Nylon fittings

[Roger Long]

Back before I knew better, I used white nylon hardware store fittings on the hand pump out line for my holding tank. The seacock is normally closed and there is no standing pressure on these fittings but I'm sure some, uhm, water, sits in there.

Rich H pointed out that nylon weakens with water absorbtion. I have no doubt this is true but am unsure about the extent. Breakage would lead to me pumping the tank into the bilge instead of overboard. Do you think I should replace these fittings?

Picture here:

http://home.roadrunner.com/~rlma/Strider06work.htm#Pumpout

It's primarily the elbow at the bottom of the pump I'm worried about. The others stay pretty dry.

 

[Peggie Hall HeadMistress]

In this case...

If it ain't broke, don't fix it.

Although nylon is highly vulnerable to UV, I'd never heard that it's vulnerable to water absorption. So I'd have a marelon replacement on hand and keep an eye on it. If you see signs of impending failure, replace it.

 

[sailingdog]

I would replace them with Marelon fittings if you can.

 

[Dick McKee]

Roger, are you talkng about fittings above the thru hull? If you are, most newly manufactured boat use nylon fittings in the fresh and salt water plumbing. I had one fail on the hot water side, and have replaced all hot water nylon fittings with brass. That being said, I agree with Peggy, if it isn't esposed ot uv you shouldn't have a worry.

 

[Allan12210]

Marelon = Nylon

Just an FYI, Marelon is a glass reinforced nylon composite. Probably has carbon black in it too which will help improve UV stability. There are many types of nylons, but in general they are only impacted by water exposure at extremely elevated temperatures. That's probably why they have been found acceptable for marine use. The worst thing that would happen is when tightening it to the through hull, don't make it "plumber's tight". You know, tighten till it cracks, then back off a 1/4 turn.