Basic methods for lightning protection at gas stations and skid-mounted refueling stations
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First, the basic equipment configuration of the gas station system 1. Buildings (including gas stations, shelters, shelters);
2. Oil tanks, tankers and pipelines;
3. Gas station power system, signal control system;
Second, the basic method of armored refueling station system lightning protection 1. Station and shelter lightning protection station directly around the top of the house using flash belt, roof grid, in order to make the roof in the range of air-termination protection should be Place a lightning rod in the corner or make the mesh belt an ohmic ring. Diagonally set steel bars (not less than two steel bars with a diameter of not less than 10mm) are used as guidewires. A horizontal grounding body is composed of not less than two welded steel rings in the base of the beam and bearing platform, and the two reinforcing bars in the pile and column are vertical grounding bodies. The grounding device is a natural grounding body composed of a horizontal grounding body and a vertical grounding body.
Sheds are made of metal roofs as air-receivers, and metal posts themselves or reinforced concrete columns are used as lead wires. For ease of detection, some terminals are specially reserved for testing. Shed column base steel is made of vertical natural grounding body, horizontal ground artificial body is laid below -0.6m, and should be laid into vertical and horizontal grounding grids. The material is hot dip galvanized flat steel (40mm x 4mm), refueling (gas) island installation refueling ( (Air) machine reserved for grounding.
2. Direct thunder and lightning protection for oil tanks, gas tanks and compressed natural gas cylinders. When the wall thickness of the metal tank is less than 4 mm, install a separate lightning rod or connect the flash line protection. The distance between the lightning arrester and the protected tank is related to Design specifications, but not less than 3m. At present, according to relevant regulations, tanks and liquefied petroleum gas tanks are laid underground, and the thickness of the steel plates of oil tanks and liquefied petroleum gas tanks is not less than 5 mm (excluding fire-resistant and explosion-proof oil tanks equipped with armored oil refueling devices). The snorkel, discharge pipe, oil inlet pipe and oil outlet pipe connected to the tank body are all welded. The heights of the snorkel and discharge pipe are respectively 4m and 2.5m above the ground. Can be used as a lightning receptor. Other oil holes, vent holes, and manholes are reliably welded to the tank body.
Natural gas cylinders are in line with "Steel Pressure Vessels" GB150. The thickness of steel plates should not be less than 6mm. Skid-mounted natural gas storage and gas refueling equipment enclosures are metal enclosures, 2m above the platform of the enclosure, 5m above the ground, and the enclosure and discharge pipe itself can be used as a lightning receptor.
3. Grounding device and equipotential connection (1) Refueling, lightning protection grounding of refueling station, anti-static grounding, working grounding of electrical equipment, safety protection ground, and information system grounding, etc. The value should not be greater than 4Ω.
(2) The lightning protection of metal cans must be made into closed loops with no less than two grounding points. The distance between arcs should not exceed 30m. The distance between the grounding body and the pipe wall should be less than 3m. The grounding resistance of the cans should not be Greater than 10Ω. The grounding body is made of hot-dip galvanized angle steel and hot-dip galvanized flat steel (40×4mm) as the vertical grounding body and the horizontal grounding body respectively. The angle steel material size is 50mm×50mm×5mm, and the length is 2.5m, and the flat steel material size is 40mm×4mm. The distance is 5m, buried below ground -0.6m.
When the metal tank body anti-corrosion measures adopts the sacrificial anode method, the tank may not be provided with a grounding pole, but the anode needs to be grounded for lightning protection. When the lightning protection grounding is separated from other grounding systems, the resistance value is not more than 10Ω. Just use a 16mm2 copper wire to connect the tank to the anode to achieve lightning protection.
When the metal tank body anti-corrosion measure adopts the forced current method, the tank may not be provided with a grounding pole, but the zinc rod or zinc-magnesium is used as a lightning protection grounding pole, and the resistance value is less than 10Ω.
(3) When the flame arrestor installed on the vent nozzle is used for unloading and refueling the oil and gas recovery system, the installed mechanical breather valve is connected to the metal pipe for equipotential bonding.
(4) Refueling, refueling machine metal shell, gas combustible gas alarm system metal pipe and body to make a reliable electrical connection and grounding. Various cables (strong and weak cables) entering the refueling and refueling machines are protected by metal pipes and grounded.
(5) Armored CNG refueling station, armored box, refueling equipment, metal housing and grounding device are reliably connected, and the grounding point is not less than two. Metal housings such as compressors, inductive pressure gauges, thermometers, etc. inside the armor are reliably connected to the reserved ground using a 2.5mm2 ground wire.
(6) Both ends of the metal sheath of the power supply system cable or both ends of the cable protection metal protection tube should be grounded; the information system should be armored cable or conductor through the steel pipe wiring; both ends of the distribution cable metal sheath and protection steel pipe should be grounded .
