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The Top 10 Mistakes in Managing Safety Performance

"Execution is the name of the game."-Paul Balmert

Managing safety performance–sending everyone home safe at the end of the day–is fundamentally a game of execution. No matter how good the game plan–policies, procedures and programs–when it comes to bottom line safety performance, the game is won or lost on the field.

If execution is the difference that makes the difference, who manages execution?

In the movie “Chicago,” there’s a song about a virtually invisible character, "Mr. Cellophane," with a line that goes, "You can walk right by me, see right through me, and never notice me at all." In just about every operation, there’s an entire level of "Mr. Cellophanes," and these are the people who are really responsible for managing execution. The organization’s safety performance is largely determined by how well they perform that duty.

The Organization Pyramid

Forty-five centuries ago, the Pharaohs of ancient Egypt commissioned one of history’s greatest construction projects–the pyramids. We suspect those employed on the project promptly returned the favor by naming the organization hierarchy in their honor. So was born the "organization pyramid."

You know the theory: The higher up the pyramid you go, the more important the manager. Sitting at the pinnacle is the most important manager in the company. The job of the rest of the enterprise is merely to carry out the goals set by the leader.

Everyone who has ever worked in an organization knows there is a certain element of truth in all this. But, there is another way to think about the question of importance on the management pecking order. It begins by considering where economic value in the enterprise is created. After all, in the theory of the firm, the reason the enterprise exists is to create economic value for the benefit of the owners.

In that sense, any business can be thought of as a printing press, designed to print money for the owners. Every good business owner knows exactly where the printing press for the business is found. In the pharmaceutical business, the printing press is in the research lab: Develop a blockbuster new drug, and the company prospers. In the athletic footwear business, designers create most of the value: The right, hot new shoe will sell off the shelves.

What about industry? In an industrial business, it’s easy to find the printing press: All you have to do is look in operations. That’s because industry is defined by making "things," whether the things happen to be steel, cars or valves.

Sure, there are plenty of other factors in play, but the ability to make products effectively and efficiently largely determines the financial success of the business. Value is created only when products are made. Cease making the product, and there’s no revenue; without cash, it’s a financial crisis. It’s just that simple.

For industrial services businesses such as painting, blasting, cleaning and repairing, the value-creation process is fundamentally the same, determined when service is delivered: Scaffolds are built; steel is blasted; paint is applied. But we know all that.

Take the logic back to the organization pyramid in an industrial or industrial services business, and it’s readily apparent that the value-creating level of the enterprise is found not at the top, but right at the bottom. Those building blocks forming the foundation of the enterprise are the folks running the printing press-and determining the fate of everyone else.

The real owners of the business–usually shareholders–get that. When a publicly traded industrial company suffers a major production outage, the stock price normally falls the next trading session; when an energy exploration and production company successfully brings a major new well into production, the share price increases. By comparison, announce a business reorganization, and the market will usually wait to determine the real impact.

Now that we understand that the base of the organization creates the value, we can appreciate that the role of everyone else in the industrial organization should be to help make that happen. It makes perfect sense, but quality guru Phillip Crosby once remarked, "I worked for 10 years before I found out that management was supposed to be there to help me."

Of all those management levels sitting above those who create value, who do you think is in the best position to provide help–on everything from production and quality to working safely? It’s the front-line supervisor: AKA, Mr. Cellophane.

Managing Safety on the Front Line

Consider the pivotal role played by front-line supervisors in the work processes that largely determine who goes home safe. The front-line supervisor is the member of management most likely to:

  • Set and communicate work standards;

  • Teach the right way to do the job;

  • Determine who’s qualified to perform the work;

  • Observe employees in action;

  • Provide performance feedback-positive and corrective;

  • Roll out safety policies and procedures;

  • Manage safety suggestions;

  • Run safety meetings;

  • Deal with injuries and near-misses.

Get these management practices right, and the odds overwhelmingly favor working safely.

Add them all up, and the result amounts to good, old-fashioned execution. The real story is that front-line supervisors have more control and influence over execution than any other level of management in the enterprise. When they do their jobs well, the team works safely.

What Were We Missing?

Why is it that so many of us mangers have failed to appreciate the critical role of the supervisor in determining execution? It seemed like any time we weren’t happy with safety performance, the last thing we’d ever think about was how to manage execution better. We never thought to ask the supervisors what they were seeing "out on the field." Instead, we would figure the problem out, and then roll out an ad campaign, write letters, call a time out for safety, or round up a few of the usual suspects.

Worse, we often put our best efforts into undermining or eliminating the role of the supervisor. In the name of high-performance work redesign, more than a few of us wiped out the job entirely. Sometimes that worked, and sometimes we’d reinstate the position after performance deteriorated. The very first step in some peer safety observation processes is to invite the front-line supervisor out of the process–only to later lament the need for leadership. Top management would meet with those doing the work–who would then often bash their immediate supervisors. All the while, we’d complain about how weak our front-line supervisors were.

Mr. Cellophane, No More!

Every time a poll is taken of the people doing the work, guess which level of management always gets voted "most trusted"? It’s never any of us in middle or upper management. For more than 50 years, in surveys done around the globe, front-line supervisors consistently were voted the most trusted members of management.

In retrospect, the biggest mistake we made managing safety performance began when we overlooked the simple virtues of execution in determining safety results. We compounded our error by failing to take full advantage of the powerful role that front-line supervisors could play in managing execution.

What we should have done was give them all the help they needed to execute our game plan for safety. If we’d paid attention to Crosby’s advice on the role of management in helping others, we would have spent more of our efforts managing safety performance by developing the leadership skills of front-line supervisors; providing them the support they need, and focusing on enabling their success. Had we done that, we would have had even better success managing safety performance–and probably spent a whole lot less effort in the process.

Front-line supervisors have the most control and influence over execution. That our generation of managers was so inclined to miss that is the biggest mistake we made managing safety performance.

Front-line supervisors manage execution, and execution determines success. Get it right, and the organization wins, and people go home safe.

NIA Sites > Insulation Outlook Magazine > Global

Keeping Asbestos Claims in Check

There are an estimated 200,000 asbestos cases pending nationwide. The U.S. Supreme Court describes this vast amount of asbestos claims as "an elephant mass." Ohio, in particular, has become a "haven" for asbestos claims and is one of the top five states for such filings, declaring at least 35,000 pending claims with the number rapidly increasing. The majority of asbestos claims filed in Ohio are by individuals who, although they have physical signs of asbestos exposure, do not suffer from any asbestos-related impairment, such as cancer.

The national impact of asbestos claims is astonishing. These cases have contributed to more than 70 companies filing for bankruptcy; at least five have been Ohio-based companies. Bankruptcy has also plagued nearly all manufacturers of asbestos textile and insulation products. Nationally, it is estimated that these bankruptcies will eventually result in the loss of 423,000 jobs.

More Stringent Criteria for Claims

House Bill 292 was created as an attempt to control the extraordinary volume of asbestos claims in Ohio. This act imposes the minimum medical requirements an exposed individual must demonstrate in an asbestos claim; establishes the burden of proof an individual must meet in tort actions involving asbestos claims; establishes liability of individuals who own, lease, rent, maintain or control property (premises owners), and liability of shareholders. This act became law in Ohio on September 2, 2004.

House Bill 292 defines an asbestos claim as any claim for damages, losses, indemnification, contribution or other relief that relates to asbestos: including mental or emotional injuries, death, loss to person, risk of disease or other injury, costs of medical monitoring or surveillance, or any other affects on the person’s health that are caused by asbestos. A tort action is defined as a civil action for damages for injury, death or loss to person.

In an effort to minimize the number of claims brought by individuals who do not suffer from any asbestos-related physical impairment, the act imposes numerous medical requirements an individual must meet in order to bring an asbestos claim. Additionally, the act requires specific evidence provided by a competent medical authority, which is defined as a medical doctor who is a board-certified internist, pulmonary specialist, oncologist, pathologist or occupational medical specialist.

The act also imposes specific conditions upon the medical doctor who provides the exposed individual with a diagnosis of an asbestos-related impairment. The medical doctor must have treated the individual, be the individual’s current treating physician and must have a doctor-patient relationship with the individual. Additionally, the medical doctor cannot rely upon reports or opinions of any doctor, clinic, laboratory or testing company that performed an examination, test or screening of the individual’s medical condition if any of the following situations applies:

  • The report or opinion is in violation of any law, regulation, licensing requirement or medical code of practice;

  • A doctor-patient relationship was not established; or

  • The individual was required to retain legal services from a law firm sponsoring the examination, test or screening.

Finally, the act states that the medical doctor cannot spend more than 25 percent of his or her time in providing consultation or expert services, and the medical doctor’s affiliated group cannot earn more than 20 percent of its revenues from providing those services.

In order for an individual to bring an asbestos claim based upon a nonmalignant condition, a condition other than cancer that may be caused by asbestos, that individual must show that the asbestos exposure caused a physical impairment, that the physical impairment is a result of a medical condition, and that the individual’s exposure to asbestos is a "substantial contributing factor" to the medical condition. That is, the asbestos exposure must be the predominate cause of the physical impairment, and a medical doctor has determined that without the asbestos exposure the physical impairment would not have occurred.

To make this showing, the individual must provide evidence establishing that a medical doctor has taken a history of all of the individual’s places of employment and any exposures to airborne contaminants, including whether each place of employment involved exposures to airborne contaminants. The individual must also provide evidence showing that a medical doctor has taken a detailed medical and smoking history, and has reviewed the individual’s past and present medical problems and determined the most probable cause of those medical problems. Additionally, a medical doctor must diagnose the individual with a permanent respiratory impairment rating of at least Class 2 under the American Medical Association guides and with either asbestosis or diffuse pleural thickening. This diagnosis must be based upon a medical examination and pulmonary function test.

In asbestos claims that involve lung cancer in individuals with a history of smoking, that individual must prove that the asbestos exposure caused a physical impairment; that the physical impairment is a result of a medical condition; and that the individual’s exposure to asbestos is a substantial contributing factor to the medical condition. The individual must provide a diagnosis by a medical doctor establishing that the individual has lung cancer and that exposure to asbestos is a substantial contributing factor to the lung cancer. The individual must also establish that 10 years have elapsed from the date the individual was first exposed to asbestos until the date of diagnosis. Finally, the individual must provide evidence of substantial occupational exposure to asbestos or evidence of exposure to asbestos at least equal to 25 fiber per cc years, as established by a certified industrial hygienist or certified safety professional.

As a result of House Bill 292, an individual who files an asbestos claim must file a written report and provide supporting test results within 30 days after filing the complaint or other initial pleading. The defendant, upon motion, is then provided an opportunity to challenge the adequacy of that individual’s evidence within 120 days from the date the evidence is filed. If the defendant uses a physician to challenge the individual’s evidence, that physician must meet all of the requirements set forth for a competent medical authority, with the exception of the requirement that the medical doctor must be treating or has treated the individual. Note that the other requirements defining competent medical authority remain in effect.

