Vessel Design

Hello Kyehia

I presume you mean the vessel is under high internal pressure, yet the entire vessel is "immersed in a vacuum".

The word "vessel" can refer to a ship, and also a container.

If you mean a ship with high internal pressures moving through a vacuum, please advise.

Sealing may mean:

1. Closure of otherwise open surfaces to prevent leakage.
2. harvesting of stream-lined sea-going mammals, for skins, fur, food.
   

Advise further with

Kind Regards....

Unless it's a pretty unusual application, I assume you mean a pressure vessel, with high internal pressure or internal vacuum, normal atmosphere outside both cases. The answer's Yes. It's also Yes for more unusual situations e.g. pressure inside, vacuum outside, as long as you put appropriate figures in the formulas.

But as Sparky says, more information would help. and "sealing" could mean various things.

Cheers......Codey

Thanks for your answer. I meant a pressure vessel; i.e. container where the undergoig process, requires high internal pressure and after a while vacuum. I thought this is difficult to be achieved because in the first case the gasket is designed to prevent leakage from inside the vessel to outside. While in the other case the gasket is required to prevent air from outside to enter into the vessel. Is it difficult, limited, or normal? if not impossible?

Thanks

K.Yehia

Thanks for your help; temperature not too high (up to 250 ºC) pressure 9 bar down to vacuum (-0.95 bar gauge). Material is some kind of polymer. I would like to advice some student to buy or make a small container for his experiment the container in the range of 50 cm diameter 60 cm height

Thanks

I think you mean, Gland sealing / Mech sealing?

Yes it is possible to design and use such vessels. You will have to choose glands accordingly which can withstand such duty conditions.

Your gland follower should be good to hold them together. We did similar applications in India with Macstar gland packings.

regards;

Devendra

Thanks Morgan.

What you call "high internal pressure"

A multi-funtional mechanical seal for vacuum and also for internal pressure up to
10 Barg is not real a problem.

If your are working with a toxic fluid you need a special sealing system, for instance API 53 or API 54 , to keep the toxic fluid inside the vessel or the system.
Your main problem is the temperature, higher temperature are more complicated to select an adequate seal.

The pressure vessels are designed with ASME -Section 8 Codes.

the general empirical relations for thikness calculations is :

t= P * R / (Sm - 0.6 P)

Where P= Internal pressure in Psi

R- radius of vessel in inches

Sm- Allowable stress intensity in Psi

eg internal pressure as 10 bar or 145 psi

radius of Vessel as 14"

material of Cosn. SS 316 for which Sm- 20000 psi

Thickness T= 145x14 / ( 20000- 0.6X145)

= 2030 / 19623 = 0.1034 IN or 2.62 MM

this can be rounded as 3 mm.

this is a simple procedure . For vacuum vessel design tht thickness is calculated with external pressure taken as 10 times the internal pressure .

thanks

p.d. gawali.

BE mech- Unieversity of pune.

Thanks for everybody, I am greatfull to all the comments I got.

K.Yehia

Yes, you can. Just calculate the thickness due to internal pressure, then make a check for external pressure. Please refer to the following CR4 Threads:

• How can i be using ASME codes on the internet to do my design?

• HOW TO CALCULATE PIPE THICKNESS FOR EXTERNAL PRESSURE.