How to perform static bonding for flange bolts

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For pipeline flanges, metal pipeline flanges used to transport flammable, combustible, and explosive substances must be bonded with wires to prevent static electricity-related accidents. So, are metal pipe flanges required to be bonded? Under what circumstances is it necessary to make a jump connection? I. Bonding of metal flanges in industrial pipelines · Article 7.13.1 of GB 50235-2010 “Code for construction of industrial metal pipeline engineering” stipulates that for pipelines requiring electrostatic grounding as per the design, a bonding wire shall be installed when the resistance value between each pair of flanges or other joints exceeds 0.03 ohms. Section 6.12.2 stipulates that when the earth resistance value of the piping system exceeds 100Ω, two grounding leads shall be provided. The grounding lead should be welded. ·GB 50184-2011 \"Code for Acceptance of Construction Quality of Industrial Metal Piping Projects\", 7.13 Static grounding installation; 7.13.1 For pipelines that require static grounding, the resistance value between each pair of flanges or other joints shall be less than or equal to 0.03Ω. ·TSG D0001-2009 “Safety Technical Supervision Regulations for Pressure Piping – Industrial Piping” defines industrial piping as follows: These regulations apply to industrial piping belonging to process units, auxiliary units, and utility systems within the plant boundary, provided that all of the following conditions are met (hereinafter referred to as “piping”). (1) Those with a maximum operating pressure of 0.1 MPa or greater (gauge pressure, the same below) ； (2) Those with a nominal diameter (Note 1) greater than 25 mm ； (3) When the medium being transported is a gas, steam, liquefied gas, a liquid whose maximum operating temperature is higher than or equal to its standard boiling point, or a liquid that is flammable, explosive, toxic, or corrosive. Most pressure pipelines encountered during routine inspections fall into the category of the aforementioned industrial pipelines. Article 80 of the \"Regulations on Safety Inspection of Pressure Piping – Industrial Piping\" (TSG D0001–2009) specifies the following regarding anti-static measures using flange connections: For pipelines that require static electricity grounding, it is necessary to measure the resistance values between each connection joint as well as the resistance value of the piping system relative to the ground. When the stress exceeds the requirements specified in the \"Code for Pressure Piping – Industrial Piping\" (GB/T20801-2006) or those outlined in the design documents, bypass wires (between flanges or threaded connections) and grounding leads shall be installed. As can be seen from this clause, to determine whether a bypass wire is needed for the flanges, it is necessary to measure the resistance between them; if the resistance value exceeds the specified limit, a bypass wire must be used. ·Article 10.12.1 of GB/T 20801.4-2006 “Code for pressure pipelines—Industrial pipelines, Part 4: Fabrication and installation” stipulates that for pipelines requiring static electricity grounding, there must be good electrical conductivity between all sections. When the resistance value between each pair of flanges or threaded joints exceeds 0.03 Ω, a wire jumper shall be installed. · GB 50041-2008 “Code for Design of Boiler Rooms”, Clause 15.2.17: Gas and liquid fuel pipelines shall be equipped with static electricity grounding devices. ·According to Clause 3.7.10 of GB 50151-2010 “Code for Design of Foam Fire Extinguishing Systems”, anti-static grounding measures shall be taken for dry pipes laid on the ground or in trenches within explosion-proof areas. ·GB 50347-2004 \"Code for Design of Dry Powder Fire Extinguishing Systems\" 7.0.7 When the system pipelines are installed in areas with explosion hazards, the metal components of the pipeline network shall be provided with anti-static grounding. ·GB 50370-2005 “Code for Design of Gas Fire Extinguishing Systems”, Clause 6.0.6: Metal components such as pipelines and enclosures located in areas with explosion hazards, as well as in transformer and switchgear rooms, shall be provided with anti-static grounding. When the voltage exceeds the limits specified in GB/T 20801-2006 “Code for pressure piping—Industrial piping” or those stipulated in the design documents, jumpers (between flanges or threaded joints) and grounding leads shall be installed. As can be seen from this clause, to determine whether a bypass wire is needed for the flanges, it is necessary to measure the resistance between them; if the resistance