6 replies to this topic

[gourav.agrawal]

I have been doing gas flow rate, pipe sizing and pressure drop calculations. Please provide me spreadsheets for calculations.

[breizh]

Consider this resource :http://www.pipeflowcalculations.com/naturalgas/

You should think about developping your own calculation sheet and using the search button you will find literature
Breizh

[Shivshankar]

Gourav,

Please put your data and calculations.

Regards
Shivshankar

[Steve Hall]

Several products are available in the store on this site.

[breizh]

Gourav,
I've attached calculation (after revision) to support . As stated initially better to develop your own sheet .

Breizh

[asade abiodun]

According to API 14E, section 2.4, the sizing criteria for a single phase Gas line is based on velocity to avoid noise which must not exceed 60 ft/s. It also listed out various pressure drop calculation equations (Weymouth, Panhandle, Spitzglass).
I would like to know when and where to use each of these equations? e.g. piping network within facility and pipelines.

[Steve Hall]

With modern methods, the Panhandle and Weymouth Equations aren't used unless dictated by a Code. (Even though the answers obtained from the equations depend on an assumed efficiency factor, if everyone in a camparable group uses the exact same equation with the same assumptions their results can be compared to each other -- this is sometimes more important than the accuracy of the results).

From Rules of Thumb for Chemical Engineers, 5th Edition:

"Three equations commonly encountered in the natural gas industry are the Panhandle A, Panhandle B, and Weymouth equations. Often cited for use in calculating pressure drop in long transmission pipelines, they each incorporate a friction factor term so the friction factor is not calculated independently. The advantage is that the pressure drop is correlated directly with flow rate. The drawback is that the friction factor term is relatively inaccurate when compared with the Darcy factor, especially at low flow rates (i.e., in the laminar region). But in each case, at low flow they are conservative and under-predict flow while at high flow they are overly optimistic and over-predict flow. The primary difference between the equations is where the low and high flow are defined.

"The equations assume isothermal flow. If temperature change is defined (due to heat transfer through the pipe wall, not from adiabatic expansion), the average temperature is used in the equation. To account for surface roughness in the pipe, as well as other factors such as bends and fittings, an “efficiency” factor is introduced, typically ranging from 0.85 to 0.92. As a pipe corrodes, the efficiency decreases. This is because the equations are arranged to return the flow rate for a given set of conditions, including pressure drop. Thus, rougher pipe means lower flow."

Edited by Steve Hall, 18 September 2012 - 06:26 AM.