steam out pipe connection

[picasa]

A vessel is rated for internal design pressure 300 psig @ 170 F. It is rated for 15 psig @ 510 F as external pressure conditions. The steam out nozzle is hardpiped to a pipe which is rated for 600 F temperature. Is it ok to connect this pipe to the vessel. Would the vessel stand 600 F temperature?

 

[GenB]

You are missing information,
you are feeding a vessel from (not to),
a 600F source and the vessel is only designed for external at 550F and internal 170F.-
Internally or externally, you can not use this vessel.
it is not designed for the temp (You do not specify pressure) I assume it is low pressure.
GB

 

[jte]

I agree that you are missing information. In particular, what temperature steam will you be using. The pipe design temperature is most likely NOT what the operating temperature of the steam supply is at the vessel nozzle. Further, as the steam is introduced into the vessel, it will cool as it expands and loses heat to the vessel metal. Remember, it is the steel temperature that you are concerned with, not the fluid temperature.

If we were to take the approach that every chunk of equipment had to be able to handle the highest rated pipe which connected to it we would have a very simplistic approach to setting equipment and piping design pressures and temperatures - and very expensive.

jt

 

[codeeng]

Most specifications I've seen for steam-out design are typically no more that full vacuum @ 450F. Just like jte says the steam cools before you reach a significant vacuum, thus its not realistic to specify the steam temperature for the external pressure design. I've seen steam-out design reduced to half vacuum on larger vessels where costs come into play.

 

[svanels]

You are steaming out a vessel, probably for inspection/repairs. The purpose of steaming out is to remove, liquid and gases. You need to open all the vents (no pressure build up) you comply to your 15 psig rule.
You need also to open all the drains to get rid of the contents of the vessel. When is your vessel gas/liquid free?
When only condensate/steam is coming out of the drains, and steam out of the vents. The steam inside of the vessel is not superheated, because the vessel itself will react like an expansion tank. you just need to monitor the temperature of the tank, that will be far below the 510F.

Steven van Els
SAvanEls@cq-link.sr

 

[jte]

svanels-

Actually, the 15 psig is external pressure - in other words, full vacuum. The concern is that steam could be introduced into the vessel to begin the steamout and then the crew goes to lunch. They haven't yet opened the outlets. They close the steam inlet. Steam cools and condenses. Causes nearly full vacuum in the vessel. Crunch. Basic HazOp.

jt