Join Date: Jun 2006
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Best suggestion for a gasketing material to separate steel and aluminum?
Yesterday, after several dozen hours of reciprocating saw work and about ten blades, I finally disconnected my aluminum pilothouse roof from the steel flange to which it was glued and bolted.
I did this to allow the removal of the engine, batteries and old tankage from my engine bay.
The job was considerably complicated not by the 40 or so bolts used (although a few of them had corroded in place), but by the use of a thick bead of 5200 sealant used to make the job what I guess was supposed to be "bulletproof".
Anyway, here's my plan for when I restore the aluminum roof.
1) Clean every trace of 5200 from the roof and from the inward facing, 5 inch wide steel flange.
2) Grind the flange top fair and rust free. Tape the flange edges in preparation for painting.
3) Prime the flange with two coats of Metal Prep.
4) Paint the flange with two coats of two-part epoxy paint, the same colour as the rest of the deck.
5) Place a rubber or rubber-like gasketing material in a 4 inch wide strip along the entire top of the flange (about 25 feet all the way around). Drill holes at the appropriate spots through the rubber. The purpose of this strip (1/8" thick) is to provide a compressible, flexible barrier to galvanic corrosion or interaction between the dissimilar metals, both of which will be carrying electrical wires for lighting and/or instruments. Most of my sawing was through "welds" formed by aluminum being bolted to steel. Never again!
6) Lay a bead of NON-tenacious sealant (like 4200 or 231 or even some kind of exterior silicone) on either side of the rubber gasket strip. This is to prevent water ingress from the outside, and condensation from the inside.
7) Bolt together with Tuf-gel or some other appropriate substance to allow corrosion-free fastening with the prospect of an easy removal in the future, if necessary.
My question is with the gasketing material.
What should I choose?
I can cut strips of neoprene or even the less gooey sort of butyl tape. I could use some sort of plastic batten or sheeting, but I suspect that would grow brittle over time (this roof gets warm in the sunshine).
Any suggestions, sources and prices? Thanks in advance to the bedding and sealing gurus!
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