Valve Shaft Material

Just buy a new valve, and be done with it.

AS James stated, stainless is the wrong metal for this application.

In my facility we use lots and lots of steam. Fermentors, Blend tanks, Centrifges, autoclaves, pakaging processes. Valves are a constant source of frustration. Our policy is to replace not repair any steam valve or fitting as you cannot estimate a life expectancy on a repaired part. Too many variables when you have materials of different ages and wear factors. This is very important since a fermentation cannot be "interupted" to replace a valve. If the process is halted we flush the fermentor and that is right around 236,000 USD and then add the cost of restoring, CIP'ing, reloading and restarting the process. Oh, and I still have to buy a new valve.

So as a previous poster has already admonished.... Replace the damn thing and be done with it. ......It will cost far less in the long run. Good luck.

for steam applications over 500 Celsius.

Valve stem material most common used is 1.4122 (X39CrMo17V).

1.4121 ia also good but the other is easyer to machine.

kind regards.

Henk klep (klep is dutch for valve)

If the plant will not operate without one, then how expensive is that <rhetorical question - NNTR>? Do let the original poster know using the internal messaging system.

<unsubscribes>

Me being curious here: what did you determine as the cause for the original valve snapping? Might be there is some other hidden issues that even an original valve would not survive longer than 2 month.

Just saying!

The valve is no longer made anymore it is for a P+T station, Steam goes through it and water comes in from the bottom to control pressure/temp(3 way valve). The internals of the valve are getting eaten away which means the plug is not seated properly which would cause vibration inside. A new system will be installed but they would like to keep this system going for longer as it will require a large downtime which is not planned for as yet.

Photo please?

Phosphor bronze or copper

inconel comes to mind

Thanks guys for the replies, got the weekend off so cant post any photos. Any chance of posting the link for that shaft material selection

I do not advocate patching up anything, but sometimes the demands of production make it a necessity.

First,make sure the valve is calibrated properly,and no "slamming shut" at the end of stroke,causing a shock load on shaft.

Then replace packing with a teflon-based packing material.Your shaft is pitting and causing stress risers and weakness in the shaft.The valve guides are possibly worn also,causing a lateral force on the shaft.This is a likely source of your vibration and root cause of the stress on the shaft.

Stellite is a material that may be more durable,even though it is hard to machine.It is very hard and consequently, somewhat brittle.It is frequently used for valve seats and hard surface applications because of it's wear resistance.

It may endure long enough for a scheduled shutdown, but sometimes, you have to bite the bullet and shut it down and do it right with a total valve replacement,which is my recommendation.

Here is a good reference for valve selection according to application.

A "Valves 101" reference material.

Good luck.

http://www.pacontrol.com/download/Emerson-Control-Valve-HandBook.pdf

316SS is not a good machinable stainless steel, try something with more carbon 303 perhaps. As dvmdsc suggests phosphor bronze may be the best with PTFE gland packing.