1 General Provisions
1.0.1 This code was formulated with view to preventing and reducing the equipment damages and personal injuries caused by lightning stroke and standardizing the lightning protection design of petrochemical plants and their support facilities.
1.0.2 This code is applicable to the lightning protection design of the constructed, reconstructed and extended petrochemical plants and their support facilities, while it is not applicable to the lightning protection design of the extraction and long-distance transportation facilities of crude oil or the petroleum product storage and marketing facilities outside the plant area of petrochemical plant.
1.0.3 The lightning protection design of petrochemical plant shall not only comply with this code, but also shall comply with those specified in the current relevant standards of the nation.
2 Terms
2.0.1 Petrochemical plant
The production plant that produces petrochemical products (or intermediates) with petroleum, natural gas and their products as the raw materials.
2.0.2 Support facilities
The facilities that are necessary to cooperate with the main process plant to complete the production process, including tank field, central laboratory, wastewater treatment plant, maintenance room and torch, etc.
2.0.3 Industrial building (warehouse)
The productive (storing) building that is built with roof and with the external envelope structure wholly adopting closed wall (including doors and windows) structure.
2.0.4 Outdoor unit
The well-ventilated place that is in the open air or is open to the atmosphere.
2.0.5 Semi-enclosed industrial buildings
The productive building that is built with roof and with the external envelope structure partially adopting wall, of which the area does not exceed 1/3 of the surface area of the external envelope of this building (excluding the area of roof and floor).
2.0.6 Opened industrial buildings
The productive building that is built with roof but without external envelope structure.
2.0.7 Lightning stroke
One electric discharge during the stroke to the ground.
2.0.8 Direct lightning flash
The stroke that directly attacks the building, other objects, the ground or the external lightning protection system and also produces electrical effect, heat effect and mechanical force.
2.0.9 Lightning induction
The lightning electrostatic induction and lightning electromagnetic induction that produces spark discharge between metal parts on the conductor nearby at the time of lightning discharge.
2.0.10 Lightning surge on incoming services
Due to the action of lightning to the overhead lines, cable lines or metal pipelines, the lightning wave, namely the lightning surge, may invade into room along these pipelines and thereby endanger the personal safety or damage the equipment.
2.0.11 Lightning protection system (LPS)
One integrated system that is used to decrease the substance damages caused by the lightning stroke on production plants and is composed of external lighting protection system and internal lighting protection system.
2.0.12 External lightning protection system
One component part of the lighting protection system, which is composed of air-termination system, down-conductor system and earth-termination system.
2.0.13 Internal lightning protection system
One component part of the lighting protection system, which is composed of bonding network and the electrical insulation of the external lighting protection system.
2.0.14 Air-termination system
The component part of the external lighting protection system, which is composed of such metal members as air-termination rod (lightning rod), air-termination wire and air-termination network.
2.0.15 Down-conductor system
The component part of the external lighting protection system, which is used to lead the lightning current from the air-termination system to the earth-termination system.
2.0.16 Earth-termination system
The component part of external lighting protection system, which is used to conduct lightning current and also distribute the lightning current to the ground.
2.0.17 Earthing electrode
The conductor buried in soil or concrete foundation for the purpose of distributing current.
2.0.18 Earthing conductor
The bonding conductor from the breaking of contact or the conductor-changing place of the down-conductor system to the earthing electrode; or the bonding conductor from the earthing terminal or equipotential bonding bar to the earthing electrode or earth-termination system.
2.0.19 Bonding network
One system interconnecting all the conductive objects (excluding the live conductors) to the earth-termination system.
2.0.20 Earthing system
The overall system combining the earth-termination system and bonding network together.
2.0.21 Ground resistance
The sum of the resistance to ground of the earthing electrode or natural earthing electrode and the resistance of earthing conductor.
2.0.22 Power frequency ground resistance
The resistance obtained by the power frequency alternating current flowing to the ground through earthing electrode.
2.0.23 Impulse ground resistance
The ground resistance obtained by the surge current flowing to the ground through earthing electrode.
