Large valve rubber lining considerations?

[PersianEng]

I am going to specify Cast Iron butterfly valves (4"-84") on a SS316L piping. In order to avoid galvanic corrosion I have specified all valves to be rubber lined on interior surfaces and flange faces with Neoprene to a thickness of 1/8".
1)Are there any potential problems in rubber lining a flange face?
2)Is it practical to rubber line a 84" buttefly valve body?

Thanks

 

[JimCasey]

Butterfly valves typically use a rubber liner as the seat and stem seal. The liner extends around the face of the body and acts as the line gasket also. If you are planning to take an existing metal butterfly valve and add a third-party coating, the coating will probably interfere with the movement of the vane in positions near closed.

Third-party linings are usually bonded. Manufactured Lined butterfly valves usually have liners that are replaceable. The valve liners are regular consumable service items.

Frequently I see stainless valves used in rubber-lined pipe. This is the first time I have seen someone wanting to rubber line valves in stainless pipe.

 

[PersianEng]

Thanks Jim. Actually, Pipes were decided to be SS316L due to agressive nature of water fed into the treatment plant. On the other hand cast CF3M (316L)valves were estimated two to three times more expensive than cast iron valves. Therefore we ended up using cast iron valves on SS316L pipe.

I know that in joining SS to CI, the valve (CI) will corrode more seriously, since it makes the anode. But how serious the corrosion will be and how fast it will progress is not known.

Majid Javaheri
Hazen and Sawyer, P.C.

http://www.hazenandsawyer.com

 

[hydrae]

In the water works area, Butterfly valves constructed to old (20 years ago) AWWA specifications that were rubber lined have a high failure rate if the lining is not continuously bonded to the metal, some brands constructed using a continious bond others just clamped the ends of the fabric. Normal operation are not a problem, but when the line is refilled after maintenance the high velocity, high dp at high throttle settings would tear the lining. Remember in water works our demanded life expectancy of buried componets is 100 years.

Hydrae

 

[PersianEng]

Thanks hydrae. These valves are not buried though. So based on what you say I should stress on bonding the lining instead of simply clamping it. I guess pretty rough surface of cast iron is a suitable base for making a strong rubber bond.

1)Do you have any information on the bonding method, procedure that is preferable?

2)Can I still consider an individual resilient seat for the valve as the maintenance part in order to avoid lining damage by opening/closing of the valve?

 

[hydrae]

PersianEng

I do not have the details on the manufactoring methods just certain brands (I do not remember which brands) purchased 20 to 30 years ago. The fix is to always refill the line through valves other than older butterflys. Current AWWA valve typically do not have this problem.

Hydrae

 

[joeswoes]

Dear Majid ;

We manufacture rubber lined butterfly valves with fiberglass composite housings, so your galvanic corrosion problems become a mute point.

good luck;

Joe

http://www.pureflex.com

 

[PersianEng]

Thanks everyone for your valuable answers. Actually besides this forum I started a research on the issue and what I got is as follows:
Actually joining a cast iron valve to a stainless steel pipe does not make a serious senario of galvanic corrosion but in order to make some cheap preventing measures, it is worth to electrically insulate the flanges in a joint. This could be done by using full face rubber gaskets, thermoplastic bolt sleeves and dielectric washers under the bolt heads. No electric current across the joint at which nonsimilar materials are present means protection against galvanic corrosion.