I have a corroded fitting on my holding tank vent that I need to identify and replace. Any suggestions please?
Holding tank vent fitting
- Thread starter keithonElan
- Start date
I have a corroded fitting on my holding tank vent that I need to identify and replace. Any suggestions
Previous pic was a crop of this one. I haven’t been able to find this fitting. It would be useful if someone recognizes it. Boat is a 2007 Hunter 33.
Any idea what it does ? Is there another vent on the top of the tank or is this intended to be the one and only vent ? The last thing in the world you want is something venting your holding tank into the interior of your boat.
That's got to be an after market install by a certified nut job.
That's got to be an after market install by a certified nut job.
The pic shows the top of the holding tank and the fitting connected to it. Not shown is a one inch flexible hose that used to lead to the vent on the side of the boat. I’ve had the boat from new when i bought it in 2007.
It looks like there is a threaded boss glued/welded to the tank, with a 90* adaptor screwed into that, and someone screwed a brass hose barb adapter into that. The brass is unsuitable and corroded.
Is that 90* piece plastic or metal? If plastic, then unscrew or pick the remaining brass piece out of it and replace the brass piece with a plastic hose barb adapter.
If the 90* piece is metal, unscrew it from the boss and replace it with plastic.
Mark
Is that 90* piece plastic or metal? If plastic, then unscrew or pick the remaining brass piece out of it and replace the brass piece with a plastic hose barb adapter.
If the 90* piece is metal, unscrew it from the boss and replace it with plastic.
Mark
Thanks Mark. The 90 deg piece is metal and I will replace with plastic. In planning to unscrew what looks like a nylon nut attaching the fitting to the flexible tank, I want to avoid possibly damaging the tank.
It is likely that nylon nut is part of the tank boss itself, and forms the threaded part of the boss fitting. That would be my guess. So you don't want to try to unscrew it. I'd try to unscrew the metal elbow thing out of the nut.
I think first I would try to remove the brass corroded piece from the elbow to get a better idea of what the elbow is made from. The pictures aren't great, but that elbow looks weird being white and oddly chunky.
Mark
Yes, that sounds like a good approach. The brass elbow is inside the white cylinder that should give good leverage. It’s not obvious what purpose the white cylinder serves.
Thanks.
Thanks.
While the term "nylon" was used, the part referred to is (I think) part of the welded tank boss, so is likely polyethylene like the rest of the tank.
Mark
Mark
Thanks Peggie, A reply from Ronco Plastics shows the vent is spin welded to the tank. It’s now clear what’s fixed to the tank I need to remove and replace the 90 deg fitting using one made from the material you mentioned.
The spin welded poly fitting is not too clear in the above photo. Are those pipe threads I see inside the fitting ? Perhaps a clearer picture would help ?
Because male hose fittings are threaded, the female tank fitting must be threaded. And because sanitation system fittings are NPT standard (very slightly tapered--in fact too slightly to see with the naked eye in such a short piece)--be careful not to over-tighten the male hose fitting...over-tightening will crack the female tank fitting...this cannot be repaired...it will have to be replaced with a new spinwelded fitting--which any plastics fabricator can do, but you'd have to take the tank to them and it's money you shouldn't have to spend. Too many boat owners learn this the hard way by trying to stop a leak by continuing to tighten till they hear that little "ping" that's the sound of the female fitting cracking. If it leaks, tighten only a quarter turn at a time till the leak stops.
--Peggie
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Thanks for this important information Peggie. My current concern is undoing the corroded fitting from the vent, without encountering the ping you mention.
I'd use a 90 degree sweep instead of a 90 elbow on a vent line 'cuz ideally vent lines should be as short, straight and rise no more sharply than 45 degrees. I realize that "ideal" is often impossible, but using a sweep will let the tank breathe (which it needs to do to prevent odor out the vent)...an elbow won't.
Ask your local yard what they recommend to use on the corroded fitting to free it up enough to remove it. You may need to let it soak awhile before trying.
--Peggie
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I'm lost here. Maybe I need a little more caffiene in my coffee. Maybe clean my glasses. Maybe I need to go for a walk to clear my head because something just ain't right.
Am correct in saying that the photo in post #14 is NOT your current situation and there is still a corroded fitting stuck in the vent ?
If this is the case, it is highly unlikely you will crack the spin welded fitting on the tank if you are undoing the corroded fitting as you have said in your post #17. Tightening the fitting is what causes the stress which may lead to cracking the welded fitting. If you meet too much resistance in trying to undo the corroded fitting, use a hair dryer on the surrounding plastic to ease the grip on the threads and release it. Maybe wrap cloth around the corroded fitting to insulate it to keep it cooler than the surrounding plastic.
Maybe also try :
........................................ before going the heat route as a last resort. Just be careful the penetrating oil you try doesn't dissolve the threads of the spin welded fitting. Try it elsewhere on the tank.
Just put a wrench on that elbow and unscrew it. Unscrewing can't hurt the female fitting. I see what looks like black sealant under it, so it will probably break loose easily. Don't worry about getting the broken piece out of the elbow - just unscrew the elbow.
Mark
Mark