Introduction
Calculates using gas packed in an isolated section of the pipe. It uses PLTB Gas Lost in a Full-Bore Rupture calculation in the Accidental Release Module.
Upstream and downstream pressures must be known at the time of calculation. In addition, the actual internal diameter and gas temperature can change the results for accounting purposes.
P_{ave} V = n_TZ_{ave} RT_{ave} \~\ P_{ave} = \frac{P_1 + P_2}{2} \text{ for small pressure drops, say 20\% of } P_1 \~\ P_{ave} = \frac{2}{3} \left[ P_1 + P_2 – \frac{P_1 P_2}{P_1 + P_2} \right] \text{ for greater precision} \~\ T_{ave} = \frac{T_1 + T_2}{2} \~\ V = \frac{\pi D^2 L}{4}
P_{ave} V = n_TZ_{ave} RT_{ave} \\~\\ P_{ave} = \frac{P_1 + P_2}{2} \text{ for small pressure drops, say 20\% of } P_1 \\~\\ P_{ave} = \frac{2}{3} \left[ P_1 + P_2 - \frac{P_1 P_2}{P_1 + P_2} \right] \text{ for greater precision} \\~\\ T_{ave} = \frac{T_1 + T_2}{2} \\~\\ V = \frac{\pi D^2 L}{4}Where:
πππ£π β Average pressure (psia)
π· β Pipe Inside Diameter (ft)
πΏ β Pipeline Length (ft)
ππ β Total numbers of moles of gas (lbβmoles)
π
β Gas constant, 10.73 (ft3βpsia/lbβmoles Β°R)
πππ£π β Average compressibility factor
πππ£π β Gas Average Temperature (Β°R)
n_T = \frac{\pi D^2 P_{\text{ave}} L}{4 Z_{\text{ave}} R T_{\text{ave}}}
n_T = \frac{\pi D^2 P_{\text{ave}} L}{4 Z_{\text{ave}} R T_{\text{ave}}}
This value will be used to determine the gas volume Vb existing in pipeline at base condition (Pb = 14.71 and Tb = 520)
V_b=\frac{n_TRT_b}{P_b}[scf]
V_b=\frac{n_TRT_b}{P_b}[scf]Case Guide
Part 1: Create Case
- Select the Pack in Pipeline application from the Testing Module
- To create a new case, click the βAdd Caseβ button
- Enter Case Name, Location, Date and any necessary notes.
- Fill out all required Parameters.
- Make sure the values you are inputting are in the correct units.
- Click the CALCULATE button to overview results.
Input Parameters
- Nominal Pipe Size (in) : (0.625β β 48β)
- Wall Thickness (in) : (0.068β- >2β)
- Internal Pipe Diameter (in)
- Pipeline Length (miles)
- Base Pressure (psia)
- Upstream Pressure (psig)
- Downstream Pressure (psig)
- Average Gas Temperature (Β°F)
- Gas Specific Gravity
Part 2: Outputs/Reports
- If you need to modify an input parameter, click the CALCULATE button after the change.
- To SAVE, fill out all required case details then click the SAVE button.
- To rename an existing file, click the SAVE As button. Provide all case info then click SAVE.
- To generate a REPORT, click the REPORT button.
- The user may export the Case/Report by clicking the Export to Excel icon.
- To delete a case, click the DELETE icon near the top of the widget.
Results
- Average Pressure (psia)
- Average Compressibility Factor
- Pack in Gas Pipeline (MCF)
References
- Pipeline Design for Hydrocarbons Gases and Liquids, Committee of pipeline planning, American Association of Civil Engineers, 1975
- Engineering Data Book, Volume II, Gas Processor Association, Revised Tenth Edition, 1994
- Pipeline Design & Construction, A Practical Approach, American Society of Mechanical Engineers, 2000
FAQ
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Gas Purging Calculations?
Purging is a process of removing gas from the pipeline. Controlled purging of gases from pipelines by direct displacement with other gases that have been safely practiced for many years with the recognition that some flammable mixture is present. Purging of gases from pipelines by direct displacement with another gas also has been similarly practiced. It works both ways; however, there will always be an atmosphere of type of a mixture. This is due to the densities of the gases. Check Out
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What are the differences between the Semiempirical Blowdown calculation and the AGA Blowdown calculation?
AGA blowdown calculation is based on the specification defined by American Gas Association. Semiempirical blowdown calculation was developed from the SW Research Report calculations for the blowdown time and mass of gas vented to atmosphere of a piping system. Check Out