Choosing the Right Insulation System
There are many types of insulation available, making it incredibly difficult to choose. There are fibrous, cellular and granular insulation materials with so many specific materials in each of those categories that it is nearly impossible to count them all. There are weather barriers galore; smooth, embossed, corrugated and a multitude of coated aluminum jacket materials. There are also stainless, PVC, and a vast array of trowel-on, brush-on and roll-on materials. How does one figure it all out?
What method do you use at your facility?
- Do you use what you used last time?
- Do you ask the insulation maintenance crew?
- Do you decide what to use based on temperature? Price?
If you have used or are currently using a method that sounds or looks similar to what is mentioned above you may have obtained an energy-efficient, long-lasting, well-performing system. However, considering all the insulation materials to pick from, combined with all the environments to which insulation may be subjected, the odds do not look very good.
The proper selection of an insulation system is not "one-stop shopping." The solution lies in a word used several times already: "System." Determining an insulation system is a little like a jigsaw puzzle; as each piece must fit properly with its partner or the whole puzzle falls apart. If we take a systematic approach, we think in a scientific, organized way, considering all elements that could affect the performance of that insulation system. This way can you be assured you get the insulation system that is correct for the specific circumstances. Simply put, you should consider:
- WHAT is being insulated
- WHY it is being insulated
- WHERE it will operate
- HOW much money it costs and will save.
This will help you ask the right questions so you get the "complete picture" of what you are asking the insulation system do plus how, where and why it will be working. Understanding the questions to ask is the first and often most important step to selecting the most appropriate insulation system.
The first thing to consider is what is going to be insulated. Is it piping, tubing, vessels or equipment? Since many insulation materials can be specific to the type of surface being insulated, it is the logical place to start your "system-thinking." Also, understand materials of construction. Is it carbon steel, stainless steel, plastics, alloys, etc.? This not only affects how the insulation system performs but gives you direction as to whether or not you need to consider additional protection for the insulating surface for corrosion protection, etc.
The next thing to consider is why it’s being insulated. There are several reasons for insulating a surface:
- Process Control
- Energy Management
- Freeze Protection
- Personnel Protection.
Why is this so important? If the sole reason for insulating the surface is to provide personnel protection or freeze protection, then the insulation thickness would likely be much less than if your reason for insulating is energy management. An example is shown in Table 1 for a 10" pipe in 400 degree Fahrenheit (F) service.
Now is the time to consider the environment in which the insulation system will operate. Yes, there is a lot to consider, but it isn’t as difficult as it first appears. These aspects can be grouped into four categories.
- Operating Temperature (steady state, cycling, extremes, etc.)
- Ambient conditions (temperature, relative humidity)
- Physical environment (chemical exposure or spillage, abuse potential, etc.)
- Special Conditions
First, what will be the operating temperature of the insulating surface? Be careful and thoughtful here ? do not just think about normal operating temperatures, consider if the system will cycle in temperature or will it have occasional highs or lows.
One chemical facility forgot this possibility. A pipeline operating at minus 40 degrees F was insulated with polyisocyanurate insulation along with an appropriate vapor retarder and weather barrier. However, what it overlooked was the fact that once a year during the planned shutdown, this pipe line is purged for 1-2 days with hot inert gas at 400 degrees F. What happened? The polyisocyanurate insulation was unable to tolerate temperatures this high and it disintegrated. The result was 400 to 600 feet of insulated line that had to be stripped and reinsulated.
Another thought ? is the insulating surface being heat traced or jacketed? If so, you need to make sure the insulation material is rated for the heat the tracing will deliver. Also, you need to note it in the specifications so the party responsible for purchasing and/or installing the insulation system knows exactly what material to purchase. It is frustrating (and probably expensive for you) to an insulation installer to purchase 4"x2" thick insulation material preformed to fit on a 4" schedule 40 carbon steel pipe, only to find it is steam traced and would have required 4.5"x 2" thick insulation!
Next, determine the ambient conditions under which the insulation system will operate. You need to determine the ambient temperature, relative humidity (RH) (if you are trying to design for condensation control), wind speed and sometimes the amount of rainfall. Again, just like understanding operating temperature, think about possible extremes. Designing an insulation system for condensation control at 50 percent is going to fail if the environment occasionally sees 90 percent RH.
You need to consider and allow for the physical environment so the insulation system will be able to give you good performance over a long time. An insulation designed for its physical environment, properly installed and maintained can easily last 15-25 years and more.
Will the insulation system be located inside or outdoors? Inside locations are not susceptible to high wind and UV rays so weather barriers may not need to be as resilient as in outside service. Also, rain and water exposure is often reduced so, again, weather barriers may not need to be as durable. Be cautious here. Water is insulation’s greatest enemy and comes from a multitude of sources besides the sky. Will the area be washed down or does it contain "deluge" type sprinkler systems that are annually activated for testing? If so, plan on getting as much or more water spray exposure as being located outside.
