Compressible Gas: Impact of Partial Blockage of Branch Connection

[sloquick]

A natural gas pipeline at around 60 psig contains a tubular innerduct. At certain points the innerduct traverses a tap hole in the main for a branch.

Diameter of main/innerduct is from 2-3"/.25", 4"/1/2", 6+"/1".

How could I determine the impact of blockage by innerduct on capacity of gas flow out the branch?

Could the accepted/published friction coefficient of a valve (e.g. a fully open butterfly valve) or other fitting be used as a proxy?

Any advice would be greatly appreciated. Thanks!

Kevin

 

[prex]

I'm not sure to understand your system.
If the innerpipe lies on main centerline and passes straight in front of the tap hole (out of curiosity: how is it supported?), then with your figures the fraction of cross section taken away by the innerduct is so small that the effect on the branch flow should be negligible. However this will depend also on branch to main diameter ratio and on the fraction of mass flow that goes into the branch. prex

http://www.xcalcs.com

Online tools for structural design

 

[sloquick]

Let me clarify. Assume the innerduct lies on the bottom of the main and traverses directly over the tap hole. Assume impact on the capacity of the main from innerduct is already accounted for. Question is what is impact on flow out the tap hole due to blockage by innerduct. Assume innerduct covers less than 30% of tap hole area. Thanks!