3 Classification of Lightning Protection Places
3.0.1 Various places of petrochemical plants shall be classified into industrial building or outdoor unit according to the environmental conditions that are able to form explosive gas mixtures and the dissipation condition of gas in the space.
3.0.2 The semi-enclosed and opened industrial buildings shall be classified into industrial building or outdoor unit according to their opening degree. The large-scale compressor plant building with roof and opened wall surface shall be classified as the industrial building; while the frame with equipment or pipes sparsely arranged shall be classified as outdoor unit.
4 Basic Requirements
4.1 Places of Industrial Building Category
4.1.1 The lightning protection design of the places of petrochemical plant industrial building category shall comply with the relevant requirements of the current national standard "Design Code for Protection of Structures against Lightning" (GB 50057).
4.1.2 The lightning protection design of the petrochemical plant outdoor unit shall comply with the relevant requirements of Chapter 5 in this code.
4.2 Places of Outdoor Unit
4.2.1 The outdoor unit of petrochemical plant shall be carried out with lightning protection design on meeting any one of the following conditions:
1 The large and tall production facilities set on the floor;
2 The production facilities set at high position by frame or support and the main pipelines led to torches, etc.;
3 Rotating equipment, like the large-scale compressor set on the floor and the pumps arranged in groups, etc.;
4 Torch, chimney and exhaust funnel in the open space;
5 The lighting facilities that are set at high position and are easy to be attacked by direct lightning flash.
4.2.2 The outdoor unit of petrochemical plant shall be carried out with protection design against direct lightning flash on meeting any one of the following conditions:
1 The water treatment places dispersedly arranged in the open space (excluding the import equipment);
2 A few pumps and small-scale metal equipment that is dispersedly arranged on the floor;
3 Ground pipelines and pipe supports.
4.2.3 The air-termination system against direct lightning flash should use the metal solid body of production facilities but shall meet the following requirements:
1 The production facility used as air-termination system shall be integrally enclosed metallic static equipment with welded structure; and the rotating equipment shall not be used as air-termination system;
2 The production facility used as air-termination system shall have metal shell, and its top and the upper part at outer side that are prone to direct lightning flash shall be thick enough. The wall thickness of steel equipment shall be greater than or equal to 4mm, and the wall thickness of other metal equipment shall be in accordance with the value of thickness t as specified in Table 6.1.5 of this code.
4.2.4 The following equipment that is prone to direct lightning flash and is outside the lightning protection scope of the nearby tall and big production equipment, frame and large-scale pipe support (have been used as air-termination system) and the like shall be set with the air-termination system separately.
1 Rotating equipment;
2 Metallic static equipment that can not be used as air-termination system;
3 Static equipment with nonmetal shell.
4.2.5 The lightning protection scope of air-termination system shall be determined by adopting with one of the following methods:
1 It shall meet the requirements on rolling sphere method as specified in the "Design Code for Protection of Structures against Lightning" (GB 50057), and the radius of rolling sphere is 45m;
2 The height difference between the top of air-termination system and the protected reference plane as well as the angle of protection shall be in accordance with those specified in Table 4.2.5 or the relevant requirements of the "Protection Against Lightning - Part 3: Physical Damage to Structures and Life Hazard" (GB/T 21714.3).
Table 4.2.5 Height Difference between the Top of Air-termination System and the Protected Reference Plane as well as the Angle of Protection
Height difference (m) 0~2 5 10 15 20 25 30 35 40 45
Angle of protection (°) 77 70 61 54 48 43 37 33 28 23
4.2.6 The down-conductor system against direct lightning flash shall meet the following requirements:
1 The tall and large production facilities that are set on the floor shall use their metal shell as the down-conductor system;
2 Where the production facilities are installed through frame or support, the metal frame should be used as the down-conductor system;
3 The tall and large furnace body, tower body, barrel bin, large scale equipment, frame and the like shall at least use two down-conductor systems, and the spacing of down-conductor systems shall not be larger than 18m;
4 The horizontal vessels and pipelines (pipeline leading to the torch) that are set overhead and are relatively long shall be set with down-conductor systems at both ends; where the spacing of down-conductor systems exceeds 18m, the quantity of down-conductor systems shall be increased;
5 The down-conductor system shall be directly led onto the earthing electrode by the straightest and shortest route as much as possible, it shall have adequate cross section and thickness and shall be set with mechanical protection above ground;
6 Where the longitudinal main bar in column is used as the down-conductor system, then the longitudinal main bar in column shall be adopted with stirrups by banding or welding.
