Pressure Reductions on CGT's System

Wednesday, July 06, 2011

PG&E recently has reduced pressure on several segments of its pipeline system, throughout the service area, to ensure the segments are operating at appropriate pressures. Some of these pressure reductions are likely to be temporary, with pressure being restored once we are able to ensure the operating pressure is appropriate. Other pressure reductions may last throughout the summer if we need to do additional work on the pipeline.

The reduced pressures will mean that, throughout any gas day, California Gas Transmission (CGT) will have less pipeline system inventory to meet hourly and daily fluctuations in demand and supply:
- Normal operating conditions - 600 MMcf
- Current operating conditions with reduced pressure - 200 Mmcf

As a result, suppliers and customers will need to more closely match gas supply and usage. Noncore customers under a Noncore Balancing Aggregation Agreement (NBAA) can look to their NBAA holder to manage this process, as can core customers managed as part of a Core Transportation Aggregation (CTA)group.

Starting this week, as early as Thursday, July 7 for gas day, Friday July 8, CGT will begin calling simultaneous high and low inventory Operational Flow Orders (OFO's). That is, an OFO with a high inventory tolerance band and a low inventory tolerance band at the same time. Visitors to this web page will see this posted as a "High/Low Inventory OFO". This will be a system-wide OFO, and will require suppliers and large customers to balance supply within a specified tolerance range, which will be announced daily.

CGT will call a High/Low Inventory OFO each day for the foreseeable future, throughout the period of pressure reductions.

We appreciate your patience and understanding during these unique circumstances. Please call your CGT Sales, Services, or Scheduling Representative with questions.

For additional information, please see this article This link will open in a new window posted on

For a more in-depth explanation of OFO rules, please see Gas Rule 14 This link will open in a new window, Sheets 14 and 15.