Retractable Grounding Assembly (RGA™)
Proactive Lightning Protection for Floating Roof Tanks
- Effective: Permanent, reliable, low-impedance bond prevents fires triggered by lightning currents
- Economical: Low initial cost and exceptional return on investment
- Easy-to-Install: 2 hour install on new and existing tanks
- Durable: Engineered for years of durability and reliable performance in corrosive environments
- Low-Maintenance: Requires virtually no upkeep as compared to shunts
- Award Winning: Winner of the E & P Innovation Award
Standards Conformant: The RGA conforms to both API 545 and NFPA 780 recommendations as a bypass conductor, necessary lightning protection equipment for floating roof petroleum storage tanks.
Certified: ATEX and CE tested and approved.
Floating Roof Tank Fires are Common
There are 15 to 20 tank fires per year, and over half of them involve Floating Roof Tanks. FRT’s are especially vulnerable to the direct and indirect effects of lightning. A direct or a nearby lightning strike will cause electrical currents to flow across the tank shell and roof. When these lightning currents arc across the roof/shell interface, they can ignite any flammable vapors that may be present. It is therefore necessary to bond the roof and shell to prevent arcing at the roof-shell interface.
Inadequate Protection to combat the risk of tank fires, the industry has been using metal strips called “shunts” that electrically bond the shell and roof of the tank in multiple locations. Unfortunately, the bond that these shunts establish is unreliable and creates a greater risk of sustained arcs:
- Rust, waxy product deposits, and paint can line the inner wall of the shell.
- The floating roof can drift slightly off-center and disconnect some of the shunts from the shell.
- API Testing proved that shunts will arc under all conditions, even if the tank wall and shunts are new and clean.
Substantially reducing the risk of sustained arcs requires a reliable, full-time, low impedance and low resistance connection between the tank shell and roof. Additionally, the connection must operate regardless of the tank wall’s condition.
The RGA is not affected by the condition of the tank because the RGA and cable are bolted and sealed to optimal locations on the tank shell and floating roof. When properly applied, multiple RGAs on each tank provide low-impedance pathways to safely discharge lightning currents.
The Dissipation Array™ System (DAS™)
DAS prevents direct lightning strikes by reducing the electric field to below lightning-collection levels, within the protected area. As a result, DAS helps to prevent downtime and loss of assets, while increasing personnel safety.
Lightning Strike Prevention
Lightning is nature’s attempt to equalize the voltage between storm clouds and the earth. In order for lightning to strike, it must connect to upward streamers, which reach up from earth-bound objects when the electrical field is strong enough. DAS interrupts the formation of these upward streamers through Point Discharge, a phenomenon where a well-grounded point exchanges ions between the air and the ground.
Point Discharge becomes more efficient when the points are connected to a low-impedance grounding system, and more ions can be transferred with a greater number of points. DAS technology takes advantage of these principles with an optimal point configuration able to interrupt the formation of upward streamers, thereby preventing direct strikes
Lightning Protection Components
The Dissipation Array System is a key component of your lightning protection system, working with grounding and surge suppression to achieve complete protection. A typical system includes:
- The Dissipation Array, available in a range of configurations for almost any structure.
- A low-impedance grounding system using chemically-charged electrodes (Chem-Rod®).
- Surge Protection Devices (SPDs) to protect against electric transients traveling through data lines and other conductive paths.
Steps to Total Lightning Prevention
- Analysis: LEC consultants evaluate the site for factors that contribute to lightning events. Existing lightning protection systems are included in the evaluation.
- Design: Engineers then specify system components, placement, and structural interfaces. Designs account for environmental factors such as wind, ice, and corrosion.
- Installation: LEC offers installation supervision for all DAS installations.
- Certification: LEC supervised installations receive our No-Strike warranty, with recertification available on a yearly basis.
- Expansion: As your facility changes, LEC works with you to evaluate how your system is affected, ensuring uninterrupted protection.