For asbestos claims that are pending on the effective date of the minimum medical requirement section of the act, the individual who filed the asbestos claim must file a written report and provide supporting test results within 120 days following the effective date. If an individual has an asbestos claim that arose prior to the effective date, then the individual must provide all of the minimum medical requirements established by the act.

Liability Issues

The act also sets forth requirements needed in order to bring an asbestos claim against a premises owner. It provides that a premises owner is not liable for any injury resulting from asbestos exposure unless the exposure occurred while the exposed individual was on the premises owner’s property.

If the individual alleges that exposure occurred prior to January 1, 1972, there is a presumption that the premises owner knew that Ohio adopted safe levels of exposure for asbestos and that products containing asbestos on the premises owner’s property were below this safe level. To overcome this presumption, the individual must prove that the premises owner knew or should have known that the levels of asbestos exceeded the safe level.

In a situation where the exposed individual works with, installs or removes asbestos products, a premises owner is presumed not liable for asbestos exposure if the exposed individual holds himself or herself out as qualified to perform the work. To overcome this presumption, the individual must prove that at the time he or she was exposed, the premises owner had actual knowledge of the dangers of asbestos that was superior to the knowledge of the exposed individual.

If a premises owner hired an individual prior to January 1, 1972, to perform work in which the individual was qualified to perform, the premises owner is not liable for any injury resulting from asbestos exposure unless the premises owner directed the activity that resulted in the injury or denied permission for critical acts that led to the individual’s injury. If a premises owner hired an individual on or after January 1, 1972, the premises owner is not liable for any injury resulting from asbestos exposure unless the individual proves that the premises owner intentionally violated an established safety standard.

In a situation where an individual claims that asbestos exposure resulted from the tortious act of multiple people, the exposed individual must show that the conduct of each person was a substantial factor in causing the injury or loss. If the individual claims an injury or loss resulted from exposure to asbestos, that individual must prove that he or she was exposed to asbestos that was manufactured, supplied, installed or used by the defendant and that the exposure was a substantial factor in causing the individual’s injury or loss.

This act does not affect a person or corporation’s right to file for bankruptcy, and does not affect the laws and rules governing workers’ compensation, veterans’ benefit program, or the exclusive right of subrogation.

At this time, foes of the legislation have filed a challenge into the Ohio Eighth District Court of Appeals in Cleveland. This action was taken on August 18, 2004. An attorney whose firm represents clients in approximately 32,000 asbestos cases in Cuyahoga County, Ohio, filed the suit on behalf of several labor unions. Although the suit contends that the law has many problems, its chief complaint of unconstitutionality is directed at the retroactivity provisions of the law.

NIA Sites > Insulation Outlook Magazine > Global

Engineer Finds Insulation Work Enjoyable

Senior Engineer Dan Samek of ALSTOM Power Inc. in Windsor, Conn., enjoys getting out of the office and out to construction project job sites, where he is involved with the design, specification and implementation of insulation systems for coal- and oil-fired power plants.

"Being out in the field and away from my desk keeps me sane," said Samek, whose responsibilities also include design and specs for power plant casing (gas-tight sealing of the boiler and backpass), structural analysis of duct systems in a power plant, and material estimates for these systems.

"On a daily basis, I ensure that the subcontractor in the field who is erecting the system follows the company insulation standards and specifications. I aid our project teams in choosing insulation installers who are technically competent and answer the subcontractor’s questions regarding the insulation system itself. I also generate any new insulation drawings for changes to our standard practices," said Samek.

When planning or designing a new system, Samek focuses on thermal efficiency as dictated by the customer’s requirements and ALSTOM’s standards, and personnel protection.

"The design and specification of an insulation system are paramount to the structural integrity of a ‘hot’ power plant and thermal efficiency. Insulation reduces thermal gradients experienced by steel components such as ductwork, stiffeners, the steel superstructure of the powerhouse and attachments. This increases structural life and reduces possible failures due to thermal cycling or thermal stresses," explained Samek.

Insulation is also paramount for the safety of power plant personnel and the thermal efficiency of the power plant. Improper insulation results in decreased heat transfer to the working fluid and also increases the power plant’s rate of fuel consumption.

Increased fuel consumption raises the operational cost and may also result in a lack of performance by the boiler, said Samek, who stays current with his knowledge of new insulation products and procedures and industry standards by networking with insulation vendors and insulation system installers.

Samek considers new high-temperature spray-on systems and new ceramic insulation materials with superior conductivity to be the most notable industry improvements in recent years.

As far as bettering the industry, Samek has several ideas. "Commercially, federal intervention to end the asbestos liability lawsuits," would be an improvement. In the technical field, Samek would like to see the development of better high-temperature, low-cost insulation materials.

"Better materials engineering is driving many of the advances in all aspects of the power industry. This trend will most likely accelerate in the future," he said.

"Domestically and in Europe, any system that reduces labor costs on installation of an insulation system will benefit the commercial viability of any power plant project. Future developments with panelized insulation systems can greatly aid in reducing labor costs for large systems that can be enclosed."

Samek often faces challenges while developing insulation systems, such as lack of space in a power plant, which sometimes restricts the type of insulation system that can be used. When this is the case, changes in materials or the designed system itself often need to be made.

"Analysis may show that the insulation system required may not fit in a given space available. Flexibility in the design can help mitigate this effect, but the biggest challenges will always be the ‘design versus construction’ issues that are often encountered on any heavy engineering project," said Samek.

In one of his more eye-opening experiences with insulation, Samek witnessed the structural failure of a flue gas duct-stiffener system that resulted from lack of proper insulation.

"The customer had thought it unimportant to properly insulate a high-temperature duct system due to concerns regarding getting the power plant back on the grid," noted Samek. As a result, the welds along the duct stiffener failed and, because of the formation of thermal gradients through the stiffener angles, the stiffeners ripped off from the duct plate. This is an expensive mistake to fix because it can lead to other structural problems. More time and resources were needed to correct the problems than would have been needed to properly re-insulate the system in the first place.

NIA Sites > Insulation Outlook Magazine > Global

The Top 10 Mistakes in Managing Safety Performance

Read the mission, vision and values statement of just about any industrial company these days, and you’re bound to find safety prominently mentioned. Words to the effect that "the safety of our stakeholders is of critical importance to the success of our business" can be found right next to the other goals and values so important in any industrial enterprise these days: to be productive, cost-conscious, customer-focused and highly ethical.

Having once authored a "plant safety philosophy" a couple of decades back, we’re the first to say that there’s nothing fundamentally wrong with this approach. After all, the role of top management is to set policy–establish long-term direction–and put the processes and culture in place to achieve the mission.

Moreover, as middle managers, we’ve spent plenty of time living on the receiving end of these policy directives. In every organization, it falls to middle managers to translate the direction from the top into action and results. Today, it’s known as "alignment."

Back in our days as managers, "cascading" was the popular term used to describe the process of passing the message down from the top. Cascading was so commonplace that most of us in the middle felt like our offices were located at the base of a waterfall.

Setting Our Priorities

Time is always the most precious asset any manager has. Every day, every manager has to decide how to allocate that asset among all the activities demanding our attention. In theory, the mission statement was designed to simplify that process, shortening up the range of choices. Most of the time, the statement simply reinforced what we already knew: Everything is important. Get it all done.

Managing safety performance fit in with everything else important we knew had to get done: Make the product; get the cost down; satisfy customer, and keep the people working for us reasonable happy, all part of running the business well.

We didn’t dare drop anything. Except, we really did drop some things all the time. Forced to set priorities, the squeaky wheel always got our attention: the problem of the day, or the flavor of the month–what our management was paying closest attention to–this time. In the case of managing safety performance, the amount of pressure we got from the top was normally a function of performance. When performance was really good, we could expect to be left alone. When things changed for the worse, we could expect a full blitz.

That’s the pressure from the top. But every manager plays to two audiences: above and below.

From those whom we managed, we knew to expect the reverse: Whether performance was good or bad, seldom did anyone beg for more and better safety. It was pretty common to find our latest "safety improvement initiative" greeted with skepticism–or outright resistance. "Leave me alone, and just let me do my job" summed up the sentiment of many.

For those of use living in the middle, this was a very strange and confusing reality: top management pressuring us to improve safety as part of running the business; the people we manage telling us how safely they worked was none of our business.

It begged a question that very few of us ever asked: "Are safety goals just like all of our other business goals?" But, most of us were just too busy to take the time to think about the question, let alone the answer.

We went about managing safety performance as if it weren’t any different. As Joe Fox explains to his competitor in “You’ve Got Mail,” when he’s running her out of business: "It’s business–not personal."

The Moment of Truth

Every once in a great while, the unfortunate among us got to face something that nobody ever prepares for as a manager: meeting the family of a seriously injured employee at the emergency room of the hospital.

From personal experience, we can tell you what a sobering moment that is. We got to witness, in clear, living color, all the really important things in someone else’s life: their family and friends; their values; their interests and passion in life.

Guess what: For them, what’s important was never about their job.

We were often asked troubling questions: "How did this happen?" or, worse, "How could you let this happen?"

(We suspect those kinds of questions got many outfits to take the position that meeting the employee family members was the duty of the human resources staff. On our team, we always took the position that we’d be there to face the family.)

On the drive home from the hospital, we’d think about what a serious injury to us would do to all the things most important in our lives. Even if you’re the most upwardly oriented manager in the world, with sights trained on the corporate suite, you realize that your job isn’t the defining part of your life. There have been more than a few of us whose work lives never were quite the same after that experience.

Business or Personal?

Is the goal of sending people home safe at the end of the day just like every other important goal the enterprise has? Is safety "business or personal?"

As individuals, we know it’s personal for us.

You can bet that it is equally personal for anyone working for us. Lose a customer; close a business; lose your job; life goes on. (We can personally attest to that.) Suffer a life-altering injury, and life doesn’t go on–at least not the way anyone is used to living it.

Fortunately, most managers go through their tenure in office without having to endure this experience. That’s one of the many benefits of having great safety performance.

Count yourself among the lucky majority if you haven’t had this experience.

Of course, the danger hidden in great safety performance is that it tempts us to take our foot off the gas–so we can spend our precious time on those other business goals that are so important to the business.

If you spend just a few minutes thinking about what a serious injury can do to people’s lives–yours, those working for you, and everyone’s families–you’ll appreciate that safety isn’t anything like any other business objective.

Once you realize that, your approach to managing safety changes forever. You never again need top management to tell you that safety is important. You can handle the resistance to your efforts to manage safety performance that naturally comes with the territory. You appreciate what’s really at stake.

Unfortunately, all too many of us managers took safety seriously when it became important to our management because it was important to our management. We didn’t always push safety as hard as we should have because dealing with resistance was seldom pleasant.

It was a mistake. One of the biggest mistakes a manager can make.

Worse, when you find out you’ve made it, it’s usually too late.

