2.Lightning protection solutions for external floating roof oil tanks
In response to the above problems, we have formulated the following solutions for lightning protection of external floating roof oil tanks:
2.1 Design Basic
"Technical Specification for Lightning Protection of External Floating Roof Oil Tanks" Part 1: Guidelines Q/SY 1718.1-2014
"Technical Specification for Lightning Protection of External Floating Roof Oil Tanks" Part 2: High and Intermediate Frequency Lightning Current Splitter Q/SY 1718.2-2014
"Technical Specifications for Lightning Protection of External Floating Roof Tanks" Part 3: Medium and low frequency lightning current shunt and monitoring system QSY-1718.3-2015
"Lightning Safety Code for Petroleum and Petroleum Facilities" GB15599-2009
"Industrial Standard for Lightning Protection of Aboveground Flammable Liquid Storage Tanks" API545-2009
"Installation Standard for Lightning Protection System" NFPA780-2011
"Measures to prevent ignition of static electricity, lightning and stray currents" API RP2003
2.2 Lightning protection solution
2.2.1 High and medium frequency lightning current
The high and intermediate frequency lightning current splitter is a high and intermediate frequency lightning current discharge device for the floating disk of the outer floating roof oil tank. The adjustable device solves the difference between the splitter and the tank wall caused by the slight deformation of the tank body and the displacement of the floating disk to ensure the floating disk. The high- and medium-frequency lightning current on the ground is released in time, avoiding sparks generated during the lightning current release process.
2.2.2 Middle and low frequency lightning current shunt technology
The low- and medium-frequency lightning current shunt is a low-frequency lightning current discharge device for the floating plate of the outer floating roof oil tank. The floating plate and the tank wall are connected through the shunt device to realize the low-impedance electrical connection between the shunt and the tank wall to ensure the middle The low-frequency lightning current is released in time, which has the advantage of low inductance when the lightning current passes, which greatly reduces the potential of the floating disk, thereby avoiding the phenomenon of interstitial ignition of the floating disk due to the passage of the lightning current. The lightning current detection device is added, which can upload the lightning current data to the monitoring center in real time, realize the monitoring and statistics of lightning strike data, and realize linkage control with other systems.
2.2.3 Quantity ratio and installation location
According to the "Technical Specification for Lightning Protection of External Floating Roof Oil Tanks": High and medium frequency lightning current splitters "set one at an interval of no more than 3m along the circumference of the floating roof."
According to the "Technical Specification for Lightning Protection of External Floating Roof Oil Tanks": "A medium and low frequency lightning current shunt should be installed between the floating roof foam weir plate of the external floating roof oil tank and the tank wall every 30m. The cross-sectional area of the shunt line is not less than 50mm2."
Take a storage tank of 20,000 cubic meters (about 40 meters in diameter and 127 meters in circumference) as an example. The installation position is based on the escalator in the tank as the starting point, and 5 diverters are evenly installed along the circumference of the storage tank at an interval of no more than 30 meters. 45 splitters are installed evenly distributed at intervals of no more than 3 meters.