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Gas Lost in Section of a Full-Bore Rupture

Contents

Full Bore Calculation

Gas lost is a calculation is a full-bore rupture where an accidental release occurs on both ends of the pipe under subsonic conditions.

Some of the limitations include pressure, location, size of pipe, time to isolate, etc. with two separate ends.

P_{ave}V=n_TZ_{ave}RT_{ave}

P_{ave}V=n_TZ_{ave}RT_{ave}

P_{ave}=\frac{P_1+P_2}{2} for \,small\,pressure\,drops,say\,20\,percent\,of\,P_1

P_{ave}=\frac{P_1+P_2}{2} for \,small\,pressure\,drops,say\,20\,percent\,of\,P_1

P_{ave}={\frac{2}{3}}[P_1+P_2-{\frac{P_1P_2}{P_1+P_2}}]\,for\,greater\,precision

P_{ave}={\frac{2}{3}}[P_1+P_2-{\frac{P_1P_2}{P_1+P_2}}]\,for\,greater\,precision

T_{ave}=\frac{T_1+T_2}{2}

T_{ave}=\frac{T_1+T_2}{2}

V={\frac{\pi D^2}{4}}L

V={\frac{\pi D^2}{4}}L

Where:
𝑃𝑎𝑣𝑒 − average pressure[psia]
𝐷 − Pipe Inside Diameter[ft].
𝐿 − Pipeline Length[ft]
𝑛𝑇 − Total numbers of moles of gas[lb∙moles]
𝑅 − Gas constant, 10.73[ft3∙psia/lb∙moles °R]
𝑍𝑎𝑣𝑒 − average compressibility factor
𝑇𝑎𝑣𝑒 − Gas Average Temperature[°R]

n_T=\frac {\pi D^2P_{ave}L}{4Z_{ave}RT_{ave}}

n_T=\frac {\pi D^2P_{ave}L}{4Z_{ave}RT_{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

  1. Select the Gas Lost in Section of a Full-Bore Rupture application in the AGR & GPRA module.
  2. To create a new case, click the “Add Case” button.
  3. Enter Case Name, Location, Date and any necessary notes.
  4. Fill out all required parameters.
  5. Make sure the values you are inputting are in the correct units.
  6. Click the CALCULATE button to overview results.

Input Parameters

  • Pipe Size
  • Wall Thickness
  • Internal Pipe Diameter
  • Pipeline Length
  • Base Pressure
  • Pressure Upstream
  • Pressure Downstream
  • Average Gas Temperature
  • Gas Specific Gravity

Part 2: Outputs/Reports

  1. If you need to modify an input parameter, click the CALCULATE button after the change.
  2. To SAVE, fill out all required case details then click the SAVE button.
  3. To rename an existing file, click the SAVE As button. Provide all case info then click SAVE.
  4. To generate a REPORT, click the REPORT button.
  5. The user may export the Case/Report by clicking the Export to Excel icon.
  6. To delete a case, click the DELETE icon near the top of the widget.

Results

  • Average Pressure
  • Average Compressibility Factor
  • Pack in Gas Pipeline

References

  • GRI-00/0189, A Model for Sizing High Consequence Areas Associated with Natural Gas Pipelines, Gas Technology Institute
  • PHMSA – Final Report TTO Number 13, Delivery Order DTRS56-02-D-70036, Michael Baker Jr., Inc. –
  • PHMSA – Final Report TTO Number 14, Delivery Order DTRS56-02-D-70036, , Michael Baker Jr., Inc.
  • Crane Limited, Flow of Fluids through Valves, Fittings, and Pipe, Technical Paper No. 410-C, Crane Engineering Division
  • Schram, W., “Prediction of Crater Caused by Underground Pipeline Rupture”, N.V. Nederland se Gasunie, Report TR/T 97.R.2515
  • NEN 3651, Annex A: “Determining Disturbance Zone Dimension”
  • PRCI L51861, “Line Rupture and Spacing of Parallel Lines”, Battelle Memorial Institute
Updated on December 14, 2023
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