March 29th, 2023 – Vancouver, Canada – CharCoat Passive Fire Protection Inc., the global leader in Passive Fire Protection, specializing in Electrical Fire Protection, Firestopping & Insulation coatings specializes in stopping Corrosion under Insulation
Corrosion under insulation (CUI) is the corrosion of piping and vessels that occurs beneath insulation as a result of water penetration. The water can come from rain water, leakage, deluge system water, wash water, or sweating from temperature cycling or low temperature operation such as refrigeration units.
Unfortunately, because the corrosion is hidden under the insulation, CUI tends to remain undetected until the insulation is removed for inspection or when leaks occur. CUI is a common problem across many industries, including refining, petrochemical, power, industrial, onshore and offshore industries.
CUI can take place under any insulation. For corrosion to occur, the carbon steel must be directly contacted by aerated water and may be accelerated by other factors such as temperature or other contaminants. Water enters an insulated system primarily through breaks in the weatherproofing from sources such as:
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- Rainfall
- Drift from cooling towers
- Condensation on cold surface after vapor barrier damage (when the temperature of the steel surface is lower than the atmospheric dew point).
Contaminants can increase the rate of corrosion by increasing the conductivity and/or the corrosiveness of the water environment and reducing the protection offered by corrosion scale product.
Chlorides and sulphides are the principal contaminants of concern and can arise from sources external to the insulation or leached from the insulation itself. Testing and plant experience shows that chlorides most frequently come from external sources such as coastal atmospheres, nearby chemical process units, fire protection deluge systems etc rather than from the actual insulation.
Elevated temperatures typically result in increased corrosion rates in proportion to the temperature rise up to temperatures around 150C where the rate of corrosion starts to decrease.
What is CharCoat CTI?
CharCoat CTI can help save on running costs due to less demand for heating and air conditioning. Condensation and radiation properties also reduce maintenance cost, and You can even Insulate the hardest-to-reach areas. CharCoat CTI Ceramic Thermal Insulation can be applied at high temperatures – no need to stop production.
To know more about CharCoat CTI, click here to read – https://www.charcoat.com/ceramic-thermal-insulation/



Designing Against CUI
A properly designed insulation system puts into place barriers to CUI occurring. This generally entails attention to the following aspects:
a) The specification and application of the correct steel coating system is the most critical aspect of the system design as water may eventually ingress into many insulation systems at some stage (maybe due to external damage, maintenance actvities).
b) The insulation should resist water and not allow wicking between the insulation and the substrate and not contribute significantly to contaminants that may increase corrosion.
c) The weatherproofing must be designed to prevent ingress of water over all areas including penetrations, supports etc. and the integrity of the weatherproofing should be able to be inspected.
d) The design of the structure being insulated should such that potential for water entrapment or ingress is minimized. Special flashing designs and details should be considered for nozzles, support rings, brackets and other protrusions from the structure. Cladding systems should be water and weatherproof with a suitable vapor barrier.
Maintenance of the insulation system is vital to the long term control of CUI. In particular, degradation or damage to the weatherproofing or the steel protection system must be identified and repaired as soon as possible.



Stopping CUI
A properly designed insulation system puts into place barriers to CUI occurring. This generally entails attention to the following aspects:
a) The specification and application of the correct steel coating system is the most critical aspect of the system design as water may eventually ingress into many insulation systems at some stage (maybe due to external damage, maintenance actvities).
b) The insulation should resist water and not allow wicking between the insulation and the substrate and not contribute significantly to contaminants that may increase corrosion.
c) The weatherproofing must be designed to prevent ingress of water over all areas including penetrations, supports etc. and the integrity of the weatherproofing should be able to be inspected.
d) The design of the structure being insulated should such that potential for water entrapment or ingress is minimized. Special flashing designs and details should be considered for nozzles, support rings, brackets and other protrusions from the structure. Cladding systems should be water and weatherproof with a suitable vapor barrier.
Maintenance of the insulation system is vital to the long term control of CUI. In particular, degradation or damage to the weatherproofing or the steel protection system must be identified and repaired as soon as possible.


Download to get more information on CharCoat CTI.
Title | Description | Size | Hits | Download |
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Charcoat CTI TDS April 2023 | 269.68 KB | 24 | DownloadPreview | |
Charcoat CTI Brochure - Feb 2023 | 6.23 MB | 40 | DownloadPreview | |
Charcoat CTI-600 TDS April 2023 | 253.19 KB | 16 | DownloadPreview | |
Charcoat CTI-450 TDS Feb 2023 | 1.53 MB | 16 | DownloadPreview | |
Charcoat CTI-300 TDS April 2023 | 256.42 KB | 15 | DownloadPreview | |
Charcoat CTI-300 J-Green TDS April 2023 | 266.37 KB | 11 | DownloadPreview | |
Charcoat CTI-120 TDS April 2023 | 253.31 KB | 21 | DownloadPreview |