![]() the angle where Knuckle radius = r) For ASME F/D head this angle is 1.084 radians (=62.09 degrees) R equals (inside) (secondary) radius of torus (knuckle radius)Īngle=ACOS((1/2-L)/(K-L)) (angle in radians)Īngle is angle of torus part i.e. R equals (inside) Radius of spherical part (dome) This missing formula for torispherical head volume kept bugging me, so I had a go at it. Jproj RE: Calculation of Head Weights TD2K (Chemical) 19 Jul 02 15:04 Not to say that the book is the end all / be all, but I don't have another reference with which to compare my results. I am almost positive the equations I am using to calculate the 2:1 and hemi head weight are correct, but the weights don't match up with the pressure vessel handbook. With a little manipulation, the volume of 2:1 elliptical head is nearly as easy to calculate (with a 2 inch straight flange). there should be no mystery about the equations to calculate the volume of a thin shelled half sphere (no straight flange). Now, I can understand why it may be difficult to come up with an equation for an ASME F&D head, but a hemispherical head is half of a sphere. I have head weights listed in a book, but I was mainly looking to define the weight using an equation. Shell weights are easily calculated, but as shown by this thread, head weights are not so easily calculated. two heads plus one shell and assorted nozzles = tank weight. Since we don't talk to fabricators unless we have the job, we must estimate the weights ourselves. When we send out our bids, our customers usually want estimated tank weights. We are a small pressure vessel design company. The best option is to find out the blank dia of the head(refer Brownell & Young) and then calculate the weight using the formula pi/4*(blankdia)^2*density*thickness.Įmail: RE: Calculation of Head Weights jproj (Chemical) If anybody needs better clarification, I can send them a sketch where this is better explained. This is beacuse, the inner side is an exact ellipse, and the outer side is not an exact ellipse)That means almost half of the thickness is not accounted when you calculate using the formula above. Now in actual case, the outer head height is 260mm (250 + 10). I.e,for a 2:1 ellipse profile, for 1000mm dia, the head height is 250mm & for 1020mm dia, the head height is 255mm. OD becomes 1020mm.for ellipse head height is D/4. This can be explained by taking an example :Ĭonsider the ID as 1000mm, say thickness of 10mm If the following equation is used, the weights that will be calculated will be almost half of the actual weight.(I tell this from my own experience as the actual weight was much more than the weight which I calculated using the formula which Mogens had suggested. Jproj RE: Calculation of Head Weights Flareman (Petroleum) 17 Jul 02 13:06 In this case, I have to extrapolate to find an approximate number (time consuming).ĭoes anyone know how to calculate the weight of these types of heads? Are there any references that address this topic? Sometimes, there are cases where the weights are not listed in the book (say a tank with a diameter of > 12 ft). Megyesy) to lookup head weights based on diameter and thickness. I'm currently using a table from the Pressure Vessel Handbook (Eugene F. I have found and verified equations based on inside diameter. I think it has to do with my equations for the volume based on the outside diameter. I am not having much luck using this method on vessel heads. To find the weight of a cylindrical shell I found the inside and outside (total) volume and subtracted to find the shell volume. I am trying to find equations for the weights of 2:1 Elliptical, Hemispherical and ASME F&D heads (without much luck I might add). ![]()
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