This document discusses liquid hammer predictions in oil/water pipelines. It explains that for shorter pipelines, the total overpressure is approximated by Joukowsky's equation, but for longer pipelines over 10 km, the total overpressure equals Joukowsky's overpressure plus an additional overpressure caused by line packing. Line packing refers to the continued pressurization of the pipeline from the forward fluid velocity after the first water hammer wave, raising pressures above Joukowsky's prediction. The document emphasizes that transient simulations are needed to properly account for line packing overpressure in long pipelines.

1. ASSESSING OIL/WATER PIPELINE LIQUID HAMMER PREDICTIONS
For Shorter Pipelines,
PTotal Over pressure  PJoukowsky
For Longer Pipelines (say, 10+ kms),
PTotal Over pressure  PJoukowsky + PLine Packing
What is Line Packing?
In long pipelines, the first water hammer wave fails to
bring the fluid to rest except at the face of the block
valve. The forward fluid velocity continues to raise
fluid pressure above PJouko causing a Line Pack
Points to Know
1. Historically, liquid hammering came under the
purview of Civil Engineers for water networks.
2. Joukowsky’s Equation is limited since it does not
cover, transient cavitation, liquid column
separation, line packing, & piping reflections by
pipe components, variable pipe dimensions &
surge suppression devices.
3. Design Pressure > % Margin x (PJouko + Pline Packing)
4. Higher Frictional P  Higher Line Packing
5. Wave Reflection Time (T) > TBlock Valve closing time
6. Transient Simulations are required to account for
Line Packing Over Pressure (PLine Packing)
Time
PressureRiseatClosedBlockvalve
Joukowsky’s
Over Pressure
Over Pressure
Caused due to
“Line Packing”
a = Wave Celerity;  = Fluid Density; u = Velocity Change
K = Fluid Bulk Modulus [Pa]; E = Young’s Modulus [Pa];
c = Pipe dispensability [-]; ID = Inner Dia [m]; WT = Wall
Thickness [m]