"It's on our collective shoulders now after this happened. We have been warned," Boxer said.
The federal agency that does those inspections acknowledged it is short-staffed.
"Each inspector is responsible for over 2,000 miles of pipeline. That's the distance from San Francisco to Chicago," Feinstein said.
The safety bill co-authored by Feinstein and Boxer also calls for more use of technology called "smart pigs." They are small sensors that can detect dents, corrosion and other defects by moving through pipelines.
The non-profit Pipeline Safety Trust has been urging their use for nearly two decades.
"Clearly smart pigs are the best available technology to assess the true condition of a pipeline. Again, this is another debate that should have been settled years ago," Pipeline Safety Trust Vice President Rick Kessler said.
Questions were raised whether the San Bruno explosion and fire could have been less catastrophic if the high-pressure gas could have been shut off sooner by automatic or remote-controlled valves.
The National Transportation Safety Board said that's an issue for local officials.
"Pipelines that run through high consequence areas need to explore whether it's appropriate to have automatic or remote controlled shutoff valves. That is ultimately the decision by the operator that's been approved or disapproved by the regulator," NTSB Vice Chairman Christopher Hart said.
The executive director of the California Public Utilities Commission also spoke at the hearing and expressed some self-criticism.
"All the work that we did leading up to Sept. 9 was inadequate and I include the PUC in that," CPUC Executive Director Paul Clanon said.
There was a surprising admission by an official from the federal pipeline inspection agency during the hearing. It has cut back on routine inspections of existing pipelines as a result of a flurry of new construction projects.