PG&E GAS LINES

San Francisco Chronicle page 1 headline for January 16, 2011: "Gas lines pushed to limit".
Reading the article under the headline, I learned that 375 psi is the standard pressure for the lines and the "spike" is 400 psi. My question is this: What is the factor of safety in these lines? If 375 psi is the "safe" level, and 400 psi is the limit, then there is no factor of safety, I believe that a reasonable safety factor should allow at least a 3 times increase in pressure without causing any weakening of the line.
We need far more rigorous engineering standards for these gas lines. Public safety before profit.