As jury selection began Tuesday in the trial of Pacific Gas & Electric Co. on criminal charges of violating pipeline-safety laws, a federal judge denied the utility’s request to dismiss charges or limit prosecution evidence because the government had shared secret grand jury information with private consultants.

Prosecutors illegally disclosed grand jury material to two consultants working on the case, but the violations were inadvertent and did not play a role in the grand jury’s decision to indict PG&E on 13 felony charges, said U.S. District Judge Thelton Henderson, who is presiding over the case.

The case stems from federal and state investigations of the September 2010 explosion and fire at a PG&E pipeline in San Bruno that killed eight people and destroyed 38 homes.

The utility is charged with 12 violations of federal laws that require operators of gas pipelines to maintain accurate records, identify risks to lines and inspect or test when pipe pressures exceed the legal maximum. PG&E is also charged with obstructing the San Bruno investigation by trying to conceal its policy of testing older lines for welding problems only if gas pressure exceeded the federal maximum by 10 percent. Convictions carry fines of up to $500 million.

The company asked Henderson to order the obstruction charge tried separately before a different jury, arguing that prosecutors are trying to sway jurors with evidence about the explosion that is irrelevant to the pipeline-safety charges. The judge rejected the request Tuesday, said Abraham Simmons, spokesman for the U.S. attorney’s office.

Henderson rejected PG&E’s request Tuesday to disqualify all prospective jurors, from a pool of 96, who had expressed negative attitudes toward the company in pretrial questionnaires. Jury selection is scheduled to last at least through Wednesday.

The company raised the issue of consultants in a May 25 filing that argued prosecutors had sidestepped laws of evidence and confidentiality by hiring private citizens who had also served as expert advisers during the state Public Utilities Commission’s investigation of the explosion. That gave prosecutors access to PG&E records and other evidence held by the state commission without notifying the company or going to court, PG&E’s lawyers contended.

Prosecutors argued that the consultants became “government personnel,” entitled to access grand jury material, once they were hired. Henderson disagreed but said he saw no evidence that prosecutors deliberately broke the rules or damaged PG&E’s rights.

Prosecutors may have acted carelessly, but “there is no indiction that the grand jury was substantially influenced” by the disclosure of information to the consultants, the judge said. He also said the prosecution didn’t need the consultants’ help in obtaining records from the state PUC, which has provided information requested by prosecutors throughout the case.

PG&E spokesman Greg Snapper declined to comment on the ruling, saying only that “we want our customers to know we are focused on the future and on re-earning their trust by leading in safety, reliability, affordability and clean energy.”

Bob Egelko is a San Francisco Chronicle staff writer. Email: begelko@sfchronicle.com Twitter: egelko