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Full Port Vs Standard (Reduced) Port Ball Valve


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#1 danish

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Posted 25 May 2011 - 03:35 AM

1.Do valve design standard like ASME 16.34, BS 5352 or BS 1873 have specific reduced (standard) port & full port diameters indiacted there?

2. Is there any specific definition for standard (reduced) & full port valve mentioned in any of the valve design standards?

3. Is it a common practice to select full port valve as one size higher reduced port valve or is it by some sort of standard (kindly indicate the standard)?

e.g. 3/4" full port valve = 1" reduced port valve

hence, port diameter of full port valve = port diameter of reduced port valve (Here I assume that standard or reduced port diameter is indicated in valve design standards).

4. Is pressure drop is the only consideration for selecting full port valve? pigging or blowdown, I assume may be the other reasons for selecting it?

5. Is the concept of full port valve is applicable to all type of valves e.g. butterfly, needle,check, Diaphragm etc. or is it limited to some specific valves like gate (full port by default I assume ),globe etc.

Thanks & regards

p.S : Standard port refers to Reduced port.

Edited by danish, 25 May 2011 - 03:37 AM.


#2 Art Montemayor

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Posted 25 May 2011 - 07:49 AM




1 & 2. To my knowledge, there are no valve standards for full port ball valves. I presume you are writing about ball valves – although you don’t mention this.

3. It is my common practice to always require or specify which kind of bore is required in a ball valve. A 3/4" full port ball valve does not necessarily have the same bore as a 1" reduced port ball valve

4. Pressure drop alone is NOT the only consideration for specifying a full bore ball valve.

5. The concept of full bore has only currently been applied to ball valves. This is probably because it is conveniently possible - and sometimes a necessity (such as in pigging). A plug type of valve presents problems. It is ridiculous to mention a butterfly valve, since this type is inherently near-full bore. A diaphragm is near-impossible because of geometry – the same as a globe valve.




#3 danish

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Posted 26 May 2011 - 05:20 AM

Thank you Art Montemayor.

I am not talking specifically about Ball valves only.

And yes, Globe valve do come in full port & same for Gate valve. I should rather say that Gate valve by default have full port due to pressure loss consideration.

What you have explained for Ball valve is 100% correct & I was fully aware of that fact.

I am attaching one pdf file for your reference.

So my questions still stands since all the awnsers correspond to Ball valve in particular except question no. 4.

Thanks,
Danish

Attached Files



#4 Jared2000

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Posted 26 May 2011 - 10:01 AM

Danish,

I was surprised by your attached file with "full-port" globe valves in it. I have not seen such a discription for port diameters for globe valves before. Unfortunately the full-port globe valves have port diameters that seem to be around the ID for schedule 160 pipe or even XX pipe, depending on which valve you look at in the tables.

I sometimes specify full-port ball valves for the purpose of controlling where the skinny spots occur in piping that has had trouble with plugging from entrained solids. I really prefer that the skinny spot be inside something that is easy to take apart. It seems that every filter is eventually bypassed, has its element distroyed, the wrong element installed, or some other negative experience.

In this case, if you are using schedule 40 piping, then the valve port is still the skinny spot in the system. Depending on what your purpose is for the valve, this could be a problem.

For the 1" ball valve that happens to be in my office, I measure it to be 1.023" in diameter, which is pretty close to 1.049" diameter for schedule 40 pipe.

My number one reason for specifying full-port valves is rod-out potential. When the system is plugged up with X and you have to clear it mechanically with rods, packing pullers, or in extreme cases, a drill bit, then a full-port ball valve is really helpful.


For slurries I use full-port ball valves because I worry (perhaps with no reason) that the eddies downstream of the ball will lead to solids deposition just behind the ball where the ball meets the valve seat. If the solids are abraisive this could spell trouble for the valve seats in the future. I also like to plan for rodding out piping in slurry service in the event a power failure, valve failure, pump failure, or other upset causes the velocity to drop in the system.

Just my 2 cents,
Jared




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