Why Install Lightning Protection on a Process Control Plant?
Have you noticed in your travels that more and more plants are being equipped with structural lightning protection (lightning rod) systems? And what is the deal with the “fuzzy ballTM” lightning rods you see sprouting up all over?
In high lightning areas, plant operators understand that lightning is a real problem, damaging equipment and producing plant outages and down time. Hence, the presence of structural lightning protection systems. However, in order to secure benefits, if any, from the system, it helps to understand the purpose, nature, and operation of such systems.
INHERENT SELF-PROTECTION OF INDUSTRIAL FACILITIES
The National Fire Protection Association NFPA 780, Standard for the Installation of Lightning Protection Systems, is the US lightning protection standard. According to that standard, certain types of structures are considered to be self-protecting, that is, they do not require a lightning protection system. The reason behind this exemption is that the primary purpose of a lightning protection system is to keep a structure from burning down. That is why lightning protection is contained in a National Fire Protection Association document.
A lightning protection system consists of three major components: the strike termination device (qualifying structural member, lightning rod, air terminal, etc.), the conductor system, and the grounding system. The strike termination device must be capable of sustaining a direct lightning strike. By accepting the strike, it prevents physical damage that could otherwise occur from the heat, current flow and physical impact of a strike. The conductor system conveys the lightning energy from the strike termination device around the structure over multiple, downward-coursing paths to the grounding system. The grounding system allows the lightning energy to equalize and dissipate into earth ground. This is the same type of lightning protection developed by Ben Franklin to prevent wood houses and barns from burning down.
According to NFPA 780, certain conductive metal components of a structure may be substituted for lightning protection system components. An industrial facility normally consists of process vessels, piping, cable trays, etc. supported by steel frames. The I-beams and frames that comprise the top of the structures are greater than 3/16” thick. Therefore, they may be substituted for strike termination devices (lightning rods). They are more than adequate to sustain direct lightning attachment and provide a zone of protection covering the process equipment. A zone of protection is the space adjacent to a lightning protection system that is substantially immune to direct lightning attachment. The zone of protection depends on the geometry of the structure, and may be determined by one or more of three methods:
- strike termination device placement
- the angle method
- the rolling sphere method.
This principle presumes that lightning will attach to the strike termination devices and not to a process vessel, field transmitter, motor, or other susceptible plant component.
The horizontal and vertical framing is also greater than 3/16” (or arguably 0.064”, depending on which section of the standard applies) thick, and provides multiple downward-coursing paths to ground, so it may be substituted for the main and down conductor system. The structures are grounded to the plant grounding system at their bases, providing the grounding system. Therefore, these structures are considered self-protecting, as the structure itself provides all of the necessary components of the lightning protection system.
PLANT LIGHTNING SUSCEPTIBILITY
This is all fine, except that, based on experience with lightning damage, these plants are obviously not self-protecting. Lightning caused fire is not the major problem in a plant. A lightning strike is highly unlikely to burn down a steel structure. In addition to the ability to start a fire, a lightning strike also has the ability to cause other types of damage to plant equipment. These plants run on microprocessor-based communications and control systems. Any direct or nearby lightning strike also creates secondary effect and electromagnetic pulse (EMP) effect. Secondary effect is the in-rush of surrounding ground charge towards the point of a strike. EMP is a pulse radiating outward from the current flow in both the lightning channel and the conductor system. Either of these effects can induce current flow in plant wiring and structural components more than capable of causing damage, interruptions and outages up to and including a plant emergency shutdown (ESD). Indeed, we have seen EMP from a lightning strike induce sufficient energy into steel components to trigger arcing and ignition of gas half a mile away from the strike.
