Lightning Protection Near Gas Vent

Is the pipe made of metal? Maybe your study could learn us something too? Probably more will be interested in that conclusion. The right arrestors will lead the lightning away on the outside of the pipe. This is safer for your equipment. It is nice to not send the gas into the atmosphere, but do you want the lightning to backfire the turbines?

Hi

Yes you need it there depend on the probability of strikes . I would recommend to fix it at suitable height so that it fully covered for more information please see NFPA 780 as a thumb rule it should be with in 45 degree angle from the top of lightning arrestor .

cheers

There are two issues here:

1. Lightning protection.
2. Igniting unburned gas.

and they have become confused. What about the igniter at the top of the vent? Is that to remain? If not, then what is to happen to the gas that comes out of the vent? Is it to blow about until it finds another source of ignition?

So the lighning strike is not going to cause the vented gas to ignite, as the gas will either be burning already or it will be absent when the bolt hits.

The only way to protect structured from lighning bolts is to erect a taller, earthed structure nearby and trust that the bolt hits that structure in preference.

In the meantime, whatever the study says, the lightning protector is quite OK at the top of the vent. There simply won't be an explosion as a result of its being hit.

It would be worth checking what the potential damage might be as a result of its supporting structure being toppled by a lightning bolt, though!

Thanks for all responses. I will clarify few things:

1. Yes, the vent pipe is made of metal.

2. It is a cold vent and there are no igniters. The gas is vented only during start-up

3. We di carry out lightning protection risk assessment using number of lightning flashes/km2/year ( flash density=2) for the area and the result shows that there is no need of lightning protection for the vent. However, there's a lightning arrestor very close to it. There is no other closeby structure higher then the vent.

4. As the lightning protection is not required for the vent, the concern is of igniting the vent gas during lightning as the lightning arrestor may attract lightning & I think it should be removed.

5. Thanks for reference to NFPA

Dear all,

I guess the vent is inside protected zone of the nearby lightning air terminal.

In case, if there is a lighting strike during gas release, it might ignite the released gas.

Most probably lightning will not hit the vent, but the air terminal. Thus the large flash will not connected to the vent. However, the vent is nearby the air terminal and there is a tiny flash to the air at the tip of vent (maybe 5 to10 cm long). This tiny flash is not visible by eyes and the temperature is 2000k or more.

This tiny flash is normally ignored since it is harmless, however, it can ignite the gas if released at the moment of the lightning strike.

To avoid this tiny flash from the top of the vent, the vent must be bonded to the air terminal, so that the charge for the tiny flash is to be discharged to the air terminal. This bonding must be at the top of vent.

Regards

Lightning arresters in and of themselves do NOT attract lightning. Their purpose is to take a lightning strike hitting a susceptible object (such as the OP's vent pipe) and direct it to ground. Leaving the arrester in place will not lead to a greater likelihood of lightning striking the vent pipe unless it is positioned higher than the pipe and with a much better ground connection than the pipe (which doesn't sound like the case here).

Just another thought - if by "lightning arrester" the OP means a lightning mast or rod rather than the actual piece of electrical apparatus called a lightning or surge arrester, then the question becomes, "Which would you rather have the lightning attracted to, a solidly grounded lightning mast that would divert the lightning energy to earth, or to your gas vent pipe?" You choose.