How to make a torispherical dome?

[frans]

I would like to know how the torispherical domes are made for pressure vessels. In particular we are quoting a 3,658m diameter vessel made out of 10mm plate, SA518Gr70. The dome has an upstand of 380mm.

 

[vesselfab]

it would either be pressed or spun

 

[frans]

Excuse my ignorance here - would it be feasible to roll the edge of the profile, weld the circumference to a thick plate and then pressurise the inside to strecth into the dome shape?

 

[vesselfab]

anything's possible....feasible? I don't think you would like the trial and error getting shape.

And if there was inconsistant thickness in the plate would cause different yielding

 

[frans]

Fair enough. So that means if it is a new size the manufacturer will have to make a mandrel especially for this job? Cheap it is not going to be!

 

[boilerone]

For a vessel of 3.6m (not 3.6 kilometer, I believe you live in Europe) diameter it is almost not possible to make the dome in one piece. It has to be made in smaller pieces and welded together so the cost is NOT going to be very high.

 

[SnTMan]

frans, it is often the case that a designer sizes a vessel around available heads, just so no tooling charges are incurred. This generally means adjusting the diameter slightly. Check with the head manufatureres to see what they can do least expensively.

Regards,

Mike