What is the meaning of Steam-out condition?
What is the meaning of Steam-out condition?
(OP)
Hi Guys,
This is a tall equipment of about 45m high which consists of two columns with different diameters placed one above the another. The below column is welded to the head of the above column by a cone structure.
Now the entire column is designed for the given condition, But one more condition is that it has to be designed for "Steam out condition". Moreover in its normal design condition, vacuum pressure of 0.175 kgf/cm2 has to be considered. Would you tell me what is the meaning of steam out condition and what are the design conditions are to considered?
Need all your expertise on this.
Thanks in advance,
AravindSujay
This is a tall equipment of about 45m high which consists of two columns with different diameters placed one above the another. The below column is welded to the head of the above column by a cone structure.
Now the entire column is designed for the given condition, But one more condition is that it has to be designed for "Steam out condition". Moreover in its normal design condition, vacuum pressure of 0.175 kgf/cm2 has to be considered. Would you tell me what is the meaning of steam out condition and what are the design conditions are to considered?
Need all your expertise on this.
Thanks in advance,
AravindSujay





RE: What is the meaning of Steam-out condition?
This can be a controlling condition for large diameter thin shells.
I think I would get clarification as to the exact conditions and verify the design.
Regards
Mike
RE: What is the meaning of Steam-out condition?
From what I learned from our process engineer, vessel steamout is done to:
1. Remove harmful chemicals left in the vessel prior to entering it for maintenance or inspection.
2. Remove air in the vessel prior to start-up
If your vessel is subjected to steamout, it should be able to withstand 2 pressure conditions @ the associated steam temperature: (plus other applicable loadings in UG-22)
1. steam pressure (i.e. internal pressure) introduced in the vessel
2. vacuum (as a result of steam condensing inside the vessel)
Thus a steamout condition should have a design internal pressure, design external pressure and a design temperature associated with it. Sometimes the steamout external pressure governs over the normal vacuum condition, which in your case is just 0.175 kgf/cm2 or 2.5 psi. In my experience, vessels subjected to steamout is designed for a MINIMUM of half vacuum (7.5 psi). Most of the time, process engineers or Clients specifies FV for steamout.
As Mike has already said, you better get the exact steamout conditions and verify your vessel design.
RE: What is the meaning of Steam-out condition?
This has become standard, and yes, it can be the controlling design on longer large diameter thin wall (low pressure) applications.
RE: What is the meaning of Steam-out condition?
jt
RE: What is the meaning of Steam-out condition?
Should I do the design for 2 cases and check the thickness for both the cases and consider the maximum?
1)Internal design conditions with external press of 0.175 kg/cm2g and
2)Full vacuum with 300 or 400 deg F
What should I do?
RE: What is the meaning of Steam-out condition?
each element should be checked in all design cases.
RE: What is the meaning of Steam-out condition?
Aravind Sujay