[PDF] RE: Galvanic Reaction Chart

If you insulate the two different metals whit an inert plate of say nylon plastic it should eliminate the problem completely. Most of my experience is in harsh saltwater but I do have experience with a steel hulled Criss Craft Roamer out of South Shore Yacht Club in Milwaukee Wisconsin. Isolation with either plastics, plating or good coatings of paint or a like has proven to work extremely well in Lake Michigan.

hi

304 is probably not the first choice for underwater 316 would be better but more expensive. anyway SKF builds some stainless series of berrings that will work underwater with a grease backup.

Make a phone call down to Jefferson Beach Marina at 9 Mile Rd. and see what they recommend. They deal with this problem all the time.

24400 Jefferson Ave ·

• Saint Clair Shores
  
• (586) 778-7600
• 
  Purchase 8-12" long 304 SS round Bar stock from Alro Steel @ 3" Dia. Cut to length, Bore a center hole at the desired O.D. bearing size less -.003". Press new bearings in place. Detroit Ball Bearing would be a good local resource..

• Detroit Ball Bearing

• (586) 978-7400
• 35430 Beattie Dr
• Sterling Heights, MI 48312

Alro Steel, Jackson Mi.

Link http://www.alro.com/DATACatalog/CatalogPages/009-Stainless.pdf#page=14

• Call these three locations and add up your costs. $250.00 maybe a good price, just thinking...
• Regards, Tim

The price of $250 would be fine if made to last (from stainless), to pay that for a-36 steel is just wrong!!!

Thanks for the info, I already have my pricing from Alro, that's where we buy most of our steel.

As far as the roller design, I need a good way to make a 4" roller, put bearings that will handle up to a 10,000# load at very low speed, weld the 3/8" plates on each side (held by a piece of angle iron between them) and have grease zirks on each end. I got the idea of boring the roller and pressing in the bearings but how do I keep access to it with grease and sealed?

Use 316 SS shafts put notch lock plates on each end . Fit in 316 SS pipe of required strength with solid bronze internal bearings, ideal for slow heavy loads, fit double lip shaft seals on each end of pipe roller housing use grease Zerk's to grease down center hole to completely pack with an appropriate grease till bearing is completely full. This will outlast your steel frame which should ideally be galvanised.

Fairly expensive material cost but would be cheap in the long term.

I am in complete agreement with Rorschach! I am not sure what you are doing with the stainless and the Mild, but you do not want them to touch in any way. Especially DO NOT weld them. You will rust worse than you can imagine.

I also agree with the responder(s) who urge to go to 316. I would if it was my project...

Finally, in a wet environment I would also skip the greased ball bearing. If you are going to put in a ball bearing, make sure it is a good double-sealed unit, and put it in there forever. If you find a cheap source (often in the <$25 range), you can replace them when they do give up, but they won't last for crap once you allow greasing. Even well trained maintenance men over-grease Zerk's and blow out the seals, surely these weekend putterers will blow them out the first week they are installed, and the bearings will be shot in a year! A better bet is the suggested oilite bushing. It will require nothing over it's life (centuries given their use), It will always remain free, and it will have a HUGE load capacity. Press in a $1 oilite bushing and forget it forever.

Another completely viable option may be a Nylon or UHMW roller with a stainless shaft trough a hole bored in it. It does not need any sort of a bearing, will also have a huge load rating, and will NEVER rust (plastic can't rust). Add that to an extremely favorable cost (as compared to 316 stainless), as well as lack of need for a separate bearing, and you have a winner all the way around.

Best of luck.

A lot of this has to do with environment. Which we cannot control. Go back and read my first post. You must have all three conditions present to have galvanic corrosion that could be a problem. They may or may not exist here. Obviously, a boat house will be damp, so it is up to the OP to decide what course to take.

And I take exception to " but you do not want them to touch in any way. Especially DO NOT weld them. You will rust worse than you can imagine." Once again, it is totally dependent on the environment.

I have welded MS to SS numeruos times, using MS wire I might add, and the rusting you describe DOES NOT OCCUR. These pieces are outdoors 24/7/365.

Cheers.

Could you incorporate "bearing buddies" into your design?

Check out this link.They have maintenance free bearings for underwater and hostile environments.

http://www.ggbearings.com/

HTRN