# From the Archives Archived discussions on CrazyEngineers

@prashpan • 23 Aug, 2012
Can Anyone give me the formula for calculating plate size needed to make the 10 % torispherical dish ends for a reactor?
Diameter of reactor is 3000 mm
Height of Reactor is 3500 mm
volume required is 25 m3
Shell Thickness is 10 mm
I Want to Know is what shall be the diameter of 12 mm circular plate required before it can be bent to form the dish ends?
@Ramani Aswath • 25 Aug, 2012 I do not think that there is any formula as such.
There is a thumb rule used in industries. It is more an internal practice.
For shallow dishing, the diameter of the plate circle is usually the final OD of the dish plus 3 x t, where t is the thickness of the original plate. During forming a bit of the material flows from the centre towards the edges, which will give some small thickness difference over the profile.
@prashpan • 26 Aug, 2012 Actually I want to calculate the weight of a reactor.
Now the weight of the cylinder can easily be calculated by multiplying volume X Density.
But in order to calculate the volume of top and bottom dish ends i need diameter of the plate from which they are fabricated.
Now the approx weight of such a reactor come out to be close to 8-8.5 tons.
But by my calculations it is coming out as only 4.5 tons. Even if we add gearbox, motor, nozzles etc. the difference should not be so large.
@Ramani Aswath • 27 Aug, 2012 Please see section 4.3.2.3 on torispherical dished ends. The formula for approximate volume (multiply by density for weight) is given there. Calculate the outside volume and the inside volume separately; the difference is the volume of the dished end.
(Pages 31-32) https://www.scribd.com/doc/36279206/32/Dished-Ends
@mechky • 27 Aug, 2012 • 1 like
prashpan
Actually I want to calculate the weight of a reactor.
Now the weight of the cylinder can easily be calculated by multiplying volume X Density.
But in order to calculate the volume of top and bottom dish ends i need diameter of the plate from which they are fabricated.
Now the approx weight of such a reactor come out to be close to 8-8.5 tons.
But by my calculations it is coming out as only 4.5 tons. Even if we add gearbox, motor, nozzles etc. the difference should not be so large.
See if the following relations help you in computing the correct mass:

CR = Do
KR = 0.1Do
SF = 3.5t
DH = 0.1935Do – 0.455t
THi = SF + DH

SF = straight flange height
DH = depth of dishing
THi = total internal head height
t = wall thickness

The external head diameter, 'Do' is usually equal to the outside diameter of cylindrical section.

Using these relations, prepare a solid model of the torispherical end in SolidWorks or any other software. Apply the material and then you can view its mass. Add it to the mass of cylindrical section and see if the total mass is coming out to be correct or not. This will ensure that the dimensions you are using are correct.

If the mass comes out to be correct, then only proceed with the theoretical formulae for volume calculations as they are approximate formulae and many simplified formulae give wrong answers.
@prashpan • 27 Aug, 2012 Okay, thanks for the formulae but i don't have solidworks.
@prashpan • 27 Aug, 2012
bioramani
Please see section 4.3.2.3 on torispherical dished ends. The formula for approximate volume (multiply by density for weight) is given there. Calculate the outside volume and the inside volume separately; the difference is the volume of the dished end.
(Pages 31-32) https://www.scribd.com/doc/36279206/32/Dished-Ends
Sir i did Calculated the volume by the formula given in the link. but by this calculation the weight is coming out as only 156.662 kg
Although the height "h" is coming as 578 mm which is correct.
Taking into consideration that R = Do for torispherical head.
@Ramani Aswath • 28 Aug, 2012 I have not done the detailed calculations. To me it appears that 156 kg is probably one tenth. I got about 1.25 tons as the weight by another approximate order of magnitude calculation. Which makes the total reactor weight more like 4.5 tons, which is what you got independently.
Have you considered the possibility that you are right?
@prashpan • 28 Aug, 2012
bioramani
Have you considered the possibility that you are right?
Maybe but i will only find out when the reactor is fabricated, will get back when i know the answer.
@feroz khan • 09 Nov, 2014 sir i want to calculate the diameter of dish to be cut for a reactor of shell having id 1000 mm & thickness 8mm.Please help me .
@deep.mec07 • 21 Oct, 2015 can anyone tell me how to calculate the development of a dish end
@gaurav bhadani • 03 Feb, 2016 blank dia of torispherical d'end is =o.d. +o.d/24 + 2/3 kr +2s.f

o.d. =outer dia of d'end
s.f. = straight face

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