Electronic Mapping to System Flow Model Electronic Mapping System Extraction.

In 1990 Southwest Gas Corporation (SWG) began a company-wide program to automate its mapping and facilities record keeping functions. A document was drafted which specified every detail of what the new system was to contain and accomplish. One feature specified in the original documentation was that the Electronic Mapping and Record System (EMRS) would create a link between EMRS and the gas system planning software currently in use by Southwest Gas Corporation. As a result of that forethought, EMRS as it exists today, is able to produce system flow model files ‘on demand.’ The models created (extracted) from EMRS contain all basic pipeline facility data required for a workable model, with the exception of customer load volumes. Customer volumes are not part of the EMRS data set. However, in order to conduct a trial balance on the EMRS produced model, a small ‘mock’ customer load is automatically added to each node during the EMRS to flow model creation process. Adding ‘real’ load data will be discussed later in this paper. All known pipeline facility data is stored in EMRS in a relational data base system. That data base is also linked to a vector data set which provides geometric information to facilitate graphic representation of the facilities. The first time EMRS creates a flow model of a specific gas system, a flat file data table is created which contains all attributes of the pipeline facilities required to create system flow model files. At this point the data is still in relational data base format. The second step in the process creates text format files that may be used directly by flow modeling software without further manipulation. The following default parameters are specified for each model:

  • All regulators have identical Cmax and Cg constants and set pressures.

  • All supply sources are set to the same pressure and flow parameters.

  • Each node has the same load.

  • If pipe wall thickness (w.t.) is unknown, a default value is applied.

  • If pipe roughness is unknown, a default value is applied.

The values applied to the foregoing parameters are specified for each specific model.

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