NIA Sites > Insulation Outlook Magazine > Global

Hot or Cold…

It is not intended that complicated thermodynamic principles be presented here to describe condensation as a desired function of a process where a liquid component is removed from a vapor. Instead, we are going to discuss some of the bad things that can result when a liquid is condensed from a vapor when the insulation system is not keeping surface temperatures above the dew point for a component in the vapor phase.

What Happens With Cold Fluids?

When a cold fluid is being transported through a system exposed to the ambient air, heat is being transferred from the air into the fluid in the system and the following occurs:

  • A temperature drop across the surface air film on the jacketing material
  • A further temperature drop across the insulation system
  • Yet a further temperature drop across the containing material
  • And finally another temperature drop across the fluid film into the fluid itself.

In this series heat flow path, the surface temperature of the jacket is therefore below the temperature of the ambient air. Depending on the value of the surface film resistance and the relative humidity of the ambient air, that surface temperature may be below the dew point temperature, and condensation will form on the outer surface of the system.

There is also a parallel heat transfer path, essentially the same except there is no insulation system in place. In this case, the thermal resistance of the outside air film is the major component and the temperature drop across the film is much greater. This means that the surface is much colder and condensation is more severe. The problem here is that condensed water may contribute to insulation system degradation and corrosion is more likely to occur.

What Happens With Hot Fluids?

When a hot fluid is being transported through a system exposed to the ambient air, heat is being transferred from the fluid in the system into the ambient air and the following occurs:

  • A temperature drop across the fluid film inside the containing material
  • A temperature drop across the containing material
  • A further temperature drop across the insulation system
  • And finally, another temperature drop across the fluid film into the ambient air.

In this series heat flow path, the surface temperature of the inside pipe surface is therefore below the temperature of the fluid in the pipe. When that hot fluid is in the vapor or gaseous phase, the inside surface temperature may be below the boiling point temperature of the fluid, and condensation will form on the inner surface of the system.

There is also a parallel heat transfer path, essentially the same except there is no insulation system in place. In this case, the thermal resistance of the inside vapor film is the major component and the temperature drop across the film is much greater. This means that the inside surface is much colder and condensation is more severe. The problem here is that condensed vapors may contribute to corrosion and shorten service life of the containing material.

Figure 1 depicts the cross section of both hot and cold systems showing temperature drops across components of each. The key to finding a solution to prevent condensation is to calculate the thermal resistances of each component with special interest to the surface film coefficients on those sides where condensation is possible so that the surface temperature will be above the critical value for the given system. In series heat flow, the thermal resistances are additive:

Rt = 1/ho + t/kins + x/kcon +1/hi

Where:

  • Rt is total system resistance, sq ft*hr/Btu
  • ho is the surface film coefficient on the side of the system exposed to ambient air, Btu/(sq ft*hr)
  • t is the thickness of the insulation, in inches
  • kins is the insulation thermal conductivity, Btu*in/(hr*sq ft*ºF)
  • x is the wall thickness of the containment, in inches
  • kcon is the thermal conductivity of the containment material, Btu*in/(hr*sq ft*ºF)
  • hi is the surface film coefficient on the interior side of the system, Btu/(sq ft*hr).

Again, in series heat flow, the quantity of heat flowing from hot to cold is the same through each component. Please remember that if the quantity of heat flowing has a negative value, it means that the heat flow is going in the other direction. For our cold service condition, the value of t3 will be lower than ta, making Q negative, which means that heat is flowing from the ambient air into the system.

Q = (t3 – ta )/( 1/ho) = (t2 – t3)/ (t/kins) = (t1 – t2)/ (x/kcon) = (tf – t1)/ (1/hi) = (ta – tf)/ Rt

The North American Insulation Manufacturers Association (NAIMA) introduced a sophisticated computer program many years ago to help architects, engineers, designers, insulation manufacturers and contractors select the appropriate insulation thickness for almost all of the situations for which a thermal insulation system is being considered. This program is entitled 3E Plus®. Figure 2 shows the home page of this program. Note that, in the energy column in the insulation thickness box, condensation control is presented. Clicking on this box generates the next screen (Figure 3) for the thickness of insulation required for personnel protection or condensation control. Most of the time we will be dealing with a single insulation material; so we click on that box and generate the next screen (Figure 4).

Note that on the left side of this screen, the boxes have a dropdown arrow at the right edge. Clicking on the arrow presents the drop-down menu for the user to select the appropriate inputs. There are four choices for reporting units. There are four choices for base metal based on the emittance of the containment material. Users have the option to include any containment material provided they supply the emittance value for it. There are 30 choices for the insulation material. If the one to be used is not in the list, one goes back to the home screen and selects the thermal conductivity option to include it in the program. There are 14 options for the external jacket material. If the one to be used is not in the list, it can be added by selecting the external covering menu from the main screen.

Cold Service

The boxes on the right side of this screen are used for inputs by the operator. At this point, the program applies to either personnel protection or condensation control. Both of these depend on the calculated value for the surface temperature of the external jacket. Personnel protection implies an elevated temperature from the contained material that could cause a burn from contact. Condensation control, on the other hand, implies a temperature below ambient that could permit condensation to form on the jacket. At this point let us assume that the fluid temperature in our system is at 34 F. Enter this value in the box. (A new screen is generated.) The third box down is now titled relative humidity. The user must consider carefully the value to be used for the ambient temperature.

If the system is located outdoors, then the value to be used should represent the design condition for summer hours applicable to the geographic location. If the system is indoors, the highest design value for indoor summer temperature should be used. Let us use 75 F for ambient temperature. The final variable affecting the surface film resistance is the wind speed. The higher the value of wind speed, the lower the surface film resistance and therefore a lower temperature drop across it results. A zero value for wind speed would reflect the design for worst conditions. For now we input a 4-inch pipe size. Now we click on the calculate box, and the thickness and surface temperature report (Figure 5) appears. The program calculates the dew point temperature at 55.1 F, and the surface temperatures and heat gains for insulation thicknesses from zero to 10 inches. It then selects the surface temperature next higher than the dew point temperature. In this case it was 60.8 F for the 1-inch thickness.

It is noteworthy that this program makes two assumptions: 1) there is no significant temperature drop across the inside surface film, and 2) the thermal conductivity of the containment material is so high and its thickness is so thin that there is no significant temperature drop across the containment material either. Click on file on the task bar at the top of Figure 5, and you may select print or save. Selecting the print option generates the written report.

Let us take a few minutes to test your feel for how the insulation thickness needed to prevent condensation will change when we alter one input variable while keeping all the others the same as in these examples. (Write "increase," "decrease," or "not change," and see the answers at the end of the article.)

1. The insulation material is one with a lower thermal conductivity; so the thickness may__________________________.

2. The jacket emissivity is higher than 0.1; so the thickness may__________________________.

3. The process temperature is less than 34 F; so the thickness may__________________________.

4. The ambient temperature is higher than 75 F; so the thickness may__________________________.

5. The relative humidity is higher than 50 percent; so the thickness may__________________________.

6. The wind speed is more than 0 mph; so the thickness may__________________________.

7. The pipe size is larger than 4 inches IPS; so the thickness may__________________________.

8. The surface geometry changes to top of tank; so the thickness may__________________________.

Hot Service

In hot service, it is the temperature drop across the inside air film which must be considered. Again, the temperature drops occur across the inside film, the containment material, the insulation (if present) and the outside ambient air film. The 3E Plus computer program does not include the resistances for the inside surface film and the containment; so it may not be applicable for some solutions in this service.

In this case, we need to rely on some other computer program. ASTM C680-03, "Estimate of the Heat Gain or Loss and the Surface Temperatures of Insulated Flat, Cylindrical, and Spherical Systems by Use of Computer Programs," is available. In this instance, there appears to be an assumption also made that the thermal resistance of the containment is negligible. This program does provide sophisticated approaches for determining the surface conductances (due to convection, conduction and radiation). Caution is suggested for users to recognize that both the inside and outside film conductances should be considered.

Section 6.3.2 of the ASTM Standard contains the statement "For the computer programs, the inside surface conductance, hi can be assumed to be very large such that Ri = 0, and t1 =ti is the given surface temperature." Purists may also include the containment as a poor insulation material adding its layer to the total heat flow path and establishing its thermal conductivity equation. The materials that could be within a contained system are almost infinite in composition, service conditions and flow rates, and the internal surfaces can be subject to roughening in service. This strongly suggests that finding a good solution for controlling unwanted condensation from vapors in contained systems requires competent engineering skills to define the operating conditions, materials and ambient conditions, and that serious consideration be given to quality assurances that the installation reflects excellent workmanship so that the affects of parallel heat flow paths are minimized.

Condensation control in hot service requires that the inside surface temperature of the containment be above some critical temperature so that fluids in the vapor phase do not undergo a phase change and form liquid on the surface.

Summary

Condensation happens, and can happen fairly easily if the insulation system specifier and/or installer does not specify and install the right combination of insulation and jacketing materials to prevent it from happening. Unwanted water, as we all know, is an enemy. Condensation is destructive to the process and the materials surrounding the system. An insulation system specified for process control or personnel protection may or may not handle the condensation issues given what is happening either to the inside or outside of the system. As stated above, controlling condensation requires competent engineering and excellent workmanship so that neither the process nor insulation system is compromised.

Answers: 1. Decrease. 2. Decrease. 3. Increase. 4. Increase. 5. Increase. 6. Decrease. 7. Not change. 8. Increase.

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NIA Sites > Insulation Outlook Magazine > Global

Energy Efficiency Works in an Economy Where Jobs Are Scarce

A sluggish "recovery" from the 2000-02 recession spurred the development of a strategic outlook document for American industry. Manufacturing in America, released in January 2004, is the U.S. Department of Commerce’s first significant response to a persistent drum-beat of U.S. job losses, plant closures and lackluster capital investment. The report does an excellent job of identifying the challenges to American manufacturing competitiveness. It also provides a thoughtful analysis of the economic trends that characterize industrial performance. However, the report offers little in the way of solutions. Manufacturing in America was developed from the body of recommendations offered at a series of 20 industry roundtables conducted during the summer of 2003. U.S. manufacturers spoke in unison. They describe a wide variety of forces that make it difficult for them to compete in the modern global marketplace. The Department of Commerce’s most significant response to date was the promise to appoint an assistant secretary for manufacturing and services, whose role would be to render policy and program assistance that boosts manufacturers’ competitiveness, but that position remains unfilled.

The Manufacturing in America report reveals some encouraging statistics that demonstrate U.S. manufacturers’ capacity for innovating, adapting and achieving astonishing rates of productivity. This is further evidenced by the buzz generated over manufacturing strategies like Six Sigma, total quality management and lean manufacturing. However, energy efficiency remains widely untapped as a competitive stimulus. Manufacturers’ lack of awareness-or perhaps misunderstanding-may explain why this is so.

