FOAMGLAS® insulation systems for mitigating corrosion under insulation

The pipes and equipment that process or carry water, steam, gas and petrochemicals must perform reliably under harsh industrial and environmental conditions that can lead to CUI. The insulating material and system is an important decision to mitigate CUI. The FOAMGLAS® Sealed System and FOAMGLAS® Spacer System are designed to help protect piping systems at risk for corrosion.

When designing process facilities, the selection of the insulation system is an important factor. Improper choices can not only lead to underperforming insulation systems, but also contribute to issues associated with corrosion under insulation (CUI).

Consequences associated with CUI can include:

  • unanticipated failure of the process
  • damage to equipment
  • costly repairs
  • downtime
  • increased potential for leaks
  • even fire hazards

Selection of the appropriate type of insulation for the system design is significant for mitigating CUI.

About FOAMGLAS® Insulation 

FOAMGLAS® cellular glass insulation is a lightweight, rigid material composed of completely sealed cells.

This closed-cell structure provides a unique combination of physical properties ideal for piping and equipment below or above ground, indoors or outdoors. 

  • Impermeable
  • Non-absorbent
  • Non-combustible
  • Non-corrosive
  • Provides long-term thermal performance


The FOAMGLAS® Sealed System utilizes the impermeability of cellular glass insulation and our new, proprietary joint sealant to help keep moisture out of the system. 

Insulation joints are to be fully-sealed – from the exterior down to the pipe – using PITTSEAL® Hi-Temp LV RTV Sealant.  This one-part, neutral cure sealant is formulated for use with FOAMGLAS® Insulation Systems, and does not contribute to corrosion.

The lower viscosity of the sealant enables efficient spreading and sealing.  It cures to an elastomeric solid at room temperature.  The sealant has a wide service temperature range from -238ºF to 450ºF (-150ºC to 232ºC).*

The system seals the joints and compartmentalizes the insulation system components to help limit the spread of corrosion.  

* 450°F (232°C) is intermittent maximum service temperature limit. Continuous maximum operating temperature is 400°F (204°C).

Application of the FOAMGLAS® Sealed System for CUI Mitigation

Where to Specify*:

Where corrosion under insulation (CUI) is a concern and:

  • Below ambient applications with high vapor drive towards the pipe
  • Above ambient applications 
  • Underground or direct buried applications
  • Cyclical applications, or where frequent shutdowns may occur

*System not intended where continuous immersion is expected.


The FOAMGLAS® Spacer System utilizes proprietary spacer technology to create a 12mm (1/2 in.) air gap between the insulation and pipe.  This can help to minimize the potential for water to remain in contact with the pipe. If the system is breached, its compartmentalized design helps promote channeling of moisture away from the pipe to points where it can be drained from the system.

Where to Specify:
Where CUI is a concern and:

  • Where water intrusion is probable from secondary sources
  • Above ambient and hot systems with continuous or near continuous
  • Offshore or marine applications
  • Acoustical consideration is needed

    *Not intended for below ambient, cryogenic or cyclical use, direct buried or where continuous immersion is expected

System Features and Benefits:

  • Available for systems with continuous operating temperatures up to 200°C (392°F).
  • Supports heat tracing configurations
  • Compartmentalized and draining configurations
  • Compatible sealants and adhesives
  • Good acoustical properties*

* Acoustical configurations available to meet ISO 15665 Class A and B



PC® Silicone Spacer and Strip

The spacers and termination strips are molded from high-temperature, high-performance silicone from exclusive RTV technology. The geometry and shape is designed to help shed water away from the piping surface. Termination strips combined with the impermeability of cellular glass insulation allow the system to be compartmentalized every few feet.

PC® Hi-Temp RTV Adhesive

The spacers and termination strips are secured to the insulation using one-part, neutral cure, high-temperature silicone adhesive. It is formulated for use with FOAMGLAS®  Insulation Systems, and provides exceptional adhesion.

PITTSEAL® Hi-Temp LV RTV Sealant

FOAMGLAS® Spacer System joints are sealed using the same sealant technology as the FOAMGLAS® Sealed System.  This one-part, neutral cure, low-viscosity sealant efficiently spreads to help seal FOAMGLAS® insulation.


 Cellular Glass Insulation Systems for CUI Mitigation

Our Technical Service Engineer for the Industrial FOAMGLAS® business at Owens Corning discusses Cellular Glass insulation systems for CUI mitigation during this online webinar. 

The presence of moisture is necessary for corrosion under insulation (CUI) to occur. Two ways that can help to mitigate CUI are: keep water out of the system or give water a way out of the system. 

This webinar will describe the risk factors for CUI and two FOAMGLAS® cellular glass insulation systems designed to help address the control of moisture – the FOAMGLAS® Sealed System and the FOAMGLAS® Spacer System.

Watch to learn more about how these systems function, where to specify, accessory products, and technical/training resources available.

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