This is just a notice to the folks who haven't heard about the recent pipeline disaster in San Bruno California. The San Francisco airport is in the small town of San Bruno.
Keith Cress
kcress -
Keith Cress
kcress -
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San Bruno 30" Natural Gas Transmission Line, -FAIL- 10
- Thread starter itsmoked
- Start date
- Thread starter
- #21
A large damage multiplier was the fact that even with two 30" openings the pipe bled huge volumes for hours. Because of the active leak fire responders.. don't! They waited until The Jets were out before they did very much.
Over and over this happens. Remember CalNev? A pipe ruptured at the bottom of Cajon Pass and 90 octane gasoline at 2000psi sprayed all over a housing tract. The safety officer said the most horrid mind altering result for him were the screaming crying people begging him to "shut it off". It couldn't be shut off. All they could do was wait until the line drained from Barstow to San Bernardino - about a day.
They now have commanded valves scattered about.
Why not put in valves every hours worth of volume?
Keith Cress
kcress -
Over and over this happens. Remember CalNev? A pipe ruptured at the bottom of Cajon Pass and 90 octane gasoline at 2000psi sprayed all over a housing tract. The safety officer said the most horrid mind altering result for him were the screaming crying people begging him to "shut it off". It couldn't be shut off. All they could do was wait until the line drained from Barstow to San Bernardino - about a day.
They now have commanded valves scattered about.
Why not put in valves every hours worth of volume?
Keith Cress
kcress -
More valves would help limit the volumes released after a break up to a point, however the argument in that situation is that each added valve actually increases the likelyhood of leaks to some extent. Although specific maximum distance limits between valves is mandated by the pipeline codes, during the valve location study, the potential spill volume contained between any two valves is balanced against a risk factor associated with spilling such a volume within the resulting pipeline segment and an optimum distance between valves, often less than the maximum permitted distance, is so obtained.
The danger of such a logical implementation of valve distancing is that the exercise is often limited to being choosen only by a computer program that balanced calculated risk with volume and without any consideration of other factors within the resulting segments. Valves were placed without regard to what was actually located in the route, without regard to actual hydraulic profiles and leak-driving pressures after the valves were cosed, valves being located without regard to the "gravitational flow" and placed on the downstream side of rivers and population centers where the closed valve would actually direct flow to the most sensitive area within the segment, (gravitational flow actually having reversed the usual flow direction), valves being located at local high points, such as at mountain ridge crossings where a break on either side would not have limited flow at all, valves located at local low points where, if a leak occured just upstream of one of them, the whole volume in the segment would be dumped into an adjoining river, valves sites being located within the flood zone of a nearby river, or even chosen without verifying that there is quick and convenient access to the valve sites.
"I am sure it can be done. I've seen it on the internet." BigInch's favorite client.
"Being GREEN isn't easy." Kermit![[frog]](/data/assets/smilies/frog.gif "[frog] [frog]")
The danger of such a logical implementation of valve distancing is that the exercise is often limited to being choosen only by a computer program that balanced calculated risk with volume and without any consideration of other factors within the resulting segments. Valves were placed without regard to what was actually located in the route, without regard to actual hydraulic profiles and leak-driving pressures after the valves were cosed, valves being located without regard to the "gravitational flow" and placed on the downstream side of rivers and population centers where the closed valve would actually direct flow to the most sensitive area within the segment, (gravitational flow actually having reversed the usual flow direction), valves being located at local high points, such as at mountain ridge crossings where a break on either side would not have limited flow at all, valves located at local low points where, if a leak occured just upstream of one of them, the whole volume in the segment would be dumped into an adjoining river, valves sites being located within the flood zone of a nearby river, or even chosen without verifying that there is quick and convenient access to the valve sites.
"I am sure it can be done. I've seen it on the internet." BigInch's favorite client.
"Being GREEN isn't easy." Kermit
At this point in the discussion, it would be interesting to compare the current regulations for USA gas pipe routing to those in Europe.
Anybody ?
It seems to me that, despite additional inspections and living with a complex piping network, that replacement improvements can be made, especially where residences are concerned or where there is a high probability of death.
Despite a vigorous and well designed inspection programs, at what point in time does it make sense to simplyreplace the underground piping ?
