10 replies to this topic

[Robert Montoya]

In a pressure vessel the nozzle of gas usually has a valve block, what is the distance recommended of the block valve of the nozzle? I understand that this block valve is used to isolate the vessel during an internal inspection.

[fallah]

Hi,

 

It should be as close as possible to the vessel. Indeed, to isolate the vessel for internal inspection a combination of isolation valve and spectacle blind is usually used...

[Robert Montoya]

Hi,

 

It should be as close as possible to the vessel. Indeed, to isolate the vessel for internal inspection a combination of isolation valve and spectacle blind is usually used...

Thank you, but how is the maximum that could be blocking the valve?

[fallah]

 

Thank you, but how is the maximum that could be blocking the valve?

 

 

 

Hi,

Your question isn't so clear. Please clarify...

[Art Montemayor]

Robert:

 

I think your use of English is what is confusing here.  fallah has correctly answered the spriit of the question you are asking:  try to place a block valve as close to the vessel you are intending to isolate.  That is logical, good practice engineering.

 

You use the word "maximum" and that doesn't make any good sense.  Maximum what?   If you intend to mean "Minimum" instead of maximum for the length of the nozzle, then common sense comes into play again.  Your nozzle would normally require a flange and, as such, bolts and nuts.  Also, your vessel might require insulation.  Therefore, by common sense, you have to have nozzle length sufficient to allow for insulation and the installation and removal of flange bolts.

 

Also, please do not make multiple posting of the same topic in our forums and do not post copies of prior postings without explaining what you mean to post.  I will leave your blank posting of a copy of your prior post for now but will delete it later.  Try to understand how our Forums work by reading the Forum guidelines and instructions.

[Art Montemayor]

Robert:

 

Like fallah, I also don't understand what you state in English.

Perhaps if you send me a message in Spanish stating what you mean, I might better understand you and translate it to English for you.   You can send a personal message by clicking on my icon and clicking on the button that says "send me a message".  I'll receive it and do my best to respond.

[Robert Montoya]

Basically, my concern is related to a 3-phase separator.

 

The existing gas outlet nozzle on this separator has a block valve presently installed directly on it.  This block valve is used to isolate the separator.  Now, a revision is being proposed for this vessel and due to required gas outlet line changes and limited available space, the block valve is now being planned for a location 1.5 meters away from the vessel nozzle.

 

My question is:  What is the maximum distance recommended between this block valve and vessel's gas outlet?  Should I install a blinded valve in the pipe length between the separator and the block valve in order to depressurize the vessel?

[fallah]

Hi,

 

The below bolded items inside the parentheses should be clarified:

 

 

 

"Basically, my concern is related to a 3-phase separator.

 

The existing gas outlet nozzle on this separator has a block valve presently installed directly on it (i.e. without a nozzle inbetween?).  This block valve is used to isolate the separator.  Now, a revision (i.e. a modification?) is being proposed for this vessel and due to required gas outlet line changes (which type of change? size? outlet point?...?) and limited available space, the block valve is now being planned for a location 1.5 meters away from the vessel nozzle.

 

My question is:  What is the maximum distance recommended between this block valve and vessel's gas outlet?  Should I install a blinded valve in the pipe length between the separator and the block valve in order to depressurize the vessel? (i.e. a gas will releave to the atmosphere by depressurizing the vessel through opening of such blinded valve? Is the modification performed to create a facility for depressurizing the vessel by adding such blinded valve?)"

 

 

Edited by fallah, 06 May 2014 - 12:25 PM.

[Robert Montoya]

Thanks Mr. Fallah:

 

- The valve is installed directly on the gas outlet line just after the nozzle.

- The revision is due to a modification.

- It is changing the diameter of the line due to a change in the dimensions of the separator.

-  The purpose of the valve blind  is  depressurize pipe section between the nozzle and the valve block due to increased separation between them.

 

In the attachment file is the sketch.

Attached Files

•  Imagen1.png   21.34KB   1 downloads

[fallah]

Hi,

 

1- If in modified vessel the outlet nozzle size has been increased equal to the outlet line size, then the valve again can be installed directly on the nozzle.

 

2- If in modified vessel the valve cannot be installed on the nozzle due to certain limitations, then a pipe segment can be considered inbetween.

 

3- If for case 2 the blinded valve is considered just for the pipe section between the nozzle and the block valve, it cannot be a manual depressurizing valve but it is a simple vent for evacuating the isolated pipe section after vessel depressirization. Obviously the blinded valve should be considered at the highest point of the pipe section to be able to vent its whole volume.

[Robert Montoya]

Thank you very much...