The Pipeline Toolbox is home to many tools and calculators. The PLTB User’s Guide presents information, guidelines and procedures for use during operations and integrity tasks for field or office applications.
The evolving demand for oil and natural gas supply along with the efficiency of distributing them by using pipelines over long distances generates need for construction of several pipelines. On the other hand, the need of easements or servitudes to provide the passage of pipelines launches a challenge to pipeline operators to design pipelines to minimize land conflicts and environmental impacts. At the same time, it is necessary to assure the safety of population. The solution to these issues often involves the construction of parallel pipelines along new or existing right-of-way (rows). The underground parallel pipelines escalation or domino effect could occur when two or more pipelines run adjacent to a gas or liquefied pipeline. When it happens, the consequences of the final event are notably greater than the consequences associated with the primary event. Therefore, neglecting the evaluation of the domino effect in the risk assessment of under-ground parallel pipelines can give rise to a risk underestimation.
𝑄𝑐 − Mass Flow Rate[lb/sec] Sonic/Chocked Conditions
𝑄 − Mass Flow Rate[lb/sec] Subsonic
𝐶𝑑 − Discharge Coefficient
𝐴 − Discharge Hole Area[ft2]
𝑔𝑐 − Gravitational Conversion Factor 32.2[ft/sec2]
𝑘 − Specific Heat Ratio of Gas
𝑅 − Universal Gas Constant=1545.3[ft∙lb/lb∙mol−°R]
𝑇 − Gas Temperature[°R]
𝑀 − Gas Molecular Weight
𝑃𝑢 − Absolute Source Pressure[lb/ft2]
𝑃𝑎 − Absolute Ambient Pressure[lb/ft2]
𝑍 − Gas Compressibility Factor
For many gases, k ranges from about 1.1 to about 1.4, and so sonic or choked gas flow usually occurs when the source gas pressure is about 25 to 28 PSIA or greater.