Flame Arrestors on Natural Gas and Oxygen Vent Lines

[Pavan Kumar]

Hi All,

I have been tasked to size and specify End of the Line Flame Arrestors (FAs) to be installed on the vent line for Natural Gas and Oxygen pipe lines. The idea is to prevent an external flame from propagating into the Pipe line when it is purged with N2 gas. The purge gas is vented to the atmosphere through the Flame Arrestor. I have used software like the one provided by Protectoseal to size in-line and end of line Flame arrestors installed upstream of Pipe Away and Conservation Vents installed on atmospheric storage tanks. The size is selected by calculating the tank pressure during the venting event by adding the pressure drop in the vent line, FA and make sure that this pressure does not exceed the tank MAWP. Now what methodology do I apply for these NG and Oxygen Venting lines for sizing /selection of the end of line FAs. Any reference or guidance will be of great help to me.

Thanks and Regards,
Pavan Kumar

 

[georgeverghese]

Why do you need a FA for O2 vent lines ? Its not flammable.

 

[Pavan Kumar]

Why do you need a FA for O2 vent lines ? Its not flammable.

Hi George,

It is said that Oxygen can heat up the piping due to high velocity and can cause the metal to burn. Particle impingement can cause this heating as well.
I recently received training to this effect.

Thanks and Regards,
Pavan Kumar

 

[georgeverghese]

But in this case, the oxidant is already within the pipe, so I dont see what the FA will do to arrest the combustion. Besides, combustion can occur anywhere in the pipe where static could generate a spark.

 

[Pavan Kumar]

But in this case, the oxidant is already within the pipe, so I dont see what the FA will do to arrest the combustion. Besides, combustion can occur anywhere in the pipe where static could generate a spark.

Agree. It makes sense to me.

Pavan