Considering a plant to be self-protecting or installing a conventional Franklin-type lightning rod system cannot help control these types of lightning damage. One solution is to install a lightning protection system employing streamer-retarding air terminals (SRAT’s) atop the plant. These are the “fuzzy ball” lightning rods. Using UL Listed stainless steel bases, the air terminals simply attach to the I-beams or frames and use the plant structure as the conductor and grounding system. The effect of the SRAT system is two-fold. First, they act as simple static wicks, similar to those on an airplane, to reduce static charge accumulation on the structures. Lower voltage potentials equal less current flow. In fact, when Lightning Master obtained its patent on this technology, our patent application referenced static wicks on aircraft. Second, they act to delay the formation of streamers from the protected structure, thereby lowering the likelihood of a direct lightning strike. Less strikes, less secondary or EMP effects, so less damage and down time. The effectiveness and reliability of this approach has been
documented by numerous, experienced and sophisticated users over the past 30+ years this system has been available.
What is the difference between Fuzzy Ball and regular old and Franklin lightning rods? Well, not much and a whole lot.
Physically, the only difference is the addition of a multiplicity of small radius electrodes (wires) inserted into the tip of the elevation conductor of the air terminal. Everything else in the system is identical, including the grounding system, main and down conductors, clips, clamps, bases, etc. In addition, all components are Underwriters Laboratories UL 96 listed, and the completed system is eligible for a UL Master Label, Letter of Findings, or Engineering Inspection Report, as appropriate. In fact, virtually any Franklin lightning rod system may be converted to a Lightning Master SRAT system by simply unscrewing the lightning rods and screwing in Lightning Master streamer-retarding air terminals.
If the differences are so small, then why the Lightning Master approach? The small wire electrodes greatly enhance dissipation of ground charge to the atmosphere by virtue of their small radius (sharpness). Lightning attachment is determined by streamer formation. Whichever object on the surface of the earth emits the best streamer, wins. Corona is the controlled, lower energy dissipation of ground charge sometimes called St. Elmo’s fire. These small radius points break down into corona under a much lower potential (voltage) than a rounded or even pointed Franklin lightning rod, reducing total charge accumulation, and making it more difficult for a sufficient amount of ground charge to accumulate to form a streamer. As the air terminal breaks down into corona sooner, it dissipates the charge over a longer period of time.
Imagine the corner of a structure. The charge on the base of the storm cloud pulls the ground charge surrounding the structure up and onto the corner of the structure. As the storm builds in intensity, the difference in potential between the cloud base charge and the corner of the structure builds. When the difference in potential overcomes the dielectric (resistance) of the intervening air, the difference in potential is equalized by a lightning strike. In order for the corner of the structure to emit a streamer, the ground charge must accumulate sufficiently to do so. The ground charge leaking off the small radius points interferes with that accumulation.
In its primary mode, the SRAT dissipates the ground charge that would otherwise form a lightning-completing streamer, reducing the likelihood of direct lightning attachment. If the ground charge rises too quickly or builds too high, the dissipation ability of the air terminal may be exceeded. In that event, the air terminal reverts to its secondary mode of a Franklin lightning rod. Since the SRAT is located at the top of the structure as required by both NFPA 780 and UL 96A, and it is already saturated with streamer constituting ground charge, the SRAT then emits a streamer, reliably collecting any strike and conveying it to ground over the lightning protection system.
GENESIS OF THE TECHNOLOGY
Lightning Master’s original exposure to structural lightning protection for buildings was at the Veterans Administration Hospital in Bay Pines, Florida. The building had suffered a direct lightning strike to the roof between lightning rods. The strike punctured the roof, melting the roofing material. Building maintenance had heard about Lightning Master and asked us to see if we could develop a solution to their problem. At that time, Lightning Master provided lightning protection mostly for broadcast and communications facilities. In response, we developed an air terminal employing streamer-retarding technology that slipped over and crimped on to a Franklin lightning rod. In order to obtain a UL Listing, we later modified the product, so it no longer slipped over, but replaced a Franklin lightning rod.
