Effect of stainless steel to bronze material 1

[catnawaporn]

Dear all

First of all, I'm sales engineer of knife gate valve trading company and I have some complain from my customer which I need suggestion from you. The complain is that our knife material of knife gate valve is SS316(CF8M) and knife top which use for support knife when it is pressed by load of product in silo is bronze. My customer confuse that if knife and knife top is metal, knife top may is destroyed by knife because knife is harder material. Do you have any advice me to describe about this point to my customer?

 

[tbuelna]

316 cres is not necessarily "harder" than bronze. There are some bronze alloys (such as aluminum bronze) that can achieve very high levels of hardness/strength. To keep your customer happy, you should explain to them that by using a softer material for the less expensive part in your valve design, that part will endure all of the wear, and it will cost less money to repair the valve.

 

[btrueblood]

Also, by using a dissimilar pair of materials, the odds of galling between the two elements is greatly reduced, thus improving the life of the valve.

 

[Jboggs]

Let me understand this. You are selling this product. But you have to go to an online forum to get the answer to why it was designed certain way? Why not go to the people that designed the valve and ask them? Any answer you get here is just a guess.

Could it be because you are trying to copy somebody else's design and you can't ask them? Hmmm...

 

[Ripz]

tbuelna said it perfectly. "by using a softer material for the less expensive part in your valve design, that part will endure all of the wear, and it will cost less money to repair the valve."

The softer material is used in the removable component, i.e. the gate and thus you are able to remove and/or replace if it ever requires it to. This as opposed to the valve body's seat having to be machined which is a very difficult task.

Also, the soft disc is expected to be deformed in order to create the metal to metal seal, similar to the way metal RTJ gaskets are "coined".

 

[IRstuff]

"Why not go to the people that designed the valve and ask them"

I don't know about the OP, but my company certainly has products that were designed in the Dark Ages, and anyone who might have had any inkling of why the design is the way it is, is retired or left or deceased.

TTFN
faq731-376

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[Jboggs]

"anyone who might have had any inkling of why the design is the way it is, is retired or left or deceased."

I understand, but still ... you go to an online forum? OK. Any answer from here is still just a guess.

Plus the best answer to the OP's customers is to simply look at the performance of existing valves. They are either working, or not.