DIY Home Improvement, Remodeling & Repair Forum > DIY Home Improvement > Roofing and Siding > Galvanic corrosion




Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old 01-20-2014, 04:38 AM  
suobs
SuperMember
 
Join Date: Dec 2011
Location: West Palm Beach, South Florida
Posts: 18
Liked 1 Times on 1 Posts

Default Galvanic corrosion

I always thought aluminum and galvanized steel should not be in contact (e.g., galvanized nails in aluminum flashing), but the galvanic action table in the Florida code has them right next to each other (at least Aluminum 1100 whatever that is is next to galvanized):

http://publicecodes.cyberregs.com/st/fl/st/b1400v07/st_fl_st_b1400v07_ras111_sec004.htm



__________________
suobs is offline  
 
Reply With Quote Quick reply to this message
Old 01-20-2014, 06:06 AM  
oldognewtrick
Moderator
HRT_MODERATOR.png
 
oldognewtrick's Avatar
 
Join Date: Jul 2009
Location: Nashville, TN
Posts: 5,413
Liked 459 Times on 382 Posts
Likes Given: 146

Default

Galvanized nails and aluminum flashing are perfectly acceptable and used all the time in roofing. You run into problems where you use galvanized nails and copper flashing.

__________________
oldognewtrick is offline  
 
Reply With Quote Quick reply to this message
Old 01-20-2014, 10:54 AM  
Wuzzat?
Banned
 
Join Date: Jan 2010
Posts: 2,328
Liked 167 Times on 154 Posts
Likes Given: 94

Default

Quote:
Originally Posted by suobs View Post
but the galvanic action table in the Florida code has them right next to each other
Which means there will be little potential difference which means one is less likely to corrode.
I had another anodic series that showed the mV between metals; you could do <50 mV in humid environments (so you could have
Zinc, wrought; zinc-base die-casting alloys; zinc plated
-1.25v
Magnesium & magnesium-base alloys, cast or wrought
-1.75v
touching each other) and <150 mV in dry environments.

That's interesting about the water flow in your link since fresh water is not a very good conductor. Perhaps rain runoff from surfaces is more conductive.

I couldn't find mine but here's one from Wikipedia

Anodic index
Metal
Index (V)

Most Cathodic
Gold, solid and plated, Gold-platinum alloy
-0.00
Rhodium plated on silver-plated copper
-0.05
Silver, solid or plated; monel metal. High nickel-copper alloys
-0.15
Nickel, solid or plated, titanium an s alloys, Monel
-0.30
Copper, solid or plated; low brasses or bronzes; silver solder; German silvery high copper-nickel alloys; nickel-chromium alloys
-0.35
Brass and bronzes
-0.40
High brasses and bronzes
-0.45
18% chromium type corrosion-resistant steels
-0.50
Chromium plated; tin plated; 12% chromium type corrosion-resistant steels
-0.60
Tin-plate; tin-lead solder
-0.65
Lead, solid or plated; high lead alloys
-0.70
2000 series wrought aluminum
-0.75
Iron, wrought, gray or malleable, plain carbon and low alloy steels
-0.85
Aluminum, wrought alloys other than 2000 series aluminum, cast alloys of the silicon type
-0.90
Aluminum, cast alloys other than silicon type, cadmium, plated and chromate
-0.95
Hot-dip-zinc plate; galvanized steel
-1.20
Zinc, wrought; zinc-base die-casting alloys; zinc plated
-1.25
Magnesium & magnesium-base alloys, cast or wrought
-1.75
Beryllium
-1.85
Most Anodic
__________________

Last edited by Wuzzat?; 01-20-2014 at 06:25 PM.
Wuzzat? is offline  
 
Reply With Quote Quick reply to this message
Reply


Quick Reply
Message:
Options

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter DIY Home Repair Forum Replies Last Post
corrosion of deck hardware ham385 Decks & Patios 1 05-15-2011 07:17 PM
bubble type corrosion on outside of clawfoot tub csweihe Plumbing Forum 1 08-26-2009 09:09 PM
2000 Flushes corrosion/CA steveellman Plumbing Forum 2 08-26-2009 12:28 PM
Corrosion in Toliet TxBuilder General Home Improvement Discussion 2 05-21-2006 08:41 PM