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Explosion at liquefied natural gas plant in Freeport Texas 7

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Better to let her drive while you and Billy Bob are passing cold ones around.
I guess the flag blows the other way when the fans are running.
That used to be a Coast Guard station there in the center of the picture.

I was crossing that bridge one time when a speeding car came over the top and a minute later, three police cars followed chasing it. Just like a Burt Reynolds movie.
And designed a 180ft stair tower and an elevated reactor building foundations and enclosure structure at the Badische plant a few miles behind you.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.
 
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Important releveant discussion:
“It’s important to remember that LNG poses unique safety risks, often above and beyond those posed by other hydrocarbon transportation, due to the high pressure and density,” said Bill Caram, executive director of the Pipeline Safety Trust, a Bellingham, Wash.-based safety advocacy group that tracks LNG safety.

Seven LNG plants are currently operating, handling billions of cubic feet of methane every day and making the United States the leading exporter of natural gas. More than a dozen new plants or production lines are planned or under construction. The United States exported nearly 10 billion cubic feet of LNG per day last year, up from essentially nothing in 2015.

The industry has indicated that it is open to new rules from the Pipeline and Hazardous Materials Safety Administration (PHMSA), but is already setting expectations. The Center for Liquefied Natural Gas is calling for flexible, “nimble” regulations and a “holistic” approach that “exchanges expertise and innovation between safety officials and industry.”

MJCronin
Sr. Process Engineer
 
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And the immense quantity of gas that could be released. It seems that they totally depend on dissipation within a rapid amount of time by mother nature. Obviously distance to other facilities is hardly relevant.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.
 
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Apparently they're claiming that the LNG that might leak at an export terminal can pose more hazard than other LNG leaks from the standpoint that it's not necessarily lighter than air due to the low temperature and the chemical composition.

The main physical danger at an LNG site is a leak forming a cloud of low-lying natural gas that drifts until it hits an ignition source — even simple static electricity — and bursts into flames. Experts worry that, since so much gas is stored at each terminal, damage could spread from one part of the facility to another and spiral out of control. That’s apparently what happened at an Algerian LNG terminal in 2004. A gas leak touched off an explosion that destroyed three of the plant’s six liquefaction trains and killed 27 people.

...Current assumptions, Havens says, are built around the properties of methane, which is lighter than air and disperses upward in the event of a leak. That might have been adequate for a previous generation of LNG terminals designed for importing methane into the United States. But at export terminals, where gas must be chilled to minus 260 degrees Fahrenheit, the production lines are rife with “heavier hydrocarbons” such as ethane and propane that present a higher risk of exploding.
Click to expand...

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They seem to place a lot of faith in vapor barriers, tall solid faced fences, to contain gas spreading out. Maybe too much for me.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.
 
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For anything that's heavier than air, those 'vapor barriers' are probably as effective as anything that they could construct around a facility like that.

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without
 
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I'm pretty clueless about the safety aspects of these things and what are the particular scenarios they're trying to protect.

I'm gathering from the discussion that the idea of the vapor barriers is to hold the vapor in at the site rather than allowing it to dissipate outward?

I guess I can see how that is supposed to protect the public outside, but at first thought it seems the opposite of what you want to do (since it makes it a lot more likely to quickly develop explosive concentration inside)

Are there any scenarios where a fire in the plant causes heating of the liquid tanks, lifting relief valves which further feeds the fire/heat? I'm not sure how all that works, but it seems like the worst case scenario would occur if all the stored energy in those liquid tanks can somehow be released.


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Compressed gas type stored energy release here depends on the liquid to gas conversion rate, which may be relatively slow. At liquid temperature, pressure is low, so there is relatively small amount of stored energy in a pressure explosion sense. You would not want the gas to form in the tanks. They won't hold gas pressure. Cracked or intentionally penetrated, or destroyed tank, by terrorist activity is probably the worst risk scenario. At least some LNG import/export sites seem to have some kind of enhanced security involving Coast Guard and harbormaster patrols, procedures and exclusion zones, but I'm not sure what or how is actually being done.

Pressure build ups must be released immediately. Relief valves to vents or blowdown locations in a "safe place" is the usual procedure. Maybe venting behind water curtains??? I do not know.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.
 
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1503-44 brings a good point. Every place that can have liquid natural gas present must be protected against over pressure, even every segment between any two valves, the vacuum space in vacuum insulation, etc. The pressure that can result from a closed in temperature excursion are really high. Ambient temperature is well above the critical point for LNG.
Screenshot_from_2022-06-30_05-18-22_ryxh1c.png

Loss of vacuum in a vacuum insulation system can cause over pressure if the hydrostatic relief valves are not sized for the increased heat gain.

So start at 700 psig, then add in the gas expansion between -110F and ambient. Perhaps upwards of 1000 psi?
 
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268 ft diam measured in Google Earth.
100ft high estimated from number of stairway flights to top.
6MM(Actual)CF
At a gas to liquid conversion of 600:1, its 3T scf/tank.
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It occurs to me to try a calculation which is undoubtedly overly alarmist (It’s probably similar to the thought process of people erroneously equating nuclear power plants to nuclear bombs). Nevertheless, if the entire tank somehow bursts and the contents combine with air in a single explosion representing complete combustion of the contents, what would be the level of destruction?