Efficiency should not be confused with conservation. That semantic distinction may be the key to unlocking the value of energy efficiency. Fuel and power are merely packages that carry the real resources that manufacturers need. Fuel becomes heat, which modifies and refines raw materials into finished products. Electricity is the carrier for data and communications that enhance accuracy and flexibility, and conservation involves forfeit, whereas efficiency extracts greater value from existing resources. We need to recognize heat utilization as the real value proposition behind energy efficiency. For manufacturers, energy efficiency is realized through operational decisions that also provide control over thermal resources. With control comes reliability of operations. With reliability comes the ability to fill orders faster and at less expense. Faster order turn-around means more orders can be filled, bringing in more revenue. As opposed to the concept of sacrifice, energy efficiency is an indispensable component of any effort to improve productivity.

The link between productivity and competitiveness is irrefutable. Energy use is an ideal opportunity for productivity improvement. Plants of all types, sizes and locations use energy; so the potential for energy-driven productivity gains is everywhere. Unchecked energy expenditures are like a tax that imposes a cumulative cost burden as manufacturing progresses from raw material to finished product. Many hard-pressed manufacturers seek value through job cutbacks or plant relocations, sometimes before realizing the savings and productivity opportunities afforded by energy efficiency. The benefits only begin with reduced energy bills. Other impacts include greater capacity utilization, reduced scrap rates, more effective emissions and safety compliance, and enhanced risk management.

U.S. MANUFACTURERS’ NEEDS AND RECOMMENDATIONS

Manufacturing in America

1. Lack of government focus on manufacturing and its competitiveness.

  • Many government assistance resources related to industrial energy issues are already in place, but are underpromoted.
  • The energy assistance network begins with the U.S. Department of Energy’s Industrial Technologies Program (DOE-ITP; http://www.eere.energy.gov/industry).
  • Outreach to industry is achieved concurrently through DOE’s six regional offices. Local outreach is further expanded by state energy agencies, non-profits, universities, the Manufacturing Extension Partnership (http://www.mep.nist.gov) and utility companies. Since 2000, DOE-ITP has increasingly collaborated with regional entities to pool resources for industry outreach. Industrial plant managers may access non-biased energy guidance, like resources from DOE-ITP, through a variety of channels, including the Internet, workshops and vendors that achieve "Allied Partner" status with DOE-ITP. A catalog of local manufacturing assistance programs can be found online (http://www.oit.doe.gov/bestpractices/nimap).

2. Manufacturers want the government to focus on encouraging stronger economic growth.

  • Benefits of energy efficiency accruing directly to industry include cost savings and productivity enhancement.
  • Industrial energy efficiency reduces stress on natural gas and other energy markets. Overall economic growth is supported when consumer goods prices and investment are free from the impact of energy inflation.
  • Economic recovery and growth depend in part on business investment. While approximately half of energy savings opportunities are associated with behavioral changes, the other half is generated from assets that incorporate advanced technologies. Economic growth can be driven in part by the promotion of industrial energy efficiency-which necessarily stimulates capital investment in equipment upgrades and modifications.

3. Manufacturers wish to see government match industry’s efforts to control costs.

  • Energy efficiency can reduce a variety of expenses, beginning with fuel bills. See the next section of this response, "Reducing Costs …"
  • DOE-ITP programs, and the larger energy efficiency assistance network, need to become more visible to industry.
  • Energy solutions relevant to today’s manufacturers are developed through the BestPractices program (http://www.oit.doe.gov/bestpractices). More than half of industrial energy purchases are consumed in steam, combustion, motors and compressed air applications that are common to the majority of manufacturing facilities. These few but widely used applications are ideal subjects for "best practices," not only for the volume of energy they use, but for their non-proprietary, non-competitive nature. Because these applications are common throughout industry, government assistance will not accrue to "winners" over "losers." All industries will benefit.
  • Many in industry misunderstand "energy efficiency" as well as the organizations that promulgate and promote it. Energy efficiency is often perceived as a distraction from true manufacturing purposes. Some observers mistakenly expect all energy policies and programs to impose costs and regulations. Accordingly, DOE-ITP and local energy agencies are sometimes at a disadvantage in being the "wrong messengers" for their own assistance programs.
  • The Manufacturing in America initiative is gathering industry attention. This is the Department of Commerce’s opportunity for promoting government assistance like DOE-ITP’s energy efficiency programs.

4. Manufacturers believe that technological leadership is critical to their future.

DOE-ITP promotes energy research and development that will become standard manufacturing applications 15 to 20 years in the future. For almost 10 years, DOE-ITP’s Industries of the Future program has stimulated government-industry collaboration in energy-intensive industries such as chemicals, pulp and paper, and aluminum (http://www.eere.energy.gov/industry/technologies/industries.html). These collaboratives chart the vision, challenges and research priorities that will sustain long-term competitiveness.

5. Manufacturers regarded education as crucial.

Two forms of education are critical to the manufacturing sector: university-based sciences and engineering, and vocational training. Both are successfully supported by DOE-ITP program initiatives.

1. University-based curricula: DOE-ITP supports 26 Industrial Assessment Centers (IACs) as operated by university mechanical engineering departments (http://www.oit.doe.gov/iac). IACs provide no-cost, one-day energy assessments to eligible small- and medium-sized manufacturing establishments. IAC activities impact industry in two ways. One, they give students a valuable hands-on component to their education, which greatly augments their employability upon graduation. Second, assessment recipients are given a prioritized checklist of energy-saving opportunities. Historically, the average assessment identified approximately $55,000 worth of annual cost-saving opportunities.

2. Vocational training designed by DOE-ITP is offered in several forms, all of which are based on BestPractices diagnostic software. First is end-user training, which is offered to small groups made up of company staff or industry association members. Second is qualified specialist training, which certifies eligible vendors and trade association personnel in the use of BestPractices software on behalf of their clients. Third is the development of an experimental community college curriculum for an Energy Efficiency Specialist Associate’s degree. DOE-ITP’s education and training initiatives (http://www.oit.doe.gov/bestpractices/training) are an effective response to industry’s ongoing need for employee skills and technical leadership. These initiatives are fully or near-fully developed. Funding limitations restrict the availability of these resources. Note, however, that they are easy to expand and replicate.

REDUCING COSTS THAT ERODE COMPETITIVENESS

Energy-related decisions impact a wide range of expenditures, including those related to environmental and safety compliance, risk management, scrap rates and idle resource costs. Naturally, energy efficiency also helps to keep fuel and power bills in check.

  • Environmental compliance: Emissions output is related to fuel usage. Any reduction of fuel consumption per unit of output will reduce emissions in direct proportion. Fuel efficiency thus provides manufacturers a wider margin of emissions compliance-exposure to penalties is reduced as is the diversion of investment capital into non-productive emissions abatement equipment.
  • Safety compliance (risk management): Industrial energy efficiency is predicated in part on management procedures and energy flow tracking. A spin-off benefit of this effort is the identification and correction of operational anomalies that may threaten life or property. The safety "dividend" of energy efficiency is in two parts: the avoidance of settlement costs and OSHA penalties, and the earned reduction in hazard insurance premiums as supported by the plant manager’s clean log book.
  • Scrap rates and raw material costs: Another energy efficiency "dividend" relates to disciplined energy flow management. Closer monitoring of energy flows within a plant assures that thermal energy is applied at the correct temperature, for proper duration, and in needed proportion to raw materials. Efficiency measures provide the control that reduces scrap rates and raw material expenses.
  • Idle resource costs: Energy flow management contributes to plant integrity, as evidenced in reduced down-time. As down-time is avoided, so are the costs of idle resources, which include non-productive labor, interest costs on stockpiled raw materials and finance costs accruing on amortized assets.
  • Energy costs: Savings potential is in several dimensions. The first is classic energy efficiency, which describes the reduction of fuel consumed per unit of production. Second is the detection of errors in fuel billing, which is achieved by plant managers who maintain energy flow data. Third is the negotiating power that accrues to energy-smart plant managers when seeking fuel purchase contracts. Finally, product fabricators may mistakenly claim that energy is a "small percent" of their production costs. This ignores the significant energy cost embedded in chemicals, fibers, metals and packaging that drive their spiraling cost of input materials. Energy efficiency contributes to industrial competitiveness when waste is reduced in all stages of value-added production.

ENERGY, TAXES, INVESTMENT AND COMMUNITY DEVELOPMENT

The Potential for Combined Heat and Power

One energy-based solution immediately engages several of the challenges cited in the DOC report. Combined heat and power (CHP) plants-facilities that localize the generation of electricity and thermal energy while supplanting traditional centralized utility plants-have positive implications for energy security, reliability, energy market stability, emissions containment and community development. For CHP development to expand beyond its current limited capacity, policy initiatives must address investment barriers posed by tax and regulatory structures.

  • CHP technology gives certain large industrial energy consumers the opportunity to generate both thermal and electric power in one, on-site power plant.
  • Traditional utility plants are only about 30 percent efficient in converting fossil fuels into electricity. The balance of fuel input to steam turbine generators is actually lost up smokestacks as heat, which is the thermal by-product of generators. Additional energy is lost as the utility’s electricity is dispatched to customers through transmission and distribution lines. This traditional system is also overburdened by demand for power that outpaces the system’s ability to provide reliable service.
  • CHP offsets the cost inefficiencies and waste inherent in traditional central utility power generation. The large energy demand posed by certain manufacturing facilities makes it feasible to generate both electrical and thermal supplies on-site in one power plant. The thermal by-product of power generation in on-site power plants can be applied to steam and process heat activities that are prevalent in manufacturing. CHP technology raises the overall efficiency of electricity generation from 30 percent to 80 percent or better.
  • Manufacturers and the overall economy would benefit from the widespread development of CHP in several ways:
    • Electricity price and supply difficulties are offset.
    • CHP development would generate capital investment and jobs in construction and plant operations.
    • CHP can boost community development as envisioned on page 52 of the DOC report. Localized manufacturing clusters can be served by core CHP infrastructures. Costs shared this way release investment capital for market and product innovation.
    • Reduced stress in energy markets (attributable to CHP’s inherently more efficient use of fuel) offsets the product price inflation that is driven by escalating energy costs.
    • CHP’s contribution to fuel efficiency has a proportional impact on the combustion emissions that are subject to regulation. The huge offset of traditional, mostly coal-fired power plant emissions reduces the regulatory pressures that increasingly burden manufacturers.

    Development of CHP can directly contribute to overcoming several challenges to U.S. manufacturing, including energy costs, capital investment and regulatory compliance. Barriers to CHP development are legal, regulatory and tax-based in nature. The U.S. Combined Heat and Power Association (http://www.uschpa.org) champions the CHP cause through its work with the U.S. Environmental Protection Agency, Department of Energy, state governments and utilities.

