3 replies to this topic

[M.Sadiq]

1) Kindly guide me for selecting appropriate head type for the LPG Bullet. Among following different head   types for pressure vessel, which one is recommended for the LPG service (LPG Bullet).

 

i) Hemispherical

ii) Elliptical

iii) Ellipsoidal

iv) Dish etc..

 

I have selected Elliptical Heads for LPG Bullet, am i correct ?

 

 

2) Furthermore, what is a reasonable aspect ratio (L/D) for the sizing of LPG Bullet ?

 

3) For calculating maximum safe fill volume in the LPG Bullet, i have used following formula as stated in Shell DP. refer attachment

 

For taking Density as per aforementioned two temperatures, what will be the basis of selecting appropriate temperature (max and lowest temperatures). can i consider day (for maximum temp) and night (for lowest temp) temperatures. OR maximum summer or process temperature and lowest temperature encountered in winters.

 

For my case, the LPG bullet will be mounded. (earth covered). 

 

 

Thanks!

 

Attached Files

•  LPG Fill Level.bmp   227.83KB   41 downloads

Edited by Saood, 15 April 2013 - 11:59 AM.

[Bobby Strain]

One would usually use an elliptical head unless the metal thickness is greater than 3 inches. Best to talk with a fabricator, or simply issue volume data for quote along with necessary information. The fabricator can then give you the lowest cost option.  You can get a good estimate with software at my site. Just Google my name to find it.

 

Bobby Strain

[Art Montemayor]

 

 

Saood:

 

I would use 2:1 Elipsoidal heads for pressure vessels designed for a working pressure above 250 psig.  LPG tanks fit that criterion.

 

There is no such thing as a “reasonable” L/D ratio for an LPG tank.  Get down to reality and practical engineering:  The fabrication of LPG tanks is standardized based on local standard sizes of steel plate and available tank heads.  The concept is to combine both in order to avoid excessive plate cutting waste.  Optimization is all about maximizing profit and avoiding wastage.  However, you can decide on whatever L/D you want and I’m sure a fabricator will build it for you – at a special price, of course.

 

I would never use the formula you submit.  I consider a 95% liquid fill much too high for any compressed liquid storage.  I have always used 85% as the working liquid fill and design for 80%.

 

Unless you are working for Shell, I wouldn’t use that formula.  If you are not working for Shell, why do you use a Shell recommendation?  You don’t know the reasons they use that relationship and what are their limitations on the application.  I don’t work for Shell and I personally am not interested in what they consider best practices.  I have my own best practices and feel very comfortable and have been successful in applying them.

 

[Zauberberg]

One star for you, Art - for explaining the importance of Shell standards