EXPLANATORY MODELS AND EXAMPLES
To explain this phenomenon, we sometimes use one or more of the following examples or models. Sometimes it helps to envision taking the protected structure, turning it upside down and dipping it in syrup. When the inverted structure is lifted from the syrup, the syrup tends to drip off the outside edges, corners, and any protrusions. These points are analogous to the charge accumulation and streamer formation points of that structure, and can help make it clear why those points are most likely to be struck by lightning. It also explains why NFPA 780 and UL 96A locate lightning rods at those locations. The SRAT’s dissipate ground charge off, and delay streamer formation from, the locations most likely to be struck by lightning.
When talking with engineers, it is sometimes helpful to use a variation of Coulomb’s law showing that the smaller the radius of a point, the greater the electric field intensity surrounding it. This explains the greater dissipation current from a SRAT than from a Franklin lightning rod.
At trade shows, we sometimes use a Van de Graaff generator to show the difference in dissipation between objects of various shapes. Where the point of a car key or Franklin lightning rod may arc 1/2” to 1” or so to a 200,000-volt Van de Graaff, a Lightning Master SRAT may be touched to the generator ball without arcing. We also use the Van de Graaff to show the ability of an electrical field to induce current in a piece of metal. That piece of metal then arcs to any other piece of metal brought into proximity to it, demonstrating a common cause of ignition, particularly at oilfield facilities.
Regarding system performance in the field under actual day-to-day operating conditions, please consider the following. This is an excerpt from a letter from a Project Manager at a large chemical plant in the southeast US. “After the installation was completed, several company personnel were skeptical of the performance of the “fuzzy ball” lightning rods. Perhaps the strongest indication of the effectiveness of your system was when it did not work. In one area of our plant, we had a particularly corrosive environment. That caused the stainless-steel dissipation electrodes at the tip of the air terminals to corrode away, turning the air terminals into the equivalent of blunt lightning rods. We immediately started experiencing damage to microprocessor equipment in that block of the plant. You worked with us to change the air terminal material to titanium, going so far as to change NFPA 780 to allow its use. When we changed out the air terminals to titanium, the problems stopped.”
A large company operates a paper plant located in the salt marshes of northeast Florida. The commercial AC power to the plant runs across the marshes and suffered numerous lightning strikes causing equipment damage and unacceptable downtime at the plant. The operator installed Lightning Master air terminals on each of the utility poles leading across the marsh. Their incidence of damage and outages dropped so dramatically that they published an article in their company newsletter explaining to its employees the decrease in lightning problems.
A Franklin lightning rod system was installed on a data center in central Florida. This system was designed by a well-known and influential engineering company specializing in the design of lightning rod systems. Because the data center was considered critical, the system was designed and installed with decreased spacing between lightning rods to enhance its level of protection. Sometime after the installation was completed, the structure suffered a direct lightning strike to its roof near, but not to, a Franklin lightning rod. After an investigation, no one could explain why it occurred or how to keep it from happening again. The installer of the original system suggested replacing the Franklin lightning rods with Lightning Master streamer-retarding air terminals. The customer did so, and there have been no incidents since.
An operator of a south Louisiana plant experienced numerous fires atop their hydrogen stacks during electrical storms causing numerous plant shutdowns. One engineer commented that after a storm, the production area “looked like Kuwait” (this was after the first Gulf War). After installing Lightning Master systems on their stacks, they only suffered one or two stack fires in the following two years.
The instrument and electronics engineers at petroleum production sites in the northern US experienced multiple failures of their guided-wave tank level sensors. The sensors were not physically damaged; they were just confused by transients and required a manual reset by a technician. Another division on the company installed Lightning Master lightning and static control systems on their sites as part of a separate project. The I&E engineers noted an immediate and drastic improvement in the reliability of the level sensors. It turned out that static has been causing the problems, and the Lightning Master system, in addition to its role in lightning protection, also solved the static-related issues.
The SRAT does not protect only itself, thus allowing nearby strikes to the protected structure. In our experience, this is actually more of a problem with Franklin lightning rods than with Lightning Master streamer-retarding air terminals.