    SUMMARY: ENERGY EFFICIENCY’S CONTRIBUTION TO U.S. INDUSTRIAL COMPETITIVENESS

    1. Short-term benefits (within two years):

    Accelerate economic recovery by reducing manufacturers’ current operating expenses. Plant energy audits for small- and medium-sized manufacturers, provided by the Department of Energy’s Industrial Assessment Centers, find an average of $55,000 cost savings per facility. DOE-ITP also sponsors a limited number of multiple-day plant-wide assessments for large manufacturers. Annual savings projections from these showcase efforts are typically counted in millions of dollars. Many energy solutions require no capital investment and pay for themselves in a matter of weeks. No-cost BestPractices software and reference materials assist the pursuit of energy improvement initiatives.

    2. Medium-term benefits (two to five years; applies to existing facilities and assets):

    Vocational training generates the skills needed to design and implement energy-saving operating procedures. This discipline provides the substance for durable energy management initiatives that return savings year in and year out. DOE-ITP’s existing, specialized training curricula can be easily replicated regionally and through industry associations for this purpose.

    Long-term benefits (five years out and beyond):

    DOE-ITP’s energy research and development supports the development of strategic technologies that will sustain U.S. manufacturing competitiveness. The existing protocol for government-industry research collaboration serves a number of energy-intensive industries, but can be replicated to serve more. University-based Industrial Assessment Centers provide current assistance to industry while simultaneously developing the skills and leadership of tomorrow’s engineers.

    How can the Department of Commerce facilitate manufacturing competitiveness through energy efficiency?

    The U.S. Department of Commerce currently assumes a leadership role while industry’s attention is captured by the Manufacturing in America report. Increased funding certainly assists in replicating and expanding proven programs and materials like those described in this response. Equally important is having the appropriate messenger carry forth the energy efficiency message to corporate leaders. Now is the time for Department of Commerce to encourage corporate leaders to adopt energy management principles that cut costs, save jobs and boost manufacturing competitiveness.

    • NIA Sites > Insulation Outlook Magazine > Global

    CHILL OUT!

    Insulation systems for piping that operate at below-ambient temperatures present special challenges due the possibility of water vapor movement to the cold surface. If the operating temperature of the system is below the dew point of the ambient air, condensation will occur on the cold surface, creating a vapor pressure gradient through the system. This vapor pressure gradient serves as the driving force for water migration toward the cold surface. If these conditions remain for extended periods of time, a significant amount of liquid water can accumulate in the system. Below-ambient systems therefore require special attention to the design to maintain thermal performance.

    The traditional approach has been to specify either a vapor-impermeable insulation material and/or a continuous vapor retarder on the warm side of the insulation to minimize vapor flow to the cold surface. A variety of facings and jacketing materials are available for use as vapor retarders. These products are designed for low water vapor permeance, with values as low as 0.02 perm achievable under laboratory conditions. Insulation materials with water vapor permeability values less than 0.005 perm per inch are available. In theory, these materials limit the rate of water vapor ingress to levels so low that the amount of condensed water is negligible. In practice, however, this approach requires that the vapor retarding system be continuous at all the joints, elbows, valves and fittings present in real installations. The degree of success therefore depends heavily on both the workmanship of the installers and degree of maintenance provided after installation. Even with careful installation of vapor retarders in conjunction with closed-cell insulation materials, a finite amount of water vapor enters the system and condenses to liquid water on the cold surface. Figure 1 shows a traditional installation with a vapor retarder jacket over a closed-cell insulation material where dripping, corrosion and mold growth are evident.

    The "Self-Drying" Concept

    An alternative approach utilizing wicking material to remove condensed water from the system has been in use since 1993. The approach accepts the fact that water vapor will eventually enter the system and condense on the cold surface, and provides a means to remove the condensed water while keeping the insulation material substantially dry.

    A schematic of the "self-drying" concept on a below-ambient pipe is shown in cross section in Figure 2. A thin layer of hydrophilic wicking material is placed around the pipe. A layer of low-conductivity insulation material is located around the wick to limit conduction heat transfer to the pipe. A vapor retarder is typically placed on the exterior surface of the insulation to limit the rate of water vapor diffusion into the system. The wicking material is extended downward through a slot in the insulation layer, and the tail of the wick is left exposed to the ambient air to serve as an evaporator section.

    Note that in the schematic the evaporator section of the wick is shown hanging straight down in a vertical position. In practice, this tail portion of the wick may be turned and adhered to the exterior of the vapor retarder. This is done for aesthetics and does not materially effect the operation of the system as long as the exposed area is sufficient to allow adequate evaporation. A commercial implementation of the concept showing an integral flap that covers the evaporator is shown in Figure 3.

    In operation, any water vapor that condenses on the pipe surface is absorbed by the wicking material and transported via the combination of capillary forces and gravity through the slot and onto the exposed tail area, where it can evaporate to the ambient air.

    Background

    The "self-drying" concept of utilizing a wicking material to remove condensed water from a below-ambient pipe insulation system was conceived by Professor Vagn Korsgaard of the Department of Buildings and Energy, Technical University of Denmark. Original patent applications were filed in Denmark in 1990, and with the United States Patent Office in 1991. Korsgaard’s initial experiments with the concept are described in a technical paper presented at the 1993 ASHRAE Winter Meeting in Chicago. The paper described results of a one-year test of several "self-drying" pipe insulation designs installed on a 33 F chilled water loop. The results of the experiment demonstrated that "? it is possible to prevent moisture accumulation in cold pipe insulation by means of a concept utilizing the wicking action of a hydrophilic fabric to remove condensed moisture from the pipe surface through a slot in the insulation to the outer surface of the insulation from which it can evaporate into the ambient air."

    Korsgaard published additional data in the Journal of Thermal Insulation in 1994, the Proceedings of the International Congress on Refrigeration in 1995 and in an ASTM Symposium on Insulation Materials in 1997.

    Theory of Operation

    To help understand the operation of the self-drying system, assume that wick and insulation are initially placed on dry pipe surface when the pipe temperature is in equilibrium with the ambient air. This is the situation that normally exists prior to system start-up. There is no condensation within the system, and the partial pressure of water vapor in the air trapped near the pipe surface is equal to the partial pressure of water vapor in the ambient air. For this equilibrium condition, there is no driving force and no water-vapor flow in the system.

    During system startup, the temperature of the fluid in the pipe is reduced, and a temperature gradient is established across the insulation layer. This results in heat flow via conduction through the insulation toward the pipe surface. As long as the pipe surface temperature remains above the dew point of the trapped layer of air nearest the pipe surface, however, no condensation will occur. The vapor pressure near the pipe remains equal to the vapor pressure in the ambient air, and no water vapor flow occurs.

    As the temperature of the fluid in the pipe is further lowered below the dew point of the air near the pipe surface, liquid water will begin to condense on the pipe surface. This reduces the vapor pressure of the layer of air immediately adjacent to the pipe to the saturation pressure, and a vapor pressure gradient is established. This vapor pressure gradient causes water vapor diffusion toward the pipe surface.

    Initially, the condensed water will be absorbed into the hydrophilic wicking material. As the amount of absorbed water increases, the pores in the wick will fill, and capillary forces will induce movement of the liquid water toward dry areas of the wick. This capillary force, aided by gravity, will move liquid water through the slot to the evaporator region, where it can evaporate to the ambient air.

    The advantage of this approach is that the wick material transports condensed water to the outside of the system. The wick keeps the hydrophobic insulation dry, allowing it to maintain its thermal performance.

    Mathematical Modeling

    The physical laws of thermodynamics, heat transfer and mass transfer that govern the performance of the self-drying concept are well known. A comprehensive mathematical modeling effort was undertaken to better understand the interactions of these physical laws as they apply to the self-drying concept1. The modeling study was also useful with product design and material selection. The study involved the solution of equations governing the transport of mass, energy and momentum in porous media. A significant, novel feature of the modeling work was that it incorporated transport processes in a hydrophilic wick fabric wrapped around the cold pipe and extending through the insulation.

    Results of the modeling effort show a rapid initial weight gain followed by a plateau. This plateau represents a state of equilibrium whereby the amount of moisture condensing equals the amount of water being drained from the system. No further weight gain is experienced. This characteristic behavior is explained by the fact that the wick must be saturated before capillary action can begin.

    The mathematical modeling effort demonstrated that the wicking concept is theoretically sound. The wicking material is capable of transporting condensed water outside the system, where it may be evaporated. The model also clearly demonstrated some key limitations of the wicking concept: 1) it is still necessary to employ a low permeance vapor retarder to limit the water vapor ingress to manageable levels, and 2) the model reinforced the requirement that the ambient conditions must provide opportunities for evaporation.

    Laboratory Testing

    While mathematical modeling is useful in understanding the theoretical performance of the pipe insulation system, an extensive experimental program was required to evaluate prototype product designs and to aid in developing installation techniques. Much of the testing was conducted in environmental chambers that allowed exposure of specimens to controlled temperature and humidity conditions.

    Figure 4 shows a photograph of one of the chambers used. This particular chamber was valuable in that it could not only maintain steady conditions accurately, it could also be programmed to mimic varying temperature/humidity conditions.

    The inside of this chamber is shown in Figure 5. For most of the tests run in the humidity chamber, 3-foot sections of insulation were installed on a 1-inch copper tubing 40 inches long. The exposed ends of the insulation sections were sealed by either dipping them in hot melt adhesive or by taping them shut. These assemblies were weighed and placed on a cold "finger" mounted in the humidity chamber. The temperature of the cold finger was maintained at the desired temperature, typically 35 F, by circulating cooled water-antifreeze solution through the system. This test configuration allowed periodic removal and weighing to determine weight gain due to water vapor ingress. The testing program involved more than 50 samples for periods ranging up to six months in duration.

    Results of one series of experiments are given in Figure 6, which shows the cumulative weight gain for three specimens of ¾-inch NPS by 1.5-inch-thick fiberglass insulation sections fitted with wicking material. For this experiment, the humidity chamber was maintained at a constant 90 F and 80 percent relative humidity. This condition corresponds to a constant dew point temperature of 83 F and is considered severe from the standpoint of vapor drive (the ASHRAE 0.4 percent design dew point temperature for Miami, Florida, is 78 F).

    As illustrated in the figure, there is a rapid weight gain within the first day of testing. Afterwards, the weight of the specimens remains relatively constant. This is consistent with results from the mathematical model in that an initial period of water accumulation must occur prior to saturation of the wick. During this initial transient period, there is no liquid water at the slot exit, leaving a relatively open path for water vapor to diffuse into the system. This "flaw" in the vapor retarder is narrow (generally less than 0.1 inches (2 mm) but runs the length of the pipe run.

    When the wick becomes saturated, it begins to remove condensed water through the slot to the evaporator area. After this point, the flow rate of water vapor into the system equals the flow rate of liquid water out of the system, and a state of dynamic equilibrium is reached. This particular series of tests were continued for a period of two months without a further increase in weight. Subsequent disassembly and examination of the specimens reveals that liquid moisture is confined to the wick material; the insulation material stays dry.

