Needle valves vs ball valves in sub-sea control system

[mustafa2014]

Dear sirs, Good day,

we are doing a sub-sea project. our company requirements in feed phase to use a needle valve in sub-sea control system.the contractor proposed ball instead of needle.

My question is which better using needle valve or ball valve in sub-sea hydraulic system, what is the main points shall be considered in the selection.
the place of the valves as attached.


Please your feed back highly appreciated

 

[gerhardl]

If the contractor proposes ball-valves he does so for a reason: experience, cost or anything else. If you propose a different solution it has also a reason. It is impossible for anyone without a very detailed information to decide what is 'best': you actually have to sort this out between yourself and the contractor.

Note: high-quality ball-valves is commonly and often used for high-pressure full-flow solutions, needle valves might possibly restrict the flow and increase particle assembly in unwanted locations, stem, seat and others.

 

[LittleInch]

These all look like isolation valves. A such ball valves would seem very suitable, especially if your going to make them ROV operated.

Needle valves are more commonly used where control of flow or start stop occurs with flowing liquid. Difficult to know why needle was proposed first.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.