After 30 - 40 - 60 Years ? Was the piping system meant to last forever ? Many bridges do not last for 50 years.
Yes, of course it will be very expensive....
But everything, sooner or later, wears out or corrodes away.
Also, am I to understand, based on the discussion above, that a 30 inch diameter pipe can have as little as 30 inches of cover ?
What would be the cover requirements in Europe ?
My opinion only...
-MJC
Anybody ?
It seems to me that, despite additional inspections and living with a complex piping network, that replacement improvements can be made, especially where residences are concerned or where there is a high probability of death.
Despite a vigorous and well designed inspection programs, at what point in time does it make sense to simplyreplace the underground piping ?
After 30 - 40 - 60 Years ? Was the piping system meant to last forever ? Many bridges do not last for 50 years.
Yes, of course it will be very expensive....
But everything, sooner or later, wears out or corrodes away.
Also, am I to understand, based on the discussion above, that a 30 inch diameter pipe can have as little as 30 inches of cover ?
What would be the cover requirements in Europe ?
My opinion only...
-MJC
Let's keep in mind that the first responders to this incident did not realize that this was a pipe failure. Being rather close to SFO (San Francisco International Airport), they assumed they were responding to a major aircraft incident. Took roughly half an hour to determine that they were dealing with a pipeline problem. I don't think this was so much of a question of deinventorying the pipe as it was of simply getting around to turning the wheel to close the valve.
The NTSB is looking into PG&E's slow response in cutting off the source: National Transportation Safety Board vice chairman Christopher Hart said Tuesday that constructing a timeline of how PG&E crews based at a pipeline-monitoring terminal reacted to the blast would be important to determining why it took the utility two hours and 46 minutes to cut the gas that fueled Thursday's devastating blaze.
Let's all keep in mind that virtually everything at this point of the investigation is somewhere between outright speculation and eyewitness accounts. The investigation will take time to complete - I'd expect to get some preliminary reports from the investigators in 30-60 days and final reports will take about a year.
jt
The NTSB is looking into PG&E's slow response in cutting off the source: National Transportation Safety Board vice chairman Christopher Hart said Tuesday that constructing a timeline of how PG&E crews based at a pipeline-monitoring terminal reacted to the blast would be important to determining why it took the utility two hours and 46 minutes to cut the gas that fueled Thursday's devastating blaze.
Let's all keep in mind that virtually everything at this point of the investigation is somewhere between outright speculation and eyewitness accounts. The investigation will take time to complete - I'd expect to get some preliminary reports from the investigators in 30-60 days and final reports will take about a year.
jt
MTPipeliner
Structural
Just because a pipeline is X years old doesn't mean that it is in good or bad condition. There are lines that are 80+ years old that are still in service with no problem, and there are also lines that haven't lasted 10-20 years before failing completely. I'm not sure that mandatory replacement at some arbitrary age will make pipelines any safer.
Natural gas pipelines are obviously used to supply fuel to people, so they need to go where people are. Since many of these lines were constructed years ago, there wasn't much there when they were built. It is amazing how land developers will try to crowd pipelines in order to get a little more developable land.
Natural gas pipelines are obviously used to supply fuel to people, so they need to go where people are. Since many of these lines were constructed years ago, there wasn't much there when they were built. It is amazing how land developers will try to crowd pipelines in order to get a little more developable land.
MJC,
Cover requirements in most places would be 36", but yes you are correct, it can be reduced to 30" when the trench is excavated in hard rock. Outside the USA, 1 meter (39.4") cover is commonly used, sometimes reduced when extra protection is provided as a compensation for the clearance reduction.
During the last few years it became mandatory in the USA to build in the capability to run instrumented pigs for periodic internal spections. The wall thickness remaining, localized corrosion and other irregularities captured during such inspections are used to determine the repair and/or retirement schedules, rehydrotest, or operating pressure reductions that might be needed to keep the risk down and safety levels high... if everything were to work like it should.
2 hours to stop a gas pipeline leak and fire would be a fine achievement by most standards. Some large diameter, high pressure pipelines with valves at maximum spacing requirements can burn for 24 hours or more until they finally run out of gas and flame out. For a significant rupture it is quite unusual to be able to put them out by any means before the gas is totally consumed by flame. In fact, its quite difficult to get near enough to them just to spit and run.
