What are the disputes regarding the scope of static grounding pipelines?
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Dispute 1: Should pipes carrying non-flammable media in explosion-hazardous areas be electrically grounded? During the implementation of projects, many people believe that only flammable media require static grounding, while non-flammable media such as instrument air, plant air, and nitrogen do not need it. We know that three conditions are required for a fire or explosion to occur: first, the presence of a combustible material; second, contact between the combustible material and oxygen; third, the presence of a spark sufficient to ignite the mixture of the combustible material and oxygen. All three conditions are essential. Fire or explosion accidents caused by static electricity occur as a result of electric sparks generated by static discharge igniting or detonating mixtures of flammable gases or flammable dusts in contact with oxygen that have leaked outside the pipes or equipment. Wherever there are areas where flammable gases or dusts accumulate, there is a risk of fire or explosion caused by static discharge. Therefore, the criterion for determining whether a regular pipeline needs to be grounded is not whether the medium inside it is flammable, but rather whether it is located in an area at risk of fire and explosion. HG20675 provides clear guidelines regarding the need to electrically ground pipelines in areas prone to explosions and fires; its clause 2.1.1 states that \"industrial static grounding measures shall be adopted for objects in environments prone to explosions and fires that may pose a static electricity hazard.\" Some argue that water is conductive, so water pipes and steam pipes do not need to be grounded. In fact, steam is not a good conductor of electricity ； Water itself does not conduct electricity; it is the water containing conductive ions that does. Many types of water used in the process industry, such as boiler water, deoxygenated water, and steam condensate, have most of their conductive ions removed, resulting in poor electrical conductivity. Even in the case of circulating water, it is softened to remove most of the calcium and magnesium ions in order to reduce scaling in heat exchange equipment. Unless experiments prove that the water used in the process equipment has good electrical conductivity within the pipes, water cannot be considered conductive, and the requirement for static grounding of steam and water pipes in areas at risk of explosion and fire cannot be waived.
Dispute 2: Should flanges connected with metal bolts be electrically grounded? Some people believe that flanges connected with metal bolts do not require electrostatic grounding, on the grounds that Section 4.3.3 of SH3097 states that \"when metal flanges are fastened using metal bolts or clamps, it is generally not necessary to install additional electrostatic connection wires, but it is essential to ensure that there is good electrical contact between at least two bolts or clamps.\" ”This understanding is incorrect. This specification states that, under certain conditions, it is not necessary to provide additional wire connections for the flanges; it does not mean that the requirement for static grounding of the pipes can be waived. The requirement for static grounding of pipelines does not mean that static bonding must be installed. The static grounding of pipelines is divided into direct grounding and indirect grounding. Direct grounding means that the pipeline’s static electricity grounding system is directly connected to the main grounding grid ； Indirect grounding refers to the situation where a pipeline is connected, indirectly, to the main grounding grid of the installation through its connection to grounded equipment or steel structures. All equipment is equipped with static grounding, and all pipes are connected to the equipment; the vast majority of these pipes are indirectly grounded.
Whether to set a wire bypass depends not only on the design requirements but also on the measured resistance between the connections. There are two necessary conditions for setting up wire bypasses; the first is that the design requires electrostatic bypassing. Secondly, for most media (except pure oxygen, gas-solid mixtures, and hydrogen), wire bypassing is required only when the measured resistance on both sides of the joint is greater than 0.03 ohms. It should be noted that for applications requiring static grounding, resistance testing is an essential procedure, regardless of whether a physical jumper wire is used or not. Additionally, for some special media, an electrostatic bonding should be installed regardless of whether the measured resistance between the connectors is less than or equal to 0.03 ohms. These media include pure oxygen, gas-solid mixtures, and hydrogen. The reasons for requiring bonding in the first two cases have been explained earlier; as for hydrogen, its low molecular weight makes it highly prone to leakage, and it has a wide explosive range along with a low ignition current. For safety reasons, high-level static electricity prevention measures must be implemented.
Thank you for sharing. A quantitative standard should be established, rather than specifying how to connect.
Water in nature conducts electricity； Does seawater conduct electricity? We reverse-install the marine facilities we handle; we connect wires to all the pipelines and structures.
Are the stricter requirements for marine equipment related to the production environment?