Right Naming for ASME Heads

[isalinasr1000]

Hi everyone!

My question is about the right way to refer to an ASME head, specifically to F&D or Torisphercial Head.

I would like to know the difference between them, my boss told me they are diferent but all post refer to them as the same, except for this page

http://www.prentex.com/glossary.php

which refer to them as different only for the way of construction of them. On that website, F&D is used for heads made by one plate, but torispherical are made by two pieces, is that correct? and how does the asme code refer to them?, I have only seen the word "torisphercial" used by the code.

Thank you

 

[MJCronin]

"On that website, F&D is used for heads made by one plate, but torispherical are made by two pieces, is that correct?"

No.... The head designation and type is a depiction of geometry only and not method of manufacture .....

A torosphere is defined here:

http://mathworld.wolfram.com/TorisphericalDome.html

The ASME code provides code equations for the evaluation of certain common types of permitted pressure vessel heads. In order to use these equations, the head must comply with certain dimensional limits. In order to meet the market demand from the ASME vessel shops, pressure vessel head fabricators also supply heads that meet these dimensional limits.

Torospherical heads (also called F&D heads) can either be sold that meet the ASME requirements or not. (As your link seems to explain. Heads that do not meet the ASME dimensions are typically used for atmospheric vessels. Torospherical heads are slightly deeper than elliptical heads, giving them some advantage in chemical mixing applications. In smaller diameter vessels (less than about 120 inches) they can be cheaper.

2:1 ASME elliptical heads are another permitted shape and are very common. For almost all applications, the required wall thickness will be the same as the vessel cylinder to which they are welded.

More information here :

http://pveng.com/comparison-between-head-types-hemi-se-fd-and-flat/

MJCronin
Sr. Process Engineer

 

[MJCronin]

A better place for this question would be the "Boiler and pressure vessel" Forum ....

MJCronin
Sr. Process Engineer

 

[MJCronin]

There are some other types of both elliptical and torospherical heads that meet the ASME code and may be attractive to the purchaser.

Brighton offers the most varieties and a good explanation of each:

http://brightontruedge.com/products/#tank-tab

MJCronin
Sr. Process Engineer