Avoiding Mechanical Insulation Damage
Mechanical insulation comes in 3 basic classifications: cellular, fibrous, and granular. These range in form from flexible to rigid, and even what is considered to be load bearing. Mechanical insulation materials vary in physical properties, such as use temperature and moisture resistance, among other factors. However, they all have 2 properties in common: thermal resistance and susceptibility to damage by human contact or by Mother Nature. This article will discuss the most common ways in which mechanical insulation is damaged and what can be done to prevent it from happening.
Before discussing how mechanical insulation can be damaged, it is worthwhile to investigate how frequently this damage tends to happen. Mechanical insulation applications can be broken down into 2 main categories: commercial and industrial, which can be further broken down into indoor and outdoor applications. The systems that use insulation can broadly be categorized as above-ambient (hot) or below-ambient (cold) systems. Most insulation that is installed indoors in commercial applications will not get damaged. It is often installed in a wall, plenum area, or a location that never encounters human contact. The vast majority of commercial jobs are indoors. Thus, most commercial jobs, if installed correctly, will easily last more than 25 years with little or no maintenance. The one area where damage can occur in indoor commercial applications is in mechanical rooms. If maintenance personnel are working on the equipment, they may damage the insulation by climbing on it, leaning ladders against it, laying tools on it, etc. Examples of commercial applications where insulation is installed outdoors and requires special considerations and jacketing include roof-top duct work, refrigeration piping in supermarkets, and rooftop chilled water systems that may be found in hospitals, universities, and commercial business campuses.
Industrial jobs, on the other hand, can vary greatly, with 85% or more of the insulation located outdoors and subject to damage from weather conditions. Combine this potential with the frequent circumstance of having personnel working around the piping, and these applications become much more susceptible to damage. The increased likelihood of damage that comes with an outdoor industrial application must be taken into consideration during the system design if it is going to perform for a long period of time. The benefit of mechanical insulation is that it has few or no moving parts (expansion/contraction joints being an exception), does not need to be oiled, and it does not need to have any batteries changed. When properly designed and installed, it is capable of doing its job—optimizing system operations and saving money and energy—for many years with minimal pkeep.
For a mechanical insulation material to perform for more than 25 years, it must be engineered correctly for the specific application (use, temperature, environment, proper thickness, etc.) and it must be installed properly (sealing all seams, joints, and termination points from moisture). Completing these 2 processes satisfies nearly all of the work required for an installation that will last for more than 25 years. In the engineering field, it is somewhat common for a project to be described as “over engineered,” but that is rarely the case for mechanical insulation. Mechanical insulation is sometimes an afterthought, and the same specification may be used repeatedly for every job, which fails to take into account the specific needs of the application and its environment. Fortunately, engineering the job correctly is fairly simple, and just requires a measure of common sense and attention to detail. For example, if stainless steel jacketing is specified, stainless steel screws must be used to fasten it. Regular screws will rust over time and the jacketing will fail prematurely, resulting in damaged insulation. For a below-ambient system with a vapor barrier, it is important to specify that NO screws are used, that the jacketing has curled edges, and is banded. It is better to put more money in the right materials up front than to pay again for labor and materials to repair it later when it will probably be more difficult to access, or would require a system shut down.
Another easy way to keep your system in perfect condition is to protect your investment from the start. The most common way mechanical insulation is damaged is by human contact: walking on the insulation, leaning ladders against it, or climbing on it. A crushed system is a compromised system. The most common time this happens is during the construction process. Other trades come after the insulation has been installed and may damage the insulation while they are completing their portion of the project.
Jacketing the insulation with metal, polyvinyl chloride (PVC), or a polymeric/metal foil laminate type jacketing will improve its resistance to damage, but does not make it damage proof. Some engineers will require insulation that resists damage or jacketing on all piping that is at ground level up to 8 feet in the air; anything over that is not required to be jacketed to avoid this type of damage. It should be noted that all-service jacket (ASJ) and foil-scrim-kraft (FSK) are integral parts of many kinds of insulation (e.g., fiber glass), but are not protective jacketing systems designed specifically for abuse protection. A jacket should be installed in cases where insulation is being replaced after being crushed under foot traffic. Even with a jacket, however, abuse such as stepping on and leaning equipment on insulation will likely damage the jacketing or underlying vapor barrier, which could ultimately lead to damaged insulation and piping.
Mother Nature can be hard on mechanical insulation that is installed outdoors. Specifying the correct type of jacket for the environment and installing it properly will go a long way
toward reducing this type of damage. Allowing for differential expansion and contraction of the insulation and jacket due to climate changes is a key design step. Protecting the insulation from snow build up and falling ice is as important as putting in walkways around and over the insulation so people will be less likely to walk on the insulation. There are a host of new “flexible/engineered” jacketing systems that are more abuse and dent resistant than the traditional systems when used over flexible insulation. They feature glued seams/joints, which are less prone to opening when the jacket is flexed and they recover instead of denting, depending upon the underlying insulation. It should be kept in mind that flexible jacketing paired with flexible insulation and rigid jacketing paired with rigid insulation offer the best results when mechanical abuse is a concern.
Lastly, periodic inspection of the insulation is necessary, as is repairing or replacing any damaged insulation as soon as possible. Replacing damaged insulation quickly is critical to avoiding greater damage, especially on below-ambient systems or systems subject to moisture intrusion. This is particularly true in industrial environments, when maintenance on piping systems will require removal of or damage to the insulation system to check systems and pipes. Plant maintenance personnel should be trained in the basics of insulation repair (applying a tourniquet) so that the integrity of the insulation system is protected until the insulation can be repaired professionally.
If the mechanical insulation system is designed, specified, installed, and maintained properly, there is no reason it should not provide the expected performance for more than 25 years.