3E9 scf NG/Tank * (1E3 BTU/FT3) * (1KilotonTNT / 4E9BTU) = 750 kilotons TNT per tank (50 times as big as Hiroshima, from one tank, if my math is right... I'm open to correction).

I don’t know how to convert that to a danger radius, but it does raise eyebrows at first glance for anyone living nearby. But without knowing details of probabilities or credibility of these types of events, at least it’s somewhat comforting to note many similar tanks have existed (for a decade or more?) and while there have been a few explosions, they have been on a much smaller scale.

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Whoa !!!!!! ......

Half your plant explodes with a giant fireball and here come the feds ?....Couldn't have seen that one coming, Jethro !!!!

REUTERS/WAPO (6/30/22) --- U.S. regulator bars Freeport LNG plant restart over safety concerns !



________________________________________________________________________________________________________________________________________

Also in Bloomberg:

Shuttered Texas LNG Plant Delays Restart After Federal Order Blast at Freeport LNG terminal has send gas futures plunging
--- Government notice raises questions about length of outage

"Preliminary evidence suggests that an isolated pressure safety valve “created an overpressure situation” in 300 feet of vacuum insulated piping, according to the federal notice. The piping then burst and allowed LNG and methane to be released into the facility, causing a subsequent explosion and fire that damaged piping and components in the plant, the agency said."


MJCronin
Sr. Process Engineer
 
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I'm glad they are going to be slow and deliberate about it.

Aside from needing to know what was the root cause (to determine whether it suggests more latent problems are hiding), there is probably a need to be able to prove that the safety-critical structures (like those big-ass insulated tanks) were not damaged/weakened by the blast in any way.

The link also states "U.S. natural gas futures tumbled 15% on Thursday due to the report and on a continued inventory build, contributing to a 33% price drop in June, the biggest monthly drop since 2018". That was surprising to me. I guess (?) the US natural gas prices are not well coupled to the European gas prices, and the loss of an export terminal only further decouples those markets.



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FacEngr called it. Vacuum insulated line.

The domestic gas price has been rising directly with increasing export capacity. The speculators think this lost export gas will find its way into the domestic market, where it will create an oversupply and reduce the domestic price. Happy days for US consumers.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.
 
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All military world wide are like this now.

Actually The USA sapper corps have more clue than most but I suspect they were kept away from this "issue" because the local Navy corps didn't want to admit there was a problem and they only wanted to make it last until the next posting and then it would be someone else's problem.
 
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Thanks for the link FacEngr.

"AN ISOLATED RELIEF VALVE caused overpressure of the pipe ..."

Disabling a relief valve! The most amature of all possible mistakes, yet one of the most common. Relief valves make too much noise. Better to close them off. I've seen that so many times that I refuse to put block valves in relief lines. The temptation to close them is just too great.

Alistair, that goes in the other thread.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.
 
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I have had some experience with welding shop cryogenic tanks. Preventing closed in sections of pipe where possible, and providing relief valves on every isolatable section is critical for safety.
The only part of the system we insulate is the storage tank, the tanks our gas supplier provides are vacuum insulated with large rupture discs on the vacuum space. The tanks are provided with duplicate relief valves on a valve block designed so one of the valves can be closed off for service, but not both at the same time. (the same thing is done with propane tank relief valves).

Screenshot_from_2022-07-02_05-29-18_g1nraq.png

I realize this approach may be difficult with 18" pipe, but if relief valves in a cryogenic system need to be removed for service with the system charged, the solution needs to maintain this same function (or you need to rely on administrative controls).
 
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DOT is now getting involved in this significant FREEPORT LNG incident and explosion



"Although the root cause of the failure has yet to be confirmed, preliminary evidence
suggests that an isolated pressure safety valve created an overpressure situation in 300 feet
of vacuum insulated piping. The 300 feet of pipe was subjected to an overpressure situation
which burst the pipe and allowed LNG and methane to be released into the facility. The
sudden release of LNG and methane from the piping caused a subsequent explosion and
fire that damaged piping and components in the plant."

MJCronin
Sr. Process Engineer
 
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The PHMSA notice provides a welcome return of confidence in some gov't depts, after the discouraging 2 yrs of dissappointment that resulted from the CDC/ NIAID handling of the Covid 19 crisis.

One may want to understand if B31.3 allows operation of a piping system with the requisite relief valves isolated. Most codes only pertain to the design and supply of equipment to be provided by the design engineer and do not specifically define operating procedures, but allowing "administrative control" of safety valves at the nation's 2nd largest LNG facility seems a bit over the top.

I had reviewed the initial design arrangement of one other LNG facility, and pointed out that the phase 1 ground level flare system made it impossible to complete construction of phase 2 if phase 1 was in service, as a release of gases to the flare ( from relief valves) would toast the workers assembling the nearby phase 2 flare system, but the criticism was ignored, as schedule/money was of the essence. Perhaps the management thinks that release of gases from a relief valve is a predictable event- one hopes they don't learn the truth the hard way.

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick
 
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