Some simple questions from a guy with little valve experience

[norwegianstuff]

I have been tasked with compiling travelling times for hundreds of valves. I am doing this by first finding the size of all these valves and have understood that it is the nominal size that typically correlates with travel time. Documentation is severely lacking so I must use this strategy.

My confusion comes from some terminology of dimensions I've encountered on design data sheets of the valves.

1) Is it correct that nominal size, nominal bore, and body size are interchangeable?

2) When body size is listed (e.g. 4") is it safe to assume this is a nominal size as well?

3) Many data sheets list only ID and OD (diameters), how can I convert this to a nominal size? I understand NPS conversion applies only on OD, but this doesn't seem intuitive to me as these different valve types have wildly varying thickness. Is regular nominal valve size taken from the OD?

4) Connection size is also sometimes a listed specification. I would think this is also interchangeable with nominal size but they always appear unusually small (e.g. 1/4" for a control valve). This connection size is listed under the "body" subheading, not the actuator. Any ideas?

I'm new to the job and finding it pretty hard to find good resources/references so I would greatly appreciate any help
Cheers!

 

[LittleInch]

It can be quite fun. I assume you mean actuated valves as manual valves are different. Pressure rating can also have an impact as can their use. ESD valves tend to close faster than isolation valves and if the actuator is electric, they can sometimes be restricted by the power available.

1) Yes, but beware that some valves have reduced bore compared to their connection sizes, especially ball and control valves so you can get for instance an 8 x 6 RB where the bore inside the valve is 6 inch, but it connects to an 8" pipe.

2) See above, mostly yes, but not always, especially with ball valves and control valves

3) OD is the fixed size, but below 12" is not the same as the nominal size, i.e. 10" is actually 10.75" OD, 8", 8.625 etc - look up a pipe code chart on google and you'll see what I mean.

4) The connections for actuators will normally refer to the control lines and pneumatic or hydraulic lines used to power the thing. Either that or if included in the body they are other lines such as vents, drains or grease lines and nothing to do with the size.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[norwegianstuff]

Thank you for your reply LittleInch, it cleared up a lot!

1) In the case of a reduced bore, is nominal size still taken relative to the OD?

4) To give a bit more context, I found an example of the datasheets we use on the net if you'd care to take a look
Link

On page 45 is a data sheet for a control valve. Under the "Body" subheading it lists "Conn. size/type proc" which I take to mean connection size to process. Typically has values such as 1/2" NPT or 1/4" NPT. Is there no chance this refers to the end connections and correlates to nominal size? And if not, is there any specification on here that could help me?

Again, thank you so much for your help

 

[LittleInch]

1) Yes, it's always relative to OD as this is the constant for steel and plastic pipe. Id changes due to wall thickness not the other way around. GRE pipe is sometimes the other way around as the y make it around a fixed ID pipe, but ignore that for the time being....

4) These are the instrument data sheets and at those sizes they may be either the regualtors used for low flow air or gas. The process data sheets are the ones giving you the connection details. to be honest I've seen better data sheets and normally you would expect a single data sheet which combines both.

Haven't you got a valve schedule for this plant?, or a P & ID?

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[norwegianstuff]

We do have process data sheets as well but I can't find the template. They are very similar; there are some differences but they both have GENERAL and BODY section with pretty much the same specifications. But as far as I understand they're both referring to the the valve itself. The same valve tag number is listed on the top for both. In this context, what is the meaning of "Conn. size/type proc" if not connection size to process?

I do have P&IDs for most of these systems, but quite a few are missing, and some have no indication of line sizes on pipes at all. I'm still learning how to interpret them but I'll have another look tomorrow to see if I can gather anything.

 

[racookpe1978]

Get out of your office, get out of your chair, get off of your b^tt and go ask several people in the field before you keep asking questions on-line.

You don't know enough (yet) to know what to ask next (yet)! You're trainable - and that's excellent. You're asking questions - and that's a good start - BUT you're asking questions on-line to people NOT at your plant and NOT in your company and NOT familiar with the "obvious" terms and abbreviations that have been used at your plant since the 1920 or 1930's ....

First.
Go track down and FIND in your plant 6 or 8 of the actuator-closed valves you are analyzing WITH a field tech WITH you for guidance and assistance/safety. Read the nameplate data and compare it to the list you have. Find out what the actual operating times are. What the actual operators are (manual, electric, hydraulic, etc,)

Learn some more basics about pipe sizes and valve id's.