Look at this propane hook up

[Aaron M]

OK, this will be my first time replacing a LP water heater. It is a power vent tape for LP gas. My concern is a piece of and pipe coming out from OK, this will be my first time replacing a LP water heater. It is a power vent type for LP gas. My concern is a piece of N pipe coming out from ATP a “T” fitting.
What’s it’s purpose? Or why did they do it the way they did it? Any clues anyone?

 

[voletl]

That's a drip leg or a sediment trap its purpose is to make sure if there's anything flowing through the gas line that's not supposed to be it will fall into that tiny piece of pipe before it clogs up anything vital in the system

 

[Aaron M]

That's a drip leg or a sediment trap its purpose is to make sure if there's anything flowing through the gas line that's not supposed to be it will fall into that tiny piece of pipe before it clogs up anything vital in the system

That’s what I was thinking.
Thank you