4.2.7 The measures against lightning induction shall meet the following requirements:
1 In the outdoor unit places, all the metal equipment, frames, pipelines, cable protective covering (amour, steel pipe and slot plate, etc.), blowdown pipe orifice and the like shall be connected to the earth-termination system against lightning induction; where special down-conductor system is set, the steel bar in steel reinforced concrete column also shall be led out nearby the highest roof and floor respectively and be connected to the earthing conductor (network);
2 The spatial distance between the metal object as described in Clause 1 of this article and the down-conductor system nearby shall be determined according to the following formula:
S≥0.075kclx (4.2.7)
Where:
S——the spatial distance (m);
kc——the shunt factor, which is 1 in case of single down-conductor system, 0.66 in case of two down-conductor systems and more than two down-conductor systems with air-termination system not forming closed loop, and 0.44 in case of more than two down-conductor systems with air-termination system forming a closed loop or net;
lx——the length from the calculation point of down-conductor system to the earthing connection point (m).
3 Where the spatial distance required in Clause 2 of this article is not met, then earthing conductors shall be added at the position where is higher than the connection point;
4 The parallelly laid metal pipelines, frames, cable metallic protective course and the like shall be carried out with metal connection every other 30m if their clear spacing is less than 100mm and also shall be connected if the clear spacing at the intersection place or separation place is less than 100mm.
4.2.8 The earth-termination system against lightning shall meet the following requirements:
1 As for the production facilities taking the metal shell as the air-termination system, the metal shell shall be connected to the earthing electrode by no less than two places at the shell bottom;
2 The separately set air-termination systems (in shape of rod, line and network) as specified in Article 4.2.4 of this code all shall be directly connected to the earthing electrode by down-conductor system;
3 As for the earthing electrode directly connected with every down-conductor system for the purpose of protection against direct lightning flash, its impulse ground resistance shall not be larger than 10Ω and it shall meet the following requirements:
1) In the calculation of ground resistance, the length of each branch line of the earthing electrode shall be less than or equal to the effective length le of earthing electrode;
2) The calculation of le and the conversion of impulse ground resistance shall comply with the relevant requirements of the current national standard "Design Code for Protection of Structures against Lightning" (GB 50057);
4 As for the earthing electrode against lightning induction, its power frequency ground resistance shall not be larger than 30Ω;
5 The earthing electrode against direct lightning flash should be connected with the earthing electrode that is used against lightning induction or used for power equipment into one integral earthing system. However, the ground resistance of such earthing electrode against direct lightning flash shall meet the requirements of Clause 3 in this article.
Contents
1 General Provisions
2 Terms
3 Classification of Lightning Protection Places
4 Basic Requirements
4.1 Places of Industrial Building Category
4.2 Places of Outdoor Unit
4.3 Discharge Facilities of Outdoor Unit
4.4 Other Measures
5 Lightning Protection of Outdoor Systems
5.1 Furnace Area
5.2 Tower Area
5.3 Static Equipment Area
5.4 Machinery Equipment Area
5.5 Tank Area
5.6 Combustible Liquid Loading Depot
5.7 Powder and Aggregate Silo
5.8 Frame, Pipe Support and Pipeline
5.9 Cooling Tower
5.10 Chimney and Torch
5.11 Discharge Facilities of the Outdoor Unit
5.12 Outdoor Lamps and Electrical Equipments
6 Lightning Protection System (LPS)
6.1 Air-Termination System
6.2 Down-Conductor System
6.3 Earth-Termination System
Explanation of Wording in This Code
List of Quoted Standards