value exceeds the specified limit, a bypass wire must be used. Section 10.12.1 stipulates that for pipelines requiring electrostatic grounding, good electrical conductivity must exist between each section of the pipeline. When the resistance value between each pair of flanges or threaded joints exceeds 0.03 Ω, a wire jumper shall be installed. ·Article 7.13.1 of GB 50235—2010, \"Code for Construction of Industrial Metal Piping Projects\", stipulates that for pipelines for which static electricity grounding is required, if the resistance value between each pair of flanges or other joints exceeds 0.03 ohms, a bonding wire should be installed. It can be seen that to determine whether metal flanges on industrial pipelines need to be bonded together, it is necessary to measure the resistance value between the flanges. When the resistance between flanges exceeds 0.03Ω, a jumper wire should be installed. ·GB 50944-2013 \"Code for Construction and Quality Acceptance of Anti-static Engineering\": 3.0.2 For new construction projects, anti-static grounding systems should be installed during the civil engineering construction phase. GB 50159-2013 \"Code for Design of Producer Gas Stations\": 17.0.5 Gas pipelines shall be equipped with grounding systems to dissipate static electricity. ·GB 50457-2008 \"Code for Design of Clean Rooms in Pharmaceutical Industries\" 6.4.2 Pipelines for transporting flammable media. Grounding facilities for dissipating static electricity should be installed. 9.5.3 The cleanroom’s air handling system shall incorporate anti-static grounding measures. 11.4.3 The clean air handling system in medical cleanrooms (areas) shall incorporate anti-static grounding measures. ·GB 50426-2016 \"Code for Design of Dyeing and Printing Factories\" 8.4.6 The ventilation system used in rooms with explosion hazards shall have reliable anti-static grounding measures. ·GB 12158-2006 \"General Guidelines for Preventing Static Electricity Accidents\" 6.4.10 Equipment for collecting and filtering powder materials shall use anti-static containers and filter media, and shall be grounded. · Article 9.2.7 of GB 50694-2011 \"Code for Fire Protection Design of Wineries\" stipulates that anti-static and lightning protection grounding devices shall be installed at the following locations of wine pipelines laid above ground or in trenches: at the starting point, ending point, branching points, and every 200m to 300m along the straight sections. 2 Boundaries of explosive hazard areas. 3 Pipeline pumps, filters, buffers, etc. 9.2.8 The lightning protection grounding device for metal storage tanks may also serve as an anti-static grounding device. The anti-static grounding device for the wine pipelines laid on the ground and in trenches can be shared with the grounding device for protecting against induced lightning; the grounding resistance should not exceed 30Ω, and the grounding points should be located at fixed pipe piers (supports). 【Explanation of the provision】: 9.2.6 When transporting alcoholic beverages such as baijiu, edible alcohol, wine, brandy, and yellow rice wine, friction between the liquid and the pipelines and filters used for transporting it generates a large amount of static electricity. If this charge is not removed through grounding devices, it can accumulate and lead to high-voltage discharges that may cause explosions and fires. Although the potential of static electricity is high, the current is low; therefore, its grounding resistance generally needs to be no more than 100 Ω. As can be seen from the above provisions, the key is to conduct away the charge through the grounding device; whether to bridge the pipeline flanges depends on the resistance value between the flanges. II. Bridging of flanges on petrochemical pipelines · Article 8.9.1 of GB 50517-2010, \"Code for Acceptance of Construction Quality of Petrochemical Metal Piping Projects\", stipulates that for pipelines requiring static grounding, a wire bridge shall be provided when the resistance value between each pair of flanges or threaded connections is greater than 0.03Ω. ·According to clause 14.3.7(3) of GB 50074-2014 \"Code for Design of Oil Depots\", the rails, process pipelines, dip pipes, steel trestles, etc. of railway tank car loading and unloading facilities shall be connected in equipotential fashion and grounded; the distance between two sets of connection points shall not exceed 20 m, and the grounding resistance of each set shall not be greater than 10 Ω. 14.3.8 Tank trucks or barrel filling facilities for Class A liquids A, B, and C shall be equipped with anti-static grounding devices connected to the tanks or barrels. 