We have been asked how it is possible for a SRAT system to dissipate the millions of volts and thousands of amps of a lightning strike. It is not necessary to do so. Only a very small percentage of that energy need to be dissipated to lower the streamer emitting threshold of the protected structure. As in the case of a dam holding back a reservoir, it is not necessary to drain the entire reservoir to prevent the dam from overflowing. It is only necessary to drain a very small percentage of the reservoir.
Neither is it possible or necessary to discharge the storm cloud. A SRAT system has no effect on the storm cloud. It only affects one small area of the surface of the earth.
MEETING INDUSTRY STANDARDS
National Fire Protection Association NFPA 780, Standard for the Installation of Lightning Protection Systems, is the US lightning protection standard. Underwriters Laboratories converts that standard into two standards for safety, UL 96, Lightning Protection Components, and UL 96A, Installation Requirements for Lightning Protection Systems. UL 96 covers components and UL 96A covers how to install those components. Underwriters Laboratories is the nationally recognized testing laboratory (NRTL) in the industry, an independent laboratory recognized by the Occupational Safety and Health Administration (OSHA) to test products to applicable safety standards. UL’s Lightning Protection System Program is accredited by International Accreditation Service (IAS), an independent 3rd party accreditation body, to the ISO 17020 standard for Inspection Certification Bodies.
Lightning Master streamer retarding air terminals meet the requirements of National Fire Protection Association NFPA 780 and are Underwriters Laboratories Listed to UL 96. The SRAT provides a zone of protection exactly the same as any other lightning rod and are designed and intended to be used as components in a NFPA 780 or UL 96A system. As such, a completed installation is eligible for a UL Master Label, Letter of Findings, or Engineering Inspection Report, the gold standard in lightning protection.
In oilfield applications, grounding requirements of American Petroleum Institute API 2003 and API 545 are applied.
Lightning Master personnel serve as principal members of NFPA 780, UL 96 STP and API 545.
In keeping with industry trends to use blunt-tipped air terminals for personnel safety, the tip of a SRAT is blunt, with a plurality of small-radius electrodes (wires) inserted into that blunt tip.
LMC has upgraded and implemented protocols and procedures to comply with cyber security maturity model certification (CMMC), a defense industrial base (DIB), qualifying LMC for projects at federal government level.
Lightning Master is a drug-free workplace. In compliance with the Drug-Free Workplace Act, Lightning Master has a longstanding commitment to provide a safe, quality-oriented and productive work environment consistent with the standards of our community and the sites on which the company operates.
It has been said that two guys with a ladder and a pickup truck are a lightning rod company. This may work for installing lightning rods on a doghouse, but you probably do not want them anywhere near a large, sophisticated plant, particularly during new construction.
Lightning Master is experienced in large and critical plant installations around the world, with an experienced administrative, engineering and manufacturing staff to support such projects. LMC carries full, appropriate insurance, works with compliance organizations including ISNetworld, Veriforce, and Avetta, and can provide document control, certified payroll and other large project services.
Lightning Master installers are full-time Company employees, appropriately insured and fully trained and certified in compliance with current codes, safety standards and requirements.
For overseas projects or if requested by the owner/operator, LMC can provide supervision. Or, if preferred, we can provide turn-key material and installation.
Lightning Master Corporation is also a UL Certified Lightning Protection System Installer. Our installation supervisors and technicians have completed UL training, and many are Journeyman Certified Installers. LMC can work efficiently with the project owner, managers, and other trades to complete a complicated project on time and within budget
So, why install lightning protection on a process control plant when it is not required by applicable standards? There is no reason for or advantage to installing Franklin-type lightning protection. However, installing Lightning Master® Streamer-Retarding Air Terminals can limit the build-up of static charge on the plant, and discourage secondary and EMP effect damage to plant equipment and reduce disruptions in plant operations caused by direct or nearby lightning strikes thereby enhancing plant reliability.
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For further information, please refer to the Lightning Master white paper, LIGHTNING MASTER® STREAMER-DELAYING vs. FRANKLIN LIGHTNING ROD TECHNOLOGY.