LNG Spherical Tank

I disagree.....

API 650 and 620 are not appropriate design codes for a high pressure LNG sphere.

Most spheres are designed to a pressure of over 200 psig and only an internationally recognized pressure vessel code such as ASME VIII should be used for the design.

It should be noted that shop fabrication of the sphere steel segments and field "fit up" of these pieces is very difficult. Only and experienced firm should attempt this.

You assume high pressure, I assume 15 psi

For High pressure: ASME VIII

For 15 Psi : API 620

200TN is not to much.

Excuse my lack of "accuracy" in my first post.

WP

As I stated above, LNG pressure vessel spheres are not designed for 15 psig service, they are designed for much higher pressures (~17 barg)

Although more expensive than cylinders, Horton spheres can be economical storage for certain volatile gasses and liquids.

API Standard 2510 is commonly used in the USA for LPG facilities. It requires vessels to be designed to ASME VIII

http://www.lpghortonsphere.com/

ASME VIII (or the equivalent EN, BS or AS pressure vessel code) has been most commonly used in the design, inspection, fabrication and testing of the spheres in the world today.

Are you sure? LPG tanks are designed for ~ 17 barg as LPG liquefies under that sort of pressure.

LNG has critical temperature below ambient so is stored cryogenically. I don't know offhand what pressure is used.

Thank you all for your comments...
The pressure of the sphere is about 2.5 barg and the capacity is about 2000 T with an approximate diameter of 21 m. The sphere is Insulated double walled with dike

EN 1437:2007 standard 6.3.1:

Equipment for which the design pressure is more than 500 mbar shall meet the requirements of applicable standards or codes used for the design of each type of pressure vessels

So the question is : What shell I use ASME VIII Division I and II for the design or API 620 considering the sphere under low pressure ?

The API 620 code is limited to ~15 psig design pressure, therefore it is not appropriate for this 2.5 barg design pressure vessel.

Yes, I understand that LNG is stored at a much lower pressure, but it is not stored in a spherical tank at this low pressure

When the OP mentioned he had selected a spherical tank, he implied a pressure vessel, in my opinion.

The EN pressure vessel standard most appropriate for field-assemble spherical pressure vessels seems to be EN 14335.... I do not understand the reference to EN 1437.

We have only succeeded in establishing that the OP understands little of what he is talking about and wants others to educate him....

Dear MJCronin;

The expert at anything was once a Beginner.

I understand exactly what am saying : In reality the idea of a having LNG spheres at such a low pressure is to replace 28 cigars operating each under 2 Barg pressure.

We are trying to find a Solution to make it happen.

The reference to EN 1437 is to indicate that vessels 500 mbar meet the requirements of applicable standards or codes used for the designing pressure vessel*.

*EN 1437 reference to EN 14335 at this stage.

Ref your #6, a sphere 21m dia would be about right for 2000 tonne of LNG (SG about 0.6). But in your original post you said 200 tonne. 2000 tonne is a lot to store of anything flammable, I hope nothing goes wrong!

I suppose operating pressure 500 mbarg is OK as long as the temperature is low enough.

Sheva, why do you want to use a spherical tank ?

Hi again.

Sheva 200Tonnes ids different to 2000T?

In my opinion you have a low pressure tank. Then apply API 620

API 620

"Design and Construction of Large,

Welded, Low-Pressure Storage

Tanks"

https://law.resource.org/pub/us/cfr/ibr/002/api.620.2002.pdf

1.2.2 The tanks described in this standard are designed for

metal temperatures not greater than 250°F and with pressures

in their gas or vapor spaces not more than 15 Ibf/in.2 gauge

4.1.1 Material Specifications

Materials used in the construction of API Standard 620

tanks shall comply with the specifications in this section (see

Appendices Q and R for specific material requirements).

Material produced to specifications other than those listed in

this section may be used if the material is certified to meet all

the requirements of a material specification listed

WP