Choosing Pressure Vessel head

Question

Can I use a conical head at the bottom for a small diameter steam manifold ( Schedule 40- 3 inch dia. and 2 inch dia. ) that needs to operate at high temperature (~450 deg Celcius) and High design pressure (25 bars = 363 psi)

Since this is a steam distribution and condensate removal manifold, I want the (bottom) head to allow all liquid condensate to be drained via a trap at the bottom.

Can I use a conical head in such a high pressure case? Or are they reserved for lower pressure applications?

Should I stick with Elliptical head?

Also, which would be cheaper and easier to manufacture?

Thanks in Advance.

Answer 1

I would advise staying away from the conical, as this is for low pressure applications. This would lead to more thermal flashing in the vessel. You would also want to consider sch 80 with high pressure steam and condensate applications.

Answer 2

High pressure applications typically involve elliptic head. This is the shape with the lowest stress from all shapes possible. See the graph at the bottom of 6th page of this paper https://www.google.com/url?sa=t&source=web&rct=j&url=https://pdfs.semanticscholar.org/bbce/eebd3ef103fe37d7f0185d193005d194e83c.pdf&ved=2ahUKEwielae8zfjlAhWWYisKHXqxBKUQFjAKegQIBhAB&usg=AOvVaw0s2shzOjwYd_dh04xFtZOI

Especially important to minimize stress on the welding seam between the head and the cylinder (even if you have flanged connection, still ellipse is the safest way to go) Liquid will fully drain from elliptical shape if you have the drain line to the trap right in the middle of the dish. 450degC is quite high too. Choose your material wisely. Yield stress is going to be much lower than at room temperature.