Methods for fastening aluminum deck-house to steel deck

A place to exchanges questions and ideas of a technical / procedural nature. Go ahead, try to stomp us !
User avatar
Sprocket
Bilge Dweller
Posts: 7
Joined: Mon Mar 03, 2008 10:22 am

Methods for fastening aluminum deck-house to steel deck

Postby Sprocket » Sat Mar 15, 2008 7:42 am

Hello everyone, I am currently working on the 2nd class naval architecture and need some help with a question. what are the methods employed to fasten aluminum to steel and what can be done to mitigate the corrosion problems. I'm not sure but i believe riveting may be used. Any help is aprreciated, thanks......................Sprocket

User avatar
Sébastien
Engineering Mentor
Posts: 97
Joined: Mon Oct 01, 2007 5:06 am
Currently located: Québec

Postby Sébastien » Sat Mar 15, 2008 10:49 am

Hi Sprocket, Reed's volume five (fifth ed) fig 12.7 is the good old fashioned way. Basically a bolt that is completely insulated with various non metallic (Neoprene) materials such as ferrules, gaskets and silicone; this is necessary to prevent galvanic action. The high tech way is with a structural adaptor that has an upper layer of aluminium and a lower layer of steel and the plates are simply welded to the adaptor in the usual way. You can check out this method at www.triclad.com Good luck

User avatar
JK
Enduring Contributor
Posts: 2678
Joined: Tue Sep 04, 2007 2:29 am
Currently located: East Coast, Canada

Postby JK » Sat Mar 15, 2008 12:03 pm

The explosion bond seam must be installed high enough in the structure that SW does not lay against it at deck level. You will get electrolysis and it is expensive to repair. So you would have a section of say 8" of steel deckhouse, then the transition to aluminum.

The riveted seam in fitted in older ships as Sebastien says and is problematic in that the neoprene insolator begins to fail after a number of years leading to leakage and corrosion problems. It is a PITA to renew in failed areas as it has to be wedged apart to allow cropping and welding of the new sections of aluminum and steel in, installation of the new insulator material and then re-rivetting. Of course this is after you strip out all the joiner bulkheads and insulation if whatever space in the accomodations that the seam has failed in. (Praying fervently that you do not discover asbestos) . If you have leakage behind the Joiner bulkheads, it will go under the deck underlay and cause deck and bulkhead corrosion. (Guess what I am repairing :roll: ).

User avatar
Sprocket
Bilge Dweller
Posts: 7
Joined: Mon Mar 03, 2008 10:22 am

Postby Sprocket » Tue Mar 18, 2008 5:36 pm

Thanks for the info. guys. Figured the old fashioned way of nuts, bolts, rivets was a given, the explosion bond process is what I was looking for, the triclad stuff is pretty cool. Are you using that stuff in your repair job JK. :roll: Betcha that stuff is expensive.

Regards..................Sprocket

User avatar
JK
Enduring Contributor
Posts: 2678
Joined: Tue Sep 04, 2007 2:29 am
Currently located: East Coast, Canada

Postby JK » Wed Mar 19, 2008 12:30 am

I am repairing the rivetted seam. Anything steel on the aluminum deck I use explosive bond pads under.


Return to “The Workshop”

Who is online

Users browsing this forum: No registered users and 1 guest