There was some guy just a month ago that was asking for advice on how to build some kind of garage over a gas pipeline RoW on his property. We red-flagged it as one of those things that simply should not be discussed in these forums and the thread was removed. No point promoting those kind of ideas in any manner, even by just giving them "press coverage". The internet has proven that 1 idiot + 1 idiot can equal millions.
"I am sure it can be done. I've seen it on the internet." BigInch's favorite client.
"Being GREEN isn't easy." Kermit
Cover requirements in most places would be 36", but yes you are correct, it can be reduced to 30" when the trench is excavated in hard rock. Outside the USA, 1 meter (39.4") cover is commonly used, sometimes reduced when extra protection is provided as a compensation for the clearance reduction.
During the last few years it became mandatory in the USA to build in the capability to run instrumented pigs for periodic internal spections. The wall thickness remaining, localized corrosion and other irregularities captured during such inspections are used to determine the repair and/or retirement schedules, rehydrotest, or operating pressure reductions that might be needed to keep the risk down and safety levels high... if everything were to work like it should.
2 hours to stop a gas pipeline leak and fire would be a fine achievement by most standards. Some large diameter, high pressure pipelines with valves at maximum spacing requirements can burn for 24 hours or more until they finally run out of gas and flame out. For a significant rupture it is quite unusual to be able to put them out by any means before the gas is totally consumed by flame. In fact, its quite difficult to get near enough to them just to spit and run.
There was some guy just a month ago that was asking for advice on how to build some kind of garage over a gas pipeline RoW on his property. We red-flagged it as one of those things that simply should not be discussed in these forums and the thread was removed. No point promoting those kind of ideas in any manner, even by just giving them "press coverage". The internet has proven that 1 idiot + 1 idiot can equal millions.
"I am sure it can be done. I've seen it on the internet." BigInch's favorite client.
"Being GREEN isn't easy." Kermit
I lived in the same subdivision in two different houses for 31 years. In the first house part of the rear of my property was a ROW for a 30" and a 24" NG pipeline. If you burned gas in the Cleveland, OH area, it probably passed through my property on its way to you. I later moved to another residence, and the pipeline ROW was immediately across the street from my front yard. My bedroom window was ~60 ft from the ROW.
A piece of one of the lines blew out of the ground in a low swampy spot about 2 miles away and something like 21 ft of 30" pipe landed more than several hundred yards away, so it wasn't like it couldn't happen here.
I only worried about those lines in the low boggy or swampy points.
To the subject of the pipeline companies paying attention, once I had some dirt hauled and borrowed a tractor with a back hoe to move it around. I had the tractor parked on the ROW (this was at the residence where the ROW was in my back yard) and within hours a pickup truck drives onto my property and the district Sup't introduces himself. When he was satisfied that my intentions were not to dig on the pipeline, just to push some dirt around away from the ROW, he left, but not until.
I was impressed at how soon after I parked the tractor that he showed up and it was a Sunday afternoon too. They regularly had an airplane fly the line and look for and report problems and things like earth moving equipment parked on the line. If you knew what to listen for you could hear or see them with regularity.
His visit gave me a real comfort with respect to living next door to that next door neighbor.
For me personally, heck, I was constantly in and out of Nuclear power plants, super critical power plants, paper mill chemical recovery boilers, chemical plants that made lethal stuff, (Phosgene the one I can remember). And, I had to drive the public highways to get to and from them. I always figured that if the Good Lord wanted me home, He had plenty of ways to take me. Frankly, I didn't worry much about the pipeline.
rmw
A piece of one of the lines blew out of the ground in a low swampy spot about 2 miles away and something like 21 ft of 30" pipe landed more than several hundred yards away, so it wasn't like it couldn't happen here.
I only worried about those lines in the low boggy or swampy points.
To the subject of the pipeline companies paying attention, once I had some dirt hauled and borrowed a tractor with a back hoe to move it around. I had the tractor parked on the ROW (this was at the residence where the ROW was in my back yard) and within hours a pickup truck drives onto my property and the district Sup't introduces himself. When he was satisfied that my intentions were not to dig on the pipeline, just to push some dirt around away from the ROW, he left, but not until.
