Keeping water out of a metal jacketing system
Water ingress into any thermal insulation system that is always a problem from the pipe upwards were CUI is the biggest threat. Layers of insulation are covered with vapour barriers with the joint taped to prevent water ingress. The aim is always to keep water out that will cause damage to mineral wool, phenolic, aerogel and most other thermal insulation materials.
Although there is always a worry about water getting to the pipe and causing corrosion one issue long before this happens is thermal efficiency. Water has a thermal conductivity up to 20 times higher most insulation materials, as a result any water ingress will severely hamper the performance of the system.
Firstly, it’s important that the correct material is selected not just the grade of material but strength and rigidity this will lead to a better fabrication. This selection will depend on the outside diameter of the piping or tank size. There are a variety of ways metal jacketing joints can be formed, a common method is to roll the cladding into pipe sections with a small gap, these are opened up to fit around the insulated section then closed up with an overlap of around 50mm (2”) . The overlap is bonded with a metal sealant such as a Foster product then banded tightly and fixed securely with wing seals. This is when workmanship is key, there are many horror stories of low cost modular builds resulting in failures costing millions. Ensuring the metal has a moisture barrier made from Surlyn® on the inside is also key.
Another popular way of joining metal jacketing and cladding widely used for tanks is blind riveting, the term is used as the reverse side of the rivet cannot be seen. This method has been popular and widely used for many years. The issue with this especially for stainless steel is standard blind rivets also referred to as pop rivets. These rivets sadly let in water as our video clearly shows when submerged under 1 metre of water. The answer is waterproof rivets these are a cup sealed rivet this means not only is the rivet itself sealed securely as a backup a small oil resistant gasket is enclosed, this ensures they are 100% waterproof even under 1 metre of water. Recently we have also found these can be used for fire resistance as they stop smoke penetrating through any gaps compared to standard rivets.
So combining the right materials, good workmanship and some innovative new products will mean the metal jacketing can deliver a durable and waterproof insulation system for many years.