Naphtha Storing in LNG Tanks

[MIANCH]

Hi Alls,
Can we store naphtha in LNG tanks as we stopped producing LNG in Libya and have plenty of Naphtha, the facility is 50 year old. can someone advice me what need to be check (inspection reports i know already related to health of LNG tanks) before giving green signal to operational team.
You response is highly appreciated.

 

[LittleInch]

Well the density is nearly double, therefore the weight is nearly double.

Many LNG tanks sit with a gap under the floor. So the total weight of a full tank is a lot more in Naptha than LNG. So this may limit the amount you can store in a tank. You may need to re qualify the tank design.

Venting and safety venting will be different.
Check nozzle entry points and exits.
LNG systems often use a lot of bellows to deal with the contraction. The health and pressure rating of those needs to be assessed.


But if the weight issue isn't an issue (might be rather difficult to check after 50 years), then in principle, a tank is a tank.

Some details would be nice to see. What is the tank made of?

And I hope you're doing a bit more design and engineering than asking some random people on a website??

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MJCronin]

Amen LittleInch, amen...


And I hope you're doing a bit more design and engineering than asking some random people on a website??

The fact that the original poster seems to only looking for "permission" from the West rather than a detailed competent engineering evaluation is deeply frightening

This really makes you wonder about the management, safety and decision making process in dangerous multi-billion dollar plants around the world ....

Has the erosive disease of engineering project management finally achieved it's ultimate goal ???

It's goal, of course, is to achieve zero cost engineering along with continuous, never ending meetings .....

We could have a reasonable and productive discussion about LNG, Naptha and aging storage tanks that might benefit others .....

But the OP, of course, only wants permission ....

OK then,..... I give you permission to use any tank of any age and any material to store any liquid !!!

Good Luck



MJCronin
Sr. Process Engineer

 

[MIANCH]

MJCronin,
Permit to store naphtha is ok but what is your studies for aging LNG tanks.our LNG plant is not operation since 2010 and Libyan government banned it because of local consumption has increased. you may know about this facility previously operated by ESSO.

 

[hacksaw]

To get the help you've ask for, you'll need to provide vessel dimensions, temperature and pressure ratings, materials of construction, nozzle sizes and location, flange rating and type, just for an initial assessment.

 

[TiCl4]

I'm pretty sure the OP is asking what evaluations need to be conducted to use an existing tank for a new service. I did not read it as asking for permission to do so. Non-native speaker, so giving him the benefit of the doubt here.

can someone advice me what need to be check

I'm not knowledgeable about LNG and naptha storage, so perhaps someone can can comment with specifics. LI has provided a few checks for the OP, listed below, with some editorializing by me:

[ul]
[li]Venting and safety venting will be different. Evaluate the tank for new relief requirements.[/li]
[li]Check nozzle entry points and exits. Should loading/unloading the tank be different for naptha than LNG - top entry, free-fall not allowed? Other considerations for nozzle locations?[/li]
[li]LNG systems often use a lot of bellows to deal with the contraction. The health and pressure rating of those needs to be assessed.[/li]
[li]Ensure vessel bottom total pressure (storage headspace pressure + static pressure) does not exceed the original design of the tank. If the original design is unknown, then a professional evaluation of tank should be conducted (FEA?) to determine the MAWP and the allowable bottom total pressure [/li]
[/ul]

Others may have more specific knowledge to comment.

 

[Compositepro]

It seems the best thing to do would be to contact the designer/builder of the tank. They would be aware of all the possible problems, if any.

 

[TiCl4]

Compositepro,

Another good check to do. However, that may not be possible if the tank is ~50 years old. Could have no stamp left on it, or the manufacturer may have gone out of business. I have equipment in my plant that is only 15 years old, design documents were either lost/not provided, and the OEM is out of business! Thus my comment on a fit-for-service inspection if original design data is unavailable.

 

[MJCronin]

.... a wild idea here !!!

Why not post in the "Storage Tank Forum" or the "Boiler and Pressure Vessel Forum where there people with tank design experience ???

MJCronin
Sr. Process Engineer

 

[georgeverghese]

LNG is virtually noncorrosive, while we dont know much about contaminants in this naphtha that could damage the internal linings of this LNG tank, perhaps even render this expensive tank unusable for LNG service after a few years of corrosion with polluted naphtha.

 

[hacksaw]

I've got an five gallon LNG tank that's sixty years old that can't be refilled, can I put naptha in it.

 

[LittleInch]

Do you mean here?

https://www.mechademy.com/lng_plant/marsa-el-brega-libya/

Another thing to consider is fire fighting and bunding.

The LNG tank may have double containment in which case you might get away without another bund.

But it probably doesn't have any firefighting or systems installed.

Also once you put Naptha in you might disqualify it from holding LNG.

Could you not import or use cryogenic LPG instead?

There are a number of old LNG facilities where they make use of the cryogenic nature of the storage to store LPG instead as it seems a big waste to use it for Naptha.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MIANCH]

Thanks for all for your valuable advice.
LNG tank is built by HORTON Tanks in 1967.
I'm agree with all of you that in house study is not possible. anyhow export is started and problem is solved.
Best Regards to all