Which Valve Must Be Used in Which Line in Piping Systems?

There are references, guides and specifications, all available by searching the web.

There are 11,800,000 results when one searches for "choosing piping valves".

Here's one. Guide to Selecting Control Valves | Piping / Pumping ...

I trust that you can, somehow, manage to find some more on your own.

God help us.

The end client's Piping Standard will give full details of the valves, flanges, piping and supports to be specified. It is simply a matter of referencing these on the call-off sheet. There may even be a dataabase that gives these particular valves and fittings as referenced from the Standard and the call-off sheet may even be a Report function from the database. It may even give the insulation standard and the insulation finish required for that particular line.

The reference number of the standard to be used for any particular pipeline will be part of the line number given on the "for construction" P&ID.

Hossein,

First, If you are a properly qualified and experienced Piping Material Engineer (PME) then you are supposed to know all of this. If you are a PME and you don't know all this then do as the others below have suggested.

If you are a piping layout designer or in any other position and not the PME for the job then you need to look at the P&ID (Piping & Instrument Diagram) which is required to show all valves (except high point vents and low point drains) by type and schematic location.

Hello dear friend

At first i must thank you and any guys in this site for helping me improving my knowledge.then accept my appologize if i have problem in my english.

I'm a quality control inspector ,maybe i didn't ask my question clearly.i should say that i know about P&ID and i can undrestand it.but my question is the person who design P&ID how does he recognize which valve for which line and position must use?for example if you want to write wps you must consider the material,welding equipment,expenses,and so on.....etc. Now what's the aspects for choosing valves?

Hossein...

I have a question relating to the always sound advice of PennPiper...

Are you a new engineer, recently hired ?

Do you have access to up-to-date PIDS for the plant systems ?

Were they somehow discarded by a previous owner of the plant ?

Do you have access to the "Piping Specifications" originally used to construct the plant ?

Has much of this crucial information been discarded by new plant management with the hopes and clear intention of "dumping things" on the new plant hire ???

Hello dear friend

At first i must thank you for helping me improving my knowledge.then accept my apologize if i have problem in my ENGLISH.

I'm a quality control inspector ,maybe i didn't ask my question clearly.i should say that i know about P&ID and i can understand it.but my question is the person who design P&ID how does he recognize which valve for which line and position must use?for example if you want to write WPS ,you must consider the material,welding equipment,expenses,and so on.....etc. Now what's the aspects for choosing valves?

Depends on the fluids and size range you're considering, but a few general rules are -

Gate - OK for isolation, should not be used for throttling, due to gate chatter. If automated, pneumatic actuator linear, electric multi-turn (more expensive than 1/4 turn)

Globe - OK for isolation or throttling/control. Multi-turn. Expensive in larger sizes.

Butterfly - OK for isolation or throttling/control, on gases or clean liquids. Not good if solids present, specially if stringy as eg in sewage. Economical, specially in larger sizes. 1/4 turn. Various configurations, wafer, lugged wafer, flanged etc.

Ball - OK for isolation. Expensive in larger sizes. 1/4 turn. Can throttle but better options for this.

Eccentric plug - OK for isolation or throttling/control, and can handle solids. 1/4 turn.

Some of the above give tighter shut-off than others, which might need to be considered. In some cases more than one type of valve might be suitable, and it comes down to cost. That's a brief overview, there are several other types out there.

more homework?

In general you use a gate valve when you want low flow loss through the piping system. On a steam ship the seawater injection piping to the condenser will need a very low flow loss since the at fairly low speeds, the delta p from condenser inlet to outlet is likely to be low. You do not want the inlet and outlet isolation valves to impede the seawater flow. Main steam isolation valves are likely to be gate valves. They are only operated under high pressure during an emergency. You need low losses in operation. A small globe valve is installed to allow gradual pressure equalization across the gate during line warm-up and when ready to use the main steam engine.

You use a globe valve when you want to be able to operate the valve against pressure or to throttle the flow. Throttling the flow will create a large delta p across the valve. This is OK as the design of the globe valve reduces the damage caused by the delta p.

The large delta p across a gate valve is likely to damage the gate and the seat. As the gate opens or closes the rapid flow around the gate will likely cause the gate to chatter or pound against the seat, causing damage. When the gate is almost fully seated, there will be high velocity flow and turbulence which can erode the mating surfaces and cause leaks. Additionally, the high delta p may cause the gate to bind or gall against the seat as the force of the fluid pushes the gate against the seat and the gate attempts to slide against the seat.

An examination of an actual valve would help you to see how these effects are likely to arise.

Google "Johnson Controls Valve regulator theory". They are a good placed to see some drawings.