heres another wording of the first law.

First Law: Every body will persist in its state of rest or of uniform motion (constant velocity) in a straight line unless it is compelled to change that state by forces impressed on it.

those forces could come from within the pipe , such as the
momentum of the air.

if you were in a pipe in space that has a ladder that runs from one end to the other.
and you climb the ladder , you must place a force in a direction
in order to climb the ladder.

suppose the pipe were very small and short , say only ten meters long , and has the same exact mass as you do.

you apply a 50 lb force to the ladder and pull yourself toward the other end , from your point of view
you are moving up the ladder , but from the point of view of someone outside the pipe , the pipe is moving.

its the same thing , action = reaction.

the same as the mass of the air moving within the pipe.
the only difference is that your mass is not distributed evenly inside the pipe.

action = reaction.

be it a external or a internal force.

which is covered in newtons third law:

Third Law: The mutual forces of action and reaction between two bodies are equal, opposite and collinear. This means that whenever a first body exerts a force F on a second body, the second body exerts a force -F on the first body. F and -F are equal in magnitude and opposite in direction. This law is sometimes referred to as the action-reaction law, with F called the "action" and -F the "reaction".

so you climbing the ladder is F
the ladder moving away from you is -F

and

the air mass moving away from the tank is F
the pipe moving away from the air mass is -F

action = reaction

so if you exert 50 lbf only half of that force is used to move
you up the ladder , the other half is used to move the pipe and ladder
in the opposite direction.

_________________________
3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.