PG&E Lying?

I have no clue about the pipe, but from personal experience I have no trust in PG&E (especially anything derived from corporate/upper management) so it wouldn't surprise me in the least if it isn't true.

You've got my curiosity up. Why do you care about something that happened so long ago? Also, it seems to be out of your normal line of work. And why would you suggest that it may be false?

My father was a pipeliner, and we were trailer trash before the term came up. The PG&E failure brought to light a misrepresentation of at least part of the failed section as seamless pipe. This has affected inspection requirements, they being more lenient for seamless pipe. I became a chiropractor at the end of my steamfitter instrument technician career. In short, I've been a pipeliner all my life; chiropractic is a recent calling.

Whether it was seamless might or might not be important. One could also check if ERW (vs SAW) was available in 1956. What about galvanic issues?

I should have said the recent failure of a 1956 gas line in San Bruno. sorry.

Well,

That certainly brings everything into perspective. I'm not sure that there's much we can uncover regarding the circumstances surrounding the installation and materials used at the time.

Good luck in your search for the truth.

Well, offhand I would say that a welded pipe would have a long weld, which might be susceptible to corrosion and weaken along the length. Then if an event happened a large section might 'unzip'.

A continuous unwelded pipe would not have this flaw, I do not know if they can make large pipe with no welds.

The pipe I have seen comes in lengths edge welded, as well as made on site from large coils welded on a bias..

There have also been reports on the local evening news that some of the weld were only welded on one side. You will remember that this was shortly post WWII and there were a lot of hastily trained welders looking for work, and a lot of companies looking to reproduce their wartime profit schedules.I live in Richmond, where ships were being built with "interesting" techniques. Liberty ships sometimes had huge weld failures.

http://www.mishalov.com/Rosie_the_riveter.html http://www.slideshare.net/drjasper/MECH211

The welded on one side issue refers to single submerged arc long seams, made against a copper shoe on the inside. Modern, post 1970 practice is to make the submerged arc weld from both inside and outside, each pass penetrating two thirds of the way through the pipe. The Liberty ship issue was more one of design. The heat affected zone adjacent to a weld is a point of weakness, no matter who welds it. Liberty ships at first had seams from top to bottom, all lined up. These tended to break up along the HAZ.

"Liberty ships at first had seams from top to bottom, all lined up"

By the look of that top pic, I think you're onto something.

Just add a few decades of fatigue.

fyi http://www.ntsb.gov/Pressrel/2010/101214.html

Did I miss something? Does that report say anywhere that the pipe broke at or next to a weld?

The earlier report at http://www.post-gazette.com/pg/10351/1111525-100.stm had stated etc., "There were longitudinal fractures in the first and second pup of the ruptured segment and a partial circumferential fracture at the girth weld between the first and second pup. There was a complete circumferential fracture at the girth weld between the fourth pup in the ruptured segment and the fifth pup in the north segment. The longitudinal fracture in the first pup continued south into the pipe ending in a circumferential fracture in the middle of the pipe."

That at least makes some sense. However, it doesn't say whether the longitudinal fracture was at or adjacent to a weld.

Whichever welding process was used, the longitudinal welds would have been factory welds, but the girth welds would have been field welds. Most of the described problems seem to be with those. But are there any mentions yet of inadequate weld penetration, undercutting, or other such defects?

Sometimes you can get inside a pipe and weld from both outside and inside. Good technique can achieve a full-penetration weld from one side.

I suspect PG&G is still evaluating their position in this matter and will adjust their story to suite circumstances and results of ongoing NTSB investigations. See http://abclocal.go.com/kgo/story?section=news/local/peninsula&id=7842621

Thanks very much, Javahead. I had searched for current availability, and found offerings sparse above 20 inch. The failed section is shown at: http://www.ntsb.gov/Pressrel/2010/images/San_Bruno_28-foot-long_ruptured_section_of_pipeline.jpg and http://www.ntsb.gov/Pressrel/2010/images/San_Bruno_NTSB_investigator_examining_facture_surfaces2.jpg Chilling pictures.

Maybe we are missing the bigger picture here. That pipe has been in the ground for over 50 years, in an area prone to ground disturbance's. Our infrastructure in the US in some places is way beyond its service life. We need to be replacing these units before this type of accident comes along. We would then put more people on pay rolls and then could afford to do more because the tax base would be there. Trickle up economics as it's called.