What is the chemical environment? Will the insulation system be subjected to acids or caustics, splashes or fumes? If so, untreated aluminum jacket materials may not perform well, as they are susceptible to these chemicals. Is the location close to an ocean coast where salt contamination is likely? Protection from its corrosive effects will need to be considered. Will there be flammable or reactive products that could come into contact with the insulation materials through leaks, fumes or splashes? If so, insulation materials that resist absorption may be more appropriate.
What is the potential for vibration? High vibration can cause some rigid insulation materials to deteriorate; a softer, more resilient material may be better. What kind of physical abuse will the insulation system see? Is it close to vehicle traffic or will personnel stand on, crawl over, or have reason to strike the insulation system? More rigid insulation material offers more structural support and often a better long-term performance.
The final "Where" to consider is the "mixed bag" of special considerations. Will this insulation system or a specific section(s) of the insulation system be subject to routine and periodic maintenance activity? If so, then installing an insulation system specifically designed for removal and replacement may be a better selection than a permanent system that would have to be repeatedly repaired or replaced after each maintenance job.
Does the insulation system have to conform to any specific regulation or requirement such as FDA or USDA requirements? Does the fire code or your insurance regulations limit any materials that may contribute "fuel load" or "flame spread" to the area the insulation will be located?
The final question is, how much do you want to spend? Now this is likely to sound like the most useless question and asked at the most inappropriate time. You want the most inexpensive system that will properly do the job for you and shouldn’t cost be the first thing considered? Well, simply put, if you consider cost first, you run a great risk of initially eliminating insulation systems or individual components of that system that appear expensive but would actually be the most cost effective if other information was considered prior to what it may cost.
Here are two examples why considering cost first is not the best approach.
I was performing an insulation assessment a few years ago for a Midwestern chemical manufacturer. During the assessment I discovered that the facility’s insulation maintenance crew was using all "field" fabricated insulation fittings and in several locations, "field" fabricated fitting covers (Picture 1 & 2). When I asked the site owner why this was being done, they informed me they had considered the cost of preformed insulation fitting and fitting covers and found them to be "considerably" more expensive than the straight stock being used to fabricate the fittings. They had also "confirmed this with the insulation crew." I informed them that custom fabricated insulation fittings and their covers are often necessary and cost effective due to a variety of reasons but their situation fit NONE of those. I showed them that the insulation materials are the smaller percentage of the total installed cost and their decision was actually costing them money and potentially increasing the possibility of moisture damage in later years due to the high number of seams that can be damaged and let water into the system.
In another case, at a Gulf Coast chemical manufacturer, a ground level pipe rack had been insulated with a fibrous insulation and an aluminum jacket weather barrier. According to interviews with the owner, this type of fibrous insulation had been chosen because:
- the material was considered to be "reasonably priced"
- it was considered to be "straightforward" to install
- it satisfied the operating temperature of the product within the piping
These points were emphatically mentioned in just this order, suggesting strongly what was most important to their decision. The owner was correct in everything they thought about, but overlooked some important items.
- This pipe rack was in an area that routinely had a high traffic and maintenance activity.
- Although there were stairs and bridges across this pipe rack, personnel routinely took short cuts by climbing directly over the piping.
Because this particular type of fibrous insulation provided minimal structural support for the aluminum jacketing, the result was badly damaged insulation jacketing that no longer provided a weather barrier to water penetration. This severely reduced some of the insulation system’s performance. Because of the Gulf Coast location, this plant ONLY suffered energy cost loss instead of the additional problems of freeze up, process control, or corrosion problems. However, the energy cost loss was more in one year than the insulation system cost.
In both of these examples, an insulation system was chosen with cost considerations being first on their lists. The result was good materials used in a manner that didn’t get optimum results.
The final cost consideration is the question of, how long do you want the system to perform? Will the facility operate well into the foreseeable future, or do you intend to run it two more years until a new unit is started up, and then shut this unit down. These are two very different operating circumstances. In the first case you would want to consider an insulation system that had a good chance of performing well for a long time (10-15 years). In the second case, spending the extra money to insure a good long term performance is likely to just waste money.
By thinking of insulation and its operating environment as a complete system instead of a bunch of unrelated parts and you have asked and gotten answers to the what, why, where and how questions, you have the necessary information you need to make an informed decision on an insulation system that will do the job intended, last a long time and be cost effective.
For additional help in selecting an insulation system the National Insulation Association has published an "Insulation Materials Specification Guide" and a "Criteria for Choosing Insulation" is available by contacting the NIA at:
National Insulation Association
99 Canal Center Plaza #222
Alexandria, VA 22314
The what, why, where and how questions I have discussed in this article are also available in a questionnaire format to help you in your insulation system selection and can be downloaded below.