Are We Doing Enough to Promote Insulation?
Fossil fuels will not last forever. Furthermore, with supplies becoming increasingly expensive to extract from the earth and the demand continuing to increase, the prices for these fuels will increase. Our reliance on foreign sources for oil can’t be ignored. It’s incumbent on all of us to do what we can to reduce the quantities of fossil fuels that we burn to provide us with the lifestyle we now expect. Sometimes I think that we in the insulation business must carry that fabled albatross on our backs. What an unglamorous product we manufacture. What a dull product we install and service. No bells, no whistles, no mysterious black boxes. Those insulation products just stay there for a long time, hardly noticed by anyone. We even put surfaces on them to make them inconspicuous. They just perform quietly day in and day out, reducing heat transfer through each square foot of surface by at least 90 percent.
We in the insulation industry are quite familiar with the reasons why thermal insulation is used on hot and cold piping, ducts, and equipment. We know that heat is transferred to or from solids, liquids, and gasses whenever they are exposed to a temperature difference. The general public is more aware than they used to be about the need to conserve energy. Sometimes we take action to turn off lights when they aren’t needed or turn down the thermostat in our homes at night. Every little bit helps-right? So we, in the insulation business, hope that everyone else knows that:
- thermal insulation slows down heat transfer so that less fuel is needed to provide hot or cold fluids to be transferred in pipes.
- people have less risk of getting burned from touching a hot surface if it’s insulated.
- cold surfaces will not have condensation collect on them if they’re properly insulated.
- the temperature of a fluid (such as hot crude oil) will not decrease as much as it flows through an insulated pipe as compared to a bare pipe of the same length.
- water standing in an insulated outdoor pipe will take longer to freeze in the winter.
Why Insulation Isn’t Being Used
So, if insulation is such a good investment, why are some pipes, ducts, equipment, smoke stacks, and other hot or cold surfaces left uninsulated? Let us begin with the valid reasons:
- The heat transfer is wanted and needed. An example could be in a pipe transferring a hot liquid from one stage of a process to another where it must be cooled. Allowing heat to escape from the pipe during transit reduces the amount of cooling required later on. This saves energy and money. As long as the pipe duct, vessel, or equipment doesn’t present a safety hazard to workmen, it may be advantageous to leave it uninsulated.
- The heat contained in the material being transported is actually considered waste. The heat contained in flue gasses going up a chimney is waste. Do we need to insulate the chimney to save energy? No, but we may need to insulate it in order to maintain the necessary draft to assure fluid flow up the stack. Should we insulate a pipe returning cooling water to a river or lake or ocean? Actually we may be doing some ecological good by allowing some of the waste heat picked up in the cooling process to be carried away to the air or ground instead of adding heat to the water at the outlet.
Other valid reasons for not using insulation may be proposed, but there may be a good basis for discussion before a consensus is established. Sometimes the normal manufacturing or processing operations may deposit scale, sediment, or other unwanted residues on heat transfer surfaces in equipment such as a heat exchanger. We often see heat exchangers built using flanged ends to permit the units to be opened for inspection and cleaning, assuring properly designed operations to continue. Sometimes units must be opened for inspection or maintenance when corrosive fluids are processed.
There are occasions when these flanges are purposely left uninsulated, stating the need for visual inspection for leaks and easy access to the bolts and nuts. It’s not uncommon to see flanges on heat exchangers operating at elevated temperatures up to 900 degrees F that are bare.
Here’s a question: "Is there an unalterable truth that there is no way to reduce the heat losses from these flanges? Is the risk for burns and personal injury acceptable?"
My answer: "Those hot flanges out there now can be insulated safely, but not while the units are in operation. Reusable covers suitable for the process temperatures can be applied to do the job. But if they’re installed while the flange is hot, then insulation will cause the temperature of the flanges and the bolts and nuts to increase significantly. This may result in problems of leakage from thermal expansion and no one wants this kind of service problem."
