How to mitigationg Vessel CUI

Mitigating vessel corrosion under insulation (CUI) using spacers and drain plugs involves creating a non-contact, self-draining system. Spacers break the direct contact between wet insulation and the vessel wall, while drain plugs installed at low points provide a clear egress path for trapped moisture to escape.

Designing with Spacers

• Physical Separation: Install high-temperature resistant polymeric or stainless steel spacers (such as molded silicone or PPS elements) directly onto the vessel surface or integrated with the insulation to maintain a uniform air gap.
• Eliminating Pockets: Prevent stagnant water collection at critical stress points, stiffener rings, and shell transitions by using specialized standoff profiles.
• Compartmentalization: Segment the air gap into smaller isolated sections using sealing strips so that any moisture ingress from a localized jacket breach stays confined rather than spreading across the entire vessel.

Installing and Managing Drain Plugs

• Low Point Placement: Position drain/breather plugs at the absolute lowest elevation points of the vessel’s external metal jacketing and at all insulation stops.
• Creating Egress Paths: Use specialized, non-combustible drainage plugs (such as those made from Polyphenylene Sulfide) that pierce through the outer cladding and insulation to connect with the inner air gap.
• Sizing and Maintenance: Adjust the length of the drain plug shaft to terminate just short of the vessel wall, ensuring water exits freely without scratching or damaging the exterior protective coating underneath.

  Mitigating vessel corrosion under insulation (CUI) using spacers and drain plugs involves creating a non-contact, self-draining system. Spacers break the direct contact between wet insulation and the vessel wall, while drain plugs installed at low points provide a clear egress path for trapped moisture to escape.

  Designing with Spacers

• Physical Separation: Install high-temperature resistant polymeric or stainless steel spacers (such as molded silicone or PPS elements) directly onto the vessel surface or integrated with the insulation to maintain a uniform air gap.
• Eliminating Pockets: Prevent stagnant water collection at critical stress points, stiffener rings, and shell transitions by using specialized standoff profiles.
• Compartmentalization: Segment the air gap into smaller isolated sections using sealing strips so that any moisture ingress from a localized jacket breach stays confined rather than spreading across the entire vessel.

• Installing and Managing Drain Plugs

• Low Point Placement: Position drain/breather plugs at the absolute lowest elevation points of the vessel’s external metal jacketing and at all insulation stops.
• Creating Egress Paths: Use specialized, non-combustible drainage plugs (such as those made from Polyphenylene Sulfide) that pierce through the outer cladding and insulation to connect with the inner air gap.
• Sizing and Maintenance: Adjust the length of the drain plug shaft to terminate just short of the vessel wall, ensuring water exits freely without scratching or damaging the exterior protective coating underneath.