Pipephase vs. GAP

To do what- what's a typical situation?

Use translation assistance for Engineers forum

Note the rules include No Student posting

Sorry - I should have been more specific. The situation is a surface gathering system piping network. Fluid is gas and condensate.

I've used both. Both have strengths. Both have hidden weaknesses. The version of PipePhase before the current one (haven't run the current one) had an unpublished hard upper limit on the number of nodes. If you reach that number it corrupts your input file and erases a couple of PipePhase system files. Recovery is go to your backup (hopefully the one that you did 2 keystrokes before you hit "run") and then reinstall PipePhase and hope that you can get a couple of runs before it dies again. There were a lot of people complaining very loudly about it a few years back. I hope that problem got fixed in the current release.

Bottom line is I always start with the same data set. Set up the model. Calibrate it to match all inputs within 5 psig and (in this model I have two off-system delivery points) all off-system volumes to within 5%. Then without adjusting any calibration parameter I load the second dataset and see if it works. There is a 14 inch line between the two compressor stations and in the second scenario the gas is reversed in that line, if the second run reverses the line then the model is acceptable. Very few ever pass. Neither Gap or PipePhase passed. For problems simpler than my test case both do a workmanlike job. I wouldn't recommend one over the other.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"

Thanks David. Yes I am aware of the node limit in Pipehase. I believe the limit used to be 256 nodes but I don't know what it is nowadays. I too found this out the hard way on a big field-wide model of a steam distibution and injection system.

I've not used GAP before but am fixing to jump in head first and am thus looking for gotchas. I've been using Pipephase for 25+ years, starting with a time share terminal on a mainframe. I figure the two are pretty similar since there's really only one way to skin this cat.

I appreciate your comment on calibration of the model. Thanks for your input and comments. Pete

I first ran into the limit in Elk Hills in Kern County. It seemed to happen at some number lower than 256 (maybe 256 minus the number of system variables?).

I've never really stressed Gap in a live environment. It didn't come close when I tried it against my test case so I dropped it.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"