Pressure Drop

[VikingUK]

Other than :-
friction
obstructions such as bends,injection quills etc
gravity
gradient
thermal expansion/contraction
compressibility factors
Is there anything else I should be taking into account when calculating pressure drops in a 7km pipe run flowing natural gas ?

 

[Zoobie]

Liquids.

Depending on where the gas is coming from and where you are in the world this could be an issue. Once you have multiple phases, the work gets much trickier.

 

[dcasto]

ground temperature and heat transfer, phase change from temperature. At 7km, the bends and quills are nearly negligable.

I asume gradient is elevation, and unless you are going over thae Alps, that will be minimal influance.