I was impressed at how soon after I parked the tractor that he showed up and it was a Sunday afternoon too. They regularly had an airplane fly the line and look for and report problems and things like earth moving equipment parked on the line. If you knew what to listen for you could hear or see them with regularity.
His visit gave me a real comfort with respect to living next door to that next door neighbor.
For me personally, heck, I was constantly in and out of Nuclear power plants, super critical power plants, paper mill chemical recovery boilers, chemical plants that made lethal stuff, (Phosgene the one I can remember). And, I had to drive the public highways to get to and from them. I always figured that if the Good Lord wanted me home, He had plenty of ways to take me. Frankly, I didn't worry much about the pipeline.
rmw
- Thread starter
- #28
jte said:
Wow. That is ridiculous. How could the operators 20 miles away, as the crow flies, not have noticed 40 feet of a 30" line missing?! I can hardly wait to read the report on that.
Shades of that Siberian train-in-canyon disaster. "Pressures dropping Igor, adjust it back up."
Keith Cress
kcress -
pmover, et al..
I think that the most important bit of information in the preliminary investigation is:
"Investigators found that while the longitudinal seams on some of the pipe segments were fusion-welded from both inside and outside the pipe, some were fusion-welded only from the outside of the pipe. In order to understand this variance, investigators are in the process of researching pipe welding standards and practices in effect at the time the pipeline was installed in 1956."
My Translation:
"... the piping met the (logitudinal seam-welded) quality standards of that time (54 years ago) BUT if we were to produce such pipe now, we would be a lot more careful"
I stand by my intuition:
Old piping standards + 54 years + unknown pressure surges + California real estate market + marginal cover = disaster
Nothing lasts forever,
-MJC
I think that the most important bit of information in the preliminary investigation is:
"Investigators found that while the longitudinal seams on some of the pipe segments were fusion-welded from both inside and outside the pipe, some were fusion-welded only from the outside of the pipe. In order to understand this variance, investigators are in the process of researching pipe welding standards and practices in effect at the time the pipeline was installed in 1956."
My Translation:
"... the piping met the (logitudinal seam-welded) quality standards of that time (54 years ago) BUT if we were to produce such pipe now, we would be a lot more careful"
I stand by my intuition:
Old piping standards + 54 years + unknown pressure surges + California real estate market + marginal cover = disaster
Nothing lasts forever,
-MJC
msquared48
Structural
Actually, it's probably a good thing you live 300 miles away.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
I don't believe you saw riveted pipe, but maybe a separator/filter since riveted pipe use was stopped at the turn of the 20th century.
BUT, from a the sprial weld pipe company,there is some possibility read this
"The first recorded installation of steel pipe with riveted seams occurred in Railroad Flat, California, in 1858. Records show that some installations of steel pipe in San Francisco laid in 1863 are still in use today. Large diameter riveted steel pipes supplied the needs of our growing nation for more than 50 years. The labor intensive assembly of riveted pipe seams and joints were replaced by the development of the lock seam method in 1905. In the early 1900s electric welding processes were being developed
and, by 1932, replaced the lock seam joining method for forming steel pipe."
BUT, from a the sprial weld pipe company,there is some possibility read this
"The first recorded installation of steel pipe with riveted seams occurred in Railroad Flat, California, in 1858. Records show that some installations of steel pipe in San Francisco laid in 1863 are still in use today. Large diameter riveted steel pipes supplied the needs of our growing nation for more than 50 years. The labor intensive assembly of riveted pipe seams and joints were replaced by the development of the lock seam method in 1905. In the early 1900s electric welding processes were being developed
and, by 1932, replaced the lock seam joining method for forming steel pipe."
I would like to know the original design operating specifications for the pipe. Pressure, flow rates and design factor(safety factors). I suspect orginally this pipeline was designed for lower specifications and at some later date there was approval to utilize this pipeline at higher pressure and flow rates. The higher specifications would probably not be a great concern however the higher specifications allowed higher flucuations in pressures during normal operations causing additional fatigue problems in the welds. I suspect the final cause will be metal fatigue in the weld joint or in the heat affected zone in the parent material.
dcasto,
You may be right about that. It may well have been a vessel in the pipe manifold although the gas field common to the area dated back to the turn of the last century. I have seen and been around several riveted drum boilers dating from earlier last century, so I didn't think too much about it either way other than to note that it was older than dirt as indicated by its being of riveted construction.
rmw
You may be right about that. It may well have been a vessel in the pipe manifold although the gas field common to the area dated back to the turn of the last century. I have seen and been around several riveted drum boilers dating from earlier last century, so I didn't think too much about it either way other than to note that it was older than dirt as indicated by its being of riveted construction.
rmw
Here is an update from NTSB, did not see it in posts above.
