What makes a pressure vessel?

[edellison]

we're working on a design for a device that will operate at or below 10 psi with a diameter of less than 24" and a total height of less than 6". the thinking right now is we'll use flat stainless plate for the ends and rolled plate for the side and it'd be welded construction. we are wanting to design and build this in house with the need for a stamped vessel. would this qualify for that or need more info.

 

[aspearin1]

I think I follow. I had a small pressure vessel made myself. Here are the specs on mine:
3" diameter (cylinder)
6" high
5.5" long 1/2" Diameter SS welded dip tube.
Welded SS plate bottom (1/8" thick)
Rolled SS plate walls. (1/8" thick)
Internal SS welded baffles. (1/8" thick)
Top welded and cut SS flange. (5/16" thick)
Removeable top SS plate with threaded fittings. (5/16" thick)
3" flange gasket to fit between the top plate and the top flange.
The plate and flange were clamped together with 3/16" hex screws (3 around the perimeter). The top plate was drilled and the flange was tapped.

The volume was about 1 liter. I used it to get pressurized flow of a high viscosity fluid. I got the pressure up to 60 psi without hint of failure.

Does this help? It's not ASME, so I wouldn't market it. But it works. Hope this helps.

aspearin1

 

[jte]

edellison-

If I understand your question right, the answer is no, the vessel does not need to be stamped due to (presumably) having less than 15 psig design pressure. You have done a quick HAZOP and determined that the vessel, while normally operating at less than 10 psig, can not ever see more than your design pressure, right? What if someone is having a bad day and closes the outlet valve while the inlet is still open?

However, with proper design and construction (by a U stamp holder) the vessel, even with a design pressure less than 15 psig, may be code stamped at your option. There are plenty of previous threads discussing this issue. My main comment would be that future repairs or alterations are less paperwork intensive if the vessel is not stamped.

jt

 

[GenB]

If you do not want to stamp it is okay, there is no need.
If you want to stamp it you need to follow procedures, your vessel qualifies to be stamped, you have to have design: drawings and calculations andof course hasto be fabricated by an ASME stamp holder.
Post if you need any help with mfrg. and stamping.
I am in L.A. Ca.
ER

 

[tickle]

In Australian standard a vessel is not considered as a pressure vessel if the internal pressure / volume is less than 10^4/(3((D+6)^2)) kPa (D is Internal diameter in m). Frim my experience with BS/PD5500 a similar (maybe the same) relationship exists.

I thought also that for ASME there was a PV value that must be exceeded to classify it as a pressure vessel.

Have a look at some mechanical design calculations and see what the required thickness of a flat end should be. There also minimum thickness of steel that must be met so that the vessel has enough structural strength to stay in shape.

 

[BenThayer]

Why not just make it out of piping components? sch 80 pipe is less than 6" ID and pipe flanges and blind flanges are readily available.

The 10 psig normal pressure vs. what you can see based on temperature or inadvertent error may make it worth it.

Just a thought.

 

[BenThayer]

never mind! i had the dimensions wrong! I need to find a way to edit these posts!