_468x60px.jpg)
Protection zones leave upstream facilities lightning strike-free
Asiaand South America. To meet demand companies have had to explore alternative methods of protection to maintain 24/7 productiondespite the elevated lightning risk. In place of antiquated lightning rods that actually attract lightning to a sitea growing number of respected petroleum companies are turning to engineered ‘zones of protection’ to avoid lightning-related equipment damage and unscheduled downtime."With dwindling world oil supply and increasing demand as economic powerhouses like China and India...With dwindling world oil supply and increasing demand as economic powerhouses like China and India continue to growpetroleum sourcing is expanding into high lightning-risk areas such as parts of AfricaAsiaand South America. To meet demand companies have had to explore alternative methods of protection to maintain 24/7 productiondespite the elevated lightning risk. In place of antiquated lightning rods that actually attract lightning to a sitea growing number of respected petroleum companies are turning to engineered ‘zones of protection’ to avoid lightning-related equipment damage and unscheduled downtime. In the heart of Africathe Chad/Cameroon Development Project opened a revenue stream a few years ago with the completion of an estimated 1-billion barrel oil field in Chad and a 663-mile pipeline through Cameroon to an offshore marine export terminal. To meet market demand and protect productionone oil production operation in Chad had to proactively consider how to protect its facilities from lightning risk. Where an isokeraunic number of 30 indicates average lighting activity of about 13.7 strikes per square mile annuallythe region developed by the oil production operation has an isokeraunic number of 120indicating about 41 annual lightning strikes per square mile. "Chad has some of the most intensemost frequent lighting strikes in the worldwith about two lightning storms a week from mid May to early October says an electrical engineer for the oil production operation in Chad. Still to meet demand and production goalswe have to stay up and running without unscheduled downtime." To protect its facilitiesincluding a central processing site and three outlying gathering sitesthe oil production operation decided against using traditional lighting rodswhich are designed to attract lightning. "The problem with lightning rods is they attract lightning explains the engineer. The question isafter you get hit by lightningcan you put the energy in the ground before it damages instrumentation and shuts down your facility?" Insteadthe oil production operation opted to proactively protect its central processing site and three outlying gathering sites. To maximise production uptime by avoiding lightning-related equipment damagethey turned to Lightning Eliminators and Consultants Inc (LEC)a leader in lightning prevention technologyto engineer ‘zones of protection’ for each facility. From simple lightning protection to lightning prevention with a 100 per cent no-strike warrantycompanies such as LEC are at the forefront of maintaining oil and gas equipment and process uptime in the face of lightning threat. For the oil production operationLEC custom engineereddesignedand deployed interconnected systems for strike prevention and low impedance groundingutilising its Dissipation Array System (DAS). DASa charge transfer technology that’s being lauded as a comprehensivepreventive solution for modern lightning protectionessentially prevents strikes by continually lowering the voltage differential between the ground and charged storm clouds to well below lightning potential. In the US and abroadDAS has proven to be the preventative solution for lightning protectionsubstantially cutting storm-induced voltages as compared to the unprotected surroundingsthus eliminating the lightning strike risk. Since it preventsDAS is often the best long-term solution to lightning strike problems. In order to protect about 1.25sqmiles of facility space – including the central site encompassing about 0.5sqmilesand three separate gathering sites encompassing about 0.25sqmiles each – LEC took into account factors such as each facility’s locationsizeshapeequipmentgeographyand exposure to lightning activity. To discharge structures of the voltage differential between the ground and charged storm cloudsDAS was deployed across the protected sites. Stack arrays were used to protect turbine generatorswhich have protruding exhaust stacks. U-bracket arrays were used to protect buildings or structures with architectural or weight restrictions. Hemisphere arrays were used to protect a telecom tower and high-mass lights used at night. While rim arrays were used to prevent lightning strikes to floating roof storage tanksmultiple Retractable Grounding Assemblies were deployed to prevent arcing at the gap between the seal of the floating roof and the tank wallcaused by lighting storm and ground current activity. The RGAa device that provides a direct connection to the tank roof from the tank walluses a widethick-braided wire cable wound on a heavy stainless steel reelwith tension held by spring loading. The path of impedance is kept to a practical minimum by the combination of the shortest pathwide braidand constant tension. In additionan ultra-low impedance grounding system was also necessary to transfer induced ground charges efficientlysince transient voltages such as lightning are affected by impedance while resistance pertains to dc voltage. An appropriate numbersizing and spacing of Chem-Rodswhich use natural mineral chemicals to improve conductivity up to ten fold over traditional grounding rodshelped achieve a significantly reduced ground resistance with a target of less than one ohm. Reducing grounding impedance was importantas the natural soil resistivity at various sites ranged from less than 30ohms near a riverbank to over 500ohms up a sandy hill. The result of such proactive protection of upstream facilities has been significant. "With the engineered ‘zones of protection’ in placenot a single lightning strike has hit us in our protected zonesand it’s been over three years now relates the engineer. Only oncewhen CCTV installers mistakenly put a camera above a protected zonedid it get struck by lightning. The CCTV camera was shattered. To meit was quite a demonstration of the effectiveness of DAS." While initially skeptical of the ‘zone of protection’ conceptthe engineer admits that he’s a believer now. He considers the odds of the facilities not getting hit in their protected zonesin over three yearsin one of the most active lightning spots in the world highly unlikely without the addition of the integrated lightning protection system. In a region with an isokeraunic number of 120indicating about 41 annual lightning strikes per square milethe oil production operation’s approximately 1.25sqmiles of upstream facilities would be expected to have about 51 lightning strikes per year and over 150 in a typical three year period. Insteadthe facilities have had zero strikes in their protected zones. The net effect of this kind of lightning protection has been significant to the bottom line.
LEC Inc is based in BoulderColoradoUSA. www.LECglobal.com
"