A question about galvanic corrosion

[sfd_656]

I am rebuilding a utility trailer that has a steel frame and an aluminium floor, the steel is freshly painted with tremclad rust paint, the aluminium floor is raw aluminium. Do I need to be concerned with galvanic corrosion or will the paint on the frame be enough to stop the effects?

[nxski]

Many people use raw aluminum roof racks against painted steel roofs so I would assume that should be fine. This also brings up an interesting point that I've been meaning to voice, which is that if galvanic corrosion is such an issue how is it possible that we're driving 20 year old vehicles with Aluminum heads on them and cast iron blocks!?

[403delica]

galvanic corrosion only occurs on untreated exposed metal so in the case of a head and block we have a head gasket separating the two... as far as the trailer i say your good to go... you could by a 2mm rubber sheet and use it as a isolator between bed and frame maybe

[yojimbo]

Yup it occurs between steel and aluminium where they are actually touching and bare.

[legionnair]

Many people use raw aluminum roof racks against painted steel roofs so I would assume that should be fine. This also brings up an interesting point that I've been meaning to voice, which is that if galvanic corrosion is such an issue how is it possible that we're driving 20 year old vehicles with Aluminum heads on them and cast iron blocks!?

This is possible because of the coolant. Take out the coolant and put in straight water it won't last very long

Dustin

[elderberry]

It will also occur with painted materials if your using dissimilar metal mounting hardware, in aviation we use a jointing compound, or a primer on the rivet/fasteners.

The rubber mat or even a good tape between mating surfaces is effective.

[sfd_656]

I decided to use old truck inner tube butchered and laid out on the steel frame. and will use primer on the hardware to attach the floor to the frame.
Thanks

PS a 7'x9' sheet of aluminium is heavy when you are trying to maneuver it and not scratch the paint

[yojimbo]

PS a 7"x9" sheet of aluminium is heavy when you are trying to maneuver it and not scratch the paint

A 7 inch by 9 inch sheet?