Lightning Protection Products

Prior to export, processed crude oil is stored in Floating Roof Tanks (FRT) to further allow any trapped gas within the crude oil to escape, and further stabilise the oil. In the oil and gas industry, FRT’s are vital in the processing of crude oil to the acceptable export specification. However, because of global climate change, the frequency of accidents which include equipment damage and fire damage caused by lightning in fuel depots is rapidly increasing with floating roof tank fire being a major threat to crude oil production.

Thus Fuel Tank Lightning protection is now an indispensable part of the oil depot safety system.

Interaction of Lightning with a floating roof tank

By design to ensure ease of movement of the floating roof within the tank shell, there exist a gap between the tank shell and the edge of the floating roof. This eliminates friction, guarantees ease of movement but creates issues in the following areas when lightning strikes.

• Sparking

When lightning strikes a floating roof, the lightning current will flow over the roof towards the edge of the roof, and at the edge there exist a discontinuity because of the tank shell-roof gap, this prevents the current from flowing through the tank shell to the ground.

• Roof surface charging

Prior to an eventual lightning strike electric charges will accumulate in the sky. This creates a difference in potential between the roof and the shell which can result in transient currents.

• Heating

The flow of high energy lightning current can cause erosion and melting of thin metal sheets and this can generate incendiary particles even around the shell-roof gap; though tanks with a thickness greater than 5mm cannot be melted by lightning.

The discussion above shows that the gap between the roof and the tank shell is a major cause of lightning voltage spark. In order to mitigate this, LEC on fuel tank lightning protection recommends RGA.

Retractable Grounding Array (RGA) is basically a self-retracting conductor. The RGA retracts and extends based on the roof level thereby maintaining the shortest electrical connection possible and by so prevents the issue associated with the use of long cables. It is made of multiple weaved strands of low resistance tinned copper wire and is typically installed on the tank shell and connected to the edge of the roof.

Society increasingly depends on petroleum products, so storage management of crude oil and its products has become particularly important. The approach to solving the lightning induced fire issue is centred on eliminating voltage differential by installing a fuel tank lightning protection system such as LEC”s Retractable Grounding Assembly.

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Due to the increased risk when storing large amounts of crude oil and the relevant final products, special personal and environmental protection measures are required. Various regulations, describe measures that ensure safe operation of storage facilities with focus on fire protection measures. Since lightning constitutes an ignition source, suitable protection measures must be taken to reduce this hazard source to the greatest possible extent.

In short fuel tank lightning protection systems should do more than just intercept incoming lightning strikes which are still likely to cause ignition of the tanks’ contents. A total lightning protection system (LPS) should be designed to eliminate all lightning related direct and indirect risks.

Offshore rigs and platforms are thought of as “grounded” to the ocean. However, the environment, and even the design of the facility itself, may lead to a compromise in bonding with rust and oil deposits that impede the energy’s path to ground. This leaves the advanced electrical and electronic systems and personnel susceptible to severe damage from not only direct strikes but dangerous secondary surge effects of lightning as well.

What we offer:

Retractable Grounding Assembly - The ATEX approved and patented RGA substantially reduces the risk of tank fires by subduing sustained arcs during lightning events and other electrical phenomena. The RGA does this better than other traditional methods for bonding floating roofs because the retractable cable is always at the shortest possible length. The resultant low resistance and impedance is too low of a voltage to sustain the arc, i.e., no fire.

In-tank Potential Equalizer - This patented product is made specifically for non-metal and lined tanks in order to combat the problem of internal electrical discharges and the subsequent ignition of the vapours inside tanks. Its no-point lightning protection design makes it safer, more economical and corrosion resistant.

Dissipation Array System - the DAS and charge transfer method reduces the naturally occurring electric field in a protected area, therefore upward streamers do not get enough energy from a storm to connect with downward leaders. It’s based on physics and state-of- the art engineering principles specifically designed to stop a lightning strike from terminating where it is not wanted in a designated “area of protection.”

With appropriate use of fuel tank lightning protection methods; replacement costs, losses due to operational shutdown, and safety liability issues can be minimized. Through our practical experience, good communication and excellent attention to details, LEC consistently delivers fuel tank lightning protection products and solutions on time and on budget.