14.3.9 Loading and unloading terminals for flammable and combustible liquids shall be equipped with anti-static grounding devices that connect to the ships. ·Explanation of Article 11.2.12 of GB 50156-2012 \"Code for Design and Construction of Automobile Fuel and Gas Stations\": Metal wires should be used for bonding at the flanges on pipelines carrying oil, LPG, LNG, and CNG in areas prone to explosions, as well as at the connections at both ends of rubber hoses. This is done to prevent static electricity or lightning sparks from occurring due to poor connections (contact resistance greater than 0.03Ω) at these connections, which could otherwise lead to explosion and fire accidents. For flanges connected by no less than 5 bolts, in a non-corrosive environment, the connection at the flange joints is good; therefore, metal wire bridging is not necessary. · Section 6.2.13 of SH 3501-2011 \"Code for Construction and Acceptance of Steel Piping Projects for Toxic and Flammable Media in the Petrochemical Industry\" stipulates that for pipelines for which the design documents require static grounding, the resistance value of the flange or threaded connections shall be measured. When the resistance value between flange or threaded connections is greater than 0.03Ω, wires should be used for bridging, in compliance with **the current standard SH3097 and the relevant provisions of the design documents. The ground resistance value and grounding location shall meet the requirements specified in the design documents. ·SH/T 3097-2017 \"Code for Design of Static Electricity Grounding in Petrochemical Industries\" 4.1.1 During production, processing, storage, and transportation, equipment, pipelines, operating tools, as well as human bodies, may generate and accumulate static electricity, which can pose static electricity hazards; therefore, measures for static electricity grounding should be taken. 5.1.1 The enclosures of fixed equipment (towers, vessels, pumps, heat exchangers, filters, etc.) shall be electrically grounded to prevent static electricity. Earth covering equipment generally does not require static grounding. ·GB 50759-2012 \"Code for Design of Oil and Gas Recovery Facilities in Oil Loading Systems\" 9.1.1 Static electricity grounding devices shall be installed on the oil pipelines, equipment, and enclosures within the oil and gas recovery facilities. ·GB 50684-2011 \"Code for Design of Sewage Treatment and Reuse in the Chemical Industry\" 5.3.10 The mechanical and electrical equipment in oil separation tanks should be equipped with explosion-proof measures, as well as anti-static grounding facilities. ·SH 3097-2017 \"Code for Design of Static Grounding in Petrochemical Industries\" serves as a corporate standard that is stricter than **national standards and industry standards. Section 4.3.3 of this standard specifies that in piping systems, when metal flanges are fastened using metal bolts or clamps, it is generally not necessary to install additional electrostatic connection wires; however, it is essential to ensure that there is good electrical contact between at least two bolts or clamps. 4.3.1 The static grounding resistance value of the static grounding system shall not exceed 106Ω. The resistance value of the dedicated static grounding electrode to the ground should not exceed 100Ω; in areas such as mountainous regions where the soil resistivity is higher, this value should not exceed 1000Ω. It can be seen from this that whether it is necessary to use bonding wires for the flanges of petrochemical pipelines depends on their resistance values or the number of bolts used, and it is not mandatory to use bonding wires for all of them. III. Summary · In summary, to determine whether a metal pipe flange requires bridging, one should first consult the design documents; if such documents are available, the specifications in them should be followed. If the design documents do not specify it, whether to use a wire to bridge the metal flanges of industrial pipelines depends on the resistance value between the flanges; when this resistance value exceeds 0.03Ω, a wire should be used for bridging ； If the resistance value is less than 0.03Ω, no bypass is required. Therefore, whether it is necessary to use a bridge across the flanges of metal pipe fittings can be determined based on the resistance value between the flanges (if the resistance value is less than 0.03Ω, no bridge is needed). A bypass should be used when the resistance value is greater than 0.03Ω; this is what is truly professional and practical. It is necessary to follow the relevant industry standards, rather than adhering to what certain \"experts\" say regarding whether a bypass is required or not.