What is an Uprate
In some cases, pipeline operators may be able to increase the throughput in their pipeline systems by uprating a pipeline segment. Simply put, uprating a pipeline is a process that is used to increase the maximum allowable pressure in a pipeline that is not being used to its full design capacity. This allows the company to utilize existing infrastructure to transport more natural gas and reduces the need to build additional pipeline facilities.
Pipelines are designed to operate at certain pressures based on the pipe metal’s yield strength, its diameter and its wall thickness. If you put these factors in a mathematic formula, you can determine the maximum pressure a pipeline can withstand. That pressure is called the maximum operating pressure (MOP).
Interstate natural gas pipeline systems are regulated by the Pipeline Hazardous Materials and Safety Administration (PHMSA), a division of the Department of Transportation. PHMSA uses a formula that incorporates both the material factors and safety factors to determine the maximum allowable pressure (MAOP) a pipeline can operate through any given area.
In New Jersey, Williams anticipates the project will require an uprate of our existing 36-inch Caldwell ‘B’ pipeline located in Essex, Passaic, Bergen and Hudson Counties. In New York Williams anticipates the project will require an uprate of our existing 1.4 miles of 24-inch pipeline under New York Bay in Richmond and Kings Counties, NY. The uprating process allows an increase in the pipeline’s maximum allowable operating pressure.
Uprate procedures
There are a number of procedures that a company is required to perform before a pipeline can be uprated. These procedures are set out in DOT CFR 49, part 192 and any other applicable code, standard, or specification. Before uprating the pipeline, Transco must first demonstrate that the pipeline can safely withstand the increased operating pressure. The primary test to demonstrate that the pipeline can safely operate at a higher pressure is known as a hydrostatic test. The test is a routine procedure that involves filling the pipe with water at pressures greater than the MAOP for at least 8 hours.
For the New Jersey section of existing pipe, Transco is proposing to increase the pressure by 13 percent, or from 638 psi to 722 psi. This proposed operating pressure is less than half of the original maximum design pressure for this pipeline section. For the New York section, Transco is proposing to increase the pressure by 47 percent, or from 350 psi to 517 psi. This proposed operating pressure is less than half of the original maximum design pressure for this pipeline section.
New Jersey Uprate
New York Uprate
When this section of pipeline was initially installed, it had sufficient strength in the steel and wall thickness to operate at higher pressures, but due to New Jersey state regulations at the time, it was purposely operated at a lower pressure. That unused pipeline capacity can now be utilized to meet the needs for additional natural gas in the region.
Before uprating portions of the pipeline, Transco must first demonstrate that the pipeline can safely withstand the increased operating pressure. The primary test to demonstrate that the pipeline can safely operate at a higher pressure is known as a hydrostatic test. The test is a routine procedure that involves filling the pipe with water at pressures greater than the MAOP for at least 8 hours.
Other procedures include:
- Review the design, historical testing, and operating and maintenance data for the section of pipe to be uprated.
- Perform any repairs, replacements, or alterations that are necessary for safe operation at the increased pressure.
- Review previous pipeline integrity assessments.
- Develop a comprehensive uprate plan based on these reviews of historical data and DOT requirements.
Stakeholders/Roles
FERC – Federal Energy Regulatory Commission. Administers applications for natural gas expansion projects. Performs environmental, safety, land use and rates analyses related to the application. Approves or denies application.
PHMSA – Pipeline and Hazardous Materials Safety Administration. Regulates the natural gas pipeline industry after in-service. Works to ensure safety and reduce risk.
