Gas Trace Tasks

Cathodic Protection Systems

Cathodic protection is used in natural gas distribution systems to prevent corrosion of pipes and devices. The Cathodic Protection System tool identifies sections of a gas distribution system that utilize cathodic protection devices.

Cathodic Protection Trace

A gas cathodic protection trace allows you to identify which sections of your distribution system utilize cathodic protection.

Pressure System Trace

A pressure system is a section of the entire gas distribution system which is operating under the same pressure. Regulators are placed between pressure systems as separators. Regulators may be set between two pressure systems that are operating under the same pressure. In this case, the regulator does not separate the systems and they are viewed as one continuous pressure system. If the pressure is modified on either side of the regulator, it then becomes a system separator and the pressure system should be re-traced. Using the Gas Traces tab in the Gas Trace Options, you may choose to stop the trace at any regulator or only those regulators with different inlet and outlet pressures.

Squeeze Off Trace

A squeeze off trace allows you to determine whether pinching the pipes at a selected location will disrupt the flow of natural gas to a specific area. The results of this trace show the outage area and any open squeeze off points which need to be closed in order to isolate the area. The trace stops at any open squeeze off points, and ignores open valves. This trace requires the existence of Squeeze Off features on the map. These features must have a Normal Position value of Open. The trace will determine which of the Squeeze Off features must be Closed to isolate the area.

This tool is not displayed on the ArcFM Gas Traces toolbar by default. It may be added using the Customize menu.

System Trace

A gas system encompasses all the pipes and devices that can be reached from a town border or regulator station. The ArcFM Gas System trace begins at the flag placed by the user and stops at any closed valves (closed valves interrupt the flow of gas). Using the Gas Traces tab in the Gas Trace Options, you may choose to stop the trace at Town Border Stations, Regulators or both as well. It returns a list of devices and pipes that are connected to the feature and allow the flow of gas.

Clear All

This button clears the results if you have selected the Results as Drawings option. If you choose to view your results as a selected set, the Selection tab will NOT be cleared. This tool may clear temporary marks placed on the map using the tools on the Gas Valve Isolation toolbar. If you want to include temporary marks in the Clear All, indicate which marks to clear using the Gas Trace Options. You may also use this tool to clear the trace buffer if it exists.

Results As Selection

Use this toggle button to determine how the trace results are displayed. When the button is depressed (or toggled on), the resulting features are selected on the map and displayed on the Selection tab. When it is toggled off, the resulting features are highlighted on the map in red (you may change the default color using the Options button).

Zoom To Results

Use this toggle button to elect whether to zoom to the trace results. When this button is depressed (or toggled on), the map view will zoom to the trace results.

Trace Options

Click this button to set various options for your gas trace.

Exclude Valve

Use this button to mark open valves on the map that should be excluded from the valve isolation trace.

Include Valve

Use this button to mark a non-critical valve on the map that should be included in the valve isolation trace when the Critical Valve option is selected.

Squeeze Off

Use this tool to place a temporary squeeze-off point, which should help reduce the number of affected services during a repair or outage. The ArcFM Gas Valve Isolation trace treats a squeeze-off as a closed point that stops the isolation trace. Temporary squeeze-off points affect the Isolation Trace in the following ways:

• If squeeze-off points isolate an area, the trace highlights the isolated area.

• The trace does not look beyond squeeze-off points that are not fed by a source.

• If you place the flag on the edge (pipe) that contains the squeeze-off point, the trace returns no results.

• If returning results as a simple graphic or selection, the results stop at the end of the edge (pipe) on which the squeeze-off was placed. Thus, it is possible the isolation results end just beyond the squeeze off itself.

• If returning results as an Advanced graphic, the results stop at the squeeze-off itself.

Temporary Source

Use this tool to designate a gas pipe as a temporary source due to line pack. In most cases, this will be on a distribution main.

Clear Temporary

This tool allows you to clear any temporary marks on the map (e.g., exclude valve, include valve, temporary shutoff, temporary source). Click the Clear Temporary button, then click each temporary mark on the map to clear it. If you want to clear multiple temporary marks with a single click, use the Clear All button.

Valve Isolation Trace

ArcFM Gas Valve isolation allows you to identify features that interrupt the flow of gas.

In the ArcFM Gas Trace Options, on the Results tab, click Drawings to highlight the isolated area in the trace task result color. Click Selection to create a selected set of the features in the isolation area including the valves and/or regulator stations that allow you to isolate the area.

Squeeze Off Points: The Valve Isolation trace uses the Squeeze Off temporary marker to indicate potential squeeze-off points.