HOUSTON (Reuters) - The U.S. Chemical Safety Board said on Tuesday workers were injured in incidents between 2010 and 2014 at Tesoro Corp's San Francisco Bay-area refinery in Martinez, California because of a weak safety culture the company permitted to exist.

"The safety culture at the Tesoro Martinez refinery created conditions conducive to the occurrence and recurrence of process safety incidents that caused worker injuries at the refinery over several years," the board said in the final report of a case study of incidents in which workers were sprayed by sulfuric acid.

The case study described 15 instances between 2010 and 2014 when workers were burned by sulfuric acid from the alkylation unit.

In an emailed statement, Tesoro said it was working on learning from the incidents at the Martinez refinery.

"We agree on the critical importance of continually learning from incidents and improving the safety of our operations, and inaccuracies in the case study do not detract from our resolve to learn from these incidents," said Tesoro spokesman Brendan Smith.

Smith declined to describe what Tesoro saw as inaccurate in the CSB case study.

The Board also said California's state workplace safety agency, Cal/OSHA, could have carried out vigorous preventive inspections that would have identified practices and equipment problems leading to the accidents.

A Cal/OSHA spokeswoman did not have an immediate comment about the board's report.

In a February 2014 incident, the CSB said two workers who were sprayed with sulfuric acid did not have needed personal protective equipment, something that a 2013 safety survey conducted by Tesoro at the refinery had identified as a problem.

Further, workers interviewed by the board said they faced constant pressure to do work more quickly than they thought safe and to operate the alkylation unit in a manner that lowered costs but increased the risk of injury.

One worker told the CSB he used his stop work authority in February 2014 to prevent a release of flammable hydrocarbon despite management pressure to keep the unit in operation. About 84,000 pounds (38,102 kilograms) of sulfuric acid was released in that incident.

The Chemical Safety Board has no regulatory authority, but was created by the U.S. Clean Air Act to determine the causes of chemical accidents and recommend safer practices.

(Reporting by Erwin Seba; Editing by Chris Reese)