It’s not within the scope of this article to address the technical aspects for designing the bolt, nut, and gasket composition and dimensions and the correct tensioning procedure that’s required to assure that the flanges operate correctly without leaking when the flange is brought into service at an elevated temperature. But it’s within the scope to draw attention to an opportunity that exists where it’s quite feasible for the equipment designers and owners and those in the insulation industry to combine their efforts and knowledge to develop a safe and cost effective technique to provide insulation systems for equipment that has been allowed to waste heat, fuel, and money for many years.
What Can Be Done?
What can be done? For new vessels brought into service, reusable covers should be part of the design for the treatment of flanges. Flanges already in service, after installing new gaskets and being tensioned cold in the appropriate manner, may be insulated with reusable covers during a shutdown period when the equipment is at ambient temperature. These covers should be designed and installed to permit easy inspection. It’s not appropriate to insulate flanges with a history of leaking unless the reasons for this leaking are determined and corrected.
So why are there still uninsulated flanges out there in service? It’s my belief that owners have been satisfied with the status quo for years. It’s possible that their equipment has been operating satisfactorily with minimum leakage problems (and high heat losses) at these flanges. The inertia against change is formidable, particularly when the emphasis is on keeping a plant operating, even if inefficiently, and there may be reluctance to tackle the admittedly highly technical work of determining the optimal bolt tensioning required getting and maintaining leak tight performance in service for a long period of time.
The ASME Boiler and Pressure Vessel Code: Section VIII, Division 1 Design & Fabrication of Pressure Vessels is widely used in North America. Peer ømbøll of Peer Engineering in Denmark provided considerable help to me in better understanding the importance of calculating the optimal bolt tensioning for flanges designed to meet this code, and also permit them to be insulated for service at elevated temperatures after start up.
Efforts Produce Mixed Results
We in the insulation industry have tried diligently for more than 50 years to help designers, engineers, owners, governments, utilities, manufacturers, and the public better understand the benefits of insulation. We have had mixed results in this mission. We have a wide assortment of insulation materials suitable for just about every pipe, duct, tank, vessel, and equipment that contains or conveys hot or cold materials. We have the calculation tools to help determine the insulation thickness required to meet design objectives of economics, energy conservation, condensation control, personnel protection, process control, and pollutant emission. We have an enviable success record for reaching design objectives in every industry. Our products are cost effective and affordable. When properly installed and maintained, our insulation has a long and efficient service life.
Could it be that we in the industry are convincing each other that the good insulation story is known and convincing to all of our customers and clients? How else does one explain why the existing inventory of "old" hot piping and associated equipment and vessels in service still has a high percentage of heat transfer area that’s either "bare" or covered with damaged insulation? We are doing a lot to tell the facts. My concern is our ineffectiveness in getting those facts of our story to those who establish and control the capital and maintenance budgets in large corporations and companies.
NIA Program a Positive Step
I think the new National Insulation Association advertising program is a positive step in getting the favorable attention of the very people who make the ultimate financial decisions and thereby help their own employees implement insulation projects with a very attractive return on investment. Strategically placed throughout "owner" offices, plants, and laboratories, these sophisticated and clever posters will catch the attention of all the employees, including the management personnel needed to energize positive actions. This is a constructive way to reach those who can and will help themselves when the message suddenly hits home.
So are we doing enough? If that we means each one of us individually, then I think we’re not doing enough. We can do a lot more listening, and then a lot more asking, before we do a lot more talking.
We need to listen to what our customers are telling us. We have to determine if the stated reasons for not doing anything are technically sound. If we believe the reasons are unsound, then we must provide substantiation for the basis of a change.
We have to ask our customers who the decision makers are in their companies. We must communicate effectively with them to demonstrate the benefits of making a change. And then, we must tell them how the insulation industry will help them make it possible to save money, save energy, reduce pollution, increase productivity, improve the safety of the workplace, and increase profits through projects that offer a big return on investment.
The rewards are terrific for all of us, and all we need do is earn them!