Regarding static grounding
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The last edit to this post was made by security on 2011-6-3 at 11:23. Section 6.12.1 of the GB 50235-97 Code for Construction and Acceptance of Industrial Metal Piping Projects states that when the transition resistance of metal flanges or valves is greater than 0.03 ohms, wires should be used for bridging； However, according to clause 4.3.3 of the SH 3097 Standard for Electrostatic Grounding in Petrochemical Industries, when metal flanges are fastened using metal bolts or clamps, it is generally not necessary to install additional electrostatic connection wires; nevertheless, it is essential to ensure that there is good electrical contact between at least two of the bolts or clamps. It’s contradictory as to whether it’s necessary to do it at the flange. Is it that if a metal gasket is used between the flanges, it’s not necessary to do it, but if it’s a non-metallic gasket, then it’s necessary? But isn’t it said that as long as the bolts make good contact, that’s enough?
This post was last edited by 494067920 on 2011-6-3 10:07. GB50235 should still be the standard; as long as the resistance is no greater than 30 ohms (0.03 kiloohms), there is no problem.
Insurance has been taken out. Bolt connections and gasketed connections are both not reliable. Some pipelines are also protected with paint. Use a ground wire of appropriate size, press it against the bolt to ensure safety. Especially with high-speed fluids, or in situations where friction generates static electricity, wire connections are guaranteed.
It’s over 0.03 ohms, not 30 ohms.
I guess as long as the resistance is not greater than 0.03 ohms, there should be no problem!
Insurance practices·······
I just took a closer look at the specifications – it is indeed 0.03 ohms. However, in practice it’s very difficult to measure the resistance between the two flanges (unless they are removed directly for testing). Therefore, it is necessary to measure the total grounding resistance, which should not be greater than 10 ohms.
Reply 1# chenglx: For safety reasons, it should be added, but in cases where the standard resistance values meet the **specified requirements, it may not be necessary to add it.
I don’t agree with your view: the resistance between two flanges can be measured directly using an ordinary multimeter, provided that the accuracy of the multimeter is sufficient.