4. Lightning prevention, anti-static induction and anti-lightning electromagnetic pulse measures (1) Both ends of the cable metal sheath of the power supply system or the cable protection metal protection tube should be grounded at both ends; the information system should be armored cable or conductor through the steel pipe Wiring, wiring cable Both metal sheath and protective steel pipe should be grounded.
(2) The joint grounding device for static electricity prevention and lightning protection shall be provided at the beginning, end, and branch of the oil, LPG and natural gas pipelines on the ground or in the trench to prevent static electricity from accumulating when the oil flows. The grounding resistance is not greater than 30Ω.
(3) Refueling and adding qiqiang rubber hoses are connected to the grounding device through the internal wiring and the grounding cable, which are used to release static electricity generated during refueling and refueling.
(4) Anti-static grounding devices shall be provided in the unloading areas of oil tanks, gas tanks and natural gas cylinders, and electrostatic grounding devices that can detect the cross-over lines and monitor the status of grounding devices shall be provided. The flanges on the pipe and the two ends of the hose are connected by metal wires. When there are no less than 5 flange bolts, it is not necessary to bridge in a non-corrosive environment. Grounding resistance is not more than 100Ω.
(5) Surge protector distribution system: The power supply and distribution system should adopt TN-S system. A three-stage surge protection device can be designed: the first level of the distribution cabinet is provided, and the second grade of the distribution box is used for the various pumps for fueling and refueling; the second level of the distribution box is designed. UPS equipment can be set to third level. Information system: To prevent the instrument from being damaged by the lightning electromagnetic pulse, it is possible to install the instrument SPD at one end of the control room circuit to effectively eliminate the over-voltage on the instrument circuit and achieve the purpose of lightning protection.
5. Regularly check the gas station to consciously accept the meteorological department's lightning protection and anti-static testing. Lightning detection personnel should do the following when testing:
The first question asked: Every time a gas station arrives, the person in charge of the station must be scrutinized to find out the name of the person in charge, the contact information, and the detection of lightning protection and anti-static electricity. The types of oil, reserves, fire protection number, and four positions Distance and whether or not there is a thunder and lightning disaster occur, and produce relevant documents, actively promulgate laws and regulations on lightning protection, and make mine protection work deeply rooted in people's hearts.
Second, look at: Look carefully at the station's lightning protection facilities: look at the shelter, whether the duty room is equipped with direct lightning protection, see if the lightning arrester and deflector are broken, if the tank is a buried tank, and if the power supply system is Is there a surge protector for the TN-S system; if so, whether the protection level meets the requirements; whether the information system is equipped with a surge protector; and whether the pipeline is bridged as required.
The third multiple test: Use the instrument to carefully check whether the grounding resistance of the refueling equipment meets the specification requirements. Install the testing instrument (4102 grounding resistance tester or other instrument). If the E wire is short, use a long wire (a wire resistance should be measured) connected to the E wire terminal. The long wire should be extended as much as possible. Coiled to avoid eddy currents affecting the test data, the measured data was subtracted from the long wire resistance. Measure carefully whether the tanker cover, shelter, oil tank, ventilation pipe, pipeline, unloading anti-static grounding and distribution cabinet grounding resistance meet the specification requirements. The measured resistance is a power frequency grounding resistance and should be converted to an impulse grounding resistance according to the formula R_=ARi. The grease gun was measured with a multimeter to see if it was well connected to the tank cover.
Note: The equipment being refueled should be measured after it is stopped.
More than the fourth record: carefully fill in the test report on the name of the unit, the responsible person's name, contact telephone, address, oil type, fire certificate number, reserves and number and the name of the measured object, grounding data, etc., testing personnel and responsible People must sign and seal. The report is made in duplicate, with one copy and one copy for the unit to be inspected. Qualified certificates shall be issued to meet the requirements, and rectification opinions shall be put forward after the problems are found, and the certificates of conformity will be issued after the tests are completed after the rectification is completed.
III Conclusion <br> <br> refueling, skid-mounted stations is flammable and explosive places, good lightning protection is to ensure the normal operation of gas stations and personal security a key ring. I think that the refueling and refueling station's lightning protection needs to fully understand the relevant lightning protection technical standards and specifications, and is familiar with the functions and functions of the various facilities within the gas station. It is necessary to design and construct the lightning protection device in all aspects from point to surface in order to fully do a good job. Gas station lightning protection work to ensure the gas station lightning protection security.
The head of a countersunk screw typically has a single slot or a cross-shaped recess, known as a Phillips or a slotted head respectively, which allows for easy installation using a compatible screwdriver or bit. The countersunk shape also enables the screw to be easily countersunk into the material, meaning it can be driven below the surface to create a smooth and level finish.
Countersunk head screws are available in various materials, such as stainless steel, brass, or zinc-plated steel, providing different levels of strength, corrosion resistance, and aesthetic appeal. They come in different sizes and lengths, allowing for versatility in different applications.
In summary, countersunk head screws are fasteners with a flat head that tapers down to a smaller diameter, allowing them to sit flush with the material's surface. They are commonly used in woodworking and metalworking projects, and are available in various materials, sizes, and lengths.