CUI prevention 3

[ak1965]

1. Which is the best method available & suggested for inspection of Corrosion Under Insulation in a chemcial process plant?

2. Is it advisable to coat the pipes, drains & vents lines of a hazardous piping system before insulating? how long the high temp coating survive normally.

3. To my knowledge, CUI occurs in the temperature range of -12 Deg.C to +175 Deg.C in Carbon Steel & Alloy Pipes & between +60 till +250 Deg C in SS pipes. I feel any painting/coating system working in this range should be useful to protect pipes from CUI attacks.

 

[SJones]

1. The best method is the one that will give the best results for the material, conditions, cost and safety requirements
2. If the risk of CUI is reduced to an acceptable level by so doing, then it would be advisable.
3. NACE SP0198 and EFC Publication 55 discuss the issue in detail.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[gr2vessels]

Just a small addition: API 570 is the piping inspection code.
API 570 specifies the following areas as susceptible to CUI:
Areas exposed to mist over-spray from cooling water towers.
Areas exposed to steam vents.
Areas exposed to deluge systems.
Areas subject to process spills, ingress of moisture, or acid vapors.
Carbon steel piping systems, including those insulated for personnel protection, operating between 25°F and 250°F (-4°C and 120°C). CUI is particularly aggressive where operating temperatures cause frequent condensation and re-evaporation of atmospheric moisture.
Carbon steel piping systems that normally operate in-service above 250°F (120°C) but are intermittent service.
Deadlegs and attachments that protrude from insulated piping and operate at a temperature different than the active line.
Austenitic stainless steel piping systems that operate between 150°F and 400°F (60°C and 204°C). These systems are susceptible to chloride stress corrosion cracking.
Vibrating piping systems that have a tendency to inflict damage to insulation jacketing providing a path for water ingress.
Steam traced piping systems that may experience tracing leaks, especially at the tubing fittings beneath the insulation.
Piping systems with deteriorated coatings and/or wrappings.
Locations where insulation plugs have been removed to permit thickness measurements on insulated piping should receive particular attention.

 

[sentjoh]

Steve is referring to the best, in my opinion, available documents.
For the record, the EFC CUI guideline is currently being updated. Part of this update is a more extensive description of insulation. One of the often underestimated influences of CUI failures.
I also would like to recommend the CINI manual for industrial insulation:

http://www.CINI.nl

Regards,

Johan Sentjens

http://www.linkedin.com/in/johansentjens