Washers to prevent electrolytic corrosion?

[[3889]]

Is using nylon washers on Monel rivets a viable alternative to Duralac? I'm riveting a stainless fitting to an alloy mast. Do the rivets also need to be isolated from the fitting?

 

[RichardS]

That sounds a bit iffy to me.

The rivet will still be in contact with the mast and the fitting internally and, under the, pressure, I suspect that the nylon will crack after a period of exposure to sunlight and the fitting will then be loose.

Richard

 

[maby]

The nylon will make no difference to corrosion, so leave it out unless it serves a structural purpose in the finished result.

 

[[3889]]

Sorry, didn't point out that I have access to mast interior for 2nd washer. Good point about UV degradation. I ask because I read somewhere that someone used a "plastic milk bottle" gasket for this purpose.

 

[bigwow]

Sorry, didn't point out that I have access to mast interior for 2nd washer. Good point about UV degradation. I ask because I read somewhere that someone used a "plastic milk bottle" gasket for this purpose.

Yep I've used a plastic milk bottle, but still used Duralac on the rivets, plastic is under the fitting so I don't see how it could be affected by UV . Fitting been up there 15yrs and not loose yet:encouragement:

 

[rogerthebodger]

Sorry, didn't point out that I have access to mast interior for 2nd washer. Good point about UV degradation. I ask because I read somewhere that someone used a "plastic milk bottle" gasket for this purpose.

I use HDPE gaskets between any stainless fittings and the aluminium mast with Durlac around the rivets or screws.

Our plastic milk bottles are made from HDPE anyway so it suits me.

If i am fitting something I think I may need to replace I bolt/rivet a stainless plate with HDPE gasket and then screw the fitting to that as even using durlac sometimes it can still be difficult to remove stainless screws/fittings after a long time as I have found to my disgust.

 

[doug748]

As above. Abrade and paint the underside of the stainless fitting or make a gasket and apply Duralac to the whole issue.

Without protection, in the fullness of time, a stainless fitting can make a hole right through the alloy. I have rarely seen problems with monel rivets, even when the barrier treatment has been questionable, use it anyway of course.