LNG Ship Safety Zone

[Kenomac]

Originally Posted by El Pinguino

Exclusion zones are normally enforced by local authorities.. not military... and I doubt the LNG company owns tugs.

How did an extra mile clearance add 3-4 miles to your passage?

The tug read LNG escort on the side, also company logo, definitely not military.

The rest... Do the math yourself. 1.5 mile radius vs 2.5 mile radius does not equal a 1 mile difference in circumference... unless you're using some new kind of math.

Here I'll make it easier for you... an escort vessel patrolling a 1.5 mile safety zone is policing a roughly 7 square mile area of the sea.

An escort vessel patrolling a 2.5 mile radius is hogging nearly 20 square miles of the sea. That's why we went more than four miles out of our way.

[El Pinguino]

Originally Posted by Kenomac

The tug read LNG escort on the side, also company logo, definitely not military.

The rest... Do the math yourself. 1.5 mile radius vs 2.5 mile radius does not equal a 1 mile difference in circumference... unless you're using some new kind of math.

Nope, I did standard 'rithmatic and stuff at school....

You were going to pass 1.5 miles off.... you alter course and pass 2.5 miles off and then set a revised course to destination when the ship is on your beam... that doesn't add 4 miles to your distance.

It does add 3.92857 miles if you were going to pass very close to the tanker.... in which case the escort's response wasn't all that remarkable.

[Kenomac]

Originally Posted by El Pinguino

Nope, I did standard 'rithmatic and stuff at school....

You were going to pass 1.5 miles off.... you alter course and pass 2.5 miles off and then set a revised course to destination when the ship is on your beam... that doesn't add 4 miles to your distance.

It does add 3.92857 miles if you were going to pass very close to the tanker.... in which case the escort's response wasn't all that remarkable.

Go back to post #1. Re read it. Done arguing with you.

[Carol24]

It's going to be interesting in the near future with these LNG ships since they are the fastest growing bulk carrier fleet in the world market. The demand is not only for land use but for ships of all kinds from harbor tugs to containerships.
The main reason is cost. Currently the cost of natural gas is down to $0.13 per liquefied gallon at the well head and around $30.00 per BCF at the pump prior to taxes. There are also massive gas reserves out there that means the supply will be around for a long time.

[NOLA_sailing]

Originally Posted by Carol24

It's going to be interesting in the near future with these LNG ships since they are the fastest growing bulk carrier fleet in the world market. The demand is not only for land use but for ships of all kinds from harbor tugs to containerships.
The main reason is cost. Currently the cost of natural gas is down to $0.13 per liquefied gallon at the well head and around $30.00 per BCF at the pump prior to taxes. There are also massive gas reserves out there that means the supply will be around for a long time.

You'll probably start seeing the development of off-shore facilities like this one in Louisiana:
https://en.wikipedia.org/wiki/Louisi...shore_Oil_Port

It allows for tankers to discharge payload within a static containment area away from port facilities and dense populations. Steamship companies and their clients like it because it saves them from taking a 30-90 mile trip up the river and having to pay pilots the whole way.

[Muckle Flugga]

Originally Posted by svlamorocha

25 years ago educated folks where very worried about boiling liquid expanding vapor explosions aka BLEVEs. I was working in natural gas and went through training for an LNG project that did ont happen. I will not forget the curve they had that showed the safe distance as a function of the mass of LNG stored. I understand that all the concern about BLEVEs was just a concern, I understand there have been no explosions in LNG ships. With a bit of luck it was the concern of people who work with that stuff that kept everyone safe.

If you stay a couple of miles away you wil be safe even if one of those nasty BLEVEs happens. Someone worked this out:

http://202.114.89.60/resource/pdf/7353.pdf

https://www.netl.doe.gov/publication...gt/Quillen.pdf

Fascinating documents thanks! The figure that really caught my attention in the 2012 paper is that with a BLEVE type explosion on an LNG carrier the immediately killed rate of 50% of all personnel would extend to a radius of 1400 meters from the centre of the blast, and to a radius of 2300 meters more than 50% would experience first degree burns. Quite something.

[BigBoater917]

Originally Posted by compassrose88

Hmmm...LNG tankers are regularly seen in Boston Harbor...safety zone, huh?

