Flange bridging on pipes in the chemical processing workshop
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Is the purpose of making a bridge connection to eliminate static electricity? When is it necessary to make a jump connection? Are there any standard regulations? What size cross-sectional area is needed? Thank you
When the number of flange bolts is 4 or less and the resistance between the flanges is greater than 0.03Ω, it is necessary to provide bonding for the process pipelines in flammable and explosive environments; this is specified in GB50057 for lightning protection design, with a requirement for flexible copper wires of at least 6mm2 in diameter
4.3 Pipeline System 4.3.1 Pipelines shall be grounded at the points where they enter and exit the equipment area (including the production workshop buildings) as well as at branching points. Long-distance unbranched pipelines should be grounded every 100 meters. 4.3.2 When the clear distance between parallel pipes is less than 100 mm, a jumper should be installed every 20 m. When pipes intersect with a clear distance of less than 100 mm, jumper wires should be added. 4.3.3 When a metal flange is fastened using metal bolts or clamps, it is generally not necessary to install additional electrostatic connection wires, but it must be ensured that there is good electrical contact between at least two of the bolts or clamps. 4.3.4 The heating tracing for process pipelines shall be equipotentially connected to the process pipelines at the steam inlet and return water inlet of the tracing. 4.3.5 When the protective covers for air ducts and insulation layers are made of thin metal sheets, they should be joined by overlapping edges, and equipotential connection should be achieved using bolts and other fixing elements. 4.3.6 For the non-conductive sections in the metal piping, in addition to requiring special anti-static treatment, the metal pipes at both ends should be connected to the grounding main line respectively, or bridged with copper-core flexible stranded wire having a cross-sectional area of not less than 6 mm2 and then grounded. 4.3.7 All metal components on non-conductive pipe sections shall be grounded. 4.3.8 Underground directly-buried metal pipes may not require electrostatic grounding.
It is to eliminate static electricity, which can cause fire, explosion, and other process accidents; the cross-sectional area is determined based on the process medium flowing within the pipeline, and it is generally not less than 6 square millimeters.
It is mainly for lightning protection, to prevent the hundreds of thousands of volts of voltage that can appear along metal pipelines during a direct lightning strike. If the resistance is greater than 0.03 ohms, it can lead to discharge-induced fires; therefore, flanges with 4 bolts or fewer require bonding.
As I understand it, the purpose of static electricity bonding is to ensure that both sides of the flange are at the same electrical potential. In other words, it involves directing the static electricity accumulated on the pipes and equipment into the ground, thereby preventing sparks from being generated as a result of static discharge. This helps avoid fires or explosions that could occur if flammable substances leak out. I recall that there is a standard stating that static electricity bonding is required for flanges with fewer than five bolts, but in practice, static electricity bonding is applied to flanges of all sizes.
Eliminating static electricity can lead to fire, explosion, and process accidents