Dish Ends Thickness

[arvindpandit]

As per the ASME heads thickness formula for various D'ends, there is variation in thickness for same design conditions. Can anybody explain me the reason for that.

Thanks & regards
Arvind Kumar

 

[chicopee]

The reason is that the hemispherical, ellipsoidal, conical and torispherical heads with and without knuckles have different geometrical configurations thereby leading the investigators to develop different formulae for thicknesses of the heads and knuckles.

 

[arvindpandit]

Still not clear.....
You are saying about different formulas derived by investigator due to different geometrical configuration.
But i would like to how these formulas derived. does it related to depth of the heads as all heads has defferent depth. so the behaviour of stress/pressure acting on the different types heads are different due to the depth of the heads. such as hemisperical has more depth and then ellisodal and the tori...accordingly hemispherical has less thickness and so on.. is it? please clarify.

Thanks in advance
Arvind Kumar

 

[MJCronin]

Arvind...

Your question seems to be about the derivation of the ASME VIII equations to determine head thicknesses.

ASME and other code equation are the resultant of both structural mechanics theory and committee decisions.

They are conservative, consensus decided statements of the desired designs. Their purpose is to give a simple set of rules to a designer

Consequently, they may be simplified or modified by the committee.

Review the Harvey book for more information on head equations.

http://www.amazon.com/Theory-Design-Pressure-Vessels-Harvey/dp/0442232489

MJCronin
Sr. Process Engineer
Venture Engineering & Construction

http://www.VentureEngr.com

 

[arvindpandit]

No, I am not asking about derivation....
I just want to know the why there is a difference between thicknesses of variouis heads....
I try to clear the thing..
For vertical flat head vessel, the stress/pressure acting on the upward direction to the head and shell juction and then turn 90 deg. and for torispehrical with some curvature, the stress/pressure acting shell & head juction and there is not 90 degree turn bcoz of curvature of the head...Similarly the ellipsoidal head more curvature then tori.. again hemispherical has curvature more than ellipsoidal.
so the behaviour of the pressure acting on the different type of heads is different.
according the thickness varies...
Am i right or not..Please make me understand.
Or simply, If some interviewer ask this qus then what will be the good & etchnically correct ans.


Thanks

Arvind Kumar

 

[chicopee]

Here there a translation here?

 

[arvindpandit]

Hi Chicopee...
i got the answer that i want in a proper manner in technically.
Actually, the head having more surface area has less thickness at same design conditions bcoz pressure distrubution is more proper way. Hemisphere having more S.A than ellipsoidal and ellipsoidal having more than torisperical, tori more than flat.
Hence the thicknesses are very for different types of head at asme design conditions.
got it?????


Here there a translation here?

 

[chicopee]

OK, so you have your answer. "Here there a translation here? " should have been "Here there a translation problem here?" because it is apparent that English is not your first language. Good Luck!