NTSB ISSUES UPDATE ON INVESTIGATION INTO FATAL PIPELINE
RUPTURE IN SAN BRUNO, CALIFORNIA
************************************************************
This is an update on the continuing investigation of the
natural gas pipeline rupture and explosion that killed eight people in San Bruno, Calif., on September 9, 2010.
The investigative group conducting the metallurgical
examination of the pipe is chaired by the National
Transportation Safety Board and includes technical experts
from the Pipeline and Hazardous Materials Safety
Administration (PHMSA), the California Public Utilities
Commission (CPUC), and Pacific Gas & Electric (PG&E). This
group is in the midst of an exhaustive evaluation of the
ruptured pipe pieces. What follows is factual information
that has been developed at this early point in the
investigation.
PG&E survey sheets and charts for the rupture location
indicate that the pipeline was constructed of 30-inch-
diameter seamless steel pipe (API5L Grade X42) with a 0.375-inch thick wall. Evidence obtained so far, however,
indicates the pipeline in the area of the rupture was
constructed, at least in part, with seam-welded pipe.
After the ruptured pipe surfaces were thoroughly surveyed,
all of the asphalt coating was removed and the pipe was
cleaned to allow for visual inspection and nondestructive
testing (NDT) of the surfaces. The condition of the welds
was evaluated by visual inspection, x-ray radiography, and
magnetic particle inspection to document any defects or
irregularities in the material. Pipe thickness surveys were conducted using ultrasonic thickness testing. Additionally, the pipe pieces were laser scanned for complete dimensional documentation.
The fracture surfaces of the ruptured pipe pieces were
examined using low-magnification optical microscopes.
Samples were then cut from the ruptured pipe pieces for
detailed metallurgical examination. The fracture surfaces
were examined under both high-magnification optical
microscopes and scanning electron microscopes to identify
and document specific fracture features. Metallurgists are
currently in the process of using this information to
determine the direction of crack propagation and the
fracture origin and failure mechanisms.
Investigators found that while the longitudinal seams on
some of the pipe segments were fusion-welded from both
inside and outside the pipe, some were fusion-welded only
from the outside of the pipe. In order to understand this
variance, investigators are in the process of researching
pipe welding standards and practices in effect at the time
the pipeline was installed in 1956.
The outer surfaces of the ruptured pipe pieces revealed no
evidence of external corrosion. No dents, gouges, or other
physical indications consistent with excavation damage were observed. Additionally, no physical evidence suggests that a pre-existing leak occurred in the ruptured pipe pieces.
The following laboratory work is ongoing:
Chemical compositional analysis and mechanical property
testing of samples taken from the ruptured pipe pieces.
Evaluation of environmental factors at the accident site.
The investigation is still in an early phase and there is
much factual information to be developed before the Safety
Board is positioned to determine the probable cause of the
accident.
Other areas that investigators are examining include
pipeline control and operations, regulation and oversight,
human performance, survival factors, and pipeline
maintenance and records.
Additional factual updates will be provided and distributed via media advisory as investigative information is developed.
NTSB ISSUES UPDATE ON INVESTIGATION INTO FATAL PIPELINE
RUPTURE IN SAN BRUNO, CALIFORNIA
************************************************************
This is an update on the continuing investigation of the
natural gas pipeline rupture and explosion that killed eight people in San Bruno, Calif., on September 9, 2010.
The investigative group conducting the metallurgical
examination of the pipe is chaired by the National
Transportation Safety Board and includes technical experts
from the Pipeline and Hazardous Materials Safety
Administration (PHMSA), the California Public Utilities
Commission (CPUC), and Pacific Gas & Electric (PG&E). This
group is in the midst of an exhaustive evaluation of the
ruptured pipe pieces. What follows is factual information
that has been developed at this early point in the
investigation.