    These data indicate that the steady state weight gain during the initial transient period is roughly 15 grams per section of pipe. Experiments have shown that, if fully saturated with water, the wick material has the capability to hold about 36 grams of water per section of pipe. From this we conclude that 1) the weight gain measured is confined to the wick material and 2) the wick material, under continuous severe conditions, is less than 50 percent saturated.

    Another interesting experiment was conducted with samples installed in the "slot-up" configuration to examine the consequence of possible misapplication of the product. Again, the conditions in the chamber were maintained at a constant 90 F/80 percent relative humidity with a 35 F operating temperature. Results are shown in Figure 7.

    The result here is that the initial weight of approximately 32 grams per day does not level off, as before. This indicates that the water-vapor ingress into the system is greater than the rate of liquid water can be removed. After a period of six days, the accumulated weight of the sample had reached nearly 200 grams. At that point, the sample was rotated 180 degrees to the normal "slot down" position. The excess water drained and evaporated and the weight gain stabilized at a normal level of about 20 grams.

    Another important series of laboratory experiments involved assessing the liquid water absorption characteristics of fiberglass insulation material relative to the wicking material. In general, fiberglass insulation is hydrophobic (sheds water) while the wicking material is hydrophilic (absorbs water). The self-drying concept relies on this distinction to keep the insulating material dry. To test this, samples of insulation were held horizontally with wicking material on top of the fiberglass. Water droplets placed on the surface of the wicking material spread smoothly. The fiberglass insulation below remained dry, and the presence of the insulation in contact with the wick did not affect the wicking pattern.

    In follow-up experiments, samples of wick material were sandwiched vertically between pieces of hydrophobic fiberglass, leaving a 1-inch-wide lead of wicking material protruding from the bottom of the insulation. Capillary rise was measured by dipping the 1-inch lead in water (keeping the bottom faces of the insulation just above the water). Results are summarized as follows:

    • The presence of the wool did not affect the capillary rise of the nylon wick.
    • There was no detectable lateral water diffusion into the fiberglass insulation.
    • These experiments confirmed the ability of the hydrophobic fiberglass insulation to remain dry even when in contact with a saturated hydrophilic wicking material.

    Field Experience

    Field trials of self-drying insulation began in April 2000. Initial installations were targeted to locations along the Gulf Coast and along the Eastern Seaboard. Table 1 (in Figure 8) provides a summary of some of the early installations.

    These field trials yielded a wealth of experience with the self-drying insulation product and identified a number of points worth highlighting. Elbows, valves and fittings have been successfully insulated by wrapping with wicking material prior to installing insulation. Various installation details have been developed to accomplish this, but the key for installers is to utilize the wicking materials to transport condensed water to the lowest point in the system where it can be removed to the outside and evaporated.

    Vertical runs are treated similarly, with the wicking material serving as the conduit to transport condensed water to a location where it can be removed from the system and evaporated.

    The ability to install insulation on operating systems has proven to be a significant benefit. In some facilities, cooling systems are critical to operations, and shutting down to install insulation is not feasible. Since the wicking products are designed to remove water from the cold surface to the environment, surfaces do not need to be dry during installation. A number of hospitals and data processing centers have chosen to use wicking products to reinsulate existing cold lines while maintaining operations.

    One of the earliest field trial installations was on the campus of the Old Dominion University in Norfolk, Virginia. Self-drying insulation was installed in a mechanical room at the Powhatan Apartments, a 23-year-old facility housing up to 384 upperclassmen. Existing pipe insulation was deteriorating in the mechanical rooms and also on pipe leading to individual apartments. The apartment project was selected for the demonstration because it offered easy access to pipe that needed new insulation and the pipe was exposed so it could be observed over time. Also, ambient conditions in the mechanical rooms would provide a good test with chilled pipe running through a hot and humid environment.

    Fifteen months after the product was installed, the insulation was working well. Before the test, there were stain lines on the floors where condensation had dripped. The lines were removed and had not reappeared in the 15 months (spanning two summers) since installation. As the installation approached its third year in service, samples of the insulation were removed, examined and found to be dry and drip-free.

    Conclusion

    The "self-drying" concept invented by Professor Korsgaard has been in commercial operation in Europe since 1993. Researchers at Owens Corning’s Science and Technology Center began evaluations of the concept in 1998. The development effort involved extensive mathematical modeling, laboratory experimentation and field trials. As a result of these studies, Owens Corning introduced its product, based on the Korsgaard patent, in 2001.

    1Karki, K.C. and Patankar, S.V., Innovative Research Inc., in partnership with M.K. Choudhary of Owens Corning, "Computational Model for Condensation in Fiberglass Insulation on a Cold Pipe," Report submitted to Owens Corning, July 1999.

    The findings in this article were presented at NIA’s 49th Annual Convention, Tucson, Arizona, March 26, 2004.

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    NIA Sites > Insulation Outlook Magazine > Global

    ASTM C16 UPDATE

    ASTM Committee C16 on Thermal Insulation met in Salt Lake City, April 18-21, 2004. The following is an C16 overview, scope, individual subcommittee scopes, and a summary of some of the activities by task groups reviewing and writing standards related to mechanical insulation. You can learn more about ASTM C16 by going to http://www.astm.org, clicking on "Technical Committees," then "Search for ASTM Committee by Designation," and finally, select "C16" from the hundred or so other ASTM committees.

    C16 Committee Overview

    ASTM Committee C16 on Thermal Insulation was formed in 1938. C16 meets twice a year, usually in April and October, with approximately 120 members attending more than three days of technical meetings capped by a discussion on relevant topics in the thermal insulation industry. The committee, with current membership of approximately 350, currently has jurisdiction of about 134 standards, published in the Annual Book of ASTM Standards, Volume 04.06. These standards continue to play a preeminent role in all aspects important to the industry of thermal insulation, including products, systems and associated coatings and coverings, excluding refractories.

    C16 Committee Scope

    The scope of the Committee C16 shall be the development of standards, promotion of knowledge and stimulation of research pertaining to thermal insulation materials, products, systems, and associated coatings and coverings, but not including insulating refractories. These activities shall be coordinated with those of other ASTM committees and national and international organizations having similar interest.

    C16 Subcommittee Scopes

    C16.16 U.S. Delegation to ISO/TC 163: Standardization in the field of thermal insulation including terminology, test methods, calculation methods and specifications for thermal insulation materials, components, constructions and systems, including a general review and coordination of work on thermal insulation within ISO. Excluded are test and calculation methods that are treated by other ISO technical committees after agreement with these technical committees.

    C16.20 Homogeneous Inorganic Thermal Insulation Materials: Develop and maintain standard test methods, definitions and nomenclature, recommended practices, classifications and specifications for all homogeneous inorganic thermal insulation materials under C16.00 jurisdiction, except those assigned to subcommittee C16.21 and C16.23.

    C16.21 Reflective Insulation: Develop and maintain product specifications and test methods applicable to thermal insulations that depend essentially on the reflectance of heat for their effectiveness. Test methods are those not generally applicable to other forms of thermal insulation or associated materials. Jurisdiction of this subcommittee on building type constructions include only materials or assemblies consisting of one or more heat reflective (low emissivity) surface(s), such as metallic foil, unmounted or mounted on thin membrane(s), such as paper or fibrous or foam sheets, all less than 1/8 inch in thickness.

    C16.22 Organic and Nonhomogeneous Inorganic Thermal Insulations: Develop and maintain standard test methods, definitions and nomenclature, recommended practices, classifications and specifications for all organic and non-homogeneous inorganic thermal insulation materials under C16.00 jurisdiction except those assigned to subcommittees C16.21 and C16.23.

    C16.23 Blanket and Loose Fill Insulation: Develop and maintain product specifications; recommended practices and test methods (when not under the jurisdiction of a methods subcommittee) for all thermal insulation materials under C16.00 jurisdiction, except those assigned to subcommittees C16.20, C16.21 and C16.22.

    C16.24 Health and Safety Hazard Potentials: To develop and review standards related to potential health and safety aspects associated with the installation and use of thermal insulation materials, accessories and systems.

    C16.30 Thermal Measurements (including calculation methods): Develop and maintain test methods and recommended practices relating to the transfer of energy within and through thermal insulating materials and systems.

    C16.31 Chemical and Physical Properties: To develop and maintain test methods and practices related to chemical and selected physical properties of thermal insulating materials.

    C16.32 Mechanical Properties: Develop and maintain test methods and practices related to selected mechanical and physical properties of thermal insulation and associated materials.

    C16.33 Insulation Finishes and Moisture: Develop and maintain material specifications, test methods, recommended practices and classification systems: 1) applicable to coatings, coverings, adhesives and sealants used in association with thermal insulations; and 2) involving the transfer of vapor through thermal insulation and associated materials, involving the accumulation of moisture in thermal insulating materials and systems.

    C16.40 Insulation Systems: The development and maintenance of performance specifications and standard practices for thermal insulation systems. The systems include all of the individual components combined in a manner to provide an effective control of heat transfer and moisture transmission within the insulation systems under the operational and environmental conditions of its intended use. Such components, if part of the system, will include the thermal insulation, supports, securements and protective coverings.

    Summaries From Salt Lake City

    The following are the summaries of recent activities in Salt Lake City on individual standards relating to mechanical insulation materials and systems. These are organized by the Subcommittee associated with each standard.

    Subcommittee C16.20-Homogeneous and Inorganic Insulation Materials

    C585 Standard on Inner and Outer Diameters: The current standard was reapproved, as is, although the task group will meet again in the fall, in Washington, to work on a revision that will include flexible pipe insulation materials. In addition, the task group will work to account for outer diameters to develop tolerances for the purposes of nesting pipe inner and outer layers of preformed pipe insulation and for the purposes of adding preformed jacketing over preformed pipe insulation. Finally, this next revision will include metric dimensions.

    C533 Standard on Calcium Silicate Pipe and Block: This standard was recently revised and successfully reballoted. The revision includes new performance data for block insulation and separate performance data for pipe insulation.

    C547 Standard on Mineral Fiber Pipe Insulation: This standard was recently successfully reballoted. The task group is working on additions of corrosivity and pH. In addition, the task group has formally requested Subcommittee C16.32, on mechanical properties, to develop a new test method for pipe insulation compressive resistance and to collect data from existing products using that method. Therefore, this task group on C547 will meet in the fall, in Washington, as will a new task group on testing pipe insulation for compressive resistance.

    C612 Standard on Mineral Fiber Board: A revised standard was recently balloted successfully and hence has been accepted for publication. One change in this revision is the addition of material performance below ambient, down to zero degrees F, when tested with an appropriate vapor retarder.

    Subcommittee C16.22-Organic and Nonhomogeneous Insulation Materials

    Recent activities on new and existing standards are as follows:

    C534 Standard Specification on Flexible Elastomeric Insulation: The Task Group, along with the Task Group for C1427-Standard for Polyolefin Foam Insulation, sponsored round robin testing amongst several manufacturers for dimensional stability. The new data will be included in the next draft.