For more information on this subject, please feel free to contact us!

Lightning is the leading known cause of storage tank fires and it’s a constant treat.

Though all industries are at a risk of lightning strikes; even areas with infrequent thunderstorms can experience rare, but high intensity lightning strikes, the Petrochemical industry has the most shared data in losses.

Problem:

Lightning on tank storage and energy sources can cause explosion and/or ignite fire that consumes millions of dollars of products, create prolonged downtime, demand environmental clean-up, incur regulatory fine and require excessive repair and replacement. Fires at the upstream end of the industry are common, primarily in salt water disposable tanks.

Solution:

There is the Lightning rod, invented by Benjamin Franklin has worked very well to protect buildings and structures. However, a large electromagnetic field generated by a lightning strike can cause damage in a ways not covered by the Franklin rod. Tank battery lightning protection requires a systematic, multi-faceted approach and the very best in modern knowledge and technology.

Though lightning rods are the oldest form of lightning protection and still used today, in the past few decades advancement in technology have provided an option – Charge Transfer System, which takes a completely opposite approach to lightning protection. A type of CTS, the Dissipation Array System (DAS), works to prevent a lightning strike in a specific area designated for protection.

LEC has developed a number of tank battery lightning protection products, including DAS to address the primary and secondary lightning effects and to ensure maximum site and tank integrity. In addition to the protection from direct lightning strikes, we manufacture a complete line of AC power low and medium voltage surge protection devices.

Backed with expert consulting and support, we have decades of experience in:

- Providing protection and grounding systems for floating roof tanks

- Providing solutions for bound static charges in the petroleum products themselves

- Protecting vents from flammable gases

- And all other challenges unique to the petrochemical industry

Petrochemical and oil and gas industries demand the highest level of protection in order to prevent incidents, especially in tank batteries, as their metal structures make them more susceptible to lightning strikes.

LEC has been creating the best custom tank battery lightning protection solutions. Should you require additional information on this subject feel free to contact us.

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Lightning strikes are characterised by very high stroke currents arriving in a very brief amount of time. This current will flow across the surface of the earth until the cell between the thundercloud and earth is neutralised. The current will flow in all directions, although the amount will vary in proportion to the path of lowest impedance.

Here we are specifically talking about fuel tank lightning protection

Petroleum products such as crude oil, gasoline, diesel fuel, etc., are commonly stored in Floating Roof Tanks. An FRT is a type of tank where the roof floats on top of the product being stored. The roof, although constructed of steel, rests on pontoons that float on the product being stored. Consequently, as the tank is filled or drained, the roof travels up and down within the shell of the tank.

Lightning may endanger an FRT if a stroke terminates on the roof, the shell, anything attached to the roof or shell, such as the gauge pole, or a grounded structure or the earth near the FRT.

An FT is most at risk and all of the hazards from lightning tend to be worse, when the roof is high. During these conditions (when the tank is full or nearly full), the lightning current flows will be concentrated in the shunts directly below the lightning strike location. In comparison, when the tank’s roof is low and a lightning strike terminates on the tank, the lightning current disperses and is more evenly distributed among the available roof-shell bonds.

One of our most recommended fuel tank lightning protection product is LEC’s RGA750 (Retractable Grounding Assembly).

- The RGA has a spring-loaded cable that attaches between the roof and shell. The bonding cable on an RGA is constructed of a wide, flat braided copper cable and the housing is entirely stainless steel for excellent corrosion protection.

- The cable is tinned for additional corrosion protection.

- The cable on the RGA is spring-tensioned, meaning that it automatically retracts on the reel when it is not under tension. Therefore, the RGA is always of the minimum possible length for superior grounding.

- It’s independent of the condition of the tank wall and that of any shunts.

- Since FRT’s tend to be of very large diameter, it is important to limit the roof-to-shell impedance by installing multiple RGA’s as per stipulated guidelines.

We also offer a full line of surge suppressors to limit internally generated transients.

If you are in any need of fuel tank lightning protection or require more information, contact our friendly staff member for assistance.

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