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pipeline inspection

Pipeline inspection

PG&E is committed to the safety of the communities it serves and is working to enhance pipeline safety throughout northern and central California. Key to this effort is the inspection of PG&E's nearly 7,000 miles of gas transmission pipelines and 42,000 miles of distribution pipelines. By regularly monitoring and inspecting these networks of gas pipelines, PG&E is able to identify and address concerns before they become a problem.

PG&E is a partner in developing and deploying new technologies that are helping transform utilities into more predictive and proactive operators and helping aid in providing detailed inspections—often in less time and with greater accuracy and precision than traditional methods.

PG&E worker working on a pipeline

3D Toolbox

PG&E is working with a new technology that looks for warning signs, such as dents, cracks or corrosion, on the outside of gas pipelines. 3D Toolbox is as easy to use as a digital camera, and with a click, it captures an image and provides measurements—giving PG&E real-time information about the condition of pipeline surfaces. This technology allows pipeline engineers and corrosion experts to view images on a laptop at the dig site, assess any surface defects or issues within minutes and put together a corrective plan immediately. In addition, a major advantage of the system is that it provides a traceable digital record of the measurements, allowing engineers to easily store and access the data in the future.


PG&E also utilizes a portable, handheld 3D laser scanner called the EXAscan. The EXAscan is able to replace time consuming manual tasks and provide a much more detailed evaluation of a pipeline than was previously available. It can measure, for example, the extent of external corrosion or characterize any warping.

A trained engineer or technician simply holds the scanner a few inches above a section of pipeline. The device transmits data to a computer program, which creates a 3D model of the object and displays it on a monitor. The software includes color coding to show where pipeline damage is most severe, along with many other measurements. The data is accurate within 40 microns, or 0.0016 of an inch.

Hydrostatic testing

Hydrostatic testing involves pressurizing a pipe with water to reveal potential weaknesses and is a proven method for verifying the capability of a natural gas pipeline to operate at a safe level of pressure. Hydrostatic testing is also used to test such familiar items as scuba tanks, fire extinguishers and air compressor tanks.

Hydrostatic pressure testing entails filling a pipe with water, pressurizing it to a much higher level than the pipe will ever operate with natural gas and then monitoring the pipe for approximately eight hours. Since 2011, PG&E has pressure tested more than 673 miles of natural gas transmission pipelines throughout its service area.