    C578 Standard Specification on Unfaced Polystyrene Insulation: The task group recently balloted a draft and received negatives that were found to be persuasive. One of these changes was to introduce a new type of high-density material in this standard based on the thermal and structural applications for 2.1 to 4.0 pfc foam. The revised draft will address the negatives and reballot.

    C591 Standard Specification on Unfaced Preformed Rigid Cellular Polyisocyanurate Thermal Insulation: The task group has been discussing the impact of pending blowing agent changes on the physical properties in the standard.

    C728 Standard Specification on Perlite Thermal Insulation: The task group recently balloted a draft, which received negatives and will be reballoted within the subcommittee.

    C1126 Standard Specification for Phenolic Foam Insulation: The latest version of this standard has been approved and has received the 2004 date.

    C1410 Standard Specification for Melamine Foam Insulation: The task group recently balloted a draft and received some negatives that they found to be persuasive. The new revised draft, which will reflect the negatives relating to smoke toxicity, will be reballoted.

    C1482 Standard Specification on Polyimide Insulation: The task group recently balloted a draft and the negatives were withdrawn; so standard will receive 2004 date.

    Subcommittee C16.23-Blanket and Loose Fill Materials

    This subcommittee addresses a number of standards for mechanical insulation and a number for building envelop insulation. Activity related to mechanical insulation is given below.

    C592-Specification for Mineral Fiber Blanket Insulation and Blanket-Type Pipe Insulation (metal mesh covered) (industrial type): This standard has recently been revised and successfully balloted. This new revision contains supplementary requirements of NAVSEA so that it now meets MIL-I-2818: Metal Mesh Blankets for Military Use. It is now available from ASTM and ready to be published. The task group will nevertheless meet in the fall, in Washington, to add below ambient performance data, on surfaces down to zero degrees.

    Subcommittee C16.30-Thermal-Measurements

    The task group for C335, Standard Test Method for Steady-State Heat Transfer Properties of Horizontal Pipe Insulation, is in the process of incorporating vertical pipe insulation into the standard. Also, when testing for thermal performance on below ambient pipe testing, it has been practice to test an ambient pipe with below-ambient surroundings on the outside of the insulation. A new draft will include a cautionary statement regarding this practice since it can give incorrect results. The task group on C680, Practice for Estimate of the Heat Gain or Loss and the Surface temperatures of Insulated Flat, Cylindrical and Spherical Systems by Use of Computer Programs, is in the process of adding new surface coefficients. This will bring C680 in line with the surface coefficients already incorporated in the program 3E Plus®, V3.2.

    Subcommittee C16.40-Insulation Systems

    This subcommittee has several major current activities. These are listed below with a short description of recent activity at the Salt Lake City meeting.

    There is a task group developing a new standard titled, "Standard Guide for the Pre-fabrication and Field Fabrication of Cellular Glass Pipe and Tubing Insulation." At the meeting, the task group completed writing the scope and a section on standard sizes and dimensions. One member is going to provide sketches showing both correct and incorrect ways to cut sections from blocks. This task group plans on meeting again in the fall, at the Washington meeting.

    There is an existing ASTM "Standard Guide for Selecting Jacketing Materials for Thermal Insulation," designated ASTM C1423. This guide will be kept as-is. However, a new task group has started writing a new "Standard Specification for Selecting Jacketing Materials for Thermal Insulation." To write a specification, the task group members focused on making lists of commercially available jacketing materials, in North America, and will be categorizing these into tables, on each for piping, ducts and equipment. It is envisioned that one side of each table will have the materials, and the perpendicular side will have the properties. Those are properties such as abuse resistance, water vapor transmission, external corrosion resistance and many others. This task group plans to meet in the fall to continue its work.

    The is an existing ASTM "Standard Guide for Flexible Removable Insulation Covers," designated ASTM C1094, which has been in existence for more than 15 years. A discussion was held, during the subcommittee meeting in Salt Lake City, about NIA’s interest in having a specification developed for removable insulation covers. Given that this is really not NIA’s mission and it is ASTM’s mission to develop standards such as this, the subcommittee decided to start a new task group to develop such a specification and to meet for the first time in the fall. Joe Bhavsar, of ABB Lummus, will chair this task group.

    Subcommittee C16.94-Terminology

    This subcommittee only has one standard to address, C168, which contains a number of insulation term definitions. The task group recently balloted definitions for five terms: polyimide foam, homogeneous material, flexible cellular, open cell and closed cell. All are currently defined in existing ASTM material standards except for homogeneous material, which is already defined in C168, but was being reballoted with an expanded definition. A number of negatives were received on each term. Therefore, all are being redefined, to address the negatives, and will be reballoted prior to the fall meeting in Washington.

    Subcommittee C16.96-Technology Transfer

    As an additional note of interest to our industry, ASHRAE is planning a symposium in February 2005, in Orlando, Fla., on the subject of mechanical insulation. ASHRAE will soon be calling for papers for that symposium. Their Web address is http://www.ashrae.org.

    C16 held a Monday night forum in Salt Lake City on the subject of testing insulation for noise reduction. David Moyer of Riverbank Acoustical Laboratories gave a talk to about 50 interested members on that subject. For the next ASTM C16 meeting, Subcommittee C16.96 plans a Monday night forum on the subject of "green buildings." While a speaker has not yet been found, Subcommittee C16.96 will be looking for an expert on this subject, possibly someone representing a Washington, D.C., area organization.

    Acknowledgements: The author wishes to thank the following people for their contributions to this article:

    • Bill Brayman, Brayman Insulation Consultants, LLC;

    • Kartik Patel, Armacell, LLC;

    • Anil Shenoy, Dow Chemical.

    NIA Sites > Insulation Outlook Magazine > Global

    Insulation Critical for Power Facilities

    For Mike McCallin of American Electric Power (AEP) in Columbus, Ohio, the most crucial benefits of insulation are energy savings and improved equipment-operating efficiency, protection from burns and hazards, increased comfort for workers due to lower ambient temperatures, and reduced noise levels.

    A good insulation system, when properly installed, delivers all of these important returns, and it is McCallin’s responsibility to ensure this success at AEP plants and facilities. In his capacity as principal coordinator in contract administration, McCallin administers blanket contracts for insulation and asbestos abatement services, refractory work and valve leak repair, among others. He prepares and maintains asbestos abatement specifications and insulation application specifications used at AEP’s fossil fuel-fired power plants. He also prepares bid specifications for major projects both mechanical and insulation-related.

    McCallin, who earned his bachelor of technology degree in mechanical technology from the University of Akron, is licensed in three states as a project designer for asbestos-related projects. He has taken classes in the field to earn and maintain his licenses.

    When choosing contractors for an insulation job, McCallin and his team look at many criteria to make sure a contractor is a good fit. Besides reviewing the company’s experience, licensing, references and safety data, among other considerations, McCallin also ensures that the contractor is able to perform asbestos abatement and reapplication, as most AEP facilities have asbestos insulation present.

    "Contractors must have a history and demonstrated experience working in the power industry due to its unique requirements," said McCallin. Once contractors have completed smaller contracts successfully, they are approved for larger projects.

    McCallin orders insulation materials directly from manufacturers to ensure that he gets the product he wants. On one occasion, when a contractor supplied the insulation, the incorrect fiberglass material was used–a low-temperature insulation was installed on a high-temperature unit. It was not long before the insulation started melting and actually caught on fire.

    Avoiding scenarios like this is one of the reasons McCallin, who works with his company’s supply chain department to maintain blanket orders for insulation, prefers to order his insulation supply personally and then hire contractors for the installation.

    McCallin constantly monitors what works and what does not in the area of insulation.

    "Our end-users bring to our attention those products or applications that have not held up or are not performing as claimed. For example, we had a problem with a fabric that was being used in making removable/replaceable insulation blankets. That product is no longer in use. Our insulation contractors have been very helpful in this respect–if a product is difficult to install or too fragile, they will bring it to our attention." The end-users’ experiences (both good and bad) with insulation systems play a large part in determining what will be used in future projects, ensuring that the best systems possible are put in place from the start.

    One of McCallin’s more challenging projects at AEP has been designing the insulation systems used on the company’s selective catalytic reduction systems (SCRs). A Clean Air Act requirement, these are expensive projects that have very large ducts and catalytic reactors. The reactors and reactor cap alone can be 50 by 55 feet by 80 feet tall, with three of these side by side. This doesn’t include the ductwork going to and from the reactors, which are also quite large and complex in shape.

    "The SCRs run at high temperatures [650 F and higher], and addressing the thermal-expansion issue for the insulation system was a challenge, compounded by the unit’s sheer size," said McCallin. Other energy companies had encountered problems with lagging buckling due to thermal expansion and the structural beams of the SCRs bowing due to improper insulation. By studying what had worked and what didn’t, AEP has been able to avoid these problems thus far.

    McCallin believes that, in order to help improve the industry, insulation installers need to be proactive in driving the manufacturers and fabricators to provide products that are more durable and easier to install.

    "In the building industry, the entire focus of material suppliers is to provide products that are less labor-intensive to install, more attractive in appearance and provide increased durability; as well as address health, safety and environmental concerns. The makers of insulation materials need to have the same focus," he said.

    Among his peers and colleagues, said McCallin, the benefits of good insulation systems don’t yet receive the attention that other systems get.

    "We are working to increase awareness of how much an improperly installed insulation system costs in the long run from multiple standpoints, including heat loss, early system failure, corrosion of the system below due to water entry, etc.," said McCallin.

    For him, the importance of good insulation systems is self-evident and has been proved time and again at his company’s facilities and power plants.

    Star Spotlight

    Name: Michael J. McCallin

    Company: American Electric Power, Columbus, Ohio

    Title: Principal Coordinator, Contract Administration

    Responsibilities: Administering blanket contracts for insulation and asbestos abatement services.

    Why He Endorses Insulation: For its benefits–energy savings and improved equipment-operating efficiency, protection from burns and hazards, increased comfort for workers due to lower ambient temperatures, and reduced noise levels.

    Nominated as Insulation Star By: Dave Andrew, Irex Corp.

    NIA Sites > Insulation Outlook Magazine > Global

    Heat? Cold? Rain? No Problem!

    Lagging is steel or aluminum finishing material used to cover many types of insulation, especially on large, flat surfaces such as boiler walls, flues, ducts, precipitators, bag houses, selective catalytic reduction systems, air heaters, economizers, scrubbers, wind boxes and fans. Also known as cladding or sheet metal, lagging does not include a vapor barrier, and ranges in thickness from 0.032 inches to 0.063 inches for aluminum, and from 20 gauge to 16 gauge for steel. Lagging, in general terms, is a tailored job of covering the insulated areas to suit the particular installation and its configurations.

    What is the purpose of lagging? First and foremost, it is used to protect the insulation it covers and is applied over insulated areas to present a true plane – a flat and even surface. It must be stiffened and fastened on adequate centers to prevent excessive deflection or "oil canning" when hot or cold.

