Why so convoluted? Nylon will absorb water and swell. If you must use plastic parts, select a plastic with greater dimensional stability in submerged service. Also, the plastic may creep, resulting in lessening torque over time. Not saying that plastic is a bad idea, but check the properties of the parts you will use to verify. Also, using a brass fastener in a stainless nut will introduce dissimilar metal corrosion. An alternate idea is to use fasteners with good corrosion resistance (i.e. type 316 stainless), and protect them with a combination of corrosion inhibiting thread lubricants, and anodic protection (zincs). Also, welding is never a great idea if it can be easily avoided - particularly with dissimilar alloys, and if the tab is thick enough, a better idea might be to tap it for Helicoil inserts and eliminate the nut entirely.
-Sean
On Jan 22, 2009, ShellyDalg@aol.com wrote:
Brent and I were having a short discussion about rust, and I made a little sketch of a fastener set-up I'll be using in a particular area that should help reduce the expected corrosion, and aid in maintenance. So I thought I'd post it under a new subject line. Anyway, the reason for this particular set-up is that the fairing mounts are tucked into an area that will be impossible to reach from both sides, so the stainless nuts are welded onto the tabs, and the nylon bushing will give me the ability to cut off the head on the brass bolt if it gets corroded/stuck. Because the brass bolt is soft, I will be able to drill it out easily without destroying the stainless nuts. The fairing is made of 3/8 fiberglass, and the nylon bushing will help protect it from minor bumps, while keeping corrosion of the brass bolt to a minimum.I have several different places where I'll be using nylon washers and bushings. The washers and bushings will be carried as spares for field maintenance in remote locations.Here's the sketch.....I'd be very interested in any comments you guys may have, and would love to see/hear of any other ideas on how to prevent corrosion on our subs. Frank D.
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