Hi Paul,,

What help u need. Pressurzing in OLGA is simple.
Build a model in OGLA having one end as closed boundary and other end as pressure boundry.
At closed boundary end add a source
At pressure boundary end add a Valve of the required orifice size.
Keep your steady state OFF and mention your initial condition in pipeline
Initially make a dummy run the simulation till you get steady state flow. Note the time
Now again Rerun the case and command the valve at the pressure boundry end (outlet) to close at the time when the flow is steady.
allow the simulation to run even after the vavle closes.
Run the simulation till you reach the line pack condition...

thats it.... Simillary for depressirization.. select suitable orifice size and slowly open the valve. Better if you have a Valve characteristics..

Friendly,
Sathyan