Dissimilar Metals and Type 304 SS Corrugated Connectors

[Ed223]

A technical question for you…….

The 304 SS corrugated connectors on the attached specification sheet state “Will not corrode or rust” and “No dielectric union required”.

What prevents corrosion if the hose is connected to copper and/or brass fittings?

 

[Tuttles Revenge]

I didn't know the answer and looked up a couple sources. I also sent an email to the manufacture to see what their response is.

From my reading.. copper and stainless steel should not have direct contact in a water system. I thought the entire flex was stainless so we just went down into the shop and tested the nut on the end of one of our stainless flexes.. They're made of brass which is the part that makes direct contact to the pipe end. The rubber washer isolates the stainless flex part from contact. So that makes them safe for connection to copper, brass and steel commonly used to stub out of water heaters and the piping from the wall.

Below is their response:

Stainless Steel & Brass are Neutral :

When it comes to stainless steel (301, 304 and 310) and brass, they are only two metals apart, which means they can be safely connected together with minimal risk of galvanic corrosion.

Falcon Stainless, Inc.....Where Quality Flows in Your Direction
The Original.... Since 1981
43153 Business Park Dr.
Temecula, CA 92590
800-814-8444 / 818-767-3569
Fax 818-768-8533
www.falconstainless.com

 

[Sponsor]

 

[Terry]

We've been using the stainless steel connectors for brass, galvanized and copper. They always look perfect years later.

 

[John Gayewski]

SS isn't a ferrous metal. My understanding has always been that you would need a ferrous and non ferrous metal to touch to create galvanic corrosion.

That said 304 is more ferrous than 316. In some ultra sensitive situations you would need to step up to 316 stainless. Most situations won't call for this and 316 is more expensive.

If it isn't magnetic than you shouldn't get galvanic corrosion.

 

[Jadnashua]

https://www.fenestration.net/pdf_documents/About-Dissimilar-Metals.pdf?msclkid=72d0e1adc66511eca71105876e39db01

The closer the materials are to each other, the less reaction there will be. The pH of your water will also be a factor in how fast any reaction is. Totally pure water would be neutral (pH=7), but it's unlikely yours is there.