Gasket Material

I have never heard of Brinell Hardenss so I googled it and not that I trust wikipedia, but they say mild steel is 120 BHN or HB. Copper is 35. So if your seal is rated at a max of 90 it should not damage the face of your flange. I would guess that the stainless steel gasket is designed for contact with a stainless steel surface instead of mild steel. You might treat the surface with a film or paste compatable with the product in your pipe to ensure a good tight seal.

Good luck

Drew

I have a hard time believing you will get a 316 ring with max 90 Brinell - that is soft iron territory (B16.20 states a maximum of 160 Brinell) Are you mixing up Brinell and Rockwell 'B'?

You definitely want to avoid using a gasket of a harder material - the purpose/theory of gasketed joints is that you want the GASKET to deform and affect a seal. If the ring is harder than the flange - then the groove with deform - you don't really want that - after a number of times, especially if overtightened, the ring groove with be so bad that you need to repair it - I have done that a number of times on vessels ... weld build up and portable machine.

Thanks all!

I told this problem with our technical consultant. He said: they use an stainless steel sheet which shape is similar with groove of the flange will be inlaid (installed) in this groove. So they can use stainless steel gasket without deform carbon steel groove (of this flange). It is too complicate, isn't it. We have to use 3 items: flange, the SS sheet, gasket...for one joint.

1. How does it help?

2. As the guest pointed out (not this one the other one ) you may not get a 90BHN stainless steel. The value is wrong and if you do manage to get it , it is any way much too softer than the carbon steel.

Dcongvt is probably mistaken about the ring's hardness. It's likely in the region of 160HB. However, the CS flange at 180HB is still harder.

Here's a link that might prove useful in this exercise :

http://teadit-na.com/catalog/index.php?main_page=product_info&cPath=5_24&products_id=71

Please keep us posted about what else your technical specialist is recommending!

SS gasket as per referred chart SS316 has a max BHN of 160 BHN (in other specs it mentions as approximate).

The CS Flange too will have typical hardness from 150 to 200 (approximately- by memory, not confirmed)

Thus the hardness span may make the gasket either softer or harder than the flange.

The other problem is the galvanic corrossion, since they are a bit away on the corrossion chart. (even more if the SS is passive)

may be the consultant is using the ss sheet as the sacrificial and not for the hardness purpose.

You may consider F5 gasket (5Cr-0.5Mo) whose hardness is <130 BHN.

Or even a soft iron gasket with the SS Sheet taking care of the galvanic corrossion.

http://www.foundry-sag.com/irons_tables.aspx (Sorry! Link no longer available.)
http://steel.keytometals.com/Articles/Art98.htm (Sorry! Link no longer available.)
Dear all!
I 've already found out that Gasket hardness is max 160HB, cast carbon steel hardness is max 120~160HB (low carbon steel) and 180~220HB (high carbon steel). So we can use the SS Gasket in this situation.

There are some thing conflict:

1. My fellow want to use this type of gasket base on his experience ( he showed me a document, which tells ring metal gasket hardness is max 90HB).
2. Specialist said it is ok. Don't worry about it ( he didn't tell me galvanize corrrosion problem) .
3. I wonder: #900 valve Working Pressure appx. 1500psi, Working Temp. app 100 degree F, service is sea water , so he must use the SS gastket ??

This just keeps getting better and better ................... Why the $^%^#!~!!!! are you putting a 316 gasket in a cast iron groove in seawater?!?!?!!?

(I think your "Specialist" needs to specialize in something else)

The guest is right (the above one)

You want to put A216 WCB in sea water service . Forget about the gasket.

For sea water application you have special stainless steels available (and in olded days cast Iron, but cast steel ? )

http://www.copper.org/applications/cuni/txt_sea_water_system_design.html

Hope it helps

False

go for copper gasket of 5 mm thk, u can cut it from plate