Torispherical head depth 2

[Joli21]

Hi,
please let me know whether the following formula is correct for depth of Torispherical head or not.
h=L - Sqrt( ( L - Di / 2) * ( L + Di / 2 - 2 * r ) )

 

[doct9960]

The formula is CORRECT assuming:
h = inside head depth (excluding straight flange)
L = inside crown radius
Di = inside diameter of head skirt
r = inside knuckle radius

 

[Bobfromoh]

When I run the numbers, the answer isn't even close.
I use h=L-sqrt((L-r)^2-(Di/2 -r)^2)...try this

 

[Joli21]

Thanks guys, can you possibly let me know the address of the formula in ASME?

 

[doct9960]

pardiss2523,
The formula is derived from geometry.

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

Bobfromoh,
Your formula & pardiss2523's formula are the same. If you expand the terms inside the square root, you should come up with the same results.
(L - Di/2)(L + Di/2 - 2r) = L² - 2rL - Di²/4 + rDi

(L - r)² - (Di/2 - r)² = L² - 2rL - Di²/4 + rDi

 

[Joli21]

Guys, just small problem with using this formula, If I have only Diameter and Thickness of the Torispherical head as it mentioned in drawing, how can i find other parameters to put them inside the formula?

 

[roca]

it depends
Torispherical head crown and knuckle radiiuses and vary
Typically crown = 0.9D and knuckle = 0.1D
Contact your head supplier

 

[Joli21]

I don't know the supplier of the head, i just have drawing.

 

[vesselfab]

Then you are screwed

different manufacturers....different formulas

a set of calculations would show it

 

[JStephen]

It's not just that different manufacturers use different dimensions, but you can buy different dimensions- and have to design accordingly.

 

[roca]

What are you actually trying to resolve?
Is it so critical?
Why not scale the drawing and then physically check the actual vessel dimensions (drawings can be wrong to actual as-built situation)?

 

[Joli21]

So, I just want to know how PV elite can calculate dome depth without all parameters like knuckle radious and ..., it only asks for dome Diameter, dome thickness and dome type and gives you H.

 

[roca]

GLad to be of help.............

 

[vpl]

pardiss2523

So, I just want to know how PV elite can calculate dome depth without all parameters like knuckle radious and ..., it only asks for dome Diameter, dome thickness and dome type and gives you H.

Maybe it makes some assumptions. You could find out by
(1) reading the accompanying manual
(2) calling the software vendor and asking or
(3) finding a forum that specializes in PV Elite

Patricia Lougheed

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.

 

[SnTMan]

Or making some assumptions your self and seeing if your answer matches.

Regards,

Mike

 

[JStephen]

ASME defines a standard F&D head in the main body, and then addresses other profiles of F&D head in Appendix 1. I would assume any software would allow you to enter the type of head required, and possibly use the ASME standard as a default.