When it comes to insulating your pipes, there are any factors to take into consideration. Take temperature, for instance. How hot are your pipes? Imagine your thermos of coffee – it does a great job of keeping your java piping hot all day long. But pour in some super-heated liquid at 1,000 degrees F and watch your thermos melt away into a puddle of plastic. Different insulation materials are made for different temperatures, both for the covering material and the insulation material itself.
The insulation industry typically divides covering materials for insulation into three temperature buckets: 450 degrees F and less, 450 to 550 F, and over 550 F. High heat applications are those that are 450 degrees F and hotter.
- Up to 450 degrees F: The covering material for this temperature range is a silicone impregnated fiberglass cloth (fiberglass / silicone composite) on the outside covers of the insulating jacket. Remember, this is not a high heat application, so the same material is used on both the "hot" side and the "cold" side. The hot side is usually the one that is inside (near the pipe, for example) and the cold side would be the outer portion of the cover. A steam room for heating is a typical situation with this level of heat.
- 450 to 550 F: At these temperatures (now considered high heat), a TEFLON / fiberglass composite is used on the hot side. This material has a higher temperature limit, while still being less expensive than the next hot step up. The fiberglass / silicone composite can still be used on the cold side, in most situations. However, there are some instances where the TEFLON / fiberglass composite would also be used on the cold side. The decision depends on the atmosphere – if the application is in a chemical plant that has a very acidic, corrosive atmosphere, the TEFLON / fiberglass covering is used on both sides. This way the pH of the atmosphere does not eat away at any of the covering. A good example of an application at this temperature would be super-heated steam for turbines in power plants.
- 550+ F: There are several options at this temperature level, including a plain fiberglass cloth, a stainless steel mesh or a silica based cloth. All of these options are slightly more expensive than the TEFLON / fiberglass covering. The real tradeoff, however, is that they do not have any water or abrasion-resistant coating. This is a problem, because sometimes you get leaks in pipes, and the water-resistance coating keeps the insulation from getting wet. Once wet, the insulation is ruined. These particular cloths are used for the hot side of the insulation jacket. For the cold side, the TEFLON / fiberglass composite or the silica based cloth can be used. If the TEFLON / fiberglass composite is used, there is the added benefit of the water- and abrasion-resistant coating. However, the silica based cloth is often chosen for its versatility in high temperature applications. An example of an extremely high temperature application is an emergency generator, like you would see at a hospital (where people can not afford to see their bedside equipment turn off when the local power company has an outage).
While the industry divides the materials into three temperature ranges, there are only two categories for the actual insulation: up to 1,200 degrees F and more than 1,200 degrees F.
- Up to 1,200 degrees F: In this temperature range, needled fiberglass insulation is used. Needling is the process of sticking actual needles into the fiberglass, resulting in a mechanical bond among the fibers. This is in contrast to resinous or inorganic binders that can deteriorate under high heat or shake apart in vibrating applications.
- 1,200+ F: For any applications that reach temperatures above 1,200 F, a needled amorphous silica insulation is used.