Valve Stem Material

[asfarali]

Hi in one of the projects, the required material for Valve stem is A182 F316L, but the supplier has provided 2 options
1. AISI 4140
2. A182 F316,

Considering following design criteria, which one can be accepted.
1. Design Pressure - 63.5 Barg
2. Design temperature - 5 to 85 Deg Celcius

 

[gerhardl]

This has less to do with an engineering material evaluation, than what rules and regulations/specifications have to be covered for the piping project.

Only if the parties involved, including inspecting authorities,agrees that a material exception can be accepted, a deviation in material can be considered.

More information is needed for the engineering evaluation part.

 

[reverman]

I would recommend asking the customer to accept F316 in place of F316L. This will most likely be accepted.

 

[asfarali]

Thanks for your post guys.

Gerhardl - The issue is that client is asking us to decide which material to accept and the justification for its acceptance. So i request you to help me in this regard. Kindly let me know what details you need in this regard. Or if any one can suggest me a good link regarding valve design.

 

[gerhardl]

Thought it was somthing like that. and agree with reverman, but check origin and cause for the selection of the original spec!

 

[MickMc]

asfarali,

For link try wermac.org (world of piping) which has good info on valve design but won't answer your question.

In my experience both forged valve body and trim where specified for this grade of stainless steel are A182 F316 unless their are weldability issues.

 

[reverman]

The only advantage I see of using 316L over 316 would be if you are welding on it. It's unlikely anybody will be welding something to the valve stem. Don't know what type of valve we are discussing but most valves don't have much reason to be welding on the valve stem. If was a valve body then this would be a bigger concern since its' much more likely a valve body will be welded on (either welded in line or have attachment welds)

F316 and F316L are chemically identical except for maximum allowable carbon content. Mechanically F316 is a little higher minimum values for yield and tensile strength than F316L which for a stem is a good thing.

Also go back to the forge stem supplier. It's fairly common for F316 forgings to be dual certified F316/F316L. If they can do that then this becomes a non-issue

 

[asfarali]

Thank you guys for your post

Revermann - yes they are supplying with dual certification. so I am going ahead with that.

 

[jbeckhou]

Question. Are there threads on the stem? If so, what type of material is the gate made from?

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