If you put a ghost elbow pipe *inline* with a flowing underground fluid pipe it will stop its flow.
This is on the latest today's 18.? download. 7/5/2020
-jim lee
Fluid: Ghost elbow pipe stops "real" fluid flow.
Re: Fluid: Ghost elbow pipe stops "real" fluid flow.
That is intended mechanic to prevent unintended flow of fluids when robots place blueprint and in general to to prevent unintended pipe connections. https://factorio.com/blog/post/fff-312