Water isn’t welcome inside an insulation system, so get it out – and fast – with the help of Johns Manville’s Cross-Flo Jacketing. This new product is perfect for industrial and mechanical insulation systems, helping to expel unwanted water.
Cross-Flo is a protective metal jacketing system with an embossed pattern designed to promote cross-directional flow. This provides a path for liquid that may enter the insulation system to reach the low point and exit the jacketing through a weep hole or drainage port.
In fact, in testing, Cross-Flo Jacketing drained 80% faster than smooth metal jacketing after one hour! There are so many opportunities to use Cross-Flo. It is recommended for indoor or outdoor applications up to 8 feet in diameter, and can be used on all pipe as well as vertical and horizontal tanks.
Corrosion Under Insulation (CUI)
CUI is a huge concern for engineers and specifiers in the industrial sector. Despite insulation systems being designed to deter water ingress, infiltration is almost inevitable. Even though JM’s industrial products are water resistant or hydrophobic (and the rigid insulations also have a corrosion inhibitor), impurities present in water can interact with metal piping and lead to corrosion. CUI is difficult to detect, which can lead to catastrophic consequences.
When does CUI occur?
• During construction and temporary shutdowns
• Through improper installation or damage during normal operation
• With exposure to water from rain, storms or improper storage
What's the Impact?
• Refineries can face lengthy downtimes
• Costly repairs
Cross-Flo™ Jacketing is a unique innovation developed by JM for ambient and hot systems. It has an embossed pattern engineered to promote cross-directional flow (CDF), thereby providing a path for liquid that may enter the insulation system to reach the low point and exit the jacketing through a weep hole or drainage port.
Although insulation systems are designed to deter water ingress, there are many ways by which water may enter a system undetected, which may lead to corrosion under insulation (CUI). Cross-Flo Jacketing reduces the risk of CUI by minimizing the time water remains in the system.
Weep holes allow any moisture trapped between the pipe and the metal jacketing to escape. JM recommends the use of a weep hole or drainage port in conjunction with Cross-Flo Jacketing to maximize efficacy and reduce the risk of CUI.
Additional Protection Layer
To test the efficacy of Cross-Flo Jacketing, JM’s team conducted a small simulation test during which 100mL of water was allowed to drain through representative insulated pipe sections jacketed with Cross-Flo, smooth, and stucco embossed patterns. Tested insulation types included calcium silicate, perlite, mineral wool, and aerogel.
Cross-Flo significantly improved the drainage rate compared to smooth and stucco embossed, regardless of insulation choice. These results emphasize the design flexibility available when choosing Cross-Flo Jacketing for CUI protection.
Why is Cross-Flo jacketing better than other jacketing patterns?
- Stucco-embossed patterns are not deep enough to allow for effective water drainage.
- Unlike cross-crimped jacketing, CDF promotes drainage almost equally well in any installed direction. Cross-crimped jacketing drains quickly when the open space between the jacketing and the insulation is oriented vertically, but halts water drainage when oriented horizontally.
Does Cross-Flo jacketing require any changes to overall system design?
In systems at risk of CUI, JM strongly recommends that Cross-Flo jacketing is installed in conjunction with weep holes, to provide anegress point for moisture. JM’s internal testing was completed with ¾” circular weep holes; specific system configurations should be designed by a qualified engineer.
Why are hydrophobic or water-repellent insulations alone insufficient to protect against CUI?
Although hydrophobic materials themselves repel water, all insulation types have seams, and water may ingress through system damage over time. Additionally, water-repellent treatments may be susceptible to degradation over time, due to burn-off or other factors. Regardless of the type of insulation used, the longer water is allowed to remain in the system, the higher the likelihood it will reach the metal surface of the pipe and result in CUI.
Can I use Cross-Flo jacketing solely for aesthetics, i.e. without a weep hole?
Where CUI is not a concern, Cross-Flo jacketing can be used without a weep hole for aesthetic purposes.
Does Cross-Flo have a polyfilm moisture barrier?
Yes, Cross-Flo jacketing comes standard with the same 3mm polyfilm moisture barrier present on all JM metal jacketing products.
Which insulation types can Cross-Flo jacketing be used with?
Cross-Flo jacketing is effective over all insulation types, rigid and non-rigid.
Read all FAQ's here
Insulation Intel® Infographic: An Overview of the Mechanism and Longevity of the XOX Corrosion Inhibitor®
Technical Bulletin: Metal Corrosion Under Thermal Insulation
Technical Bulletin: Stress Corrosion Cracking of Stainless Steel
Technical Bulletin: Insulation Coating Vs. Traditional Insulation
Polyfilm Moisture Barrier (PFMB) Data Sheet