Grounding Lugs on Return Cooling Water Piping
Grounding Lugs on Return Cooling Water Piping
(OP)
Hello Experts,
First of all, my apologies if this belongs in the wrong thread; I feel like it borders between Mechanical and Electrical.
I'm a long time reader and usually am able to find my answers searching through these forums but I have looked everywhere and haven't found any useful info so I'm hoping someone may be able to help me out here.
I'm working on a project where several hundred feet of 24" A106-B Cooling Water Piping is being replaced due to soil/air interface corrosion. Some of the wasted pipe runs just below/adjacent to a T&D cable tray conveying high voltage cables. The piping is fitted with a thin welded pad and three identical grounding lugs welded on top of that plate. My guess is that because of the proximity to the cable tray, the original designer was concerned about a voltage being induced on the pipe from the cables and placed the grounding lugs to prevent any static charge build up.
My issue is that I've read about grounding requirements for equipment but I can't find anything in the Owner's standards or in relevant Code that talks about requirements for grounding pipe. Hoping someone can provide me any info that'll send me in the right direction.
Picture of the lugs here: http://files.engineering.com/getfile.aspx?folder=b...
Thank you,
SMEIT
First of all, my apologies if this belongs in the wrong thread; I feel like it borders between Mechanical and Electrical.
I'm a long time reader and usually am able to find my answers searching through these forums but I have looked everywhere and haven't found any useful info so I'm hoping someone may be able to help me out here.
I'm working on a project where several hundred feet of 24" A106-B Cooling Water Piping is being replaced due to soil/air interface corrosion. Some of the wasted pipe runs just below/adjacent to a T&D cable tray conveying high voltage cables. The piping is fitted with a thin welded pad and three identical grounding lugs welded on top of that plate. My guess is that because of the proximity to the cable tray, the original designer was concerned about a voltage being induced on the pipe from the cables and placed the grounding lugs to prevent any static charge build up.
My issue is that I've read about grounding requirements for equipment but I can't find anything in the Owner's standards or in relevant Code that talks about requirements for grounding pipe. Hoping someone can provide me any info that'll send me in the right direction.
Picture of the lugs here: http://files.engineering.com/getfile.aspx?folder=b...
Thank you,
SMEIT
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RE: Grounding Lugs on Return Cooling Water Piping
Is this pie buried or part buried or??
Has it got an electrically insulating coating?
If the cable is armoured, then there should be no interference or induced current - you only get that from bare overhead wires normally.
I'm just not sure really what your question is?
Pipe earthing on racks is part of the earthing design.
You don't normally earth buried pipes, partly because they often have CP and also there is no reason
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Grounding Lugs on Return Cooling Water Piping
My question was: are there any code requirements for electrical grounding of pipe, if so, which code? I haven't been able to find one that covers this topic.
Thank you.
RE: Grounding Lugs on Return Cooling Water Piping
pipe is generally pretty good about transmitting electrical charge to the nearest point through welded or bolted connections so you don't normally get a static charge.
I guess there was a reason why these things are there, but probably lost in the mists of time and based on some premise which may no longer be applicable.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Grounding Lugs on Return Cooling Water Piping
Dik
RE: Grounding Lugs on Return Cooling Water Piping
Classifying Explosion Prone Areas for the Petroleum, Chemical and Related
Cable Trays
RE: Grounding Lugs on Return Cooling Water Piping
I guess I'll never know why these were required.
RE: Grounding Lugs on Return Cooling Water Piping
You have not stated what wires are connected to it.
If the wires are in trays, is it possible that the trays are not continuous? If so, perhaps the trays are being bonded together.
RE: Grounding Lugs on Return Cooling Water Piping
This earthing is to prevent voltage levels between the steel pipe and the ground.
This can be over kill. Station fault levels and ground resistance can be studied. Often the piping shoe-support-foundation provides enough earthing .
AS/NZS 4853 covers this.
RE: Grounding Lugs on Return Cooling Water Piping
Dik
RE: Grounding Lugs on Return Cooling Water Piping
KevinNZ, I agree that it seems like overkill and a pipeshoe (of which there are many) would be a more ideal location for attaching a ground wire to. I was thinking maybe it's because all of our pipe shoes rest on concrete sleeper blocks which would insulate itself from the ground but that wouldn't have any affect on the path of the electrons through the grounding wire. And thanks for the reference! I would like to better understand the reasoning behind why this may have been required.
Thanks again everyone for your input.