PG&E survey sheets and charts for the rupture location
indicate that the pipeline was constructed of 30-inch-
diameter seamless steel pipe (API5L Grade X42) with a 0.375-inch thick wall. Evidence obtained so far, however,
indicates the pipeline in the area of the rupture was
constructed, at least in part, with seam-welded pipe.
After the ruptured pipe surfaces were thoroughly surveyed,
all of the asphalt coating was removed and the pipe was
cleaned to allow for visual inspection and nondestructive
testing (NDT) of the surfaces. The condition of the welds
was evaluated by visual inspection, x-ray radiography, and
magnetic particle inspection to document any defects or
irregularities in the material. Pipe thickness surveys were conducted using ultrasonic thickness testing. Additionally, the pipe pieces were laser scanned for complete dimensional documentation.
The fracture surfaces of the ruptured pipe pieces were
examined using low-magnification optical microscopes.
Samples were then cut from the ruptured pipe pieces for
detailed metallurgical examination. The fracture surfaces
were examined under both high-magnification optical
microscopes and scanning electron microscopes to identify
and document specific fracture features. Metallurgists are
currently in the process of using this information to
determine the direction of crack propagation and the
fracture origin and failure mechanisms.
Investigators found that while the longitudinal seams on
some of the pipe segments were fusion-welded from both
inside and outside the pipe, some were fusion-welded only
from the outside of the pipe. In order to understand this
variance, investigators are in the process of researching
pipe welding standards and practices in effect at the time
the pipeline was installed in 1956.
The outer surfaces of the ruptured pipe pieces revealed no
evidence of external corrosion. No dents, gouges, or other
physical indications consistent with excavation damage were observed. Additionally, no physical evidence suggests that a pre-existing leak occurred in the ruptured pipe pieces.
The following laboratory work is ongoing:
Chemical compositional analysis and mechanical property
testing of samples taken from the ruptured pipe pieces.
Evaluation of environmental factors at the accident site.
The investigation is still in an early phase and there is
much factual information to be developed before the Safety
Board is positioned to determine the probable cause of the
accident.
Other areas that investigators are examining include
pipeline control and operations, regulation and oversight,
human performance, survival factors, and pipeline
maintenance and records.
Additional factual updates will be provided and distributed via media advisory as investigative information is developed.
All,
a link to recent update from ntsb w/ letters:
-pmover
a link to recent update from ntsb w/ letters:
-pmover
All,
"While it may seem like a small paperwork error, if companies are basing operating pressures on inadequate or erroneous information contained in their records, safety may be compromised," said NTSB Chairman Deborah A.P. Hersman.
Duuhhhhh...!!!!
Nope,... As a practicing Mechanical Engineer the loss or confusion of important design information does not seem like a "small paperwork error" to me Debby....
When you cannot determine the MAOP of an entire pipeline; one that has been operating for 54 years, it is not a small paperwork error....
When innocent people have been burned alive; in thier homes, it is not a small paperwork error....
But perhaps to a "lifetime federal employee" making a large salary looking forward to a huge pension, detailed and accurate welding records means very little.
Anyone ????
"While it may seem like a small paperwork error, if companies are basing operating pressures on inadequate or erroneous information contained in their records, safety may be compromised," said NTSB Chairman Deborah A.P. Hersman.
Duuhhhhh...!!!!
Nope,... As a practicing Mechanical Engineer the loss or confusion of important design information does not seem like a "small paperwork error" to me Debby....
When you cannot determine the MAOP of an entire pipeline; one that has been operating for 54 years, it is not a small paperwork error....
When innocent people have been burned alive; in thier homes, it is not a small paperwork error....
But perhaps to a "lifetime federal employee" making a large salary looking forward to a huge pension, detailed and accurate welding records means very little.
Anyone ????
not disagreeing with you at all . . .
obviously, the gov-trained employee "assumes" the contractor followed design docs/dwgs and "assumes" the inspection records (if any) concur (lacking as-built data) with the design.
i could rant more, but not worth it for now . . .
-pmover
obviously, the gov-trained employee "assumes" the contractor followed design docs/dwgs and "assumes" the inspection records (if any) concur (lacking as-built data) with the design.
i could rant more, but not worth it for now . . .
-pmover
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