globe or plug 4

[flinana]

Easy question for you experts, Is a plug valve a globe valve?

thanks

 

[gerhardl]

The brief answer is no.

Globe valve: A valve where a disc (or for for instance for regulating globe valves a plug) is moved (screwed multiturn, usually) down to close the valve.

A plug valve: a valve where a cylindrical or sligtly cone formed plug with a throughgoing cylindrical opening, is moved 90 degrees on the stem axis to open or close the valve (similar to a ball valve).

I believe the english language itself is contributing to your question. 'Plug' could in some cases cover the description of the form of the 'disc' usually closing a globe valve.

Other languages uses other common group names/partitions between group of valves or description of valve constructions than english. German is often more precise in this matter than english as an example.

 

[flinana]

dann bitte auf Deutsche

Danke

 

[gerhardl]

No problem answering or describing or giving examples in German if you wish, but please first try to expand a bit with details on what your real problem or detailed question is.

 

[flinana]

ok,
I was joking about the German, I am not German but I do speak it.

The question was based on the fact that according to a our isometric dwg the flange to flange distance is 295 mm for a 4" globe valve, however the actual FF distance of the valve 352,5 mm. I attach the drawing of the valve. I understand that the FF distance must be according to ASME B16.10 where there is a difference between globe and plug valve. But after reading your answer it is clear to me that our valve is a globe valve with a plug, but then it does not match ASME.

 

[gerhardl]

OK! Sorry I didn't catch the joke, but then neither English, nor German, is my mother tongue, although I'm catching most of the jokes in both!

Back to your valve.

This seems to be a valve selected or installed for a special application. To select a replacement or another valve with other building length you have to go back to the basic requirements and ask suppliers what they can offer.

If present L-L is too long for a shorter valve an extra spoolpiece or flange will of course solve your problem.

Good luck!

 

[flinana]

My mother tongue is Spanish and English so we can communicate in basically any language.
Back to the valve, what makes you say it is for a special application?

 

[pennpiper]

flinana,
Re: the drawing you posted.
That is NOT a Globe Valve and it is NOT a Plug Valve.

What you are showing is a Control Valve.
It is a Cage Guided, Globe Body, Pneumatic Diaphragm Operated Control Valve.

Your drawing shows lots of technical details but it is still just a Control Valve.

 

[GrimesFrank]

PennPiper,
Globe describes the body flow pattern design, so indeed it is a globe valve. The fact its disc travels in a cage leads you to believe its for 'controlled' movement. I would agree. However usually a 'disc' rather than a 'plug' is used. I don't usually see full isolation capability with a control valve, sister valves usually handle that function.
I believe that it is a globe pattern control valve.

Today is gone. Today was fun.
Tomorrow is another one.
Every day, from here to there,
funny things are everywhere. ~'Dr.' Theodor Geisel

 

[flinana]

pennpiper, it is a control valve. But as far as I know a control valve can be a globe valve. So you think this valve will not properlly control???

 

[pennpiper]

flinana,
Quite the opposite! In fact I think this type of Control Valve is a very good Control Valve.

 

[insult2injury]

flinana, it is common for control valves not to follow the B16.10 Face-to-Face dimensions which has no effect on the operation of the valve.

I2I

 

[flinana]

Now I am lost. You mean control valves do not need to follow B16.10. Isn't that code made for all types of valves?

 

[flinana]

Thanks pennpiper, for your information, this valve is made in INDIA

 

[BillBirch]

Insult2injury is correct. In my experience, we would always base our isometrics on the certified drawings from the selected control valve manufacturers.
Regards,
Bill

 

[flinana]

Problem was that the isometrics were made way before selecting manufacturer.

 

[gerhardl]

Checking status on this thread, I observe two parallell discussions:

1. Semantic / nomenclature, which is always difficult, no 100% facit is worldwide given, but in my experience:

a) A control valve can be of different constructions, and a 'normal' valve can in certain cases be used for control. Beeing a control valve does then in nomenclature not exclude the valve from being called a plug or globe (control) valve.

What is most correct can be a very long discussion. I myself would have used both words: plug control as a brief undetailled description.

b) Most control valves are not constructed for 100% thight closure (as 'Absperrventile'. flinana: this is my attempt at an answering joke in German ; ) !), and one need an added valve in the pipeline for 100% closure.

c) There is several exceptions on b, for instance needle control valves, wich will close 100%.

d) The english 'needle valve' is in itself a good example of an English 'group name' that covers a large group of different constructed valves both in size, construction and purpose, and not very precise. The German name would be 'Ringkolbenventil' translated as 'Ring-piston valve' and describing far better the construction.

2. This is all way out from your real problem:

2.1 What to do when a valve has a longer building length than drawn or planned?

2.2 Don't every valve, even control valves, have to be to a standard building length?

To answer 2-2 first:

aa) Normally standard building lengths is sought to be kept by all producers also for regulating valves, perhaps more regulary now in Europe to EN standards than for US standards in US (I don't really know if the last is true).

bb) There are exceptions, especially for older pattern valves, or newer large valves of special construction. (Could your Indian produced valve be a copy of an earlier, now non-existing pattern from US?)

2-1 What to do:

cc. There might be existing on the market similar valves (check all fluid regulating data!) that will do the job at correct building length.

dd. What does the purchase contract or inquiry say about standards and required information before purchase is valid and supplied valve accepted?

Again: Good luck to you, and thank you, all others, for interesting comments and discussion!