Yes. 1/2 mile ahead and astern 1/4 mile on the beams. Look at the 8-10 armed USCG and Boston PD boats as well as the 5 tugs that bring them in. They even run patrol air cover when they're offshore.

[thinwater]

Was there a radio hail? Was the OP monitoring?

There are some pretty big exclusion zones in the Chesapeake, bay, depending on firing practice, and you monitor the radio. They will send a security boat your way, but only if you ignore the radio.

There is also an LNG terminal. You will get a radio call long before you will get company. And this terminal hasn't unloaded a drop in 15 years, and isn't likely too (US gas is cheap), but they enforce it anyway.

[svlamorocha]

Originally Posted by Muckle Flugga

Fascinating documents thanks! The figure that really caught my attention in the 2012 paper is ttahthat with a BLEVE type explosion on an LNG carrier the immediately killed rate of 50% of all personnel would extend to a radius of 1400 meters from the centre of the blast, and to a radius of 2300 meters more than 50% would experience first degree burns. Quite something.

That is what we engineers call cool stuff. Other people just get scared. I remember watching thd instructor sumarize the whole story in one x-y chart. X was how much LNG there was; Y was how far away you had to be if/when it blew up.. The good thing is that as far as I know there has never been a BLEVE explosion on a ship.


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[svlamorocha]

Originally Posted by thinwater

There is also an LNG terminal. You will get a radio call long before you will get company. And this terminal hasn't unloaded a drop in 15 years, and isn't likely too (US gas is cheap), but they enforce it anyway.

If you are referring to the Cove Point terminal you are right in that it is unlikely to import LNG any time soon but it is being permitted for conversion to export. Yeap, fracking has changed things...

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[Cadence]

If refrigeration shuts down they have been known to take all but a refrigerant repair crew for it off.


The geometry stinks as far as additional sailing. Lay to the ship is moving, go astern, of her. She is steaming one hell of a lot fast than you can sail.


Seems like a minor gripe.

[Muckle Flugga]

Taken last year crossing the Singapore Straits. Just for giggles.

[Muckle Flugga]

I wonder if he was aware of the exclusion zone? Rowing sampan in between the centre two of the four lanes of the Singapore Straits TSS. Just for giggles.

[Shrew]

Originally Posted by Kenomac

Go back to post #1. Re read it. Done arguing with you.

Throwing temper tantrums because nobody agrees with you does not really make you right.

[Trimax]

"If refrigeration shuts down they have been known to take all but a refrigerant repair crew for it off."

95% of the ships don't have refrigeration plants onboard, we maintain the cargo pressure (or NBO Natural Boil-off) onboard by using the cargo in the main/auxiliary engines. This might be steam turbine ships or the new generation DFE (Dual Fuel Engines).
The ships which has Reliquification Plants onboard has two units onboard, then there is a GCU (Gas Combustion Unit) which is a back-up. Lastly there is is the final option to vent - this is not taken lightly, but is only a last resort.
At no time is the ship crew allowed to leave - leaving a ship will again by a final resort when all is lost.
There are different sizes of these ships ranging from 130,000m3 - 210,000m3.
The cargoes are carried at -160 deg Celsius (no typo, its -160).
As far as BLEVE's go - The next time you pass one of these ships, have a look at the masts on the ship. They are venting masts, when all has failed these masts will automatically open (mechanically, no need for power or signals/inputs) to firstly insure the cargo tanks don't over-pressurise and secondly to vent excess gas to atmosphere. LNG (or methane) is the only gas which becomes "buoyant" when at ambient temperature and will "float" off. This means that the gas cannot accumulate in one area on deck or at sea level.
If you see an cloud of LNG it will normally only be the outer layer that can explode due to LEL/UEL (Lower/Upper Explosive Limits). The cloud dissipates in seconds.
People far cleverer than us has made sure that every aspect of safety has been looked at when constructing and managing these ships.
Even when we, the crew, mess up the ship will only allow us to "mess up" so far before the automatic system takes over (these cannot be overridden).
There has been groundings/collisions - there still hasn't been any failure of the containment systems.
Two giants collided: Hanjin Italy vs Al Gharrafa in Malacca Strait| SeaNews
LNG Carrier Grounded off Nigeria May Offload Cargo to Break Free - gCaptain

People are very afraid of these ships, because they don't know them. Some countries close the whole canal just to let us through without the risk of having an accident, with other countries where seafarers have knowledge - its business as usual.