Full Port Gate Valves? 6

[11echo]

I'm a piping designer with afew years of experience, I was doing a project where the engineer wanted to hot tap thur a 4" valve into a 6" line (this is hydrocarbon service). I normally like to use full port ball valves for this but the engineer indicated he want to use a gate valve to save money. I've run across this before so nothing new. As I was filling out the material requisition I had noted that we needed "full port" gate valves to do this hot tap. My boss saw this and said "ALL" gate valves are "full port" regardless, and didn't need to be indicated! ...News to me, But to be honest I really don't know! I've sent email to some major valve manufactures, but they ALL seems to be too busy to answer my question. Can ANYBODY help me here!!?? THX! ...Mark

 

[Ashereng]

Your boss may be stating an industry "truism". That is, unless otherwise stated, people in the industry assumes certain things due to regular industry "commoness".

To my experience, gate valves are usually always "full port". Gate valves are usually only used in on/off service (they are either open or closed), and a full port gives the least pressure lost.

In the case of a slab gate (through conduit?), I suppose you can have a hole that is not "full port", although I don't know why one would do that, and I haven't seen one.

In my opionion, it doesn't hurt to state full port gate.

Many "oldtimeers" sort of "sneer" at this as something an inexperienced person does. I don't share that opinion. There are lots of people in my industry now that could benefit from having the obvious stated.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[Hench]

11Echo,

With all due respect to Ashereng, I have to disagree with his comment. Full Port Gate valves are not the norm/standard. Full Port valves are more expensive than Conventional Port, thus the one reason they are not the norm.

I would suggest you contact your valve supplier and get his input. Find out what they normally supply your company, and just to be safe, put "Full Port" on your MR.

Good Luck!

Hench

 

[jte]

Mark-

My experience agrees with Hench's. I'd suggest looking at some valve catalogs such as one from Edward Vogt at

http://fcd.flowserve.com/valves/documents/Vogt/VVACT0001-Gate.pdf

. Print out the dimension sheet for CL-150 gate valves (page 5 of the .pdf) and toss it on your boss' desk. Ask him what exactly dimension D, the seat diameter, means. For a 4" valve it's listed as 2.75" which I suspect does not fall into his definition of "full port". What I've seen in my industry (petroleum refining) is that larger valves tend to be full port while smaller valves tend to be reduced port. For a hot tap, it's best to just be sure and specify "full port".

jt

 

[Ashereng]

Hench, jte,

You are correct. I took a look at Flowserve's documents, and they do reference conventional AND full port.

I have talked to my colleagues, and they, as myself, are surprised by this. We are currently looking into it more. This is great - I will learn another new thing today.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[Ashereng]

Well... I am chalking this up to one of those regional industry truisms.

Evidently, I (and 11echo's boss I guess) come from an area/industry where we only use full port gate valves, even though evidently, reduced port is more commonly used elsewhere.

I called Flowserve USA, and they confirm that they sell a whole bunch of conventional port gate valves into the oil and gas industry.

I will have to be more diligent in the future when I fill out my gate valve datasheets.

Thanks to Hench and jte. It is greatly appreciated. Stars to you guys.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[11echo]

I want to thank ALL participating authors here. I in deed marched into my boss office and "showed" him a copy of these data sheets! ...He hmmm'd and haaa'd abit but finally bowed to my newly found knowledge. Only thing that would have made it better if he was an a$$, but normally he's a nice guy, so didn't want to "rub it in" too much! *G*
THX for the brownie points!!! ...Mark

 

[shopper1732]

Maybe someone will add some discussion here as to why some gates are standard and other full.
Seems to me that probably they both have same bodies whether cast or forged, same bonnets, stems, packing ... whatever.

Also, are ports same size among all manufactured brands as per API, ASME standards?

I can see that full would have slightly enlarged bore, but am not sure if the pre-machined disc blank could not be the same part for both port types.

So, what is the basic advantage of buying standard rather than full port valve? Can whatever cost savings for standard ports be really significant?

Another question:
Please compare the Classes such as 150, 300, 600, 800, 900, 1500, 2500, 4500 as opposed to ANSI Classes such as 1690, 2680, and 4350. (Of course, pressures would be temperature dependant for any material) but what engendered such oddly numbered classes? They do not seem to have an evenly numbered metric correlation. So, is it some historical consideration associated with a particular industry?

 

[NozzleTwister]

shopper1732,

Refer to the following standards for the minimum port openings allowed:

For valves manufactured to API 600 (generally cast valves, flanged and butt-weld, like is made by Crane Valve)
API 600, Sect. 5.3.3.1, Table 4, Minimum Port Diameters.

For valves manufactured to ANSI/API 602 (generally small forged valves, threaded, socket-weld and flanged, like is made by Vogt)
ANSI/API 602, Sect. 5.2, Table 1, Minimum Diameter of Equivalent Flow Passageway.

Generally, for forged valves per API 602, a standard port is a reduced port. As well as system block valves, these valves also include vents, drains and instrument connections. As far as system block valves are concerned, they are usually 2" and below for forged and for pipe sizes this small, pressure drop is usually not a problem. And yes, cost is a big factor; a forged full port valve body is the body for the next valve size up. The valve weight and cost can be double or triple.

For cast valves per API 600, the minimum port allowed is considered to be full port.

Note that 'full port' really means 'considered as full port for flow calculations'. Full port does not mean full size un-obstructed bore. Although the minimum bores are established in the standards noted above, the actual bore diameter will vary from manufacturer to manufacturer.

If you need a straight through bore of a certain diameter (for hot-tapping for example) you need to be specific about that in your purchase specifications and verify that on your approval and certified drawings. Don't trust catalog info, some major valve companies contract with valve manufacturers all over the world so the valve you get might not match the one shown in the catalog but it should meet all of the standards and specifications.

I hope this helps


NozzleTwister
Houston, Texas

 

[IVNJ]

.... While I have over 25 years in the valve distribution industry, I would never consider myself an expert. My experience is that even when a manufacturer presents the valve as "full port" it may not be suitable for hot-tap applications. In the wedge style gate valve, the seat rings are angled to match the wedge disc. While the outside edge of the seat ring may match the "full bore" of the valve body, the lower inside mating surface of the seat is may protrude into the flow path. Using a full bore tap will damage this lower portion of the seat ring, and compromise the sealing surface between the wedge and seat.
That is not much of a technical description, but I hope you get the picture. I have also seen valves with a screwed-in seat ring, with lugs protruding into the bore. When in doubt, insist the valves be examined by a reputable valve service facility - this precaution up front will save a lot of headaches later.

 

[mizzoueng]

I always thought gates were full port. But then I always bought the flanged cast iron gates mainly in the 4" and larger range. But it is always good to mention to the supplier that this valve is for a hot tap.

Also, the take-off for a gate valve can be considerably less than a ball valve when you are talking in the 4" range. And with a threaded valve, you run the risk of someone unsrcewing the valve from the main while trying to take the hot-tapper apart.

 

[Ashereng]

mizzoueng,

You are not alone. We here have also thought that.

I guess that's why I participate in Eng-Tips.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?