    Secondly, lagging is used to provide a weatherproof construction complete with proper flashings, slopes and seals to ensure water runoff without the possibility of ponding or accumulation of water. You might think that this only applies to outdoor installations, but it can also be a problem in indoor installations where companies water-wash their steam-generating boilers and equipment. Water is the enemy of any insulation system, regardless of how it gets there.

    Material Specifications

    There are three standard types of metals used for lagging: galvanized steel, stainless steel and aluminum.

    • Galvanized Steel* – Galvanized steel lagging is available plain or treated for painting. It can either be a ribbed or flat sheet material and should be specified as being a commercial-quality material and conform to ASTM specifications A924 with a commercial zinc coating of at least 0.90 ounces per square foot.

      *Galvanized is a term long used to describe steel sheets coated with zinc. A galvanized lagging sheet has a shiny-flaked look while the treated-for-painting galvanized lagging will either have a dull weathered appearance or actually be painted with a primer coat.

    • Stainless Steel – Stainless steel lagging is normally provided in type 304 but can be provided in other types. The outside exposed surface of the stainless steel lagging should have a 2B finish. The temper of the stainless steel material should bend in half or back on itself without cracking.

    • Aluminum – Aluminum lagging is usually provided with a stucco-embossed finish. The core material for the aluminum lagging must conform to ASTM Specification B209 and have a cladding of 7072. Ribbed aluminum lagging must have a temper of H 174, and flat aluminum lagging must have a temper of H 154.

    Environmental Concerns

    As with any product, particular precautions must be taken in the handling and storage of aluminum or steel lagging materials. The finish on both materials is susceptible to atmospheric contamination. It is advisable to take the following precautions:

      1. Store the material inside.

      2. Elevate the material above the ground or floor to allow air circulation.

      3. Always place ribbed sheets, flat sheets or coiled material on end or edge to allow water or moisture to drain.

      4. Material should not be tightly sealed with covers such as plastic. This tends to create a sweating condition that will produce oxide damage. Some ventilation is necessary.

    Special attention must be given to coastal projects. It has been found that on coastal jobs, contamination and discoloration can occur from atmospheric condensation between sheets when they are laid flat. You should carry out routine inspections. Sheets should be separated and ventilated if any condensation is found.

    Also, where aluminum lagging comes in direct contact with another type of metal such as steel, it is necessary to paint all of these other surfaces with a heat-resistant aluminum paint that has a temperature service limit of up to 350 F. This will prevent galvanic action between the aluminum and the steel.

    Structural Concerns

    All lagging is attached to a support or structural system by the use of sheet metal screws. A sheet metal screw should be applied on every other rib, regardless of the material involved. On flat sheets, sheet metal screws should be applied on a maximum of 2-foot vertical by 3-foot horizontal centers. Common sense should prevail in the use of screws. Excessive numbers are costly and detract from appearance. The lagging screws are installed properly when they are pulled down tight. A screw is considered loose when you can wiggle the washer with your fingertips.

    It is also important to take into consideration the weight of lagging, which is required for calculating structural steel design. Lagging weight is also a consideration in crane sizing for lifting pieces of equipment (i.e., flues, ducts, selective catalytic reactors) to elevation if you intend to ground-install the lagging to the equipment prior to lifting. See the chart below for approximate weights of standard lagging material thickness.

    Expansion and Contraction

    Expansion and contraction requirements represent a major problem in lagging. Necessary provisions for expansion and contraction must be provided in the lagging design to maintain a neat and proper design when in service. When the lagging is properly installed over insulated areas, it presents a true plane, stiffened and fastened on adequate centers to prevent excessive deflection or "oil canning" when hot (expansion) or cold (contraction).

    Expansion and contraction are a function of temperature. As the temperature of the surface (i.e., flue plate) to be insulated and lagged goes up, so does the amount of expansion and contraction that must be incorporated into the lagging system. The higher the temperature, the more attention must be made to the lagging system. This is especially true when a Selective Catalytic Reduction (SCR) system is installed at a power plant to help reduce the plant’s NOx emissions. The SCR system is usually installed between the boiler gas outlet and the air heater. Under normal operation, an SCR system operates with gas temperatures between 600 and 700 F.

    Lagging expansion and contraction are absorbed by any combination of the following, with each part carrying some portion of the expansion and/or contraction:

    • The lagging support system.

    • The ribs of the box rib-type lagging because they will allow the lagging to move with the contraction and expansion of the surface being covered.

    • The standing seam between flat lagging sheets.

    • The flashing.

    The expansion or contraction is done through the lagging support system being used (i.e., sub-girt, angle iron, stud, pin, Z support or H support system). It is their ability to bend, expand or contract that will contribute to the expansion and contraction of the lagging system.

    When using either sub-girt, Z or H-type support systems, it is recommended to use short spans with a maximum of 10-foot lengths wherever possible. This allows the expansion and contraction to be taken within each short support assembly. Small gaps must be left between the short spans of the sub-girt, Z or H assembly equal to the amount of expansion expected in that particular direction. This small gap can be anywhere from an 1/8-inch to a 1/2-inch wide. In no case should the short sections of the sub-girt, Z or H assembly be welded together as this will inhibit the expansion and/or contraction of the lagging.

    Use an "S" lap* on the vertical seams of the lagging for hot systems (surfaces above 350 F) such as SCR flue systems, which normally have long vertical walls and a large amount of side-to-side expansion. If the lagging is applied when the unit is not running (referred to as being "cold"), then the straight edge would be jammed completely into the "S" lap. If the lagging is being installed while the unit is running (referred to as being "hot"), then the flat edge would only be partially placed into the "S" lap, leaving a gap or room between the flat edge and the back of the "S" lap. This gap will normally be about an 1/8-inch to a 1/4-inch, depending on the amount of expansion the entire SCR is designed to move from side to side. This gap will allow the lagging to contract back when the unit is shut down and would prevent "oil canning" or buckling of the lagging. The use of an "S" lap would also eliminate the need of stitch screwing of the lagging panels together at the lagging seams. This would also save money and time. Screws are required every 6 to 12 inches.

    *An "S" lap looks a little like a Pittsburgh lap. It is formed on a machine on one side of the outer long edge of a rib sheet. (This is best done at a mill or shop.) The other side of the rib sheet is kept straight without any bent edge, as is normally done on a conventional rib sheet. The flat edge side of the ribbed lagging panel would then be placed into the "S" lap of the adjacent lagging panel.

    Use an H flashing on the horizontal seams of the lagging for hot systems (surfaces above 350 F) such as SCR flue systems, which normally have long vertical walls and a large amount of top-to-bottom expansion. The H lap should only be screwed to the top sheet. This will allow the bottom sheet to expand or contract within the H flashing.

    Surfaces 350 F and below are considered cold systems. The expansion or contraction of a cold system is not as great and, therefore, the lagging can be attached directly to the external stiffeners. This can be done as long as the stiffener spacing meets the required wind loading.

    Flat Sheet Versus Box Rib

    It is recommended that rib lagging should always be used wherever possible in lieu of flat sheet lagging because it helps in the expansion and contraction of the lagging system. Flat sheet lagging, in most cases, should be used for flashing, round surfaces, elliptical or irregular surfaces such as drumheads, or areas where space prohibits the use of rib lagging.

    Here are some reasons for using a rib lagging versus a flat lagging:

      1. The ribs or boxes of the rib lagging will aid in the expansion and contraction of the lagging system. A manufactured standing seam is required for flat sheet and is more labor-intensive than using a rib-type lagging.

      2. Rib lagging is much easier to work with when covering large flat areas. The ribs help to give the material strength and rigidity, which is especially helpful on top surfaces where foot traffic may occur. On top surfaces that are exposed to the weather, rib lagging, if installed correctly, will help prevent water from ponding, or sitting. Ponding water on any lagging surface (rib or flat) will eventually penetrate the lagging system and damage the insulation underneath.

      3. The problem of foiling occurs when the flat lagging is too thin or insufficient in rigidity for the application. Crinkling can occur when pressure is applied to the lagging during installation, for example, in screw locations. Depending on the surface area of application, this can be quite pronounced. This crinkling on the surface of the lagging looks like reused aluminum foil.

      4. Rib lagging is nicer to look at on large flat or round areas than flat sheet. The ribs help break up the surface areas and present a more aesthetically pleasing view, especially from a distance.

      5. Rib lagging can be cut or manufactured to any desirable length (up to 20 feet or longer). Flat lagging comes in either a coil or individual sheets manufactured up to only 10 feet long.

      6. Flat lagging can bend easier than rib lagging due to the temper of the metals.

      7. The pitch of the lagging on top surfaces exposed to the weather should be sloped for drainage at a minimum of a 1/4-inch per foot.

      8. All hanger rods, pipes or other items penetrating the lagging should be provided with cover plates, boot, hoods or flashing made from the same type of metal as the lagging. This will prevent water from penetrating into the insulation and ensure that none of the insulation is visible. Provisions should always be made for any relative movement between the lagging and the penetration.

    General Application Techniques

    In most cases, erection of lagging follows the sequencing of applied insulation. On outside jobs, it is imperative that the insulation be covered at the earliest possible time, considering present-day insulation materials and techniques (only one or two days behind the insulator).

    Generally, the success or failure of a lagging job depends on the basic setup of the job, the soundness of the preparatory work, and the ability of the shop crew to keep material flowing to the erecting crews. Under normal job conditions, a shop crew of two men can keep material flowing for two to three application crews. On the larger contracts, the shop forces must be increased according to the number of installation crews to ensure a completely efficient operation.

    Unfortunately, many in the industry are having all of their corner flashing cut and broken into standard 6-inch by 6-inch corners offsite and sent to the job. This means the flat corner flashing will not be custom-fit at the corners at the job. This is not good lagging technique. A prefab corner flashing has the potential to overlap too far over the adjacent high rib and looks aesthetically displeasing. It could also allow water to sit or pond on the top surface areas of the lagging, where there is a trough between the high ribs. The trough is created when the excess overhang of the prefab corner flashing opens a long vertical space between the ribs.

    Conclusion

    Installing lagging means installing a tailored job for the purpose of covering the insulated areas to suit the particular installation, its configurations, and for aesthetics. You cannot separate the importance of lagging from insulation. Each part of insulation and lagging must work together to ensure a proper working system. Good lagging practices must be enforced in the design of the system and at the job site. Pay attention to all aspects of your insulation and lagging system, and remember that while lagging may be the last thing you do, it should be the first thing you think about when designing and installing an insulation system.

    Figure 1

    Buckled lagging flashing on a Selective Catalytic Reducation System sidewall.

    Figure 2

    H flashing.

    Figure 3

    Penetrations through lagging.

    Figure 4

    An example of a sheet metal screw that is not screwed down tightly.

    Figure 5

    “S” lap flashing.

    Figure 6

    Typical lagging flashing at roof cans.

    Figure 7

    Weight per square foot for lagging.