are normally operating below the guideline temperatures if they are *heat-traced* /*steamed-out*.

*Guidelines*: If the appropriate guidelines (e.g., NACE and API RP 945) are followed, the likelihood of cracking will be low.

<editor360-custom-block data-preprocessing="true" data-sanitizationtags="a"><h2><a></a><a></a>Confidence – Step 10</h2></editor360-custom-block>

See [Step 10](/v414/docs/step-10-assess-the-confidence-1).

Follow the guidance below to determine answers for an amine SCC Confidence Assessment.

Amine SCC Confidence Assessment Guidance:

| Key Questions | Guidance |
| --- | --- |
| Degradation mechanism can be properly controlled. | - "Yes": Process stability, e.g., no temperature excursions, confirmed and stable amine strength, known maintenance condition of steam tracing (or no tracing). - "Intermediate": E.g., unknown maintenance condition of steam tracing. - "No": High likelihood of operating conditions that cause cracking. |
| Relevant process parameters are reliably monitored. | - "Yes": All relevant process variables known and actively monitored. - "Intermediate": Relevant process variables known but not actively monitored. - "No": No IOW available. |
| Reliable inspections were carried out. | - "Yes": 3 inspections above “usually effective”. - "Intermediate": 1 – 2 inspections above “usually effective”. - "No": No inspections or ineffective inspections. |

<editor360-custom-block data-preprocessing="true" data-sanitizationtags="a"><h2><a></a><a></a>Required Inspection Effectiveness – Step 11 &amp; Step 12</h2></editor360-custom-block>

See [Step 11](/v414/docs/step-11-review-the-results-nid-mii-is-inspection-effectiveness) and [Step 12](/v414/docs/step-12-assign-s-rbi-results-to-inspectioncorrosion-schedules-andor-update-monitoring-plan).

Use the Required Inspection Effectiveness, determined in [Step 11](/v414/docs/step-11-review-the-results-nid-mii-is-inspection-effectiveness), to determine the Inspection technique and coverage. See below examples of highly and usually effective inspections.

Amine SCC examples of highly and usually effective inspections:

| Required Inspection Effectiveness | Intrusive Inspection | Non-Intrusive Inspection |
| --- | --- | --- |
| A – Highly effective | WFMPT or ACFM of 50–100% of welds/cold bends in susceptible areas - as identified by a corrosion / materials engineer or other knowledgeable specialist. | None |
| B – Usually effective | WFMPT or ACFM of 20–49% at welds/cold bends in susceptible areas - as identified by a corrosion / materials engineer or other knowledgeable specialist. | Shear wave ultrasonic testing of 50-100% of welds/cold bends, OR Acoustic Emission testing with follow-up shear wave ultrasonic testing |